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Discussion Starter · #1 ·
I am considering purchasing a PMSM 30KW motor and controller from a supplier on Alibaba -
I realise I am taking a gamble for so many reasons but I really want this motor because weight is critical in my conversion.

My question is to anyone who can shed light on weather or not I am being fed a line of bull-loony or not. I have been given a very simple stat sheet on the motor and controller which I have attached -

It seems odd that they insist that it is a 30KW system when the 96 volt motor has a rated amps of 180 - I don't know a lot about how the "Rated" system is sorted out but my simple math says 96 X 180 = 17280 or 17.2 KW

Please if you can add constructive advise I would sure appreciate
 

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The rated speed (3600 RPM) and torque (53 Nm) correspond to 20 kW, not the listed rating of 30 kW.

The listed peak speed (5500 RPM) and torque (180 Nm) would correspond to 104 kW (verus the listed peak of 40 kW), but there's no chance it can produce the peak (or even rated) torque while turning at the maximum speed, so those won't line up - the graph shows that. If it produced the peak torque (180 Nm) all the way up to the rated speed (3600 RPM), that would be 68 kW, so the 40 kW peak power is plausible, and that does correspond to the graph (in which peak torque is maintained to about 2400 RPM, and torque is about 80 Nm at 5500 RPM).

The problem with any of the electrical ratings is that they are not consistently identified as DC values for the power from the battery to the controller, or AC values (peak-to-peak? RMS?) for the three phases from controller to motor. Production EV specs usually consider the controller and motor as a "black box" system, and quote only DC link values for voltage, current, and electrical power. Specs for AC motors usually only give supply (DC) voltage, electrical power, and mechanical values (speed and torque).
 

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Discussion Starter · #4 ·
The rated speed (3600 RPM) and torque (53 Nm) correspond to 20 kW, not the listed rating of 30 kW.

The listed peak speed (5500 RPM) and torque (180 Nm) would correspond to 104 kW (verus the listed peak of 40 kW), but there's no chance it can produce the peak (or even rated) torque while turning at the maximum speed, so those won't line up - the graph shows that. If it produced the peak torque (180 Nm) all the way up to the rated speed (3600 RPM), that would be 68 kW, so the 40 kW peak power is plausible, and that does correspond to the graph (in which peak torque is maintained to about 2400 RPM, and torque is about 80 Nm at 5500 RPM).

The problem with any of the electrical ratings is that they are not consistently identified as DC values for the power from the battery to the controller, or AC values (peak-to-peak? RMS?) for the three phases from controller to motor. Production EV specs usually consider the controller and motor as a "black box" system, and quote only DC link values for voltage, current, and electrical power. Specs for AC motors usually only give supply (DC) voltage, electrical power, and mechanical values (speed and torque).
Thanks for the input - I see on the drawing of the motor it has both AC rated amps (191) and AC rated voltage (67) if you multiply 191 X 67 you get 12797 does that mean the rated KW should be 12.7kw? How do they get the rated KW ?
 

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Rated kW is usually related to the amount of current you can run the motor windings at indefinitely, using recommended cooling, without letting out its magic smoke. Sometimes it's shaft or bearing that determine limits, but usually it's the magic smoke.

This is why you can run motors at 2-3x or more their rated kW as a peak value, typically for 10 sec or so.
 
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