Nice, as I mentioned in the DM I sent, I aim to continue the effort by trying to minimally modify boards that other more skilled people make, in order to add features I believe are important. That way no one person has to do everything.
You note that current sense costs $ and I agree however if I can find some cheap 30 milliohm resistors or something, or maybe even use a suitably sized length of wire of suitable gauge, I think that would be worth it, IIRC the g431 mcu already has built in op amps (3 or 2? it would suck a bit if it was only 2 but that still works because you can infer the current of the third phase from the other 2).
Even a single resistor on one side of the input to the half h-bridges would still be useful for safety to limit current I think. It’s easier to program and easier to reset and ultimately still cheaper than a circuit breaker of some kind. I found this to be useful in my context in case the motor jams or something else goes wrong.
Secondly I do believe that good current sense has a lot of value because sensorless has great potential because these sensors themselves may be inexpensive but the calibration, extra parts they require, ,mounting provisions, wires and connetors, additional assembly and design effort etc. really adds up on you. In my case of a simple fan it came to like $70 per fan to add the sensor. There is even the potential discussed elsewhere and realized in other motor drivers to use high frequency injection techniques to get the motor position even at zero and very low speeds. That could allow for a sort of servo motor that was totally plug and play which I think would be really cool, although it may not be able to tell absolute position.
Actually, I was wondering recently if by very carefully observing variations during a full revolution caused by imperfections in the motor, one might actually be able to detect motor position on an absolute basis… But don’t want to change the subject of course and that’s a little far fetched. My main point is that current sensing has really a lot of potential and may actually save money in a lot of cases.