how to reduce back-EMF voltage when appling six-step commutation for BLDC motor?

[ausera uirwaij]

Hello,

I'm using F429 to control BLDC motor with 6step_lib on my drive board.

But compared to the other ESC board sold on market, my drive has higher current:

I write TIM1 registers such as CCRx and CCER when HALL sensor edges triggering. And uncomplementary PWM for 6step.c.

My peak-peak current are about 1 Ampere bigger than other ESC drive board when dragging the same bldc motor at full speed. I attached captures of one phase current, its hall sensor and terminal Voltage of my board and the other ESC board separately. I don't know where consume this 1A current.

I suppose that the other drive board may apply some "field weaken" technique because I found the terminal voltage has jump at turning point showed in second capture, however, I'm also confused that THIS voltage does not advance hall sensor . My board has no voltage jump at turning point showed in first capture.

​regards,

my drive board:

 

the other ESC board:

​

[Laurent Ca...]

Dear @ausera uirwaij​ 

Sorry for the late answer.

Do you have still this problem to solve?

And just in case, if not, do not hesitate to share the final solution you found. Thanks by advance.

Best regards

[ausera uirwaij]

Hi, @Laurent Ca...​  I'm still confused that why there have voltage "jump " at turning point showed in capture of of-the-shelf ESC board,but my own board has no such "jump". The other problem is my peak current is higher about 0.5A than the other board.

Thank you in advance.