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What parameter decide the optimum PWM frequency for commutation of the BLDC?

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krunal_299

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Hi everyone!
I have query regarding BLDC motor.
What parameter decide the optimum PWM frequency for commutaion of the BLDC?

I mean what will be the maximum PWM frequency to control the MOSFETs at driver side of BLDC controller and how one can know that value?

What will be the effect on motor performance if PWM frequency is too high ot too low?

Regards!
 

pwm technique

What is the relation between Inductance of BLDC motor winding and PWM frequency by which motor got power?
 

Re: BLDC pwm technique

krunal_299 said:
Hi everyone!
I have query regarding BLDC motor.
What parameter decide the optimum PWM frequency for commutaion of the BLDC?

I mean what will be the maximum PWM frequency to control the MOSFETs at driver side of BLDC controller and how one can know that value?

What will be the effect on motor performance if PWM frequency is too high ot too low?

Regards!
Click to expand...

What is your maximum speed for your application?

You can run the motor to the maximum duty cycle but you would draw a lot of current and your FETs will overheat that is why employ heatsinks. For the low duty cycle, this will depend on your load. I can run the BLDC to 8% duty cycle but below 8%, the motor does stutters due to loading.
 

BLDC pwm technique

If you increase the PWM frequency, your mosfets will heat up more, but your AC ripple current will be smaller. On the other hand, as your ripple increases you will get more core losses in your motor. The maximum frequency will be dictated by your mosfets' cooling and the PWM resolution you want (if digital control).
 

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