# Best motor controller for the buck



## electric transport compan (Sep 17, 2010)

We are doing a conversion for our company vehicle. I am very familiar with the smaller Curtis, Alltrax, and Logisystem controllers. However, I am a novice when It comes to the higher end controllers and motors. I have heard a lot of good things about the Soliton, but for half the price I can get the 120v Curtis. I have a customer here in town, getting great results with the Curtis at about 50 miles per charge, with daily freeway use. We are on a tight budget for this project, but will be spending a lot of it on the controller. We have a great inside connection for AC drives and AC motors, but not for DC/AC inverters.  What is the best higher voltage dc controller for the buck? 

Until someone creates an affordable DC/AC inverter like Prius, DC is where we are heading with this project. 

The Prius inverter might work, we will be trying to gather the 280+ volts it needs to start testing it. (Sorted through years of info and wiring diagrams, but still no headway besides basic inputs and outputs.)

Prius Inverter









In conclusion, what's the best controller for the money?
I can get top of the line AC motors, so will the Prius Inverter work in a stand alone enviroment?


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## dtbaker (Jan 5, 2008)

if you don't need flexibility and just want something that works... Curtis has been rock solid for me. The 1221 for 120v is just great with 8" DC, or 1231 for 144v or higher amp performance with a 9" or 11" DC.


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## electric transport compan (Sep 17, 2010)

@ dtbaker,

Thank you for your input, I really appreciate it.

What kind of flexibility do others offer? Computer programmable? This project's second phase includes a diesel generator, I may need the flexibility. 

I was maybe looking into the AC curtis with the Regen capability, so I could send the generator power into the aux regen input (if it has one, I also hear they can get pretty hot). Does the Soliton or any of the big namers have regen capabilities? Not so much for diverting the generator power to, I will do that with a separate system, but for extending the range with the regen.

I wanted to take a solid 40-50 mile range system, then experiment with the generator from there.

Thanks again,

Brian


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## dtbaker (Jan 5, 2008)

electric transport compan said:


> What kind of flexibility do others offer? Computer programmable? This project's second phase includes a diesel generator, I may need the flexibility.


I don't know much about settable parameters for the Zilla, Solitron, etc. I think you can dial in amp limits, regen limits for the AC ones, etc. I dunno if any of those settings would be affected whether a generator is present or not since the controller just manages the volts/amps out, except for the AC regen. If you are talking AC its a whole different ballgame.

My personal feeling is that the cost/benefit from AC regen for 10-20% extra range is just not there compared to paying a little more for more batteries in a simple DC motor/controller.


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## electric transport compan (Sep 17, 2010)

I agree with you about regen, and for now will stick to a simple setup. This will keep most of the new problems possible limited to the generator hook up only. 

Thanks again

Brian


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## Tesseract (Sep 27, 2008)

electric transport compan said:


> I have heard a lot of good things about the Soliton, but for half the price I can get the 120v Curtis.


[disclaimer - I designed the Soliton1 hardware and so apologies in advance for the inevitable "sales spiel"]

You are comparing apples and oranges here. If the much higher power output and more advanced design of the Soliton1 isn't important or necessary for your project then it doesn't make sense to choose it over the Curtis, but if you are truly interested in who delivers the best motor controller value then the Soliton1 is seriously hard to beat. For example, the continuous power output of the Soliton1 is 4x higher than the peak power output of the Curtis 1231C, making it a relative bargain in that respect.

The Soliton1 is a 1000A controller while the 1231C is a 500A, so in that respect the relative costs are equivalent (ignoring the fact that the Soliton1 can deliver 1000A continuous with liquid cooling).

The Soliton1 uses a modern digital microcontroller design which allows you to change parameters and settings through a web page interface while the Curtis uses an analog comparator based circuit that was designed about 30 years ago and is about as dumb as a box of rocks.

Now whether any of the benefits of the Soliton1 are worth the price of admission is totally up to the individual, however. 

That said, we understand that most people simply don't need that much power and/or can't really justify the nearly $3k cost of the Soliton1 so we are about to release a half-power version of the controller - rated at 300V/500A - which will cost just a little more than a Curtis 1231C and hopefully render moot any argument as to which is the better choice for a smaller and/or budget EV conversion. Expected release date for the lower power controller is down to a few weeks at this point. [/sales spiel]




electric transport compan said:


> I can get top of the line AC motors, so will the Prius Inverter work in a stand alone enviroment?


Unlikely, as it requires the presence of many engine and powertrain sensors to operate and it's a rather small inverter, anyway. I've heard that someone has hacked into the ECM for the Prius inverter and managed to get it to sort of work, but I'm fuzzy on the details. A search on "hack prius inverter" turned up the same message posted to several forums which usually spells spam. Dunno. YMMV, literally.


