TMS320F28069F: Is it OK to set USER_MAX_VS_MAG_PU value bigger than 0.6666 ?

Hae Ryong Jung

Expert 2150 points

Part Number: TMS320F28069F

Dear TI members,

I have a question about USER_MAX_VS_MAG_PU value.

This value seems to be limited by 0.6666

What is the expected problem if it is bigger than 0.6666, for example 0.8 or bigger ?

Thanks in advance.

Best Regards,

Hae Ryong

over 7 years ago

0 Krishna Allam over 7 years ago

TI__Expert 7985 points

Hi Hae,
Would you kindly provide a more detailed context for your question.
Thanks,
Krishna

0 Yanming Luo over 7 years ago in reply to Krishna Allam

TI__Guru** 115470 points

The PWM duty can't be set correctly and motor will stop for over current fault. According to the PWM technique algorithm, the maximum value of USER_MAX_VS_MAG_PU is 0.6666 (=2/3) as the definition comments for this parameter in user.h. Generally, you should set it to 0.5 or less if you don't' use current reconstruction technique.

0 Hae Ryong Jung over 7 years ago in reply to Yanming Luo

Expert 2150 points

Thanks for your response.

As I know, USER_MAX_VS_MAG_PU is for overmodulation.

overmodulation seems to increase current usage, so I thought bigger value for USER_MAX_VS_MAG_PU increase current usage.

is it correct ?

FYI, my custom board don't use current hall sensor rather than shunt, so don't need to use current reconstruction.

Best Regards,

Hae Ryong

0 Yanming Luo over 7 years ago in reply to Hae Ryong Jung

TI__Guru** 115470 points

The USER_MAX_VS_MAG_PU must be less than 0.6666 (=2/3) always for any current sensors. You don't need current reconstruction technique if you are using hall sensor or inline current shunt and USER_MAX_VS_MAG_PU is higher than 0.5.

0 Hae Ryong Jung over 7 years ago in reply to Yanming Luo

Expert 2150 points

OK, thanks for your confirmation.

Best Regards,

Hae Ryong

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28069F: Is it OK to set USER_MAX_VS_MAG_PU value bigger than 0.6666 ?