Mismatch between driver carrier frequency and motor winding inductance

[Jordin]

Hello everyone.

A stepper motor with a driver emits a sharp switching frequency whine upon power-up under no-load conditions, with sound pressure levels measured around 10kHz.

The motor casing is warmer than normal, but the current setting is not high. Measuring the winding inductance after removing the motor revealed it to be significantly lower than the nominal value, causing subharmonic oscillations in the driver's current loop at the default carrier frequency.

Manually lowering the carrier frequency eliminates the whine, but increases low-speed torque ripple.

Is there a carrier frequency selection principle that avoids the whine while maintaining smooth low-speed operation, or is it necessary to adjust the current loop modulation method?