# The most powerful controller for 144-255V system?



## circuit (Jan 16, 2012)

Hello,

I am looking for a 3 phase motor controller with this spec:
Voltage 144V
Battery current 700A
Phase current 2400A

Or:
Voltage 250V
Battery Current 400A
Phase current 1400A

Or: two twice smaller ones.


Was looking at Kelly's "high power" models, but not exactly what I need (low on voltage). And I don't like selecting from one....

So, anything you could suggest?
Also I will need a motor(s)...


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## Tomdb (Jan 28, 2013)

so a 100kw controller.

What do you want to power with it? Also the controller will depend on your motors so choosing motors will be usually the first step.

else rhinehart pm150

http://www.rinehartmotion.com/uploads/5/1/3/0/51309945/pm100-150datasheet_1.pdf


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## circuit (Jan 16, 2012)

Rinehart looks too small... And omg, too expensive.

Priority would be for PMSM/BLDC, but brushed is also an option.


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## Tomdb (Jan 28, 2013)

Budget, and specs then.

Because 100kw is not alot to go on.

Example, rpm bands torques ect.


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## circuit (Jan 16, 2012)

We can work with many types of motors. Let's say RPM is anywhere 3000-10000 range.
The motor should be powerful enough to hold 80kW 10sec peaks and 40kW average at 30% RPM.


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## Tomdb (Jan 28, 2013)

EMRAX 228 Medium Voltage with controller that works with it is a good light weight option. 

http://www.enstroj.si/Electric-products/emrax-228-motorsgen.html

However this will set you back around 6-8 thousand euro's.

It all comes down to, what do you want it to cost. Plus are your expectations realistic for what you want to spend.


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## circuit (Jan 16, 2012)

Emrax medium voltage will give 3000 RPM at 250V.
If we calculate peak power at:
* 250V battery
* 340A peak current
* 30% RPM
We get ~18kW only. Which means we will need 4 such motors to get closer required levels.

Also Emrax is totally overpriced for what it is. Our budget for motor(s) + controller(s) is 6k€.


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## jhuebner (Apr 30, 2010)

circuit said:


> Also Emrax is totally overpriced for what it is. Our budget for motor(s) + controller(s) is 6k€.


Is asynchronous motor + DIY controller an option? If so, see below.

I'd always opt for higher voltage instead of current, it's just more efficient, cables can be skinnier etc.


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## circuit (Jan 16, 2012)

Unfortunaletty DIY stuff is not an option in this case.
Max system voltage can be up to 300V, which means ~250V working voltage, and probably ~220V under load.

It could be possible to use 4x kelly brushed controllers for 4x600$ + 4xAGNI 155R, for whatever the price, but I guess they go for 1000$ each...


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## riba2233 (Apr 29, 2015)

What about something like Kostov K9 HV DC motor (45 kg) and soliton 1 controller (8-400 V 1000 A)? I know it's not 1400 A phase, but since series DC motors have different torque curve I think It should be ok, and thast controller is also 1000 A batt continuous, and all together should fit your budget.


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## Hollie Maea (Dec 9, 2009)

circuit said:


> The motor should be powerful enough to hold 80kW 10sec peaks and 40kW average at 30% RPM.


So how is the Rinehart too small? Even their smallest entry can do better than that.


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## circuit (Jan 16, 2012)

Hollie Maea said:


> So how is the Rinehart too small? Even their smallest entry can do better than that.


Which one are you referring to? For example PM100DX: 50-400V, so in our case 250V, 220V under load.
Peak motor current is 350A. So 350A*220V = 77kVA.
However, on 30% RPM, we will have 30% output voltage, so 350A*220V*0.3=23kVA

Or PM150DX, which is 450A motor current, will give us 30kVA.

So in our case we would need at least 4x PM100DX (4wd) or 3x PM150DX (2 rear, 1 front).

Is your math different? Of course this math would be more interesting if they would do field weakening, which I don't see in the datasheet. And there's no performance data curve.


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## major (Apr 4, 2008)

circuit said:


> Peak motor current is 350A. So 350A*220V = 77kVA.


You're missing √3. Ref: http://www.diyelectriccar.com/forums/showpost.php?p=376274&postcount=9


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## circuit (Jan 16, 2012)

major said:


> You're missing √3. Ref: http://www.diyelectriccar.com/forums/showpost.php?p=376274&postcount=9


Yes, you are correct. In such case power will be even lower than what I calculated.
But √3 is not always relevant. For example in BLDC we have square wave. In PMAC/PMSMs we often have space vector modulation, which also gives better voltage utilization.
But generally yes, actual numbers will be even less.


