Acoustic noise characteristics in position sensorless control for IPMSM based on EEMF and voltage injection synchronized with PWM carrier

In this paper, we propose a new position sensorless control system for an interior permanent magnet synchronous motor (IPMSM). The proposed method is based on an extended electromotive force (EEMF) and voltage injection synchronized with a pulse-width modulated (PWM) carrier. In the proposed method, in order to estimate the magnetic pole position using the EEMF, there is no need to vary the estimation method with speed, even at low speeds. Further, the amplitude of the injected voltage varies with the EEMF, compared to the conventional method involving a fixed voltage, and the acoustic noise characteristics are improved. The effectiveness of the proposed sensorless control system is verified experimentally.