# Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

If you use a different controller, and run them at higher voltage, yes you
will develop more power, however, it will be at a higher rpm. 
So no increase in torque.

To get 175kw, you would need a traction pack voltage of 936v (after any
sag), and a controller that can do it.
That would get you a maximum power point of 280Nm at 6000rpm.

An Evisol controller might be able to do it.

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of electroauto.ru
Sent: Sunday, 11 October 2009 8:28 AM
To: [email protected]
Subject: [EVDL] Maxium power from Solectria AC42 and AC55 motors


Hi all,

I have got Solectria AC42 and AC55 motors and think about using them in
performance EV conversion.

According to specifications, this motors provide 75-80 kW maximum power at
312V and 240-250Amps.

I wonder, if it is possible to boost these motors further than 75-80 kW
maximum power? I would like to get 160-200 kW. How can I do that?

If I increase the voltage and amps by about 1.5 times (450-500V, 400Amps),
can I get 160-200 kW power from these motors? Of course, for these purpose I
need custom controller, since stock Solectria controllers do not provide
such power.

-----
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http://www.electroauto.ru http://www.electroauto.ru
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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*



> On 12 Oct 2009 at 2:02, Matt Lacey wrote:
> 
> > If you use a different controller, and run them at higher voltage, yes you
> > will develop more power, however, it will be at a higher rpm. So no increase
> ...


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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*



> Matt Lacey wrote:
> >
> > If you use a different controller, and run them at higher voltage, yes you
> > will develop more power, however, it will be at a higher rpm.
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

Hi David,

For an induction motor of that size, im fairly certain the original
controller is already running the motor into saturation. 
Increasing current would still increase torque, however, the increases in
torque would be marginal.

It is probable the gt20-t motor was not being run into saturation, however,
I am not familiar with it.

>Again, based on my understanding of the way AC induction drives work, just
increasing the voltage doesn't 
>increase the motor rpm. That's also related to the drive's output
frequency. But I don't think you'd want to 
>do that anyway; the motors are going to have a redline that you shouldn't
exceed 
>(probably 8k - 10k). 

According to the data sheet, the AC55 motor max rpm is 8000rpm.

>Raising the voltage should affect the torque curve, though, maintaining
maximum torque to a higher rpm, no?
Yes. 
With the stock controller, motor side back emf reaches traction pack voltage
limit (so controller modulation index has reached 1) at 2000rpm.
This is the maximum power point. 
Beyond this, torque drops off rather rapidly (as does power)

So yes, tripling the voltage the controller can supply pushes the maximum
power point out to 6000rpm, with full torque, thus tripling power output.

The controller does of course increase frequency for higher rpm.

I had another look at the evisol inverter specs, and it only goes up to
900v. So 3x voltage isn't actually possible with that inverter.

Matt


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of David Roden
Sent: Monday, 12 October 2009 4:48 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors



> On 12 Oct 2009 at 2:02, Matt Lacey wrote:
> 
> > If you use a different controller, and run them at higher voltage, yes
> > you will develop more power, however, it will be at a higher rpm. So
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

Hi,

>Why there is no increase in torque?

Im relatively certain the original controller is running the motor into
saturation already.
Increasing current further will still increase torque, however, the increase
would be small since the current flowing on the stator can't be directly
increased they way a DC motors' stator can.

>Could you explain how the voltage increasing resulting in torque curve?
>Could you show your calculations?


Im relatively certain the AC55 motor design started its life as a 18kw 208v
60Hz 1760rpm ACIM motor (4-pole motor).
It is run by a VFD/controller/inverter from a DC bus. The DC bus has to be
sqrt(2) (or 1.414) x the RMS voltage.
The V/Hz ratio is 3.47v/Hz (RMS) or 4.9v/Hz when referenced from the DC
bus/traction pack voltage.

Approx 4.62v is used to make the current flow at rated.
The rest is consumed by the back-emf of the motor
Motors direct online may present this as "slip"
For this particular motor, it means the shaft turns 40rpm slower than
sychronous.
Synchronous is rpm = 120 * frequency (Hz) / # of poles 

In general,
Voltage at motor = back-emf + I^2R + reactive
For a motor with ratings out of a catalogue, 
Back-emf = (rated voltage / rated frequency)*actual frequency
I^2R + reactive can be bundled into a value called "air-gap" and is:
Air-gap = (rated voltage/rated frequency)*(synchronous speed at rated
frequecy - rated rpm)

Back to the 18kw 4-pole motor mentioned earlier,
At rated, 60Hz 1760rpm 18kw 97Nm the voltage at motor will be 208v (RMS), DC
bus min ~295v.
At half rated frequency, 30Hz 860rpm 97Nm, ~9kw, the voltage at motor will
be 104v (RMS), DC bus min ~147v
At triple rated frequency, 180Hz 5360rpm, 97Nm ~54kw, the voltage at motor
will be 624v, DC bus min ~882v.

At triple rated torque, approx 18.48v is used to make the current flow (4x
current required for 3x torque due to saturation effects).

