bearing wrote:I'm impressed by your work Lebowski, and looking forward to follow your progress.
One thing is bugging me, though. You say the motor is driven with true three-phase sinusoidal currents. I like that. But I don't understand how it can be sensorless at the same time. If all phases are continuously driven, then there is never an undriven phase to measure the back-EMF on. Would you like to explain how this works? (or is it part of the secret sauce that you don't want to give away for free?)
The question does not make sense to me. The current and voltage are switched, (AC) going from zero to maximum and back to zero. Therefore there is back-EMF to measure. Where does the conclusion that true three-phase current is a DC state come from? The phases are driven one at a time, the same as with all BLDC motors. The motor/controller waveform is identical to a sensored setup. The difference is that Lebo does it with an algorithym which takes over at a very low rpm.