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## major (Apr 4, 2008)

circuit said:


> Yes, you are correct. In such case power will be even lower than what I calculated.
> But √3 is not always relevant. For example in BLDC we have square wave. In PMAC/PMSMs we often have space vector modulation, which also gives better voltage utilization.
> But generally yes, actual numbers will be even less.


You missed the point. RMS is almost always used for phase current. 1.73 factor increases power due to 3-phase, depending on PF.


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## circuit (Jan 16, 2012)

major said:


> You missed the point. RMS is almost always used for phase current. 1.73 factor increases power due to 3-phase, depending on PF.


To my understanding, 1.73 factor is used in industrial AC systems where your "phase" voltage is 220V for example, so your phase-to-phase is 380.
In this case your phase-to-phase is actually your battery voltage.
So I don't think that 'industrial' 3-phase rule should be used here.


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## dcb (Dec 5, 2009)

circuit said:


> For example in BLDC we have square wave.


if your motor has zero inductance, sure... but you already knew that


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## circuit (Jan 16, 2012)

dcb said:


> if your motor has zero inductance, sure... but you already knew that


Are you trying to suggest field weakening? That is entirely different thing and depends on motor and controller. For example emrax can go up to 2x rpm (but 0.5x torque). Most OEM EV motors go up to 4x speed. But that does not increase power.


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## major (Apr 4, 2008)

circuit said:


> To my understanding, 1.73 factor is used in industrial AC systems where your "phase" voltage is 220V for example, so your phase-to-phase is 380.
> In this case your phase-to-phase is actually your battery voltage.
> So I don't think that 'industrial' 3-phase rule should be used here.


No. You are mistaken. This isn't unusual because they like to spec out DC, battery Volts and AC RMS phase current. Power equations are the same for industrial and EV motors. And 220VAC RMS is the line to line potential in either case.


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## circuit (Jan 16, 2012)

major said:


> No. You are mistaken. This isn't unusual because they like to spec out DC, battery Volts and AC RMS phase current. Power equations are the same for industrial and EV motors. And 220VAC RMS is the line to line potential in either case.


Again, 1.73 is used to get actual phase-to-phase voltage. Since we are already multiplying battery voltage, which is basically a phase-to-phase voltage, I can't see where 1.73 comes in.

Anyway we are going off topic.


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## dcb (Dec 5, 2009)

circuit said:


> Are you trying to suggest field weakening?


No, I'm saying bldc *isn't* a square wave, since we are getting pedantic.

edit, trapezoidal perhaps.


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## major (Apr 4, 2008)

circuit said:


> Again, 1.73 is used to get actual phase-to-phase voltage. Since we are already multiplying battery voltage, which is basically a phase-to-phase voltage, I can't see where 1.73 comes in.
> 
> Anyway we are going off topic.


Did you read my reference? Look up 3-phase power calculation? Electrical Engineer's handbook or textbook?


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## circuit (Jan 16, 2012)

I have read books. And checked your reference, where you state that you have no idea how that applies to us. Also it is important to understand which numbers you are multiplying, what are the RMS'es of, etc.
As an example, take a specsheet from emrax. Multiply phase current by max battery voltage. You will get max stated power.
Anyway, since this discussion went south, I am not going to go even deeper.


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## major (Apr 4, 2008)

circuit said:


> I have read books. And checked your reference, where *you state that you have no idea how that applies to us*. Also it is important to understand which numbers you are multiplying, what are the RMS'es of, etc.
> As an example, take a specsheet from emrax. Multiply phase current by max battery voltage. You will get max stated power.
> Anyway, since this discussion went south, I am not going to go even deeper.


You must mean this sentence:


major said:


> I do have a difficult time envisioning how this happens in our typical 3 phase bridge circuit.


Nice job taking that out of context. I was speaking specifically about the battery current exceeding the phase current.

If you had read, or maybe you did read, the rest of that thread, the theme was how unreliable AC EV drive manufacturers' specifications are. I'm through here. I thought you might like to know what you're doing with specifications for the most powerful controller. But obviously you're content with your current level.


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## Hollie Maea (Dec 9, 2009)

circuit said:


> But √3 is not always relevant. For example in BLDC we have square wave. In PMAC/PMSMs we often have space vector modulation, which also gives better voltage utilization.


You seem to have a lack of understanding about 3 phase power.

When you measure voltage and current at the terminals of a 3 phase machine, one value will always be phase and one will be line (which one depends on if it is Y or Delta wound). But to get your power, you need to be measuring voltage and current at the same points. So you have to convert the line value to phase, so you are multiplying phase voltage by phase current. Regardless of which on you are converting, this will involve DIVIDING by Sqrt(3). But that just gives you the power of a single phase, so you have to multiply by 3. The result is that you have to multiply your measurements by Sqrt(3) to get the power. ALWAYS--that's the nature of 3 phase power. It has nothing to do with wave form, or industrial vs automotive. It's just how 3 phase power is. This isn't a rabbit hole--it's a fundamental concept. If you don't understand it, you should research more before arguing with everyone.


