# Home Built AC (alternating current) Systems



## aeroscott (Jan 5, 2008)

The motors are rated on the companies own system.millatary motors for instance often are way under rated.So for us take weight of the motor as the rating.


----------



## aeroscott (Jan 5, 2008)

1200 rpm at 60hertz =6 pole armeture,1800 rpm is 4 pole, 3600 rpm =2 pole .most ac ev drives run 4 pole. Some will spin them up over 12000 rpm. that's in the 400 hertz


----------



## Madmac (Mar 14, 2008)

A standard DC motor only needs to drive one coil. A BLDC (brushless DC) or an AC motor need to drive three coils. That means the controller is going to be roughly 3 times as complex.

To chop the drive for a DC motor does not need to be calculated in any way. The relation ship of the 3 drive signals for an AC motor need to be calculated from the current value to increase or decrease speed. 

Madmac


----------



## ecvs (Mar 4, 2008)

Hi xrotary,

I'm the fellow who is involved with the design in yahoo group evcs (electric vehicle control system) open source of information. 
And your talking about the system found in circuitcellar.com 
It is a fairly complicated design that could be scaled down some. I intend to do this in a while. First I'm building a single channel for a DC brushed system.
An Ac system requires approx 3 times the components. This is due to needing to drive 3 seperate coils. A DC brushed system (meaning there will be a comutator and brushes only requires one because the comutator distributes the electrical energy as required to create turning. We only need one channel of energy to supply the motor and it doesn't need timing, again because the commutator does this for us.
With an AC system there are at least 3 coils (you can have more but not likely) These 3 coils need to be driven and the energy has to be timed. The energy will be pulsed at some frequency and be available to each coil based on where the rotary portion of the motor is. Think of it almost like a regular engine that needs firing in a certain order. In an AC system we generally use some sort of feedback to tell us where the rotary section is. These are usually called hall effect transistors that are sensitive to magnets. These are strategically placed on the rotary portion creating feedback pulses that we use with some sort of electronic control (pic microcontroller) that reads the pulses and controls the energy delivered to the coil drives to create the rotary motion. 
Tom


----------



## ngrimm (Oct 19, 2007)

I was thinking that too when I first looked at the Circuit Cellar site but then I thought about a UPS power supply and how complicated they are. And a ups is only single phase. Norm


----------



## xrotaryguy (Jul 26, 2007)

I just noticed that the AC discussion really took off in the other thread. Maybe I should have posted this in there. Oh well.

Let me make sure that I understand what I am reading. An AC motor generally has 3 coils and specific timing is required to either attract or repel these coils at the desired time. This is in contrast to a series wound DC motor where the timing is basically executed by the brushes and the commutators. DC motors generally have static timing, so they tend to work better at specific rpm ,though I have seen some with variable timing, but that is not the norm. Because an AC motor's timing is carried out by a control unit, the timing can be manipulated without the addition of specialized mechanisms being added to the motor itself. I have heard that AC motors, particularly 3-phase motors are more efficient than DC motors. Perhaps the variable timing is responsible for this?

Thanks for the information so far. I will keep researching.


----------



## aeroscott (Jan 5, 2008)

ngrimm said:


> I was thinking that too when I first looked at the Circuit Cellar site but then I thought about a UPS power supply and how complicated they are. And a ups is only single phase. Norm


hi all, the timing for 1 leg is all that's needed the 2nd and 3ed are 1/3 and 2/3 (120 deg and 240 deg) away ,that's a fixed timing. the other timing is variable with speed, the faster you want to the faster the pulses but only one leg is being changed by the active or reactive part of the program .the other 2 legs are just coming on at 120 and 240 deg. later, part of fixed or burned chip. that chip monitors speed or frequency .and changes timing on the throttle (I want to go slower or faster).if we add the svm chip $10.00 it makes sine wave out of all this . it's a fixed math program that increases efficiency ,increases torque , reduces noise. a state of the art addition (only high end ac drives have this). if we go dc we will have to deal with no re gen ,heat from the commutator, brushes that limit max voltage), no oil cooling possible, more expensive motors (junk yard for ac), less rpm range.but we save 4 igbt's, 4 driver cards. double check this stuff , i'm only at this ac control for a few months and not a programmer.John stubbe


----------



## aeroscott (Jan 5, 2008)

the dc timing that you mention is handled by the commutator . but the power pulse (pulse width modulation) is varied by the controller.thats the on time of the pulse. ac also uses pwm to control power. ac also is smoother off the line. ac can be done without encoder ( better with encoder )


----------



## Dennis (Feb 25, 2008)

An ac motor's speed is determined by frequency and number of poles. A very crude method of controlling the speed of the motor is by varying the frequency, however you must also very the voltage because there is a little thing called inductive reactance that changes with frequency and therefore you must vary the voltage with frequency to compensate for the inductive reactance impedance. This type of speed control is called volts per hertz ratio. The down side of this control is their is no way to control the current responsible for torque production. In that respect you do whats called *field oriented control* or sometimes called *flux vector control*. 

This type of control separates the two current components that control the motors rotor flux induced current (the current the produces the magnetic field in the rotor) and the current that controls the actual torque production of the motor (or current that produces the revolving magnetic field in the stator). This process of separating the currents is extremely mathematically intensive for a MPU and complex to someone who's math skills are a bit rusty to program into the MPU.

Here is a good article on the subject: http://www.embedded.com/2000/0009/0009spectra.htm



So its obvious there is nothing easy about an AC induction motor with speed control. Now for brushless DC motors you don't have to worry about rotor flux current because the rotor's magnetic field is produced by permanent magnets. So there is no highly complex math involved to separate two currents. Its just one current which is the rotor current to worry about.

So its like this:

AC induction motors are very reliable as there are no permanent magnets to worry about getting weak over time and no brushes to worry about, but extremely complex to control torque with speed and controller design is very expensive.

Brushless DC motors have permanent magnets for the rotor, but also do not have brushes. The controller design is easier to implement than AC induction.

Brushed DC motors can be pure electromagnet stator or use permanent magnet stator. The rotor is always electromagnet called an armature that requires brushes, therefore it is high maintenance. Controller is the simplest to implement and cheapest.


----------



## aeroscott (Jan 5, 2008)

thanks Dennis, checked it out i'll go over to microchip and recheck there. since I don't have good handle on this it's great to go over it . john stubbe


----------



## Madmac (Mar 14, 2008)

"The controller design is easier to implement than AC induction."

The same hardware design of controller can be used for both BLDC and AC.


AC motor control gives best efficiency and performance. It should also be the lowest cost solution. Most DC motors are made by small companies, the overall volume made is relatively small and then compete with each other to keep the price low'sh. All the current AC motors aimed a traction applications are part of large industrial groups. These motors are considered specials as the volume made is low and they mark the price correspondingly high. Up to four times the corresponding power industrial motor.

The design of an AC motor for traction use is more difficult that a brushed DC motor, but simpler to make. Hopefully at some point the small DC motor companies will expand their product ranges to AC types and introduce some competition. 

Madmac


----------



## Dennis (Feb 25, 2008)

> "The controller design is easier to implement than AC induction."
> 
> The same hardware design of controller can be used for both BLDC and AC.
> 
> ...


I never said AC induction motors were expensive. I did say the controller is very expensive. As far as the controller for brushless DC motors can be used for AC induction motors, well that is not entirely true. It may work as far as getting the motor to rotate. It will not allow you to have *accurate control over torque* of the motor. The rotor of an AC induction motor is an electromagnet that requires the current responsible for producing those magnetic field lines in the rotor in order for the rotor to follow the revolving magnetic field of the stator although it lags behind slightly from the revolving magnetic field. The problem is trying to separate the current that produces the torque from the current that induces the magnetic field in the rotor. This requires complex math to separate the two current vectors into a rotating two coordinate system. A BLDC on the other hand only requires one current which is directly responsible for torque production.


AC induction flux vector control:

http://www.motionsystemdesign.com/Issue/Article/17792/Flux_vector_drive_review_and_update.aspx

Here field orientated control is the best and allows EXPLICIT control over the torque current INDEPENDENTLY of the flux producing current:

http://www.ab.com/drives/techpapers/PWMDrives01.pdf


Field orientated control theory:

http://www.embedded.com/2000/0009/0009spectra.htm

If you can follow the mathematics then you are much closer to being able to control the torque of a 3-phase motor:

http://focus.ti.com/lit/an/bpra073/bpra073.pdf


If you really want to make a decent 3-phase induction motor controller then it needs to be able to separate the two currents. If you can follow the math involved then it should be no problem to do.


----------



## aeroscott (Jan 5, 2008)

Dennis you the man,thanks for getting these links together. I was up to 4 am going over your links and microchips notes (pic 18F4431 and svm)I'll need to learn the math . still need to go over the circuitcellar project notes.we can do this. I remember the tesla guys having to tweak there code. john stubbe


----------



## Madmac (Mar 14, 2008)

With modern micro controllers or DSP's the cost difference in a device to control a BLDC or an AC with field vector control is negligible. The micro controllers in the two kits controlling AC motors with field control mentioned often, the Microchip (already mentioned in this thread) and http://www.luminarymicro.com/products/rdk_acim.html
cost around $5 in modest quantities. 

You may want to use a slightly cheaper device for a BLDC and save a dollar or two. The power side will be the same for both types for the same current / voltage requirements. On the AC motor side a second current sensor is needed (third is not needed as currents sum to zero). 

Computational power is very cheap these days.

The software development is an order more complex for the field vector approach, particularly if you also include outer control loops for acceleration, deacceleration, regeneration and traction control.

Treating the field vector code as black box code, as done by the circuit cellar team, is attractive to get something running. The down side is the device they use is only 30mips and to do a good job of motor control in an EV about 80 to 100 mips would seem to be needed. (roughly flow charting the code and then estimating number of lines per block x update rate)

Madmac


----------



## aeroscott (Jan 5, 2008)

madmac, checked out the link nice development kit.


----------



## xrotaryguy (Jul 26, 2007)

Whew, I got a couple of tests out of the way (calc and physics yay!), so I finally have some time to catch up on this thread.

Another reason for my coming back to this thread is that I stumbled across a 3 phase motor and controller that I can probably pick up for about $150.00. I don’t think that the controller was originally designed to run off of battery voltage though. I think that it is very possibly a modified CNC-lathe-type speed controller. As such, it was probably originally designed to run off of 3 phase @ 60Hz. I don’t know if that signal is supposed to be 110V or 220V. I know I’m showing my ac newb-ness here.  



aeroscott said:


> 1200 rpm at 60hertz =6 pole armeture,1800 rpm is 4 pole, 3600 rpm =2 pole .most ac ev drives run 4 pole. Some will spin them up over 12000 rpm. that's in the 400 hertz


 Hmmm… I am a little confused about this. Since 3 phase ac motors have 3 coils, I would have expected the poles to come in multiples of 3 as well. 



aeroscott said:


> we save 4 igbt's, 4 driver cards


 Why would we need 4 IGBTs? Wouldn’t we be able to get away with 3 of them? I’m guessing that the IGBTs could be run by a single PIC. The programming on the PIC would take sensor information from the motor to determine timing of each sine wave (or more specifically sine wave #1… the other two waves would simply be 120 degrees out of phase). Additionally, the PIC would take the signal from a 5k pot (or similar device) linked to the accelerator pedal and determine max pulse amplitude. I guess in this way the PIC and the 3 IGBTs would be doing chopping at 2 frequencies at the same time. One frequency might be at 60 to 400Hz to keep the motor timed properly at specific speeds. Perhaps this could be called the “timing frequency”. Simultaneously, the other frequency might be at 100kHz, to effectively regulate the amplitude of the of the “timing wave”.


