PWM Deadtime compensation

[dekutree64]

@Candas1

Anybody interested in giving this a try ?
It should already give good results in openloop at slow speed/low load.
I just want to make sure I am not fighting with a problem only I have with my setup.

I can summarize what I did so far.

I declared a global variable for deadtime compensation so I can update it and observe the waveform.

float dtcomp = 0;

Here I added the code for the deadtime compensation.

if (dtcomp > 0){
  center = driver->voltage_limit/2;
  Ua += (Ua > center ? 1:-1) * dtcomp;
  Ub += (Ub > center ? 1:-1) * dtcomp;
  Uc += (Uc > center ? 1:-1) * dtcomp;
}
// set the voltages in driver
driver->setPwm(Ua, Ub, Uc);

Here, I compensate the voltage command so that the amplitude is same with or without the deadtime compensation.

if (dtcomp > 0 && abs(dtcomp) > abs(Uq)) Uq -= _sign(Uq) * dtcomp; 

I ended up compensating for 0.70V, which in my case is almost the power supply voltage * Deadtime% * 2.
I am not sure if it’s a coincidence, based on this paper I am compensating both for the deadtime and the stiction.

I’m a few years late and haven’t read the whole thread in detail, but this is incredible I’ve been trying to do deadtime compensation in the driver setPwm and failing badly, but this works beautifully.

I also tried putting it inside the SVPWM section of setPhaseVoltage where the offset center voltage is known rather than using driver->voltage_limit/2, but I couldn’t tell any difference.

In my case, the ideal dtcomp is power supply voltage * deadtime%. Not x2 like yours, but still seems oddly coincidental. And it seems to need the voltage command offset by dtcomp*1.25 to keep the current amplitude unchanged. These images are without modifying the commanded voltage, so compensated amplitude is much higher.