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## PatricioIN (Jun 13, 2008)

Tesseract said:


> That said, we understand that most people simply don't need that much power and/or can't really justify the nearly $3k cost of the Soliton1 so we are about to release a half-power version of the controller - rated at 300V/500A - which will cost just a little more than a Curtis 1231C and hopefully render moot any argument as to which is the better choice for a smaller and/or budget EV conversion. Expected release date for the lower power controller is down to a few weeks at this point. [/sales spiel]


Ok, I don't want to steal this thread.. but I have to ask/comment.. What will the peak of this new controller be? 500a peak...? Why not even 600? Just a BIT more than the Curtis. Is there a thread I've missed where you talk about the new controller? I would love a Soliton in my next conversion, but just can't quite justify 3k for the controller alone.


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## Tesseract (Sep 27, 2008)

PatricioIN said:


> What will the peak of this new controller be? 500a peak...? Why not even 600? Just a BIT more than the Curtis. Is there a thread I've missed where you talk about the new controller?..


There isn't a specific thread about the 300V/500A controller, just several mentions of it here and there (not unlike this post).

As to why it won't be rated for 600A peak, that is mainly because IGBT modules come in distinct voltage and current ratings and the really big ones are only available in 1200V and higher voltages (and higher voltage IGBTs cost more). Also, we need to derate the IGBTs to accommodate thermal lag in the heatsink. It just so happens that the newest IGBT modules have temperature sensors built into them, though, so that may allow us to run closer to the stated current rating of the module, but that won't be known until real-world testing is done on the beta units.

That said, 600A is 20% more than 500A, which is "a bit more" than my interpretation of what "a bit more" means...


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## PatricioIN (Jun 13, 2008)

Tesseract said:


> There isn't a specific thread about the 300V/500A controller, just several mentions of it here and there (not unlike this post).


hmmm, well I will be anxiously awaiting further development on this less expensive version. I like everything I've read about the Soliton 1 - except the price. Isn't that always the case? And really, I just don't need 1000amps.


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## dtbaker (Jan 5, 2008)

PatricioIN said:


> And really, I just don't need 1000amps.


I don't want more than 500, and really only need 300, to avoid killing 100ah cells 'by accident'.

d


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## electric transport compan (Sep 17, 2010)

I agree the Soiltion is BA, and would love to have and use one. The thought of a smaller amp version is great. I would use them in my kits from now on. I used to use the higher amperage controllers like the 700 amp and above, but it was hard to keep foot off the pedal to save that double amp output I was using, double the amps, half the range for me. Once again, I think the Soliton is awesome, programmable, and liquid cooled, but will I get more range with the extra $1500? Does it have a current limit you can set, so I could set them for my customers? I know watching your ampmeter and keeping your power output low is fine for us ev'ers, but I need to look out for the average Joe.

Thanks for everyones input. I have heard so much good things about Soliton and will definitely purchase the 1000 amp version, and the smaller version once it is released.


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## Qer (May 7, 2008)

dtbaker said:


> I don't want more than 500, and really only need 300, to avoid killing 100ah cells 'by accident'.


Not a problem.

To begin with motor amps are higher or equal to battery amps so even 100 Ah-cells can handle motor amps as high as the S1's maximum 1000 Amps, but only up to a motor voltage up to 30% of pack voltage. Also, the Soliton allows you to set a limit to both maximum motor and battery current separatedly so if you limit the controller to a maximum battery current to, say, 300 Amps it will still allow you to set motor current to a higher current without risking your batteries.


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## electric transport compan (Sep 17, 2010)

Its definite, there will be a Soliton headed my way soon. 

Thanks everyone for your input.


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## dtbaker (Jan 5, 2008)

Qer said:


> To begin with motor amps are higher or equal to battery amps so even 100 Ah-cells can handle motor amps as high as the S1's maximum 1000 Amps, but only up to a motor voltage up to 30% of pack voltage.



perhaps a little remedial lesson in amps 101? I don't understand....
If I have a 8"DC motor, with a 400 amp limit, and a 120v pack of 100ah batteries... How much can I pull when?

d


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## electric transport compan (Sep 17, 2010)

Are you using an ampmeter to watch your current usage? If not you need to, this will show you how much your actually using. Also, you will be able to try yo use the throttle less to save battery power. I'm sure more threads are coming our way....


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## dtbaker (Jan 5, 2008)

electric transport compan said:


> Are you using an ampmeter to watch your current usage?


uuuhhhh, yes. I do have an ammeter. My question is just to gain a better understanding of how 'motor amps' can be different than 'battery amps' so I can understand how a new-tech expensive controller capable of 1000 amps would do me any good versus a more modest old one that is limited at 400amps (within my motor rating and under 5C burst rating for batteries).


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## major (Apr 4, 2008)

dtbaker said:


> My question is just to gain a better understanding of how 'motor amps' can be different than 'battery amps' so I can understand how a new-tech expensive controller capable of 1000 amps would do me any good versus a more modest old one that is limited at 400amps (within my motor rating and under 5C burst rating for batteries).


Hi dt,

Seems like I, or Tesseract, have explained this multiple times. It took me longer to search this down than it would have to written it over again. There really should be some type of index on the site. Oh well, look at this thread, http://www.diyelectriccar.com/forums/showthread.php?t=46017 Posts #8 and 9 in particular.