----------



## aeroscott (Jan 5, 2008)

I never figured how the pole count rely worked out . But lets see 1 north 1 south so is this a mono pole or 2 pole think that's 2 pole so we go up by 2 poles 2 , 4 , 6 , 8 etc . it takes 2 igbt's that's 1 for + and 1 for - for each leg or 6 for 3 phases , but some are doubles so only 3 would be needed . I have some that are 6 packs , that's 6 individuals in one package . these don't get rid of heat as well as individuals do . then we need gate drivers to control and protect the igbt ( turn on and off and monitor making sort of fixed part of the control ) cost $30 to $80 the drives I've Sean only had one . except the 100 hp drive had 3 and I think for the big singles it take 1 each / 6 drivers 6 igbt's . the bus comes next made of layered copper plates with insulation between .this works as a capacitor . capacitors will be needed . also using the laminated buss . that takes care of the power section . all the control that is complex is on chips that are not expensive . In the past this was the major part of the project


----------



## xrotaryguy (Jul 26, 2007)

Interesting. I'm still a ways off from really understanding exactly how this works. fortunately, I am in calc 3 and physics 2 right now, so the math and the concepts are as fresh as they're ever going to be. 

I read through that first link. It is very informative. the Diagrams are a bit difficult to interpret because the notation is very small. Some of the diagram text is too small or is too low resolution to read. Same with the formulas. I'm sure that if I already had a better handle on this, the tiny text would be easier to de-cypher, but I can't read it at this point.

Oh well, I have four more links to read yet. Hopefully those will help. Thanks again for all the information.


----------



## Madmac (Mar 14, 2008)

"I don’t think that the controller was originally designed to run off of battery voltage though. I think that it is very possibly a modified CNC-lathe-type speed controller. As such, it was probably originally designed to run off of 3 phase @ 60Hz. I don’t know if that signal is supposed to be 110V or 220V. I know I’m showing my ac newb-ness here."

The power input side to an inverter has two configurations. The older type was a 3phase bridge rectifier followered by a smoothing capacitor and possibly a filter inductor. On this type measure the DC voltage on this cap and that is the required value for your battery pack (with a bit of leeway) and the point you can inject DC. You will also need to supply a low voltage for thre control electronics (usually supplied by a small transformer)

The more modern power input has power factor correction, PFC, and uses a lot more electronics. The PFC stage still, has a large value capacitor on its output that is charged to the inverters running voltage. Again measure this and the DC can be injected at this point. You will also need to check that the PFC is not supplying power to the inverter control electronics. This is sometime obtained from an extra winding on the PFC inductor.

Some industrial controllers have limited speed range.

Madmac


----------



## Madmac (Mar 14, 2008)

"Why would we need 4 IGBTs"


If you are planning to do regeneration then you will need at least one IGBT to convert the generated voltage into a tight band to charge the batteries.

Another IGBT or FET is needed to protect the system when the batteries are fully charged and the generated power needs to be dumped.

Madmac


----------



## xrotaryguy (Jul 26, 2007)

Woohoo! I just bought a big pile of AC stuff that was scrapped from a college-built hybrid Ford Escort. I got a 15hp motor, a controller (kinda... lots of parts that I can use to make a controller), high current switches, an inductive current sensor (AC only  ), 4 large capacitors, 3 IGBTs on a pair of bus bars (at least I think that's what they are), a trio of programmable digital displays, an adjustable circuit breaker for 3 phase AC, etc. Such a score! I am very grateful to the local EVer who hooked me up  

Now I have even more questions! I'll bet that's what everyone was hoping for right  First, I am confused about the units on the side of these large capacitors. I expected to see a farad measurement, but instead I get 3500MFD.
. .
What the heck is an MFD? The capitol MF looks like megafarads, but that's impossible. Is this supposed to be short for microfarads? Maybe their printing machine didn't have a micro character on it.



aeroscott said:


> But lets see 1 north 1 south so is this a mono pole or 2 pole think that's 2 pole so we go up by 2 poles 2 , 4 , 6 , 8 etc . it takes 2 igbt's that's 1 for + and 1 for - for each leg or 6 for 3 phases


Ok, so the poles come in multiples of two. I should have expected that. They are called "poles" after all. duh


----------



## ww321q (Mar 28, 2008)

microfarad . I read some place MFD usually were made for amplifiers and power storage or something like that . J.W.


----------



## xrotaryguy (Jul 26, 2007)

Is it just me, or does the image below have a couple of issues? The battery symbols are either up-side-down, or the plus signs should be on the other side of each of the battery symbol. Also, the coils are labeled phase a, phase b, and phase b. Shouldn't one of those be a phase c? Is the drawing funny, or is my understanding of electronics not as good as I think it is?


----------



## xrotaryguy (Jul 26, 2007)

ww321q said:


> microfarad . I read some place MFD usually were made for amplifiers and power storage or something like that . J.W.


Excellent. Thanks.


----------



## xrotaryguy (Jul 26, 2007)

Here are a handful of neat animations. Not all of them are actually for 3 phase AC motors, but they all use magnetic fields to turn electrical energy into mechanical energy or visa versa.

http://www.edumedia-sciences.com/a499_l2-ac-motor.html

http://micro.magnet.fsu.edu/electromag/java/generator/ac.html

http://micro.magnet.fsu.edu/electromag/java/generator/ac.html


----------



## ww321q (Mar 28, 2008)

xrotaryguy where did you find that schematic ? A good example of just because you can use a cad program , it don't mean you know what's going on  J.W.


----------



## ww321q (Mar 28, 2008)

I'm an x smoker so I like this one to  J.W.

http://www.compgoparts.com/TechnicalResources/FourStrokeEngineBasics.asp


----------



## xrotaryguy (Jul 26, 2007)

Whew! I was starting to think that I was waaaay off with my understanding of AC motors. That piston engine animation is pretty cool. The simplicity of flat head motors is awesome. Laughable even.  Of course, I like this one better

http://www.youtube.com/watch?v=WOtQG35EK_s


----------



## Evan (Feb 20, 2008)

Yes those capacitors are used in very large audio systems. The fools with the +100 Watt systems need them to prevent the power in their cars from going out every time a really low frequency sound comes threw the system. They typically used polarized caps for that though. These are not?? They look like large electrolytic caps. The funny thing is that for all their talk about loving music the stuff they use does nothing but distort because if they were using class A amplifiers the current drain on the car would be much more constant. A class A amp burns that power to give low crossover distortion. So if the amp needs these kinds of caps it is likely not a class A. Two make an ac system you want to avoid operation in the linear region though so this is all irrelevant. 

Effectively what I think you want to build is more like a 3 channel class B or D amplifier.


----------



## xrotaryguy (Jul 26, 2007)

I have been researching more. Here is a neat site that details a lecture and a lab experiment for a physics teacher.

http://hsc.csu.edu.au/physics/core/motors/2698/Phy935net.htm

I thought that this diagram was pretty decent too.










Also, this chip is listed on eBay. Does anyone have experience with this chip? It looks like it is basically already programmed to do what I would otherwise need to do myself. If that's the case, SWEET!


----------



## xrotaryguy (Jul 26, 2007)

I just realized that my capacitors are only 0.0035 farad. Is this simply because they are old? I think that the car was converted in about 1996 or so.


----------



## ww321q (Mar 28, 2008)

_xrotaryguy the MC33033 chip is talked about in the book "Build Your Own Electric Vehicle". It talks about both AC and DC controllers using this chip .If you don't have the book you can read most of the pages on Google books . Page 198 ...................................................J.W.
_


----------



## xrotaryguy (Jul 26, 2007)

ww321q said:


> _xrotaryguy the MC33033 chip is talked about in the book "Build Your Own Electric Vehicle". It talks about both AC and DC controllers using this chip .If you don't have the book you can read most of the pages on Google books . Page 198 ...................................................J.W.
> _


I just bid on a MC33035. This chip looks like it will do everything that I need. Evidently the MC33033 is a watered down version of the MC33035. There's also an MC33034 which is functionally identical to the MC33035.

One question on IGBT configuration. All the diagrams that I have looked at (that I can understand) use 6 IGBTs. The pile of parts that I got only has 3 IGBTs. How the heck did this 3 phase motor run on only 3 IGBTs? Is that actually possible? I wonder if the original builder was making a single phase current and then using capacitors to fake the 2nd and 3rd phases.


----------



## aeroscott (Jan 5, 2008)

you have 2 packs that's 2igbt's in 1 package . that's what was used in the circuit cellar design too . cheaper , doesn't get rid of heat as well as singles .


----------



## dec7td (Apr 18, 2008)

Has anyone ever considering modifying an industrial Adjustable Speed Drive/Variable Frequency Drive to control an AC motor? There are millions in production so picking up a used one would be cheap. 

With the help of an Electrical Engineer and/or Electrician the ASD/VFD could be disassembled to the point where the inverter converts the "rectified AC signal" (aka DC). After "removing" the front-half (aka the rectifier) an appropriate DC source could be attached to the input of the inverter.

Then a skilled Computer Engineer and/or Computer Technician could hack the electronic controls of the ASD/VFD so it would accept the new DC source, as well as, other necessities and safety features that may not be inherent to industrial drives.

Just a thought...


----------



## MrCrabs (Mar 7, 2008)

No hacking required.... Just look for a VFD that has terminals for DC Bus + and DC Bus - or GND.
Some of them are meant to share the DC Bus between multiple VFD's in the same panel, so 1 motor slowing down, can power 1 motor speeding up.

See http://www.evalbum.com/1149


----------



## xrotaryguy (Jul 26, 2007)

dec7td said:


> Has anyone ever considering modifying an industrial Adjustable Speed Drive/Variable Frequency Drive to control an AC motor? There are millions in production so picking up a used one would be cheap.
> 
> With the help of an Electrical Engineer and/or Electrician the ASD/VFD could be disassembled to the point where the inverter converts the "rectified AC signal" (aka DC). After "removing" the front-half (aka the rectifier) an appropriate DC source could be attached to the input of the inverter.
> 
> ...


I'm pretty sure this is how my motor speed controller started life. It has been partially disassembled, so I am not going to use it. I am trying to use some of its parts to make my own AC speed controller.