This means the motor turns 160rpm slower than synchronous
At 3x rated torque, 60Hz 1640rpm, ~50.3kw, 295Nm voltage at motor is 208v
RMS
At 3x rated torque, 30Hz 740rpm, ~22.7kw, 295Nm voltage at motor is 104v RMS
At 3x rated torque, 180Hz 5240rpm, ~160.8kw, 295Nm voltage at motor is 624v
RMS

Now, take the situation in an EV, where the pack voltage is limited.
Say the pack voltage never goes below 312v (controller can always produce
220vac RMS)

Same motor, looking at max power,
At 3x rated torque, 60Hz 1640rpm, ~50.3kw, 295Nm voltage at motor is 208v -
all is well
At 3x rated torque, 30Hz 740rpm 22.7kw, 295Nm, voltage at motor is 104v -
all is well
At 3x rated torque, 180Hz 5240 rpm, voltage at motor is limited to 220v -
V/Hz ratio couldn't be maintained.

When running at 3x rated torque (sometimes referred to pull-out for direct
online applications), a reduction in voltage applied to the motor reduces
torque and power by:

Torque = (torque expected)*(actual voltage/expected voltage)^2
Power = (power expected)*(actual voltage/expected voltage)^2

So torque at 5400rpm with only 220vac = 295 * (220/624)^2
= 36.7Nm
Power at 5400rpm with only 220vac	= 160.8 * (220/624)^2
= 19.9 kw

Which does agree with the graph here:
http://www.azuredynamics.com/products/force-drive/documents/AC55_DMOC445Prod
uctSheet.pdf

Matt


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of electroauto.ru
Sent: Monday, 12 October 2009 5:27 AM
To: [email protected]
Subject: Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors






> Matt Lacey wrote:
> >
> > If you use a different controller, and run them at higher voltage, yes
> > you will develop more power, however, it will be at a higher rpm.
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

On Mon, 2009-10-12 at 12:56 +0800, Matt Lacey wrote:

> I had another look at the evisol inverter specs, and it only goes up to
> 900v. So 3x voltage isn't actually possible with that inverter.

Except that there are problems with that inverter.

See http://www.metricmind.com/audi/evisol.htm

I have personally tried to get an EVI200 working. In December 2008 they
sent us firmware and while we did get it to pull in the main contactors,
it never started PWM and it never turned the motor. The monitoring
software was extremely primitive and didn't give us any clues as to what
was wrong.

My friend Philip Court still has the inverter (and Evisol still have his
money) and an immobile race car. He is working on an open source control
board for the Semikron power stage. He now has it running at low power
and is in the process of scaling up his testing.

See http://tumanako.net/ for the open source inverter project.

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## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

>Except that there are problems with that inverter.

Thanks for the heads up Tom.


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Tom Parker
Sent: Monday, 12 October 2009 4:07 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors

On Mon, 2009-10-12 at 12:56 +0800, Matt Lacey wrote:

> I had another look at the evisol inverter specs, and it only goes up 
> to 900v. So 3x voltage isn't actually possible with that inverter.

Except that there are problems with that inverter.

See http://www.metricmind.com/audi/evisol.htm

I have personally tried to get an EVI200 working. In December 2008 they sent
us firmware and while we did get it to pull in the main contactors, it never
started PWM and it never turned the motor. The monitoring software was
extremely primitive and didn't give us any clues as to what was wrong.

My friend Philip Court still has the inverter (and Evisol still have his
money) and an immobile race car. He is working on an open source control
board for the Semikron power stage. He now has it running at low power and
is in the process of scaling up his testing.

See http://tumanako.net/ for the open source inverter project.

_______________________________________________
General EVDL support: http://evdl.org/help/ Usage guidelines:
http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

Thank you Matt, for such detailed explanation!

So, if I understand, if I increase the nominal voltage in 2 times (from 312V
to 624V), I just extend the torque "straight line" from 2000 to 4000 rpm (in
case of AC55 motor)?

And increasing of the current will not provide the equivalent increasing of
torque? (efficiency go down)





> Matt Lacey wrote:
> >
> > Hi,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

*Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors*

>So, if I understand, if I increase the nominal voltage in 2 times (from
312V to 624V), I just extend the torque 
>"straight line" from 2000 to 4000 rpm (in case of AC55 motor)?

Yes, that's what Im saying

For a modification like that, you may be interested in this demonstration by
one of the AEVA guys a while back:
http://www.aeva.asn.au/forums/forum_posts.asp?TID=1237&KW=0.37kw

>And increasing of the current will not provide the equivalent increasing of
torque? (efficiency go down)
Im less certain of this, mainly because I haven't seen this tested.
I think increasing current won't increase torque much.
At least that fits in with the rest of the theory 
Most of the extra current will go towards a worse PF, rather than actual
loss of efficiency I think.

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of electroauto.ru
Sent: Thursday, 15 October 2009 1:20 AM
To: [email protected]
Subject: Re: [EVDL] Maxium power from Solectria AC42 and AC55 motors


Thank you Matt, for such detailed explanation!

So, if I understand, if I increase the nominal voltage in 2 times (from 312V
to 624V), I just extend the torque "straight line" from 2000 to 4000 rpm (in
case of AC55 motor)?

And increasing of the current will not provide the equivalent increasing of
torque? (efficiency go down)





> Matt Lacey wrote:
> >
> > Hi,
> >
> ...


----------

