noise from CIM motors driven with Victor controllers

[philso]

Hello

I am a first time mentor working with a team where the members are competing for the first or second time.

Can anyone confirm that the growling noise we are getting from the drive motors at "low throttle" is normal?

The main drive motors are a pair of CIM motors. The motor controllers were recently changed from the (black) Jaguars to the Victor controllers. There was no perceptible noise when using the Jaguars. Some of the team members are worried about burning up the motors or controllers because of the noise.

I found some threads (such as http://www.chiefdelphi.com/forums/sh...ad.php?t=83973) indicating that the switching frequency of the Victors is about 150Hz whereas the switching frequency of the Jaguars is about 15kHz. Based on this information and my experience doing R&D on 3-phase motor drives, I would expect the motors connected to the Victors to make the noise that I am hearing.

Thanks.

Phil

[Jared Russell]

What you are describing is perfectly normal for CIMs driven by Victors.

[Racer26]

Yup, perfectly normal. I expect this is an artifact of 150Hz being well within human hearing range of 20Hz-~20kHz. The 15kHz of the Jags is much higher up the spectrum, and thus many people can't perceive sounds of that frequency (hearing range decreases with age).

Compare this to the high-pitched screech emitted by many older CRT televisions. Children and teens can hear an energized TV like that from rooms away, while adults can't hear it at all.

[Ether]

Originally Posted by philso

Some of the team members are worried about burning up the motors or controllers because of the noise.

The high ripple current caused by the low switching frequency of the Vics will cause more motor heating compared to the higher switching frequency of the Jags, for the same motor torque. Unless you are running the motors for long periods at high torques this shouldn't be a problem; the CIMs are pretty rugged.