I do have a question on another matter though. I can't find any informatin on the switching speed of my IGBTs. They're a Powerex KD242520. I have looked at several sites. All the sites seem to have the same data sheet on them, and the data sheet doesn't explicitly provide the switching frequency. Maybe I can derive it from some of the other information on the sheet. Or am I to assume that these can be switched at 40MHz like so many other IGBTs. Technically the data sheet says that these are darlington transistors. I don't know if that makes any difference. They look to be the same.


----------



## Madmac (Mar 14, 2008)

The frequency you use this device at will be determined by the turn on and turn off times. These are in the data sheet along with two plots to give more detail.

Your 40MHz is a typo I hope.

Typical electrolytic capacitor values in an inverter would be 1000 to 20,000 MFD or microfarad. (MFD marking was common, less so these days)

Madmac


----------



## xrotaryguy (Jul 26, 2007)

Madmac said:


> The frequency you use this device at will be determined by the turn on and turn off times. These are in the data sheet along with two plots to give more detail.
> 
> Your 40MHz is a typo I hope.


Ok, I just reread my source for the 40MHz number. Oops, I don't think I was wearing my glasses that day. Heh, I thought 40 million Hz sounded kinda fast  . I was looking at the graphs on the data sheet too. I couldn't see how the heck those numbers would add up to 40MHz. I guess now I know why. Thanks for the clarification.



madmac said:


> Typical electrolytic capacitor values in an inverter would be 1000 to 20,000 MFD or microfarad. (MFD marking was common, less so these days)


Aah, so at 3500 microfarads, my caps are at the small end of that spectrum. Why the wide spread for typical inverter capacitors?

One more thing. I won my bid for a lot of 3 MC33035 microcontrollers. As Al Gore would say, "I'm sthuper sthuper stoked! EXCELSIOR!"

I guess I need to start designing my speed controller so that I can screw up some more


----------



## Wirecutter (Jul 26, 2007)

xrotaryguy said:


> I just noticed that the AC discussion really took off in the other thread. Maybe I should have posted this in there. Oh well.


I must be a little dense. I've seen reference to this "other thread", but can't find it. Do you mean the evcs group on Yahoo?

-Mark


----------



## Wirecutter (Jul 26, 2007)

dec7td said:


> Has anyone ever considering modifying an industrial Adjustable Speed Drive/Variable Frequency Drive to control an AC motor? There are millions in production so picking up a used one would be cheap.


 Yeah, I did. What I found:

1. It's tough to find a drive rated for over 3 horsepower that can run from single phase 220v. They're out there, but they're expensive, and then you have to have AC source big enough to drive it.

2. Over about 10 horsepower, most VFDs require 3 phase 460v or better. To source that with batteries, you'd need something like 600v worth of DC. (Remember, that's 460v RMS - peak is higher)

3. An industrial VFD rated for enough horsepower to drive a car would be a big honkin' VFD. I'm thinking you'd need one of at least 30 HP, and preferably more like 50.

In short, yeah, it can be done, but I don't think it's exactly and _easy_ adaptation.

-Mark


----------



## xrotaryguy (Jul 26, 2007)

Wirecutter said:


> I must be a little dense. I've seen reference to this "other thread", but can't find it. Do you mean the evcs group on Yahoo?
> 
> -Mark


I'm sure you're not dense  I should have posted a link.
http://www.diyelectriccar.com/forums/showthread.php/homemade-controller-features-6954.html


----------



## xrotaryguy (Jul 26, 2007)

Wirecutter said:


> Yeah, I did. What I found:
> 
> 1. It's tough to find a drive rated for over 3 horsepower that can run from single phase 220v. They're out there, but they're expensive, and then you have to have AC source big enough to drive it.
> 
> ...


The DC voltage required to make 480V rms is 648V. I think that this is actually what I'm going to do. I may have already lined up the batteries.

That is some good information. Thanks for that.

ps: Big Honkin'... is that a technical term?


----------



## xrotaryguy (Jul 26, 2007)

I just did a little more work on my EV spread sheet. Here's the link. About half way down on the right hand side is where the meat of the update took place. I added two columns that include 54 small 12V 17ah batteries wired in series to make 648V. I have been emailing back and forth with the guy that has these batteries and still need to hear from him how much these batteries weigh.

I also added some nifty graphics 

Here's the link.

http://www.box.net/shared/iaab2kb34g


----------



## 3dplane (Feb 27, 2008)

xrotary!
Baterry weight:Are those sealed lead acid? I just went outside and weighed my 18 ah jump box batteries(2 of them for more accurate reading) comes out to 12 lb each. Maybe you can compare. Sorry if I missed something in the thread.Barna.


----------



## Wirecutter (Jul 26, 2007)

xrotaryguy said:


> Big Honkin'... is that a technical term?


Actually, the technical term is unprintable here, but it rhymes
with "Wig Brother Truckin'." 

I started to write a kind of rant about running an EV on such high
voltage, but I got to thinkin'...

At such voltages, the currents should come down a bit, and perhaps
you'll cut down on copper weight. At 60A, your electrical power would
work out to around 50 HP. If you can get a 50 hp VFD at a reasonable
cost, it's starting to sound like a workable hack. Yeah, 50 HP doesn't
sound like much for a gasser, but in the EV world, it may be pretty
decent.

OTOH, I've been shocked by ~400 VDC, and it's real unpleasant. 
Nearly 50% higher voltage would be, well you get the idea. Be careful, 
dude. There may be another contender for the moniker "Plasma Boy".
(With apologies to John Weiland.)

Ok, so 54 of your 17aH cells work out to about 650lbs. Heck, that's
just a couple of fat guys! I've got 300 lbs worth of batteries in my gokart,
and it goes ok. I'm interested in seeing how this turns out.

-Mark


----------



## Da_Fish (Apr 28, 2008)

Been looking into this, following the links etc... and have a few questions. This seems very do-able at this point.
1). How should you size your IGBT's? I have found bunches of em on ebay for cheap but the voltages are 1200 to get a 300A current. Are these peak numbers and the IGBT's operate at lower voltages up to 1200V and does the current limit plane up linearly with the voltage (1200V=300A, 600V=150A) or are these just max numbers and current is dictated by load of motor?
2). There is a reference to a Luminary Micro board in this thread. Is this the main control and switching frequency board with programing abilities to set curves (just add IGBT's) or is this in addition to everything else?


----------



## Madmac (Mar 14, 2008)

Has anybody tried to compile the modified Microchip code for the Circuit Cellar published AC inverter and succeeded?

Madmac


----------



## Wirecutter (Jul 26, 2007)

Madmac said:


> Has anybody tried to compile the modified Microchip code for the Circuit Cellar published AC inverter and succeeded?
> 
> Madmac


 I've compiled some of it, but not all. I have a whole suite of Microchip development hw and sw, but was disturbed to discover that the compiler for that code costs $800+. I applied for the educational (free for 60 days) version, and that's how I did it. I've yet to dig in and start implementing code - I'm still working on hardware.

I've also done a lot of Labview in my time, and I've contacted the developers of the Circuit Cellar design about getting Labview source. That would be a helpful thing to have, since I have the Labview runtime and development stuff.

-Mark


----------



## xrotaryguy (Jul 26, 2007)

Wirecutter said:


> Actually, the technical term is unprintable here, but it rhymes
> with "Wig Brother Truckin'."


hehe love it.


> At such voltages, the currents should come down a bit, and perhaps
> you'll cut down on copper weight At 60A, your electrical power would
> work out to around 50 HP. If you can get a 50 hp VFD at a reasonable
> cost, it's starting to sound like a workable hack. Yeah, 50 HP doesn't
> ...


Exactly! having low current through the motor would keep the motor cooler too. This is a concern of mine here in AZ where summer temps can be above 110 F for months on end. Our record high is 123 F and 118 is not uncommon. Furthermore, the more heat you make, the more energy you're losing. I think that this is another place where AC really outshines DC. This is probably one of the reasons that the T-Zero guys could run so dang far on lead acid. Can you imagine the crummy of an EV starting out from a light with 600A coursing through 1 gauge wires? I realize that it's only momentary, but still, energy is at a premium in an electric car. 

And you're right about saving on copper too. The gauge of the wire goes down to... What? 8 gauge? I'll need to do the calculations on this soon.



> OTOH, I've been shocked by ~400 VDC, and it's real unpleasant.
> Nearly 50% higher voltage would be, well you get the idea. Be careful,
> dude. There may be another contender for the moniker "Plasma Boy".
> (With apologies to John Weiland.)


I guess I need to trade my tin foil cap for some rubber gloves. You're right though. I will need to be extremely careful while wiring the car. Now if the car were in a collision... I will have my kid in the passenger seat much of the time, so I need to design some safety in to the car as well. I'm 5/16" angle and flat iron battery boxes with 1/4" abs (or other weldable plastic) lining to keep the batteries from arcing in a collision. Also, an impact-sensitive switch would be a good idea. Oh, and lots of shiny yellow and orange high voltage stickers in the appropriate places for mentally challenged DMV inspectors. God I hate the DMV! 


> Ok, so 54 of your 17aH cells work out to about 650lbs. Heck, that's
> just a couple of fat guys! I've got 300 lbs worth of batteries in my gokart,
> and it goes ok. I'm interested in seeing how this turns out.


Man, it seems light doesn't it? I hope I'm not setting myself up for a puny battery pack and limited range. I need to build my spread sheet up some more so that I can do speed, acceleration, and range calculations again.

Thanks so much for the feedback guys. I really appreciate it.


----------



## xrotaryguy (Jul 26, 2007)

3dplane said:


> xrotary!
> Baterry weight:Are those sealed lead acid? I just went outside and weighed my 18 ah jump box batteries(2 of them for more accurate reading) comes out to 12 lb each. Maybe you can compare. Sorry if I missed something in the thread.Barna.


You didn't miss anything. I am still waiting on a weight quote from the guy selling the batteries. He did say that these batteries are on the heavy side (aka lots of lead = above-average quality).


----------



## xrotaryguy (Jul 26, 2007)

Da_Fish said:


> Been looking into this, following the links etc... and have a few questions. This seems very do-able at this point.
> 1). How should you size your IGBT's? I have found bunches of em on ebay for cheap but the voltages are 1200 to get a 300A current. Are these peak numbers and the IGBT's operate at lower voltages up to 1200V and does the current limit plane up linearly with the voltage (1200V=300A, 600V=150A) or are these just max numbers and current is dictated by load of motor?


Those 1200V 300A igbts are more than adequate. This design will be a ways off from 300A. A typical DC motor might like 500 or 600 amps while starting from a stop, but a high voltage design doesn't need that. The amperage will be determined by motor demand, pulse width (aka throttle position), etc. As pulse width increases, the voltage that the motor sees increases, and the amperage increases with it. At lower rpm, the current would be higher. I don't know of any to control voltage and amperage independently.


> 2). There is a reference to a Luminary Micro board in this thread. Is this the main control and switching frequency board with programing abilities to set curves (just add IGBT's) or is this in addition to everything else?


