KMS Max commutation frequency

[borjagomez]

Dear Mr/Mrs

My company is designing a 150Kw inverter for electric vehicles power trains. This inverter includes SiC IGBTS, so a high frequency commutation could be desirable. KMS based microcontroller is an alternative for the logic part, but I would like to know which should be the maximum possible commutation frequency for this control suite and KV4x family.

Thank you in advance

Borja Gómez

[linestream-adam]

Borja,

For maximum commutation speed, we don't recommend exceeding 1/10th of the Fast ISR frequency. This way you will still get 10 samples per period of the phase current. This is enough in order to maintain good control of the motor while at high speeds. 

In KMS, the Fast ISR frequency is an integer multiple (default being 1) of the PWM frequency. On the KV4, you should be able to run a FAST ISR frequency of up to 25 kHz. Which would result in a maximum commutation frequency of 2500 Hz. Obviously you can exceed this number, but it may result in poor performance.

With the less powerful KV3, I've been able to run motors above 100 krpm without issues.

Adam