EMI in Sensorless PMSM Drive System Based on Disturbance Observer

This paper proposes a disturbance observer to estimate position and speed of the rotor of sensorless permanent magnet synchronous motor (PMSM), via detecting voltages and currents, which contain electromagnetic interference (EMI) produced by switching processes of inverters. Then, according to three elements of EMI, interference sources, interference transmission paths and sensitive equipment in sensorless motor drive system are analyzed theoretically. Finally, the inverter circuit with ideal and non-ideal metal-oxide-semiconductor field effect transistor (MOSFET) is established in Matlab/Simulink. Simulation results show that EMI enlarges estimation errors of speed and position. In addition, different gain coefficients of back-electromotive force (EMF) are carried out. Comparing with sliding-mode observer, disturbance observer reducing estimation errors provides a novel thought and idea against the impact of EMI.