I hope there is a real professional in electronics in the community.
The picture below shows the signal of PWM output of STM32 in red and the signal after MOSFET of a DRV8302 driver board.
Massive ringing on both lines. This is captured at 6V rising. At my usual 20V I see -16V peak-output of the driver on each phase.
I can’t believe that this wave-form-fit is random.
I’m aware that the Drain-to-Source-voltage of a half-bridge tends to ring. Usually the inductivity of the motor is smoothing the current.
Because I’m working with a motor typ that has nearly no inductivity I was faced with the problem that I loose 50% of efficiency with this ringing. If I add a 3A toroidal inductor to each phase the current consumption for an equal load drop by 50%. But this double the size and weight of the ESC, adding additional resistance and limits the current to the max of the inductor.
The question is: is it possible to influence the ringing of the half-bridge by flattening the PWM Input. How to do? Or is it just the feedback of the MOSFET that I can see on the GPIO output.
Additional question: Is there another way to smooth the current of a driver even if I have no inductive load.
Thanks in advance for any hint.