[OCCRA]: recomended PWM frequency for CIM motors?

[lonoty]

Hi, our team is trying to create a motor-controller with Mosfet transistors (its not FRC legal but its a nice off season project ). We are going to control the motor-controller with an arduino, but we read that if the frequency is too high the mosfets are going to waste energy switching, and if the frequency is too low the motor might shake and create a buzzing sound. What would be a good frequency to control the motor?

[Al Skierkiewicz]

Well, to copy known good devices, the Jaguars (and Talons I think) switch at 15kHz, the Victor 884 at 120Hz. There is a lot of discussion on the effect of the higher frequency vs. motor inductance in terms of linearity here on CD.

[DonRotolo]

It doesn't matter much, but as you increase frequency you do see Eddy current issues, which can cause the MOSFET to dissipate more heat. Not a huge factor below 20 kHz, but be aware.

Frequencies in the audio range will cause the motor to make noise - at that frequency.

12-16 kHz seems like a good starting spot. You should then vary this and repeat your measurements - what works best??

[Ether]

Originally Posted by DonRotolo

as you increase [PWM switching] frequency you do see Eddy current issues

Don, could you please provide link(s) to some technical articles discussing this as it applies to DC brushed motors?