DRV8702-Q1: DRV8702 drive disk brush，using slow decay have a high voltage on VM and reverse current

Hi user,

Can you capture SH1 and SH2 as well during this event?

How much bulk capacitance is utilized?

we power on the motor before it stopped when using slow decay.

when slow decay over,but the motor not stopped,It will generate reverse voltage and reverse current?

which path can release the reverse current and reverse vlotage when four mosfets off !

tks

Hi user,

Can you capture SH1 and SH2 as well as current and VM during this event? A complete capture with the timescale would be appreciated.

Can you confirm what component burned?

I am sorry for late reply.

we use 24V power supply. When we reduce PWM duty, VM goes high,sometimes over 60V,and burns other component powered by 24V .

The motor we used is a disk bursh DC motor.The waveform is below:we reduced PWM duty from 80% to 70%.

How can we eliminate the VM goes high. Thanks

Hi user,

If you can share schematic, please do so. If it needs to be in private, we can take it offline.

Hi,

I send to you in private,please check your private message.

Thank you!

Hi user,

Thank you. Can you do one more scope capture, zoomed in on the signals previously shared, ending right when the current starts to drop? I want to see if the motor is driven forward/reverse and verify there is not a direction change.

Hi,we use MODE 0,when we reduced PWM duty,did not change PH/IN1.So,there is not direction change.

We think when we reduce PWM duty,this circuit like boost circuit,and the volgate goes high,is it right?

How can we eliminate the boost effect？ thank you！

Hi user,

If you can capture the zoomed in scope capture I can see what is happening right before the current starts to drop and the voltage increases.