topic Speed Feedback Issue in HVPKV31F120M ACIM Control (V/f Mode) in Kinetis Microcontrollers

Speed Feedback Issue in HVPKV31F120M ACIM Control (V/f Mode)

AJITH_KUMAR — Thu, 27 Mar 2025 14:23:35 GMT

Hello everyone,

I am working on HVPKV31F120M ACIM control using FreeMASTER. After modifying the hardware settings (changing current and voltage levels), I observed that V/f control is working properly, but the speed feedback is incorrect. As per the documentation, the Rotor Flux Observer should still run in the background while operating in V/f mode.

Upon investigation, I noticed that in the sensorless control section, the Rotor Flux Observer and MRAS Speed Estimator parameters have not been adjusted automatically based on the new hardware scaling. I suspect that this might be causing the issue.

Could anyone provide guidance on how to properly recalculate and tune these observer gains for the new hardware settings? Are there any recommended formulas or tools to adjust M1_MRAS_KP_GAIN and M1_MRAS_KI_GAIN accordingly?

Any insights or documentation references would be greatly appreciated.

Best Regards

AJITH KUMAR

Re: Speed Feedback Issue in HVPKV31F120M ACIM Control (V/f Mode)

Celeste_Liu — Wed, 02 Apr 2025 03:14:40 GMT

Hello @AJITH_KUMAR ,

Thanks for your post. Please refer to the section "5.3.2. Sensorless rotor flux position and speed estimation" of the AN5051 which I attached.

The document DRM150 mentioned will be also attached.

Hope it can help you. If you have any further questions or need more information, please let me know.

BRs,

Celeste

Re: Speed Feedback Issue in HVPKV31F120M ACIM Control (V/f Mode)

AJITH_KUMAR — Sat, 05 Apr 2025 04:48:22 GMT

Hello, @Celeste_Liu

Thank you for your response.

The observer gains are set correctly, and the issue was identified as a mismatch in the current measurement design between the NXP reference board and our custom hardware. Due to this difference, the current feedback was not accurate. We addressed this by modifying the software to match our hardware’s current sensing configuration, and the feedback is now working correctly.

Kind Regards,

AJITH KUMAR