Shown here are some actual waveforms of InstaSPIN-BLDC in operation using bipolar PWMs and the designer has actually superimposed the theoretical value of the neutral node voltage on top of these waveforms which should represent the zero crossing point for the back-EMF reading that is being measured. Since the neutral point voltage is not changing, the back-EMF signal is very smooth through the period where the reading has been taken. There is some PWM coupling in that waveform but the nice thing again about InstaSPIN-BLDC is this is not the waveform being used for commutation. Actually the waveform is being integrated in and using that for commutation. This waveform and all of its noise is being run through an integrator, what is an integrator? It is basically a low pass filter with a pole at zero to get a much cleaner waveform to base the commutation on. While the bipolar PWM technique does tend to keep the neutral voltage at a fairly fixed value, it is not compatible with all motors especially motors that have very low inductance. The reason for that is because the voltage waveform is as the name implies, bipolar. That is a positive and negative portion during the PWM cycle.