distorted current wave

guochunhua — Tue, 21 Feb 2017 10:20:04 GMT

Hi.

Excuse me, in codewarrior 10.7, the MCU is 56f84789 ,I use VVVF algotithms to control a PMSM, the motor current measured by hall sensor is distorted near the rising edge, the dead time is 3us, perhaps the distorted wave is influenced by dead time, how can I configure the dead time rigister correctly? the attachment is my current wave and my deadtime compensation program， what is wrong with my deadtime compensation program? thanks a lot.

Guo Chunhua

Re: distorted current wave

xiangjun_rong — Fri, 24 Feb 2017 03:56:47 GMT

Hi, Guo,

I am curious about the algorithms to generate 3-phase voltage, can you tell me how you generate 3-phase voltage? for example, what is the api function you called to generate the 3-phase voltage?

Regarding your question how to compensate the deadtime, first of all, the dead time is must, the deadtime spec is only determinedmy the MOSFET or IGBT device you are using.

I remeber I have given you the an1728.pdf, which focuses on the deadtime compensation. As you know that you have to detect the direction of 3-phase current, after know the current, you can compensate, so the old PWM module provides the IS0/IS1/IS2 three pins to detect the logic, but current eFlexPWM for MC56F84xxx does not have the function because of technology progress.

I think you can use space vector PWM technology to bypass the deadtime compensation issue which is caused by the voltage sine.

Hope it can help you

XiangJun Rong

topic Re: distorted current wave in CodeWarrior for MCU

distorted current wave

Re: distorted current wave