All controllers use motor current as the "current limit" rating. But with the newer ones, you can also set a battery current limit. This allows you have high motor current at low RPM yet not overtax your batteries at higher speeds.

Regards,

major


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## rillip3 (Jun 19, 2009)

major said:


> Hi dt,
> 
> Seems like I, or Tesseract, have explained this multiple times. It took me longer to search this down than it would have to written it over again. There really should be some type of index on the site. Oh well, look at this thread, http://www.diyelectriccar.com/forums/showthread.php?t=46017 Posts #8 and 9 in particular.
> 
> ...


Okay, to make sure I understand, let me try and sum up. The controller uses pulse width modulation (PWM) to make it so that your 200v (or whatever) pack is delivering an appropriate amount of voltage (say 100v) to accomplish the work being asked (current work load). This difference in the actual voltage delivered to the motor and the nominal pack voltage is the reason for the difference between battery amps and motor amps, yes?


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## dtbaker (Jan 5, 2008)

major said:


> ...with the newer ones, you can also set a battery current limit. This allows you have high motor current at low RPM yet not overtax your batteries at higher speeds.



ok, starting to make sense.... so with a 'modern' controller i might get better acceleration off the line, still without killing batteries from 3C+ draw.


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## major (Apr 4, 2008)

rillip3 said:


> This difference in the actual voltage delivered to the motor and the nominal pack voltage is the reason for the difference between battery amps and motor amps, yes?


In simple terms, you pretty much have it. Difference, eh, more of a ratio type of thing. Similar to the transformation ratio primary to secondary with AC transformers, or speed torque ratios with gear sets. Neglecting some minor loss in the controller (or transformer or gear set), power in equals power out, in all these cases.

Regards,

major


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## EVfun (Mar 14, 2010)

dtbaker said:


> perhaps a little remedial lesson in amps 101? I don't understand....
> If I have a 8"DC motor, with a 400 amp limit, and a 120v pack of 100ah batteries... How much can I pull when?
> d


My ADC 8 inch doesn't know it has a 400 amp limit 

I'm not sure of all your settings so I will use mine. I have my Zilla set up for a limit of 300 battery amps and 600 motor amps. The pack minimum voltage is 105 volts but I've never threatened that one so it is not relevant. My pack is 40, 60 amp hour TS cells. At 300 amps the pack sags to 118 volts (117.xx.) 

I can pull a maximum power of 300 amps at 118 volts from the pack so my peak power is limited to 35 kW. I don't have a tach so the following rpm numbers are approximate. On a full throttle takeoff the battery amps increase from 0 to 300 from 0 rpm to 2100 rpm. During this time the motor is at 600 amps (about 95 ft-lb. of torque) and the voltage on it is increasing. At 2100 rpm the motor is seeing 59 volts at 600 amps and is at the start of peak power. From 2100 rpm to 4200 rpm the pack is putting out peak power, a full 300 amps while the pack voltage hangs at 118. The motor voltage is increasing, while the motor amps are decreasing to keep the watts being fed to the motor the same. At 4200 rpm the motor is seeing 118 volts at 300 amps, the top end of the motors peak power range. Torque is down to about 50 ft-lb. at 300 amps. As the motor rpm rises further the battery amps is the same as motor amps as the transistors in the controller are fully on (at full throttle.) The amps, and power, are declining. The motor is above its peak power range.


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## dtbaker (Jan 5, 2008)

EVfun said:


> My ADC 8 inch doesn't know it has a 400 amp limit
> I have my Zilla set up for a limit of 300 battery amps and 600 motor amps. My pack is 40, 60 amp hour TS cells. At 300 amps the pack sags to 118 volts (117.xx.)



this just doesn't sound good for 60ah cells..... I thought that brief 3C was ok, but over that is kinda asking for trouble, isn't it?


d


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## rillip3 (Jun 19, 2009)

major said:


> In simple terms, you pretty much have it. Difference, eh, more of a ratio type of thing. Similar to the transformation ratio primary to secondary with AC transformers, or speed torque ratios with gear sets. Neglecting some minor loss in the controller (or transformer or gear set), power in equals power out, in all these cases.
> 
> Regards,
> 
> major


Sorry, I meant difference in the normal English language sense, not the mathematical, strictly subtraction sense; I should have picked a more precise word. Thanks for digging that up, I have now learned something new.


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## EVfun (Mar 14, 2010)

dtbaker said:


> this just doesn't sound good for 60ah cells..... I thought that brief 3C was ok, but over that is kinda asking for trouble, isn't it?


It fits well within the specs of the newer (2010) LFP and LYP cells. I haven't noticed any issues but I haven't ever discharged deeply. Until I get my fuel gauge wired up I have been keeping trips short. I have repeatedly felt every post after a drive and none have ever been warm. My cells manufacturers sheet indicates they where built in Feb. 2010. I have been considering cranking the Zilla up to 360 battery amps. That would take my power up from about 39 horsepower to about 46 horsepower.


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