Saturation Saliency Response Analysis and Rotor Position Estimation Based on Square-Wave Voltage Signal Injection for Surface-Mounted Permanent Magnet Synchronous Motor

This paper proposed a position sensorless control technique for surface-mounted permanent magnet synchronous motor (SPMSM), based on square-wave voltage injection. The peak envelopes of response currents in the αβ reference frame can be extracted through injecting persistent square-wave voltage into the stator windings in different angles when the rotor is locked, and the sinusoidal degree of these envelopes was used to reflect the saturation saliency response. A simple signal processing method was designed for traditional square-wave voltage injection method, which avoids the use of filters for extracting fundamental current and high frequency response current. Hardware-in-the-loop simulation system based on RTLAB for SPMSM was constructed. The simulation and experimental results show that the proposed method can eliminate the time delay problem caused by filters and improve the position estimation precision, which can be effectively applied in low switching frequency situations.