Why do high speed e-motors require high PWM frequencies?
High speed dynos/e-motors always come with a high fundamental electrical frequency (pole pairs*rpm/60). In standard motor drive systems, the PWM frequency of the inverter should be at least 8-10 times the electrical frequency to get acceptable sinusoidal current waveforms and optimal control. In high speed motor drive systems, due to the small inductance of the e-motors, a factor of 20 instead of 10 is highly recommended. For example if you drive a 25.000 rpm dyno with 6 poles, you end up in needed PWM frequencies of around 24 kHz. However our measurements have shown that the optimal frequency is around 40 kHz. Here we get both minimal e-motor and inverter losses, high dynamics and accuracy, and there is no need for any additional chokes. Big advantage for our customers.
Propulsion Technology & Business Development Leader
2 年Akm Arafat, Ph.D., Quentin Coret - thought you guys might be interested in this one!
Shaping the Future of Development with AI Innovation
2 年Amazing to achieve such high pwm frequency. Such high frequency is only possible with SiC-Inverter. In my experience there are big challenge in the software to handle this high frequency. I think you use here **FPGA** to control the motor. My question is, if you do the Sampling, controller and PWM tasks synchronously in 40KHz or do you calculate the controller slower then 40KHz? Is there any challenging by such high frequency to measure and evaluate the value of current sensor or rotor position sensor? Here you need an correct selected edge frequency for the hardware lowpads filter (Aliasing filter )
EV Power Train Architect
2 年To reduce motor phase current ripples and better torque performance