# Why a motor controller?



## AlexZ (Aug 26, 2008)

Why do we use motor controllers for EV? sorry if im being extremly ignorant.

But for very basic conversions, with manual transmision, we dont use the following of the features which a controller could gives:

-motor in reverse, we dont need this since our trani does this.
-regenerative breaking, not practical for a basic conversion.
-speed controll, couldnt this be just done with a variable resistor that handles the correct ammount of power?

Or just a very basic DIY controller that manages the RPM/torque-Volts/AMPS?

Thanks,

Alex.


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## TheSGC (Nov 15, 2007)

Do a forum search and you should find a similar thread. A controller is a must because without one, there is no way to control the motor.

Resistive controllers just do not exist for the high AMPs requirements of an EV because they are the most inefficient way of controlling power. Probably 50% efficient and generate motherloads of hear. More than your oven probably ever could.

Most DC controllers do not have regen breaking, and most also do not reverse the motor. The volts/amps control is done by Pulse Width Modulation, and this controls the speed of the motor and limit the amps, with proper measurement. These are also usually 95-98% efficient.


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## OHM (Jun 30, 2008)

Contactor Controllers are not that inefficient, only about 5-10% if designed properly and although speed control is not as sophisticated they are more than ample to suit many EVers.
Im getting a 5 speed or maybe an 8 speed 72V CC custom made with silver coatings and this will be enough for me for normal commuting, like freeway and climbing some hills. It will be rated at 1200amps which is what I need for direct drive and will have the necessary precautionary shutdown safety switches with separate connections and switches for emergency lighting.
Contact me if anyone is seriously interested as Im getting some made now by someone who has little time to be bothered and I can maybe help with some of the basic queries.
Please note the CC Im getting is a 72v one as this voltage is versatile and affordable for beginners and those after a simple system with less downtime due to some of the problems suffered by mass produced modern controllers, CC just simply work and have been used for over 100 years. They are like a carburettor vs computerized Fuel injection. 
Also all related 72v parts besides wiring is cheaper. 
Best battery combinations for small vehicles is 12 x 6v GC type batteries (eg. T-105, us220 etc) floodeds or SLA.
Maybe even paralleled 6v x 2 x 12 for 24 battery packs for longer range and heavier vehicles using a gearbox.


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## Chris Sandberg (Sep 13, 2008)

Hello everyone and OHM, Is the GE ev1 control an early version of a controller but still using the CC (contactor control ) type of system. I have a GEev1 and am wanting to use it as a starting point for my project. Does anyone have one in use or how it is wired and controlled. Is it possible with the right combination of motor and battery voltage, it is rated 24-48vdc? My ev car is a Geo Metro.
Thanks Chris 
A newbie/beginner


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## OHM (Jun 30, 2008)

Is there a forum for gm ev1 enthusiasts? Im sure there is and could be a good starting point for your good little project.


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## major (Apr 4, 2008)

OHM said:


> Is there a forum for gm ev1 enthusiasts? Im sure there is and could be a good starting point for your good little project.


Hey OHM,

He has a GE EV1 controller, not a controller from a GM EV1. I've seen it confused before. Completely different animals.

Regards,

major


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## major (Apr 4, 2008)

Chris Sandberg said:


> Is the GE ev1 control an early version of a controller but still using the CC (contactor control ) type of system. Thanks Chris
> A newbie/beginner


Hi Chris,

That GE EV1 controller is a PWM type controller. If you have the whole control board, there will be contactors there for main line, by-pass and maybe auxiliary stuff, like pump motor, since it most likely came off a forklift.

Regards,

major


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## OHM (Jun 30, 2008)

fancy that couldnt GM use a different name for that wonderful car


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## major (Apr 4, 2008)

OHM said:


> fancy that couldnt GM use a different name for that wonderful car


In preproduction it was called the Impact. I guess that sounded too much like a car for crash-test dummies.


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## Chris Sandberg (Sep 13, 2008)

Hello Major and DIY group, Thanks for the clarification on the GE controller. By the way I am the same guy that has the motor that you have helped me trouble shoot but I have'nt goten back to it yet. Does anyone have the terminal input wiring of this GE controller? I want to test mine with my motor but do not have the wiring diagram. Anyone using one or know of someone using one that could help would be Great.
Thanks Chris 
a newbie/beginner


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## TX_Dj (Jul 25, 2008)

The others have covered this quite well. I want to throw in my $0.02 as well, just in case you have further questions based on their answers... maybe my answers will shed some light, maybe they're entirely useless, I dunno... but here goes. 