Sorry, I don't follow. I plan on using an MC33035 microcontroller, a trio of dual IGBTs, and 6 drivers + associated hardware. I am still learning a LOT about controller design. This will be the most challenging part of the design for me.


----------



## Madmac (Mar 14, 2008)

Quote
"but was disturbed to discover that the compiler for that code costs $800+. I applied for the educational (free for 60 days) version, and that's how I did it."


Was hoping someone would have said they have managed to compile with a low cost or free compiler.

Have also been working on the hardware, have added a second micro to control BMS, interface to PC over USB to give detailed system info and system functions, monitoring coolant temp starting fan, PWM outputs to drive dash fuel / RMP / temp gauges. Also doing safety to prevent motor changing direction until stationary, and shutting down if G readings are exceeded or vehicle tips over. Also a PWM driven load resistor to keep DC rail in spec if batteries are fully charged.

Have redesigned the IGBT drive to a lower cost solution. Almost at the point of doing PCB layout, just need to decide on including support for regeneration converter ( Inverter can control to some degree but to get battery charging voltage within close control) and also using these parts as an offline charger to save cost. 


Quote
"I've also done a lot of Labview in my time, and I've contacted the developers of the Circuit Cellar design about getting Labview source. That would be a helpful thing to have, since I have the Labview runtime and development stuff."

Have never used Labview. Had planned on writing a small program to take its place. 

Madmac


----------



## Da_Fish (Apr 28, 2008)

http://www.luminarymicro.com/products/rdk_acim.html

That is the mocro controller Xrotary. Then my question goes back to is this just to help develop curves or is it an actual controller?


----------



## Wirecutter (Jul 26, 2007)

Madmac said:


> Was hoping someone would have said they have managed to compile with a low cost or free compiler.


 Well, it _was_ free, but I had to jump through the hoop and learn the secret handshake. 



Madmac said:


> Have never used Labview. Had planned on writing a small program to take its place.


 Labview is interesting because it's programming with pictures and diagrams. It seems geared toward non-programmer scientific types. It's great to set something up and hit the ground running, but with large projects like what I've worked on, it gets complicated. It wouldn't necessarily be my first choice for a programming language, but I had no choice. It's most handy for doing GUI interfaces to instrumentation.

I'm still in the stage of gathering hardware. I've got the 600V 400A IGBTs and the drivers for them, as well as the Microchip stuff. My current focus is the power distribution assembly, but other things have been keeping me out of the shop.

I'm hoping to collaborate with people. Once I get the buss plates worked out, maybe I can trade one with someone in exchange for some other part.

-Mark


----------



## Wirecutter (Jul 26, 2007)

xrotaryguy said:


> Oh, and lots of shiny yellow and orange high voltage stickers in the appropriate places for mentally challenged DMV inspectors. God I hate the DMV!


My favorite was the scenario of having an EV conversion smog tested. Bolt the tailpipe back on and let 'em test it. 

-Mark


----------



## Da_Fish (Apr 28, 2008)

Wirecutter are you talking about flow chart programming?

What drivers are you guys using for the IGBT's?


----------



## frodus (Apr 12, 2008)

Da_Fish said:


> Wirecutter are you talking about flow chart programming?


labview is a graphic programming language... you set up blocks with input, output and inside each they handle the i/o and process it. They use it alot for testing in the lab so they can make nice GUI's for stuff, and take data in from i/o cards, soundcards, serial, USB, tcpip and stuff. Student version is free, but limited.

kind of like visual studio, but geared more to the scientist/engineer and not a programmer.


----------



## xrotaryguy (Jul 26, 2007)

Madmac said:


> just need to decide on including support for regeneration converter ( Inverter can control to some degree but to get battery charging voltage within close control) and also using these parts as an offline charger to save cost.


I like this idea a LOT! Using existing components to do more than one job makes lots of sense. Motor speed control, regen, and charging all in one package. hmmm... that's starting to sound like AC Propulsion's system. Maybe they came to the same conclusion.

You can download several versions of Labview from any number of torrnet sites... But that's illegal. ONOZ!

That luminary Micro speed controller is pretty cool, but I think that it is designed to run smaller motors. I would imagine that their design would require some creative engineering before it could run at 600+ volts at 100 amps. That being the likely case, one would probably be money ahead to build a controller from the ground up.


----------



## Wirecutter (Jul 26, 2007)

Yeah, I actually have Labview at work, but the version we use is older than the one shown in the previous post. It's best described as "programming with pictures". If you've ever used a schematic capture program, the programming interface will be easy for you.

As for the IGBT, I'm using the PowerEx parts and the driver boards PowerEx recommends for them.

-Mark


----------



## xrotaryguy (Jul 26, 2007)

The Circuit Cellar design used liquid cooling so that their dual IGBTs would not overheat. Are you guys using liquid too? I wonder how hard it would be to do my own liquid cooling. I could simply weld up a steel box and pump water through it and then through a transmission cooler. I could even attach some aluminum heat sink to the inside of the box to help transfer heat away from the IGBTs and the wall of the box and into the coolant.


----------



## Wirecutter (Jul 26, 2007)

I got a cold plate of the same type used in the Circuit Cellar/Camosun College design, but it's not really right for the application. The way the pipes route through the plate appears right for a "2 by 2" arrangement of the IGBTs rather than the "3 in line" setup shown. That's why the spacing appears kind of funky. (You don't want to run a mounting hole through the coolant pipes, after all.) So I decided to make one. I start with an aluminum plate about 1" thick, then use a ball-end mill to cut grooves for copper pipe. Then mill bars similarly that act as covers for the trenches the copper goes in. I'm going to try to use a motorcycle radiator and run the coolant through that, but it may not be large enough. I'll allow for upsizing in that case.

-Mark


----------



## aeroscott (Jan 5, 2008)

point to remember about heat exchangers is the less the temp . differential the bigger the heat exchanger needed . this is probably not important for our work . I was trying to exchange heat at less then 10 deg. diff . it takes a lot of exchanger .


----------



## xrotaryguy (Jul 26, 2007)

Making your own cold plate with a ball end mill is a sweet idea. I wonder if I can mimic that with a router.


----------



## Wirecutter (Jul 26, 2007)

Well, I've cut aluminum plate in my circular table saw using a carbide tipped blade, and it does work. It's also fast, noisy, and sprays aluminum chips _everywhere_. I wear a ballcap turned backwards to keep the chips out of my hair, a welding helmet with the shade up, my leather welding apron, and hearing protection. (Yeah, call me a sissy, but I've grown fond of being able to hear and see...)

I suppose you could use a router, at least in theory. It'll be faster, noisier, and scarier. Routers go _fast_. Make sure to clamp the work down real well, and have the router in a tight guide. Watch out for the bit filling up with aluminum swarf, feed real slow, take light cuts, and have 911 on the speed dial.  Seriously though - please be careful.

PS: As an alternative, send me your plate and specs, and trade me something interesting. I need front tires for my gokart - I think they run about $45 for the pair. Milling straight slots in aluminum is pretty easy for me.


----------



## ViolentBlue (Apr 19, 2008)

xrotaryguy said:


> The Circuit Cellar design used liquid cooling so that their dual IGBTs would not overheat. Are you guys using liquid too? I wonder how hard it would be to do my own liquid cooling. I could simply weld up a steel box and pump water through it and then through a transmission cooler. I could even attach some aluminum heat sink to the inside of the box to help transfer heat away from the IGBTs and the wall of the box and into the coolant.


I'd reccomend a big piece of copper. Copper has much better thermal conductive properties than steel, besides which it is much easier to seal up with solder than weld.


----------



## Wirecutter (Jul 26, 2007)

I went with aluminum plate and copper pipe, largely due to cost, and partly because the design is inspired by the D6 plate used in the CCC design. A hunk of copper for the whole thing would be expensive, and it's also not as easy to machine. Aluminum conducts heat quite well, and it's very easy to work with.

-Mark


----------



## aeroscott (Jan 5, 2008)

what about bronze great machining , solder , tig , silver solder. thermal conductivity I don't know .


----------



## aeroscott (Jan 5, 2008)

is silver solder a great thermal conducter ?


----------



## Wirecutter (Jul 26, 2007)

aeroscott said:


> is silver solder a great thermal conducter ?


 Well, I don't know about the _solder_, but silver is a very good electrical and thermal conductor. Shame that it isn't more resistant to corrosion.

As for bronze - doesn't it contain zinc? If so, that would make welding it a bad idea. Nasty fumes that make you sick. Of course, there's still soldering and brazing.

I guess there are multiple answers here, but I've now got material in hand...

-Mark


----------



## aeroscott (Jan 5, 2008)

bronze uses tin , brass uses zinc, that said there are 1000 alloys that are called bronze . I have been collecting silver contacts for years . what to do with them ? how about a silver /bronze / tin heat sink or silver wire alloy motor wire .


----------



## CNCRouterman (May 5, 2008)

Wirecutter said:


> Well, I've cut aluminum plate in my circular table saw using a carbide tipped blade, and it does work. It's also fast, noisy, and sprays aluminum chips _everywhere_. I wear a ballcap turned backwards to keep the chips out of my hair, a welding helmet with the shade up, my leather welding apron, and hearing protection. (Yeah, call me a sissy, but I've grown fond of being able to hear and see...)
> 
> I suppose you could use a router, at least in theory. It'll be faster, noisier, and scarier. Routers go _fast_. Make sure to clamp the work down real well, and have the router in a tight guide. Watch out for the bit filling up with aluminum swarf, feed real slow, take light cuts, and have 911 on the speed dial.  Seriously though - please be careful.
> 
> PS: As an alternative, send me your plate and specs, and trade me something interesting. I need front tires for my gokart - I think they run about $45 for the pair. Milling straight slots in aluminum is pretty easy for me.



Regarding the routing of aluminum:
There are many factors that will affect the end results, here are a few things to consider.
1) Aluminum comes in many flavors, 3000 series, specifically 3003 is essentially commercially pure aluminum, very corrosion resistant, but is the softest of the readily available options. It also sucks as far as routing goes. 3000 series aluminum has the annoying propensity to turn your routerbits into lolipops. Trust me on this one. It can be successfully routed, but it is a PIA. Basically, the harder the aluminum alloy, the easier it is to route, not easier in terms of torque, but in terms of less reweld, better finish, cleaner cuts (and tools). 5052-h32/h34 is a very good comprimise, it is only a little more expensive than 3003, much stronger, good corrosive resistance, and great for annodizing. 6061 and 6063 are considerably more money, tougher yet, but not quite as corrosive resistant, unless in "alclad" form, ie: coated with a thin layer of 3000 series aluminum.