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## circuit (Jan 16, 2012)

OK, just reviewed this thread again and now I understand what you are talking about. We are discussing different things.
Power is calculated as follows: phase(to neutral) voltage * phase current * 3 phases = U_LN * I_L * 3.
Since phase-to-phase voltage is √3*phase-to-neutral, the formula gets:
U_LL/√3 * I_L * 3 = U_LL * I_L * √3.

You are proposing to use battery voltage as phase-to-phase voltage. This is where you are wrong. The equation above applies ONLY to pure sinewave and ONLY for line-driven (without inverters) machines. Or with some kind of old inverters, that output simple sinewaves. Also you need to get RMS values using √2, however that applies only to sinewave as well.

It very much depends on type of commutation type. For example:
* Space vector modulation will give you +15% (*2/√3) of phase-to-phase voltage from same battery, compared to standard 3-phase line. You have to include that in your math as well, if battery voltage is used as equation input. Go read on SVPWM to understand why.
* FOC can give you interesting results, that are not always representing perfect sinewave (depends on algorithms used and particular motor's type and shape of BEMF).
* BLDC in trapezoidal mode - only two phases are active at any given time and it can be calculated as a DC system. Usually these are rated in peak values, not RMS: out of 6 sectors, 2 are sinking, 2 are sourcing and 2 are floating. In this case "phase current" RMS value would be 2/3 of that provided in specification, and "phase voltage" would be half of battery voltage. Add all of that in your equation and you will get same result as in DC step-down system: 2/3 * 1/2* 3 = 1. But that does not matter, because total motor current is still as specified.

It is very important to note: wording in specifications means a lot. There is a difference between "phase current" and "motor current".
Your suggested √3 is applicable when phase current is in question, not motor current, as it already has this accounted for. And this exact value, 1.73, is only for sinewave in line-driven induction motor systems. You can not use it if BEMF shape is not exactly sinewave (in most EV PM motors) or if space vector modulation is used, which gives higher phase-to-phase voltages from same battery voltage (unless you account for it too).
Almost all modern EV drives use space vector modulation and FOC.

So knowing actual phase current is not that important (only for selecting connectors and cables), and "motor current" should be used to find overall power and loss. In most EV cases, motor current is given, not phase (even if they call it phase sometimes). Real phase current will be misleading to say the least.
Now "motor current" is not something you can measure with ammeter on a phase, but is convenient to use in various calculations.

Maybe my previous calculations are off, but your's are too. So thanks for explaining, but not everything is as simple as it looks. In the end, we should use existing specifications without overthinking it.

Now can we get back on topic please.


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## dcb (Dec 5, 2009)

I kind of have to agree that the phase 2 phase part is confusing from a battery perspective, but it is the bulk 3 phase power and thus the nomenclature. But to be fair the FOC guys are 10x as cryptic (for not a lot of gain). 

But bldc is not historically a candidate for "most powerful controller", heck PM isn't really a good candidate either. I mean things like the YASA-400 are making their way into it, but it is still essentially sine wave based. I don't know of any high power motors that like trapezoidal.

And the thing about svpwm is that the voltage valleys looks wonky in relation to battery ground or neutral, but that is precisely to set up the maximal phase to phase voltage for a given battery/bus voltage, again based on sine waves afaik, except on cheap motors and controllers. 

After a low pass filter everything starts looking like a sine wave for the most part, even a pc speaker, so that terminology/assumption is reasonable for the time being.


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## circuit (Jan 16, 2012)

You can of course assume it is sinewave and probably calculations won't be far from truth, but in case of SVPWM, 15% is still something. Just note that LP filter is not going to change anything on SVPWM: even though phase-to-neutral shape is all weird and messed up, phase-to-phase is an ideal sinewave.
As for sinewave shape, it can get very important with low inductance motor. For example if driving a BLDC motor with sinewave controller... Higher inductance will soften it all down of course, but at these voltages and power levels, high inductance is something you don't often get. For example I was surprised that emrax allows field weakening up to +100% speed, even at 10μH inductance of their low voltage motor.

As for BLDC or DC motors in "most powerful" system, many DIYers have proved it plausible. Of course it is less efficient and for sure much louder, but is dead simple and easy to setup. And often fits in the budget: not only the system itself is cheaper, but you don't have to buy expensive software and programming cables, and don't waste your time on it.
In our case, budget is around 5k€, so I am looking even at kelly 2Q DC/BLDC controllers and AGNI motors...


