# AC Controller



## frodus (Apr 12, 2008)

whats the question?


----------



## Jeff (Sep 25, 2008)

Jokerzwild said:


> I have a Mitsubishi 200 (400v) Controller:
> http://www.meau.com/eprise/main/sit...ies=000152002520115&Line=00015200252011520735
> 
> All schematics show AC input but I have found the following:
> ...



I made the assumption that you wish to power this controller from a DC source.

Yes, you can power this industrial AC controller from a HVDC source. 
As you can see in the technical block of the controller FRV200E (page 14), the 3ph AC supply is converted to a HVDC rail to power the IGBT's.

A semiconductor fuse and snubber caps across the DC input are critical to decoupling your DC supply if you chose this route.

Have Fun!


----------



## jackbauer (Jan 12, 2008)

You would also need a precharge circuit to bring the caps up to power before connecting the dc bus.


----------



## frodus (Apr 12, 2008)

And hopefully you can disable AC Line Detection, some drives won't start because they don't detect any line voltage coming from the AC side.


----------



## Jokerzwild (Jun 11, 2009)

I think thats why you need to change the jumpers, i think.


----------



## frodus (Apr 12, 2008)

Joker,
CAN YOU PLEASE STOP POSTING NEW THREADS every time you have a motor question, or inverter question..... keep them in your original threads, it makes it much easier for people to get an idea of what you're doing if they can go back through the thread and read it.


Next thing,
After reading these posts you started:
http://www.diyelectriccar.com/forums/search.php?searchid=168485
Its apparent that you have no clear direction about what you're doing.... and don't seem to know much about motors or AC drives...

Getting a VFD working off of DC is no trivial task, many have tried, many have failed and given up. Its not just "plug and go".

I'd be asking the manufacturer about this, not us.... we're just guessing, but the manufacturer will know how to get it working. See if there a Rep in the area that could shine some light on how to get the drive working on DC.


----------



## Jokerzwild (Jun 11, 2009)

Your right I do not know much about AC drives if I did I wouldn't be asking. 

I am going this rote to learn, if I fail its no big deal because I didn’t pay much at all. I know which motor and controller I am going to use. Now I will be purchasing batteries soon, this I do care about because if I have to change to a DC set up I will need more C then the AC system. 

Thanks to all that have went out of there way to help me out.


----------



## frodus (Apr 12, 2008)

We're not the ones to be asking about the drive, that should be a question for the manufacturer.... I haven't seen anyone here that knows anything specifically about that particular drive.... so they wouldn't know if you can in fact hook it to DC directly without problems ....

We are pretty sure that most AC drives are able to, but it might lock you out if you bypass the AC Mains. Also, the drive controls may be powered off of the AC mains, and not the DC bus.... 

Just be VERY safe when powering up for the first time..... I'd hate to see you get hurt.


----------



## Jokerzwild (Jun 11, 2009)

Thanks and I agree 100%, I almost just abandoned this due to the fact of 600v DC just scary. Thats why I was asking if I can somehow make this system a lower voltage drive, but I have learned there are a lot of advantages with high voltage (dis-advantage death).


----------



## samborambo (Aug 27, 2008)

Far more people are killed from low voltage (60V - 300V) than high voltage. It's a manageable risk if you're aware of what protection you need to put in place.

For the same type of cell, high voltage, high impedance packs are safer in a short circuit than low voltage, low impedance packs because the fault current is lower. A high voltage string of TS 40Ah can still only develop around 20C in a dead short circuit meaning a fault current of 800A. A low voltage string of 200Ah cells would have a fault current of 4000A. Remember, its current that causes copper bus bars and terminals to vapourise like dynamite, not voltage.

With an unprotected high voltage pack, you're at risk of a hand-to-hand shock. With a protected HV pack, there's very low risk. With a low voltage pack, you're at risk of severe burns, fire and shrapnel from a dead short from, say, dropping a spanner across the terminals. Fusing won't help you if the fault occurs within the pack string.


----------



## Jokerzwild (Jun 11, 2009)

Once again thank you so much:
I am going to go forward with this and I will keep you all up to date:
If I fail you will be in my will


----------



## jackbauer (Jan 12, 2008)

This may be of interest:
http://www.youtube.com/watch?v=LsAIqnqKulE


----------



## Zuglet (Oct 17, 2009)

Jokerzwild said:


> I have a Mitsubishi 200 (400v) Controller:


It's my understanding that if an AC controller does not have a means of monitoring the shaft position, the controller is not suitable for an EV. This controller does not appear to have that capability.

For an EV, the desired speed of an AC motor should be determined by the voltage applied to the coils. Then, the frequency is determined by the feedback from sensors on the motor shaft. The controller always knows the speed and shaft position of the motor.