2) Tool selection. There are a host of tools specifically design for cutting aluminum, however, there are only a few that are truly suitable for ROUTING aluminum. Wood geometry router bits are closer in geometry for aluminum than those designed to run in a mill, that said, however, they still tend to load and reweld (aka aluminum lolipop). Obviously, the best choice is an aluminum geometry ROUTER-bit. Second best is one for Hard Plastics. Getting the feeds and speeds is what determines success with a CNC router. Getting the feeds and speeds right with a hand router is tough. More like "not going to happen", so the work around is to run way on the light side of the chipload spectrum and trading time and tool life for efficiency. I have to go with wirecutter on light passes and safety. Count on picking aluminum chips out of your socks for a long time too.
As for tool selection, try to use a tool with a shank no smaller than the cutter diameter (up to 1/2" for hand router use). I would suggest Onsrud Cutter for routing tools, specifically the aluminum cutting section.
Spiral ball end tools may not be the best choice for your application, rather a low shear carbide core box stile tool might work best in a hand router. Frankly, I almost never hand route aluminum, except occasionally a flush trim bit to clean up some flashing, or a bevel bit to chamfer. Round overs and fillets I typically do on my CNC router.

3) Spindle (router head). Bigger and beefier is better. A heavy, old Porter Cable (with good bearings in it) beats a brand new wimpy Craftsman or Ryobi hands down every time. The mass of a heavier spindle will help to offset the lack of rigidity, to a degree. Having your parts milled on a milling machine, or routed on a CNC router (rated for aluminum) is much safer, better, safer, more accurate, safer, and you won't be pulling sharp annoying little aluminum chips out of your socks for the next two weeks. Did I mention safer?

As for my interest in this thread. My wife and I are very interested in building and EV or Hybrid, maybe several. I am a big fan of 3 phase industrial motors, primarily because, as an industrial user, I have seen first hand the much better performance of 3 phase AC motors over the same or higher rating single phase AC counterparts. I do not have much first hand experience with DC motors, though I am learning as I go. I have access to some 3 phase motors and am considering the practicality of buying or building a 3 phase controller to run them, as compared to a DC motor. 
That does not mean I will not consider using a DC motor and controller, just that I lean toward 3 phase.

Eric


----------



## Wirecutter (Jul 26, 2007)

Eric - That's just the information that was needed here. You confirmed from experience what I had suspected. Especially the part about picking chips out of your socks.  It's also a hassle to get welded aluminum off of those nice HSS and carbide mills.

Welcome aboard - I have to say I share your thoughts on AC motors, but perhaps for different reasons. I've suspected all along that 3PAC motors were superior to DC, but the consensus everywhere is that the controllers are killers - complicated and expensive. The first time I disassembled an AC motor, I was really disappointed. It's just so simple - there seems to be nothing to it. (No offense to anyone who might _design_ them - I know a lot of thought goes into it, the result just _looks_ simple.) The design is just so much more robust. 

Hopefully, I can get my controller working ok. Things have slowed down for me a bit. Uncertainty in other areas of life signal that I need to avoid large purchases for at least a little while.

-Mark


----------



## Madmac (Mar 14, 2008)

Hi Wirecutter
" 've also done a lot of Labview in my time, and I've contacted the developers of the Circuit Cellar design about getting Labview source. That would be a helpful thing to have, since I have the Labview runtime and development stuff.

-Mark"

Did you get a reply from the CC developers? 

Madmac


----------



## aeroscott (Jan 5, 2008)

I have some igbt heat exchangers for inverter solar service . 4"x 10 3/8"x1 1/4" with 5/8"id x 7/8" od tubes mounted on each end . exchanger mounted vertically for gravity flow . aluminium plate with welded box . tubes welded on small ends .


----------



## CNCRouterman (May 5, 2008)

Regarding liquid cooling and routing aluminum:

First off, hat's off to wirecutter and his Karts. Very nice. Watched a couple of your Youtube vids.

In my first post, I mentioned feeds and speeds, and selecting the right tools. After being thoroughly impressed with Mark's work, and a fine shop to build it in too, I was itching for an opportunity to show something somewhat impressive that we have done on our CNC Router, and still try to stay on topic.

I found a lot of pictures of products, however, they are almost all 1.2 Mbit files. Maybe tomorrow I can resize a couple.

Until then, you are invited to visit our website where there are a few pictures on the Routing Capabilities page.

http://www.cncrouterworks.com/capabilities.htm

Click on one of the material catagories for a few sample pictures.

The website's home page is http://www.cncrouterworks.com/


My intent was to show some possibilities that CNC routers (or mills for that matter) can provide. Regular shop pricing may not be so great for "one off" or prototypes, but sometimes you find a company willing to work with you to help you develop your product, with the tacit understanding that they will be favorably positioned to provide production volumes when it takes off. We do this for several of our customers.

Hopefully I will get some picts or CAD/CAM renderings up soon to contribute to the heat sink portion of this thread.

Best wishes,
Eric


----------



## Wirecutter (Jul 26, 2007)

Madmac said:


> Hi Wirecutter
> " 've also done a lot of Labview in my time, and I've contacted the developers of the Circuit Cellar design about getting Labview source. That would be a helpful thing to have, since I have the Labview runtime and development stuff.
> 
> -Mark"
> ...


 It took a while, but I did. I have to assume that the developers have moved on to other things, and they're quite busy. But I did hear back, and I should share what I got. I'll try to figure out how to post files first thing tomorrow, and with any luck, we can all see how they instrumented their project.

-Mark


----------



## xrotaryguy (Jul 26, 2007)

Wirecutter said:


> It took a while, but I did. I have to assume that the developers have moved on to other things, and they're quite busy. But I did hear back, and I should share what I got. I'll try to figure out how to post files first thing tomorrow, and with any luck, we can all see how they instrumented their project.
> 
> -Mark


I highly reccomend using BOX.NET to host your files. BOX will host ANYTHING you can think of. I hose pictures, Autocad files, Ti83 and Ti89 calculator programs, Graphical Analysis files, Word Docs, EVERYTHING. You can get a free account that has... 5 gigs of storage?... and a HUGE file size limit. You can leave links to your files in forums like this one. You can actually leave links to entire file folders too. Get BOX.NET! It's an awesome file host!


----------



## xrotaryguy (Jul 26, 2007)

I am a little confused about one of the pins on the IXDD414PI driver that I'm considering. One of the pins is labeled Ven. I think that this is intended to be a fault sensing pin. Dan Fredricson has his set up so that the Ven pin is receivig +5V just like the Vin pin. Is that how it's supposed to be? I know that the pin needs sufficient voltage for the driver to run, but what is the point in supplying it with the same source as Vin? I mean, if Vin isn't getting sufficient voltage either, then the thing isn't going to work any way right? Here is a pic of Dan's controller design. #3 is the Vin pin. #'s 1 & 8 are both V1n.















Here are some images from the spec sheet.




























From the spec sheet it looks like the driver is supposed to respond a fault/no fault signal from the micro-controller. However, looking at Dan's diagram, I'm not so sure. Do you guys know the deal this this?


----------



## Madmac (Mar 14, 2008)

AS the pin names describes it is a system enable pin. In the circuit above you would not want to use it as the IGBT gate has no pull down to make sure it is off. Without this the gate could float high with stray leakage and turn full on.

Add a resistor from gate to source to make sure this does not happen. Adding a zener diode in the same position is also a good idea. This will clamp any voltage that may cause early failure that may be caused by spikes or ringing on the drive signal. Remember most zeners are 10% tolerance when choosing a suitable one.

Using this input as a fault shut off line, over current for example, would require careful design as it does not force the output low so turnoff times could be quite long.


You could connect it to the micro for shutting down the output if the PWM output developed a fault. Looking at the DC specs the turn off threshold VENH is 2/3 supply or 10 volt in this circuit so a level translator would be needed.

A good use of the pin would be to force the drive off during power up until the micro has set up its pins to the required output state. A cap to ground with a pull up resistor would achieve this. The device does have an internal 200k pull up.

Madmac


----------



## MitchJi (Dec 14, 2007)

xrotaryguy said:


> Obviously buying a purpose-built AC drive system for an automobile is very expensive. However, building an AC system from a homemade controller and a used industrial 3-phase motor looks like it could be pretty cheap; In fact, it looks like it could be cheaper than DC.


Hi,

Maybe Prius motors, invertors and transmission with a homemade controller might be easier and better. Check the following thread (a few brief excerpts below):
http://www.diyelectriccar.com/forums/showthread.php/using-prius-components-build-ev-12614.html



> With my new knowledge of the Prius components I have been working with for the UDHEV hybrid classes, I have come up with a simple way to convert the Prius power split transmission into a full EV power combiner. This simple mechanical hack, will allow both MG1 and MG2 to work together in parallel at a 1:1 ratio. The beauty of this system is that the transmission oil pump, and the ICE input shaft will turn with the two MG's, so the transmission has a third input/output shaft.The built in differential and output gearing with parking pawl, makes this a full EV drive system that is ready to go.
> 
> The combined HP would bring the system to about 55 HP continuous, with peak possibly over 90.





> MG2 alone outputs 258 lbfoot, with a 3.9:1 final drive ratio , for over 1000 lb foot output from the differential. That should push an Insight or other light car or pickup just fine without the need for a transmission, since like all electric motors, that torque is available through most to the rpm range. Add the 18KW from MG1, and we could have a tire burner.





> I paid $500 for the drive, and $600 for the inverter.
> The controller should be under $100?


Best Wishes,

Mitch


----------



## xrotaryguy (Jul 26, 2007)

Madmac said:


> As the pin names describes, it is a system enable pin. In the circuit on the previous page, you would not want to use it because the IGBT gate has no pull down to make sure it is off. Without this the gate could float high with stray leakage and turn full on.
> 
> Add a resistor from gate to source to make sure this does not happen. Adding a zener diode in the same position is also a good idea. This will clamp any voltage that may cause early failure that may be caused by spikes or ringing on the drive signal. Remember most zeners are 10% tolerance when choosing a suitable one.


 So you're saying that a resistor needs to be placed between the power supply and the driver's #1 pin (and pin #8 by default too I guess)? Or are you saying that I need a pull-down resistor and diode on the signal wire from the PIC to the driver? After doing a little research, I'm guessing that I need the pull-down circuit on the signal wire between the PIC and the driver. 

I have actually been working on my board schematic lately. Here is a pic of what I have so far. I'm NOT done, so please don't point out things like "you don't have power supplied to the PIC."  So far, I have the phase A drivers and optocouplers pretty much set up. I don't have pull-down circuits between the drivers and the IGBTs yet. I am using an optocoupler on each driver circuit because they have the ability to filter out any of the scary voltage spikes that are possible from a system that runs 650V of peak of voltage. I have pull down circuits on the signal wires from the PIC to the optocoupler and again from the optocoupler to the IGBT driver and I will add them on the signal wire from the driver to the IGBT.


----------



## kittydog42 (Sep 18, 2007)

Back to the original question - yes, people have sucessfully converted cars using industrial VFD's. There is one on austinev.org that uses an ABB motor with a Danfoss VLT series. The DC buss is backfed 288V or so which powers the drive, and it is recharged by putting 200V power into the AC input. The owner also claims the regen is awesome on this setup. I don't think that the performance is that good.