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## dcb (Dec 5, 2009)

svpwm still results in sinusoidal phase to phase voltage is what I'm getting at, it only looks weird to the battery. I'm sure there is some nerdy explanation with greek letters and weird pictures and whatnot. The motor only understand phase to phase, there is no other way to interface with it. In fact the peak phase to phase voltage IS the pack voltage with svpwm since the inverter can do a full reversal on each phase, but it is usually stated in rms on the motors (.707 x peak)


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## major (Apr 4, 2008)

circuit said:


> OK, just reviewed this thread again and now I understand what you are talking about. We are discussing different things.
> Power is calculated as follows: phase(to neutral) voltage * phase current * 3 phases = U_LN * I_L * 3.
> Since phase-to-phase voltage is √3*phase-to-neutral, the formula gets:
> U_LL/√3 * I_L * 3 = U_LL * I_L * √3.
> ...





circuit said:


> *You* are proposing to use battery voltage as phase-to-phase voltage. This is where you are wrong.


It is a bit unclear, but if "you" means me, I never proposed using battery voltage as phase-to-phase voltage. You were the only one I saw doing that.



circuit said:


> Maybe my previous calculations are *off, but your's are too*. So thanks for explaining, but not everything is as simple as it looks.


Again, if you're addressing me, show me a calculation of mine that is off.

And if the thanks was directed to me; you're welcome.

Regards,

major

edit: Thanks to Hollie Maea for post #25. That is a very clear statement of 3-phase power.


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## dcb (Dec 5, 2009)

major said:


> I never proposed using battery voltage as phase-to-phase voltage. You were the only one I saw doing that.


It is true though, the peak phase to phase voltage IS equal to pack/bus voltage, though you need to translate from pack to phase via svwpm to get there, which presumably most controllers are doing, at least the open source ones are, don't know about proprietary stuff.


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## jhuebner (Apr 30, 2010)

dcb said:


> svpwm still results in sinusoidal phase to phase voltage is what I'm getting at, it only looks weird to the battery. I'm sure there is some nerdy explanation with greek letters and weird pictures and whatnot. The motor only understand phase to phase, there is no other way to interface with it. In fact the peak phase to phase voltage IS the pack voltage with svpwm since the inverter can do a full reversal on each phase, but it is usually stated in rms on the motors (.707 x peak)


Maybe this helps: http://www.diyelectriccar.com/forums/showthread.php?p=635913#post635913

SVPWM doesn't gain anything, it just wastes less.

Just like driving an EV doesn't save the environment, it just hurts it less 

No matter which modulation is used: S=sqrt(3)*Urms*Irms (measured on any of the three phases)

Assuming Udc=220V, Irms=350A, SVPWM:
Urms=220V/sqrt(2)=156V
S=1.73*156V*350A=94.5kVA

EDIT: Assuming efficiency is 90% and power factor is 0.9
P_mech = 0.9*0.9*94.5kVA=76.5kW

Objections anyone?


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## circuit (Jan 16, 2012)

Different approach:
With 220V battery, phase-to-neutral Vrms, in case of simple PWM is: 220/2/1.41=78V. In case of SVPWM: *1.15=90V.
And then your input power is: 3*90*350=94kVA (same result).
In EV systems (FOC without field weakening) should be close to 1.
But that all depends where do we get 350A value from. Is it rms value of single phase? Or is it total motor current? Or is it peak phase current, not rms?


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## major (Apr 4, 2008)

circuit said:


> But that all depends where do we get 350A value from. Is it rms value of single phase? Or is it total motor current? Or is it peak phase current, not rms?


The AC motor controller (inverter) has 3 output wires to the motor. In every case I have ever heard about, it is the current in one of those 3 wires and called the motor phase current, RMS, regardless of the type or configuration of the load motor. Opposed to continuous, when referred to as "peak", it is the short duration RMS value usually rated for 1 or 2 minutes, or possibly for seconds. It is not the instantaneous peak of the AC waveform. That is considered when designing the controller but never, of which I am aware, used in the application or rating or specification of the motor controller.


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## MPaulHolmes (Feb 23, 2008)

My way to remember 3 phase power is to just do 1.5 * battery pack voltage * peak phase current (pretending power factor of 1):


```
power = Vbatt*sin(0)*Ipeak*sin(0) + Vbatt*sin(120)*Ipeak*sin(120) + Vbatt*sin(240)*Ipeak*sin(240)
power = Vbat * Ipeak * sqrt(3)/2 * sqrt(3)/2 + Vbatt*Ipeak * sqrt(3)/2*sqrt(3)/2
power = Vbatt*Ipeak * 3/2
```


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