Position sensorless drive for IPMSM based on EEMF with maximum torque control in all speed ranges

In this paper, we propose a new position sensorless drive system for an interior permanent magnet synchronous motor (IPMSM) with maximum torque control. The proposed method is based on 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 proposed voltage injection method is more efficient and quieter than the conventional method. The effectiveness of the proposed sensorless maximum torque control system is verified experimentally.