----------



## xrotaryguy (Jul 26, 2007)

Ya know, looking at the spec sheet for this Toshiba IGBT, it looks like I can send a 12V signal to the gate without any real problem. If this is the case, why the heck do I need a driver at all? Couldn't I just use the optocoupler and be done with it? In fact, the optocoupler could work even better than the the driver because it does a better job of isolating the PIC from the IGBT. Am I right in this, or am I missing something?


----------



## xrotaryguy (Jul 26, 2007)

Madmac said:


> Quote
> "but was disturbed to discover that the compiler for that code costs $800+. I applied for the educational (free for 60 days) version, and that's how I did it."


Are all compilers not created equal? Ok, I'm sure that not ALL of them are, but it seems like some of the compilers are suitable for a great many PICs. I'm assuming this also means that one PIC could use many different compilers without too much trouble... I hope. Here is a bit of what leads be to believe that several compilers should be useable.

http://www.motorola.com


> Add to that a full suite of development tools such as C compilers, assemblers, adn development hardware which are available today. the reuslt is a low-cost, full-featured microcontroller that can "get your motor running" today, as well as meet teh needs of tomorrow's motor control applications


----------



## Madmac (Mar 14, 2008)

" Add a resistor from gate to source" My terminology was crossed.... a FET is gate to source an IGBT is gate to emitter. The purpose of the resistor and zener is to protect the device. Exceeding the maximum drive voltage (usually about 20V) will kill the device. A resistor and zener cost a few cents and can save a device costing many 10's of dollars. In production you can leave them off. Best place is to wire them directly on the device so that any issues with connection on a prototype don't become expensive. Also it will protect from any ringing on the drive until it is debugged.

The gate on both a FET and IGBT looks like a capacitor to the drive circuit (simple view). You can drive with the opto but it will take longer to charge and discharge this capacitance. To do fast switching it is not uncommon to have 5Amp or more drivers. This current is only needed on the edge of the switching signal, it is not flowing all the time.

The aim is to switch on and off as quickly as possible in a very controlled manner. The longer the transition from off to on (or reverse) takes, the more power the device will have to dissipate. The down side to this is that the rate of change of voltage over time gets larger, this is known as dv/dt. Very fast rate of change, high dv/dt, causes many problems. Designers use complex drive designs for a reason. High dv/dt can cause stray capacitance inside a device to turn itself on for example.

You may also want to consider current limit protection by looking at the device saturation voltage, again a few low cost components can save expensive devices if things go wrong.

You may want to look at the wiring of your output bridge...turning C2 on shorts the power rails.

Also look at the power for the drivers on the top and bottom IGBT's of one leg.

Look at the gate series resistors, what is the time constant of them and the gate capacitance?

Check into the current limiting resistors on the opto LED drive...are they in the right place... the right value...is the micro output able to switch fast with this load?

You have also considered what happens as the micro powers up so that it does not turn on all IGBT's until the outputs are configured?

You will, of course, put in decoupling caps as well as some low ERS caps on the isolated driver power rails.

Probably missed a few other issues as well.

Madmac


----------



## xrotaryguy (Jul 26, 2007)

Hey wait, I'm using an MC33035. Do I even need to compile any code? the site below says that my PIC isn't programmable. Heh, I guess if it's not programmable, then it's not a pic huh.  

http://www.ece.uakron.edu/SDmaterial/fall2004/DT2DesignFall2004.pdf


> The final solution to consider is the ASIC approach. The biggest advantage to this solution is that everything has already been designed and no algorithms need to be written, just drop in the IC and it works. The disadvantages to this approach are the cost and the inability to change any aspects to how the controller functions. The cost of the ASICs range from $2.00 to $18.00 US. Of course, the $2.00 ASIC MC33035 has very few features, and the $18.00 MC73110 for example has all of the desired features built in, but the cost takes up almost half the target budget of $40.00.


Hmmm... does this mean that I should have purchased an MC73110? Crud!


----------



## Madmac (Mar 14, 2008)

The MC73110 is intended for use in 3-phase brushless DC motor servo systems. It has an on board motion command interpreter. It might be useable in an AC motor system but there are better choices.

Madmac


----------



## xrotaryguy (Jul 26, 2007)

Madmac said:


> The MC73110 is intended for use in 3-phase brushless DC motor servo systems. It has an on board motion command interpreter. It might be useable in an AC motor system but there are better choices.
> 
> Madmac


Aah, so the MC33035 is the better choice then. Bob Brant's book, Build Your Own Electric Vehicle says that Motorola developed it specifically for use in EVs.


----------



## Madmac (Mar 14, 2008)

The MC33035 was designed to drive small 3 phase brushless DC motors with 3 hall effect sensors. It is a very simple fixed design aimed at low cost applications. As with the MC73110 there are much better choices for high power AC induction motor control, but they do require software.

Madmac


----------



## xrotaryguy (Jul 26, 2007)

Hmmm... well that kinda stinks. I was under the impression that this was a fairly powerful and purpose built EV microcontroller. Oh well, I am trying to build this as quickly as I can at this point, so I don't really want to learn how to program the darn thing on top of figure out board layout. Perhaps this should just be my 1st gen design. This way I can get the experience I need to physically build a controller and get my project on the road in the shortest time possible. Once I have a working version of this controller, and indeed a working car, I can look into building a controller with a programmable microcontroller.

So you say the controller is designed to work with a brushless DC motor with 3 hall effect sensors. It still works for a 3 phase motor right? Am I going to need 3 separate rotor position sensors? I guess I see now where the 3 sensor inputs go (Pins 4, 5, 6 or Sa Sb Sc).


----------



## xrotaryguy (Jul 26, 2007)

Ok, I have a couple more questions. I know, big surprise right?  I am trying to figure out how to set up the brake (pin 23 - not shown), 60/120 (pin 22), and the fwd/rev (pin 3) pins on the microcontroller. It looks like I just ground these pins or leave them disconnected depending on which feature I want from them. However, I can't figure out whether a closed circuit will give me what I want, or if an open circuit is what I need. For example, the 60/120 degree pin can be either grounded, or left ungrounded. But does grounding it give me 120 degrees, or does grounding it give me 60 degrees? I don't know, maybe I just need to wait until I have the board partially assembled to figure this out.

There is some symbolism on the spec sheet that I don't understand. I think that if I understood a couple of them, I might be able to discern which values do what for pins 3, 22, and 23. The first one looks like this:







. Why is there that line over the 120? does that indicate that closing the switch puts the switch in 120 mode? The other symbol that I'm a tad confused about looks like this:







I don't know for sure, but that looks like a circuit that is connected to a power supply through a resistor. given the schematic at the bottom of this post, having the switch open would send a signal to the Rotor Position Decoder. Having the switch closed would pull the circuit's voltage down to zero so that the Rotor Position Decoder sees no signal or zero voltage. Am I correct on this?

To put all of these symbols in context, here is part of the schematic from which the symbols were pulled.


----------



## MrCrabs (Mar 7, 2008)

The line above the 120 is a negative symbol.
So logic high = 60, logic low = 120

The resistors are Pull-Up resistors. When the switches are open, the input pin is connected to the +V, and sees logic high. When the switch is closed, the input pin now sees ground (because the voltage drops across the resistor), and the resistor limits the current that flows to ground.
They are called Pull-Up resistors, because the pull the signal high when the switch is open, this prevents the voltage on the input pin from floating, and giving false inputs.


----------



## xrotaryguy (Jul 26, 2007)

MrCrabs said:


> The line above the 120 is a negative symbol.
> So logic high = 60, logic low = 120
> 
> The resistors are Pull-Up resistors. When the switches are open, the input pin is connected to the +V, and sees logic high. When the switch is closed, the input pin now sees ground (because the voltage drops across the resistor), and the resistor limits the current that flows to ground.
> They are called Pull-Up resistors, because the pull the signal high when the switch is open, this prevents the voltage on the input pin from floating, and giving false inputs.


Ok then. Thanks. So that solves what to do with the 60/120 pin and the brake pin, but now what to do with the fwd/rev pin. The darn thing doesn't indicate which logic input does what. Perhaps I am supposed to assume that + gives me forward and 0 (switch closed) gives me 
reverse.


----------



## xrotaryguy (Jul 26, 2007)

Ok, I have finished my first AC controller board diagram. I realize that it is not drawn conventionally. This is only about the second such diagram that I have ever attempted, so I have a steep learning curve. I'll try to make the next one a little easier to read. I still need to go around and check current and voltage across several of the resistors too. Anyway, it's hosted at this location. 

http://www.box.net/shared/wegqm99s88

Hopefully you guys will be able to view it well enough. My photobucket is busy uploading a video right now. 

Please poke holes in this design as much as you can and let me know just how crummy it is. I'm sure that if I tried to test it right now it would probably not do much other than start smoking, but I wanted to get some feedback before ordering parts, doing more revisions, etc.


----------



## Madmac (Mar 14, 2008)

There is no defined level for the for/rev line as the direction will depend on how you wire the motor and sensors.

http://www.box.net/shared/wegqm99s88 look forward to the photo of it going bang!!!

Madmac


----------



## xrotaryguy (Jul 26, 2007)

madmac said:


> look forward to the photo of it going bang!!!


Hahaha your confidence is overwhelming. I will probably be taking video so that all of internet land can have a good laugh at my electrical skills. I'll try to keep the cloud from the fire extinguisher from obstructing your view. 



Madmac said:


> There is no defined level for the for/rev line as the direction will depend on how you wire the motor and sensors.


Ok, that makes sense. I was thinking more along the lines of, "It depends on whether or not I use a Honda transaxle," but same difference.


----------



## xrotaryguy (Jul 26, 2007)

I went down to Fry's Electronics today and rounded up a fist full of optocouplers, resistors, zener diodes, etc. Unfortunately, I forgot that I'm going to need some sort of hall effect sensor. What are you guys doing for this? 

I have read that it is possible to use some sort of feed back on the same wires that are being used to run the motor, but I don't think I can do that. My electrical skills are not quite there yet and my IC is not programmable. 

Some literature reads like the sensors simply pick up on the magnetic field outside the motor. Is that right? I wonder if my controller will actually recognize that type of signal. I don't know what kind of sensor I would use for that type of setup.

The only type of hall effect sensor I'm familiar with is the type that sits in the bottom of a distributor, the side of a cam shaft or behind an ABS brake rotor. 

Actually, I think I still have several Rx7 distributors lying around. Those have 2 hall sensors each. Wonder if those world work...

And one more thing. As I mentioned, I picked up some optocouplers today. Unfortunately, I didn't see any gate drivers that I liked. Since I am already using a device that isolate the IC from the IGBTs and that can be used as an amplifier, do I really need a conventional gate driver or FET? The optocoupler looks like it could do the trick on its own.


----------



## oregongt (May 15, 2008)

I am new here, sorry if I step on toes. The discussion quoted below is incorect in regards to DC voltage required for a Variable Frequency Drive (VFD). A little lesson: 480 volts RMS AC rectified creates approximately 480 volts DC on the VFD DC buss. The 480 3 phase on the line side of the VFD is the only voltage with peaks aproaching 600 volts. The inverter in the VFD creates a square sine wave with a flat peak right at DC buss voltage. I've been kicking around the idea of using a VFD because they have a built in programable logic controller that you can set all the variables such as locked rotor torque and voltage, accellaration curves, regenerative breaking curves, and many others. I've even ran across some liquid cooled ones that drive 150 HP motors on the job. 

