Estimation method of rotor position of PMSM with filterless high-frequency square-wave injection

For the traditional methods of rotor position estimation for permanent magnet synchronous motor (PMSM), the phase shift caused by the introduction of filter will affect the accuracy of rotor position estimation to some extent. This paper presents an improved rotor position estimation method for high frequency square wave signal injection without filter. Firstly, the traditional method injects high-frequency pulse vibration signals into the estimated shafting, and the proposed method injects high-frequency square wave signals into the estimated shafting to avoid the introduction of filters in the process of extracting rotor position information. Then, the rotor position signal is decoupled in the stationary shafting, and the rotor position error after demodulation is processed by PLL. The system realized the signal processing of rotor position without filter, which improved the convergence speed and estimation precision of rotor position and the dynamic response performance of the system. The simulation results showed that the proposed method had fast convergence speed and small phase delay, and better improved the precision of rotor position detection.