Increasing PWM frequency for Sensorless FOC Example

We are currently operating our PMSM motor using the F280049C controller and the BOOSTXL-DRV8323 driver board, following this MATLAB example.

We have wired the connection between the controller board and driver board based on the datasheet pinout (similar to this post) and updated the relevant motor and inverter parameters. The motor performs well in both open-loop and closed-loop modes at a PWM frequency of 20 kHz. Our goal is to analyze current harmonics at higher PWM frequencies, specifically at 32 kHz and 40 kHz. However, when we increase the PWM frequency beyond 24 kHz, we observe that the actual motor speed (measured via external sensor) drops to approximately half of the commanded speed. Interestingly, this discrepancy is not visible in the Simulink host model scopes, which misleadingly show the speed tracking the command accurately. The system functions correctly at 24 kHz, but fails to run at the correct speed at any PWM frequency above that.

We would appreciate your assistance in diagnosing and resolving this issue. We have already contacted Texas Instruments, and they have referred us to MathWorks for further support.