Position sensorless control of permanent magnet synchronous motor at low speed range using harmonic voltage injection

This paper examines the relationship among injected harmonic voltage, acoustic noise, and position estimation error in a position sensorless control method at low speed range using harmonic voltage injection. Moreover, a novel injected voltage control method for reducing the acoustic noise is proposed. The proposed control method is verified by numerical simulations and experiments using a 4-pole, 2 kW, 2100 rpm mini model test prototype.