In an industrial controller, the voltage is always at the max and the speed is controlled by the frequency. The controller has no way of knowing the speed or shaft position of the motor. This is too inefficient for an EV -- there will be too much slip -- plus you won't have regenerative braking.



jackbauer said:


> This may be of interest:
> http://www.youtube.com/watch?v=LsAIqnqKulE


This video illustrates what I'm talking about. He appears to be using an off the shelf Baldor motor with no feedback provided to the controller. The whining noise that you hear should not be that loud, but it is since the peak to peak voltage is at the max even at low RPM. I would guess that the motor is a current hog even under minimal load and low speed. Also, with no motor feedback to the controller the vehicle operator must use extreme care with the speed control since it will be controlling frequency rather than voltage. If the frequency is too far ahead of the motor speed, the car might not move.

Alternately, if the controller varies the voltage and monitors the motor shaft, there will be no slip and minimal current under low load. In this video, you can hear the sound of an Azure motor during acceleration and then regenerative braking...

http://www.zuglet.com/video/index.php?video=wheels

Then again, I could be completely wrong about all of this.


----------



## major (Apr 4, 2008)

HI Zug,

A few things are not quite right here.



Zuglet said:


> It's my understanding that if an AC controller does not have a means of monitoring the shaft position, the controller is not suitable for an EV.


He has a controller for an induction motor. It is rotor velocity which is needed, not position. Of course if you had position, you derive velocity from that. But usually an encoder is used giving a pulse train which then indicates frequency and consequently RPM.



> For an EV, the desired speed of an AC motor should be determined by the voltage applied to the coils. Then, the frequency is determined by the feedback from sensors on the motor shaft. The controller always knows the speed and shaft position of the motor.


Actually the speed is more dependent on the frequency, but the voltage must be carefully controlled to yield the proper torque at that frequency.



> In an industrial controller, the voltage is always at the max and the speed is controlled by the frequency.


No, industrial induction motor controllers vary the voltage to the motor as well as the frequency. Often times called VVVF, Variable Voltage Variable Frequency. But sometimes just variable frequency drives, VFD for short. But always the voltage is altered in conjunction with frequency, mostly in a V/f ratio.



> The controller has no way of knowing the speed or shaft position of the motor. This is too inefficient for an EV -- there will be too much slip -- plus you won't have regenerative braking.


For simple speed control, like often done in industry for machine drives, pumps and fans, simple V/f is suitable and in fact very efficient and capable of regeneration or dynamic braking. 

Regards,

major


----------



## Zuglet (Oct 17, 2009)

major said:


> No, industrial induction motor controllers vary the voltage to the motor as well as the frequency. Often times called VVVF, Variable Voltage Variable Frequency. But sometimes just variable frequency drives, VFD for short. But always the voltage is altered in conjunction with frequency, mostly in a V/f ratio.


Thanks Major, I did not know this. As you can tell by my post count, my feet are barely wet.



major said:


> It is rotor velocity which is needed, not position.


Again, I know that I'm kind of green here, but I was under the impression that my Azure controller knows the exact shaft position so that the correct electrical angle of the three phases is given to the motor. Also, when I dismantled the Ford Siemens motor, the quadrature encoder appeared to match the windings in the motor. Is seems to me that the position of the shaft is critical for the controller to know thereby avoiding slip of any kind. As you said, motor velocity (and consequently frequency) is derived from the shaft position.

Sorry I if misguided anyone on this.


----------



## bliksem (Aug 3, 2009)

Also slip is not a bad thing with an AC induction (asynchronous) motor.
Torque is a function of slip on an asynchronous motor. If the rotor turns
at exact same speed as the field then zero torque will be produced.
Too much slip and you may overheat the motor. Modern inverters can sense
this and correct this by manipulating the current , voltage and or frequency. 

An encoder is desirable but not critical.

The problem with industrial inverters are they are bulky and the voltage issue.
The largest inverter that I have seen that can run on 240V is 30Kw .


----------



## JustinUther (Oct 18, 2009)

I just signed on to this forum because I was reading some of the posts here and had to give my two cents. I've been working with AC drives for several years now in the drilling industry. For a couple of years I would teach classes on how to configure the converter/inverters to run various motors. We use them to power many different size motors for various applications. Cranes, draw-works (basically a big block and tackle), high pressure/high volume pumps, tubular handling equipment, conveyors etc. That is where I began to get the idea of doing an AC conversion. 
I figured if I can set up these drives (controllers) to do what I want how I want it done then it will be easy to apply that to a drivable application. There are several drive manufaturers whose products I've used. Two of my favorite are Siemens and ABB. Both have drives that can be used with various supply voltages and can be set up to run a various motors. Because they are fully configurable either can be set up to run pretty much any motor I came accross. I know caost will be a factor but aside from that is there any reason that I don't see any mention of using these?


----------

