Design of Position Estimation Strategy of Sensorless Interior PMSM at Standstill Using Minimum Voltage Vector Injection Method

This paper presents a new initial rotor position estimation method for an interior permanent magnet synchronous motor. The proposed method includes two steps. First, the minimum voltage vectors are injected to estimate the rotor position. Second, in order to identify the magnet polarity accurately, two opposite voltage pulses are injected on the estimated d-axis. In the proposed method, no filter is needed to draw the high frequency current signal for position estimation and no low-pass filter is required in the current control loop for extracting the fundamental current component for field-oriented control. The fast and reliable feature of this proposed method allows starting the motor with 100% load torque. The effectiveness of the proposed method is verified experimentally and the maximum position estimation error is around 6 electrical degrees.