Towards an industrially implementable PWM-injection scheme

We show how the rotor position of a PWM-fed PMSM can be recovered, even at low velocity or standstill, from the measured currents. The method is based on the excitation created by the PWM, without the need for an external probing signal. One originality of the approach is that we directly process the bitstream output by a Sigma-Delta modulator, hence do not require special derivative current sensors nor fast multibit ADCs, thereby opening the way for an effective implementation in an industrial drive.