PS. you guys have a wealth of info floating around in the forums, thanks.




Wirecutter said:


> Yeah, I did. What I found:





Wirecutter said:


> 1. It's tough to find a drive rated for over 3 horsepower that can run from single phase 220v. They're out there, but they're expensive, and then you have to have AC source big enough to drive it.
> 
> 2. Over about 10 horsepower, most VFDs require 3 phase 460v or better. To source that with batteries, you'd need something like 600v worth of DC. (Remember, that's 460v RMS - peak is higher)
> 
> ...


----------



## xrotaryguy (Jul 26, 2007)

Well, after lots of hunting and researching, I can not find much in the way of information on how to setup the rotor position sensors for the MC33035 chip. I assume that the processor wants to see the sensor inputs come in in a steady 1-2-3-1-2-3-1-2-3 fashion. I have drawn up a little diagram to illustrate what I am thinking about building. 



The reluctor wheel has 16 teeth, so the three sensors will each transmit a signal 120 degrees our of phase from one another. Here is a spec sheet on the sensors.

Hall Effect Sensors

So whaddya think? Am I way off base here, or is this basically what I need to build?


----------



## major (Apr 4, 2008)

oregongt said:


> A little lesson: 480 volts RMS AC rectified creates approximately 480 volts DC on the VFD DC buss.


Hi oregongt,

The DC bus voltage needs to be the value of the peak AC voltage synthesized by the inverter. So a 480 VAC inverter needs a DC input of 680 volts.

Regards,

major


----------



## coil_nine (Apr 22, 2008)

What instruments would you use to test the home-built 3-phase controllers? as you build it?


----------



## xrotaryguy (Jul 26, 2007)

coil_nine said:


> What instruments would you use to test the home-built 3-phase controllers? as you build it?


One good way to test things like your oscillator is with an oscilloscope. You could also test the voltage from your hall effect sensors (if applicable), etc. I realize that an oscilloscope is rather expensive new, but used ones aren't always so bad. I recently picked one up that was listed on Craigslist for $50. That's a lot better than the 500-1000 dollars or more that a new one might cost.

It depends on what PIC you choose too (assuming you're using a programmable chip). Some chip manufacturers sell hardware and software that can be used to test the programming on the chip itself.


----------



## xrotaryguy (Jul 26, 2007)

I now realize that the MC33035 chip that I was going to use is not intended for use with an AC induction motor. This despite a chapter in Bob Brant's book Build Your Own Electric Vehicle stating that it is designed specifically for use with an ACIM. At least that's how I read it.

I have been looking at a couple of chips that are intended for use in CNC machines. Check this link and this link for more info.

I am now looking into using an Atmel AT90PWM3.


----------



## aeroscott (Jan 5, 2008)

I talked to LTI yesterday , it started on gear reduction but soon switched to switched reluctance motors . check out my posts on direct drive efficiency improvements .


----------



## dfwheelman (May 15, 2008)

VF Control of 3-Phase Induction Motors Using PIC16F7X7 Microcontrollers

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1824&appnote=en012129

good info with source

are we close to posting a working schematic?


----------



## coil_nine (Apr 22, 2008)

aeroscott said:


> I talked to LTI yesterday ,... switched to switched reluctance motors .


too much info... must tighten band around head... The LTI post lead to another post and another and...

I quickly looked up switched reluctance motors (SWM) and in my snap judgment, they seem a great match for EVs. In the _future_. I have not found SWMs widely available now. Me, I'm going to start with small AC to learn, then try more stuff

Here is a quick, comprehensive SWM tutorial at freescale (g-d, I love the info at freescale):
http://tinyurl.com/2m65fg

link to matlab simulation:
http://tinyurl.com/5x5m5v

which bibleography leads to books at amazon.com:
http://tinyurl.com/6xcmbh
http://tinyurl.com/579ud4

and this summation from the amazon description:
"The geometry is beguilingly simple and everything about the motor and its control seems at first sight to be a gift to the production engineer. Yet the attainment of good designs and satisfactory performance is practically impossible by traditional design methods"

Read: SWMs are simple, but making them go is new and strange.

I think SWM has a very decent future with EVs because it is cheaper to make than either DC or AC motors. That initial cost thing will drive manufacturers and buyers.

It is cheaper because it has a solid rotor without any windings or magnets. It does not have any commutation, either mechanical (DC) or frequency (AC) to switch the current and make it go. SWM is a bone-stupid motor.

If one part of a system is stupid and cheap, then other parts must be smart and costly to compensate. In this case you need a smart, very fast controller to do the commutation. Now very fast computing power is cheap(er), and even DC controllers for EVs have a great deal of sophisitication. Using SWMs is a matter of altering a controller design, not inventing a whole new thing.

SWMs do have large drawbacks. They don't start well (a critical ability on hills from a stop). They can be noisy (but compare this to an ICE). They have large EMI from inverter. 

But they just look so sweet.


----------



## aeroscott (Jan 5, 2008)

the guy from LTI talked to me for a mear 20 minutes , I didn't have a chance to make notes as I could hardly stay with him . starting with the 3 phase induction will be hard enough . but the common ground is space vector modulation and the upcoming developments in the development tools .p.s. saw a 145 lbs. motor 795 hp 20,000 rpm on satcom site searched under sr motors.


----------



## dfwheelman (May 15, 2008)

Does a 3 phase motor less than $500 suitable for a 2 door car exist?

Anyone got specific make/model?


----------



## xrotaryguy (Jul 26, 2007)

I picked up a used ACIM for about $100. I don't know if you can buy a used one for as little as $500. The copper in such a motor might cost near that price. Ok, maybe that's a bit of an exaggeration, but you get the idea.


----------



## xrotaryguy (Jul 26, 2007)

I finally got around to building something - Not a speed controller yet, but something. I built a Dragon Rider for use on an AVR Dragon. The AVR Dragon is a device that can be used to program various chips, but it doesn't come with much in the way of hardware for interfacing with specifiv chips. The Dragon rider is a bag of parts and a circuit board that provides a number of sockets for various popular chips - once the bag of parts is soldered togehter of course. I'm pretty happy about this. I can finally get a chip and start programming. I will only be programming a chip for a DC controller but, at least this will get my feet wet for programming and building circuit boards. Here are the obligatory pics


----------



## etischer (Jun 16, 2008)

Im working on my own 3 phase controller. I bought a eurotherm AC drive. It is 2 hp, and can run on a 300 volt dc bus. I am using this drive as a firing circuit for 6 external IGBT packs which are rated 600 amps











I bought my drive for about 50 bucks. 










I bought 6 IGBTs for around 200 bucks

I should be getting started shortly, I already have my drive in hand, waiting for my motor and IGBTs. I've talked to an engineer that worked on the Curtis 3 phase controller design and he seems to think my idea should work. I also have quite a bit of experience with 3 phase motor controllers.


----------



## major (Apr 4, 2008)

etischer said:


> Im working on my own 3 phase controller. I bought a eurotherm AC drive. It is 2 hp, and can run on a 300 volt dc bus. I am using this drive as a firing circuit for 6 external IGBT packs which are rated 600 amps
> I should be getting started shortly, I already have my drive in hand, waiting for my motor and IGBTs. I've talked to an engineer that worked on the Curtis 3 phase controller design and he seems to think my idea should work. I also have quite a bit of experience with 3 phase motor controllers.


Hey etischer,

Basically a good plan. Suggestion: Start by using the drive on a smaller motor, .5 to 2 hp. You can run from the mains and don't have to worry about a big power supply or battery. Learn how the thing works. Get a scope and look at the signals. Learn the parameter settings. Learn how to do "closed loop vector control" using an encoder on the motor. You'll need this for vehicle propulsion.

Learn all you can about the stock drive before you put a big power inverter section together. See what you need in the way of gate drivers, current sensing, bus capacitance, snubbers, etc. You'll be less likely to blow those 600 amp modules by the dozens.

Regards,

major


----------



## etischer (Jun 16, 2008)

Thanks for the suggestion. I have a 2 horse motor to go with the 2 horse drive, I am going to use the 2 horse motor to run AC, power steering and an alternator. 

I was planing on trying to run the 2 horse motor with the external igbt pack before trying to run the 90 horse. I got my 90 horse motor today!


----------



## Madmac (Mar 14, 2008)

Circuit cellar has included the 100KWatt inverter design based on the Microchip DsPic device in this months magazine. It can be read on line at

http://www.circuitcellar.com/archives/viewable/217-Ponech_McIntyre_Krahn_Hall_Kasmer/index.html

along with links to all the support files

Madmac


----------



## JAFO (Aug 2, 2008)

you techie people make my brain hurt... 

glad I'm on ya'lls side... hehe

I may not get ANY of the posts in this thread, but I do appreciate the sharing...

Thanks


----------



## Bugzuki (Jan 15, 2008)

That article looks to have a lot more information then the previous one. I will have to try and read it. Thanks


----------



## aeroscott (Jan 5, 2008)

thanks for putting that up Madmac . I first saw it in Dec or Jan . We or should I say you guys brought so much learning to me and we are just getting started . I can smell the sr motors , nano iron cores .


----------



## judebert (Apr 16, 2008)

Unfortunately, all the code is still copyrighted, and can't be used in non-Microchip devices.


----------



## Madmac (Mar 14, 2008)

A good reason to stick with the DsPic devices.

Madmac


----------



## flame0086 (Aug 20, 2008)

Madmac said:


> Circuit cellar has included the 100KWatt inverter design based on the Microchip DsPic device in this months magazine. It can be read on line at
> 
> http://www.circuitcellar.com/archives/viewable/217-Ponech_McIntyre_Krahn_Hall_Kasmer/index.html
> 
> ...


Not sure if I'm bring a thread back from the dead, but I am a student at Western Washington University studying electronics engineering technology (EET). I plan building this inverter for my senior project. So far I haven't found any reviews on how well it worked. I figured that I would just replicate the design and do a review on how well it works.

For class right now I am working on the proposal. This project is not just for the EET program. Once complete, I will work the Vehicle Research Institute (VRI) to test the product. Both advisors from the EET and VRI are encouraging me to do the project.

As I said, right now I'm doing mostly research and a proposal. I'd figure when I get going on the project, I can post my progress whenever I get a chance.

Anyways, I just wanted to introduce myself and see what everyone thought of this project and the idea of me posting what I can here.


----------



## Wirecutter (Jul 26, 2007)

I'm glad to hear that someone else is working on it. I just read the article again. Apparently, the write-up was cleaned up a lot for the magazine article, too. The original submission had the schematics on 4 "A" size sheets.

I haven't posted much about my progress because there hasn't been that much, but it's my Winter project this year. I've got all the major parts, including the IGBTs and the driver boards, which were a bit difficult and expensive. A lot of the big power stuff only gets built about once a year, so you may face long lead times.