1) Motor in reverse- This is actually a function of "reversing contactors", and not the controller. Their purpose is to "re-wire" the motor so that when the controller provides power to it, it turns in reverse instead of normal rotation. Some EVs don't use transmissions with a reverse gear, or in some cases the EV does not need to exceed the speed that one gear in the transmission provides. In the latter case, some converters actually remove the gearshift lever and leave the transmission permanently in 2nd gear. In this case, reversing contactors are very helpful.

2) Regen - Regen is only handled by controllers that can handle regen... this doesn't apply to all types of controllers, but for motor types that work well with regen it is common to find this functionality built into the controller.

3) Speed control - a variable resistor is still a resistor. It will pass some current, and bleed the rest off as heat. Very inefficient. Early EVs used resistive speed controls and contactor controllers which switched voltages to provide higher speeds (i.e. reconfigured the battery pack to provide 12, 24, 36, etc up to the max). In either case, there is nothing that provides a current limiting for the motor, letting the motor instead seek its own current draw. The closer you are to 0 RPM, the more the motor looks like a dead short to the batteries. With a contactor controller, you may limit to 12v when starting out, but if the motor wants to try and pull 3000A from the batteries, it's going to try to do that... in turn, burning itself up, possibly welding the contacts on the contactor, possibly melting down the battery terminals or cables, or causing internal damage to the batteries. We use PWM (pulse-width modulation) controllers these days, and these provide "pulses" of power to the motor, along with a current limitation... this allows much more finite control than a contactor controller, with far better efficiency than a resistive controller.

Efficiency is one of the keys to range and performance.

No worries about your question- the only "dumb questions" are the ones that aren't asked. Everyone has to learn somehow, and asking questions is one of the best methods to learn!


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## ga2500ev (Apr 20, 2008)

AlexZ said:


> Why do we use motor controllers for EV? sorry if im being extremly ignorant.
> 
> But for very basic conversions, with manual transmision, we dont use the following of the features which a controller could gives:
> 
> -motor in reverse, we dont need this since our trani does this.


This is true. Most motor controllers do not reverse the motor. In fact with most high speed, high voltage motors, they are tuned, or advanced, so that they have optimal rotation in one direction only.



> -regenerative breaking, not practical for a basic conversion.


It's not that it isn't practical, it's just the fact that the series wound DC motor is challenging to generate regen for.



> -speed controll, couldnt this be just done with a variable resistor that handles the correct ammount of power?


Now this is the critical argument. A variable resistor would convert all of the wasted energy to heat. This gives you two massive problems. First is the fact that you have to disappate all that extra heat. The other is that the energy that generates that heat is totally wasted, which will severely cut into your range for your vehicle.



> Or just a very basic DIY controller that manages the RPM/torque-Volts/AMPS?


But that's what a PWM controller does. By pulsing the full power of the battery and controlling the width of the pulse, the controller can generate any percentage of full voltage as an average of the pulse. Also with precise measurement, the current draw of the motor can be limited simply by cutting the pulse short if the current is overloaded. This manages all of the parameters you list above.

Truthfully a PWM controller is the simplest controller. That's why everyone uses it.

ga2500ev


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## OHM (Jun 30, 2008)

If PWM controller is simpler then does it last as long as a CC?
Looking at the forums for sometime it seems the PWM controller is less reliable than trusty old CC. I could be wrong but how did those old Detroit electric tanks and others last so long without failure?

Also the motor Im using is designed to work from 24v to 72v its designed as a variable low voltage motor which might help compared to 72v-144v motors.

My CC setup will also benefit from battery packs in series parallel (eg. 36v and 72v) to help with take off and cruising.

I was lucky enough to just recently get the motors Ive been after for a while in N.O.S. (2 of them as they where too good to refuse) and the only problem is the lack of info on them. Can anyone help to identify what is A AA Y YY on the following pic?


















It an amazing modular motor design with the iron octagonal housing section made up of layers of octagonal flat washers that can be increased if making longer motors saving on castings. The commutator is flat also like on the Lynch motors saving space.
The washer sections appear to be designed as quad sided then combined to form one octagonal washer by fusing with TIG welding.
So the the only money on casting was spent for the alloy ends, brush holders (cast not tin like others). The C-like flat washers would
save a packet on solid housing designs.


