I have been trying to decide what version of the QS 4000W 205 V3 motor would be best for my EV application. I have gotten a couple data sets from the QS sales guy: 3T- (Fast) @ 72 V and 3T (Balance) @ 72 V. He didn't have 4T (Torque) data. My nominal battery voltage is 88.8 V and I am planning on using an Elmo Gold Drum 100/100 controller.

I am trying to quantify what the motor performance would look like at my nominal voltage level for the 4T (Torque) and 3T (Balance) windings. I plotted the data from QS and my predicted performance (Calc) in the attached file. Below are the main input parameters I used for my calculations.

Parameter Value Unit

4T

Nominal voltage 88.8 V

Max current 70 A

Max torque 190 N-m

Kv 11.5 rpm/V

Max speed 1020 rpm

3T

Nominal voltage 88.8 V

Max current 77 A

Max torque 180 N-m

Kv 15.6 rpm/V

Max speed 1390 rpm

My calculation procedure was basically as follows. First, determine input power (nominal voltage x max current). Then I calculate efficiency as a function of speed from polynomial curve fits (3T data up to 1000 rpm, 3T- curve above 1000 rpm). Then calculate output power (input power x efficiency) and torque (output power / speed).

Do my calculated 3T and 4T torque versus speed curves look right?