The C compiler for the processor they used is around $800 from Microchip. There's a trial version I got, but I'm not going to install it until I need it, because it's time-limited. (60 days, IIRC) I was also able to get the Labview code from one of the article's authors, but I haven't picked through it much.

I got the same coldplate used in the article, but I'm not going to use it. If it's used with this kind of IGBT package, the plumbing in the plate seems to be configured for a 2-by-2 layout, rather than 3 in line. Hence the odd spacing of the IGBTs in the article photo - they didn't want to drill the mounting holes through the cooling pipes. I'll probably machine my own plate to conform to the layout I'd like to use. Aluminum plate, copper pipe, and ball end mills are all available to me, and I have a small machine shop at home.

I've also got the Microchip control board and the high-voltage motor driver module. I've run the code from the app notes, but as written, the code won't turn the motor up to speed in constant-torque or any other closed loop mode. It's just not fast enough.

What I can say with a fair degree of certainty is that the controller featured in the actual article has _never_ been tested at anything approaching full power. It may have turned a motor of 1 HP or so, but as it's configured in the photos, it couldn't produce any real power without failing. Those bars would allow for too much noise on the DC bus - I'm told that "the pros" use bus _plates_ for high current distribution to keep the inductance down and capacitance up. Also, that coldplate hasn't had cooling water plumbed to it, and the hall sensors on phase 1 and phase 3 aren't installed correctly to measure the current, so the feedback wouldn't work as shown in the photo.

I haven't decided yet whether to respin the control board, as Camosun did, or just use the Microchip development board. A respin could shrink it down to about half the size, not counting the high power stuff. I'll be fabricating copper bus plates for the DC distribution, and I'm considering braided copper strap for the outputs of the IGBTs.

The August 2008 article is cleaned up, as I said, and there appears to be more info on the Canbus remote card. I'll be looking it over more this week. Thanks for waking up the thread - I'll post more as info develops.

-Mark


----------



## flame0086 (Aug 20, 2008)

I'm glad to hear you didn't give up on it. Good to know about the lead times on the IGBT and driver board. I didn't think about lead time (this is our first real application project). Where did you get your IGBTs from? I think I'll start looking into this tomorrow.

I never found a real review from the creators. However, I did run across a little forum where one guy said that they had an issue with noise from the induction motor feeding back into IGBTs. He said it could be solved using snubber circuits. Like I said, that was one guy and he wasn't part of the build team.

I emailed Camosun College's electronic and computer engineering department and an email mentioned in the competition article; never got a reply. One of the faculty here is emailing each of the students trying to get a response from them. 

A few years ago, another senior project was some sort of CAN Bus board that we put in a vehicle at the VRI (V32). My advisor mentioned something about using that CAN Bus board and send it over the controller. I haven't looked much into this, but it sounds like the open source inverter had a board to take in CAN Bus and deliver the information to the inverter USB, right?

I'll post more as I go, and as long as this project continues, I would like a forum like there were I can post my progress and reviews. Once my professor gets the website up and I have useful infromation, I'll post links.


----------



## Wirecutter (Jul 26, 2007)

I got the PowerEx parts from Richardson Electronics, which is simply the first place I found that had what I was looking for in stock. The IGBTs were available in a slightly improved (faster) version, so that's what I got. I had to buy the parts for the driver boards separately. They each have two DC-DC converters and two driver modules. Those can be hard to find, but I got them. I think I had to use 2 different sources, but I forget the second one. The "popcorn" parts for the rest of the driver boards were purchased from Digikey.

I think someone _here_ pointed out that the DC bus really needed *plates*, not just bars. I looked up a company that makes them, but they do it on a "custom" basis. I could have them provide bus plates, and it's possible they have a boiler plate design, but they don't have a real product line that you can select from. I talked to a guy from this company (guy and co. name I forgot) and he told me a lot about how they make the plates. He calculated some things with me on the phone, and said that if they were doing it, they'd use .062" thick plate. Between the layers, they'd put .010" nomex film. They punch the appropriate holes, and emboss the terminals on the different layers in such a way so that the terminals all end up in the same plane so they'll mate to the IGBTs. Then they'd apply an adhesive, put the assembly in a press, and bake it at around 350 F for several hours.

Anyway, the plates are supposed to allow for very low resistance and inductance, and provide a little bit of distributed capacitance. The problem with power spikes feeding back to the IGBTs is an alleged killer of expensive semiconductors. When you're switching hundreds of amps at tens of kilohertz, these things matter a lot. That's also why the driver boards have their own DC-DC converters. With all the voltage fluctuations caused by all those amps being switched, it's best to have a separate and robust supply driving the gates of the IGBTs. In order to control switching times, you also want a sturdy driver, which is provided with modules on the driver boars.

Like many things in the world of electronics, going to the extremes causes things to get a bit weird. Ask anyone working in very high power, very low power, or very high frequency. I'm not really one of those people, so I'm trying to absorb as much info as I can.

The other problem I think I'll eventually be faced with is a safe source of power for testing. 100 kW at 240 Vac exceeds the power company feed into my "laboratory" (home), so the only way to do it will probably be a massive bank of batteries. That's a long way off, though. I first need to get to the stage where I can even turn a (rather large) _unloaded_ ACIM.

-Mark




flame0086 said:


> I'm glad to hear you didn't give up on it. Good to know about the lead times on the IGBT and driver board. I didn't think about lead time (this is our first real application project). Where did you get your IGBTs from? I think I'll start looking into this tomorrow.
> 
> I never found a real review from the creators. However, I did run across a little forum where one guy said that they had an issue with noise from the induction motor feeding back into IGBTs. He said it could be solved using snubber circuits. Like I said, that was one guy and he wasn't part of the build team.
> 
> ...


----------



## flame0086 (Aug 20, 2008)

Wirecutter said:


> Like many things in the world of electronics, going to the extremes causes things to get a bit weird. Ask anyone working in very high power, very low power, or very high frequency. I'm not really one of those people, so I'm trying to absorb as much info as I can.


You and me both.

I'm under the impression that I can make the board here at the university. Testing high power isn't going to be a problem for me. We have an EV1 motor that we can test with, but I'm pretty sure we'll try a different motor first.

Thanks for the info on the IGBTs


----------



## Wirecutter (Jul 26, 2007)

flame0086 said:


> You and me both.
> 
> I'm under the impression that I can make the board here at the university. Testing high power isn't going to be a problem for me. We have an EV1 motor that we can test with, but I'm pretty sure we'll try a different motor first.
> 
> Thanks for the info on the IGBTs


 The EV1 motor is a good "get". My company uses a contract manufacturer to build our product. The CM's aqueous wash developed leaks in the water pumps, and it was better for them to replace the pump and motor assemblies, rather than just the pumps. They gave me the two 10 hp, 240v AC induction motors that came out, and the motors are in great shape. I'll start with those, but I can't rule out more searching for a better or more suitable motor.

-Mark


----------



## I-ESON (Oct 26, 2008)

summing up, which are the (avarage) overall cost differences (motor+controller+extras) between the 3 options?

a) AC induction motor
b) DC brushless motor
c) DC brushed motor

assuming i want to install a 50 kw motor for a Class-A mercedes?

What woul your components suggestions for such a conversion (motor type n power, controller, battery type, etc)?

rob


----------



## flame0086 (Aug 20, 2008)

I-ESON said:


> summing up, which are the (avarage) overall cost differences (motor+controller+extras) between the 3 options?
> 
> a) AC induction motor
> b) DC brushless motor
> ...


I really don't look at converting cars, we build our own in the VRI. In the past we bought our motor and controllers from UQM. There a great product but your going to spend $20k eaisly. We also buy 75+kW motors.


----------



## flame0086 (Aug 20, 2008)

Wirecutter said:


> I The C compiler for the processor they used is around $800 from Microchip. There's a trial version I got, but I'm not going to install it until I need it, because it's time-limited. (60 days, IIRC) I was also able to get the Labview code from one of the article's authors, but I haven't picked through it much.


I thought I read somewhere that you have to use Microchip's software for some encoding reason. Is this ture? I've opened up some of the code in a different program and I haven't seen any issues, but then again, I'm not looking hard.


----------



## kugmo (Oct 31, 2008)

Actually building an AC system from home is not that hard, even grade school students who has physic subject know about this, lolz, it is not hard but it is also not that easy.


----------



## rfengineers (Jun 2, 2008)

kugmo said:


> Actually building an AC system from home is not that hard, even grade school students who has physic subject know about this, lolz, it is not hard but it is also not that easy.


Oh, so you're saying that even a ruddy English schoolboy(RESB) can do it!

Unfortunately, we have been suffering from a serious RESB shortage here in Florida.


----------



## Turbotom (Jul 13, 2008)

kugmo said:


> Actually building an AC system from home is not that hard, even grade school students who has physic subject know about this, lolz, it is not hard but it is also not that easy.


 
I took quite a few physics courses earning my engineering degree, but I must have slept through the home built AC system because I don't remember that being covered.


----------



## etischer (Jun 16, 2008)

Here's my working prototype. I have a video of it turning my 90hp Siemens motor on my webpage... http://etischer.com/awdev/ I also got a 2 hp motor up to about 4000 rpm with it. It's running volts/hz mode right now. 

I'm hoping to have it run sensorless vector and under battery power in a few months. If I can get sensorless vector running properly, closed loop vector control will just be a flick of a bit and the hassle of mounting an encoder.









That is my firing signal to the IGBT, its a little droopy, I think mainly due to the thin wire wrap wire i used. 









That is the top half of my sine wave.


----------



## flame0086 (Aug 20, 2008)

^^^ looks good. I'm guessing that you arn't using the open source design in circuit cellar? Not sure if mention this somewhere else, but what if VFD? 

I'm still working on all the paper work my senior design class. I'm looking at different options than the Microchip dsPIC30F6010A with eighter a freescale or coldfire boards.


----------



## Mesuge (Mar 6, 2008)

Wirecutter said:


> What I can say with a fair degree of certainty is that the controller featured in the actual article has _never_ been tested at anything approaching full power. It may have turned a motor of 1 HP or so, but as it's configured in the photos, it couldn't produce any real power without failing. Those bars would allow for too much noise on the DC bus - I'm told that "the pros" use bus _plates_ for high current distribution to keep the inductance down and capacitance up. Also, that coldplate hasn't had cooling water plumbed to it, and the hall sensors on phase 1 and phase 3 aren't installed correctly to measure the current, so the feedback wouldn't work as shown in the photo.


Mark, have you seen their video/presentation, they are running quite a big motor, although at constant flux.. 
(you can use free VLC player if not playable per your default setting):
http://www.elex.camosun.bc.ca/programs/2007/driveteam/DriveTeamPresentationJune2007.flv

they have also somewhat updated the documentation (docs for regen section still missing):
http://www.elex.camosun.bc.ca/programs/2007/driveteam/driveteam.htm


----------