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## ngrimm (Oct 19, 2007)

I used serial/parallel contactors before I got a pwm controller working. They work but it's certainly not as smooth. Have you ever had to pour gas down a carburetor to keep an engine running? That's what contactors remind be of. The arcing of the contactors at night made me feel like Batman. Or was it Frankenstein? I don't think I would want go back but hey, have fun whatever you decide to do!


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## OHM (Jun 30, 2008)

Oooohhh I like the sound of this rawness with lightning evil EVs terrorizing those smelly smoky urban jungles igniting the fumes in the air with sparks. 

Now can anyone help with the alphabet soup on my motor?


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## Qer (May 7, 2008)

OHM said:


> If PWM controller is simpler then does it last as long as a CC?
> Looking at the forums for sometime it seems the PWM controller is less reliable than trusty old CC. I could be wrong but how did those old Detroit electric tanks and others last so long without failure?


In general there's no reason why a silicone based controller shouldn't last as long as an old-time Frankenstein controller, in fact sine there's no moving parts and no arcing it has the potential to last virtually forever. What I've read in this forum (still only dreaming the EV-dream myself, unfortunately) is that some controllers simply either are of a low quality (for example Kelly) or badly constructed (for example some Curtis controller) but if you steer clear of the rotten ones it seems that the controllers are generally very reliable. 

Also, when it comes to modern motor controllers for industrial designs they tend to all be silicon based today and they're expected to be maintenance free. If they aren't, that company's not gonna sell many controllers in the future so for them quality is first priority. My guess is that the China based companies that has realised that the EV-market is an expanding market unfortunately has a focus on low price rather than reliable design. I guess it'll change in the future when the rumour spreads.

That said, I think the idea of going with the Frankenstein controller at least to begin with is a good idea. If nothing else it'll lower the initial conversion cost and then you can always change to a silicon based controller later on + that you can always keep the Frankenstein thingie as a spare part in case you have a total controller breakdown in the future. And, well, the idea of arcing and bzzing sounds is pretty cool. Perhaps you should go for the mad scientist look and do the instrumentation in the same style? Efficient? Not a bit. Cool? Definitely!


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## Chris Sandberg (Sep 13, 2008)

Hello OHM, I am new at this EV stuff also but I will give it a try. The reading that I have done and looking at the pictures tells me that AA-A are probably the brushes and this would be easy to check by a visual inspection to see if the terminal lugs are connected to a wire that goes to a set of 2 brushes 90* apart from each other. As to the other set Y-YY these will be the field windings if the first inspection checks out as I say. Do you know if this is a series wound motor? Also I have been to the public library and found some books on electric motors maintenance and troubleshooting with a chapter on DC motors, this may be a good thing for you to think about it helped me understand what some of the talk on this forum is about. I hope this answers your question and good luck on the CC control Idea.
Chris 
a newbie/ beginner


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## OHM (Jun 30, 2008)

Thanks fellas Steampunk it is, Ill make up for it by using better batteries at least. Ive been thinking of lithiums from a non TS source but will wait like others are and also LifePo4 doesnt put out the amps needed for DDrive.

After inspection and comparing to the Warp ones I figured the A AA and Y YY where as described just needed confirmation case I buggered it. Also wanted to make sure as I want to run the brushes in at 24v.


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## Windy (Jun 27, 2008)

Hello Everyone, In reply to Chris Sandberg's question about the GE-EV1 controller a very good reprint manual and step-by-step operation sequence is available from Flight Systems Industrial Products. Also included is a typical installation wiring diagram. They have a web site. Hope this helps Windy


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## 68 Electric Kadett (Oct 24, 2008)

Chris Sandberg said:


> Hello Major and DIY group, Thanks for the clarification on the GE controller. By the way I am the same guy that has the motor that you have helped me trouble shoot but I have'nt goten back to it yet. Does anyone have the terminal input wiring of this GE controller? I want to test mine with my motor but do not have the wiring diagram. Anyone using one or know of someone using one that could help would be Great.
> Thanks Chris
> a newbie/beginner


I have a EV-1 controller - and am troubleshooting my car controller system. I purchased an GE Ev-1 manual from Fight Systems Industrial. http://www.fsip.biz/ I got the manual in about a week cost was close to $30 with shipping. I just got the manual today so I will let you know how helpful it is.


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