Sensorless Control for Permanent Magnet Synchronous Motor in Rail Transit Application Using Segmented Synchronous Modulation

This paper proposes a position sensorless control technique for permanent magnet synchronous motor (PMSM) used in rail transit application, where a segmented synchronous modulation (SSM) is usually applied. The arbitrary signal injection-based sensorless control is adopted to estimate rotor position. In a switching period, an oversampling technique is used to obtain the average current slope that contains the rotor position information during the active voltage-vector operation. In SSM, the hysteresis zone is set near the carrier ratio (CR) switching critical point to eliminate the influence of the repeated oscillation on the current measurement accuracy. Furthermore, a load disturbance compensation method is designed so that the failure of hysteresis zone is avoided. Through the analysis of power spectral density (PSD) of phase current, the optimization of harmonic energy distribution with hysteresis zone is also verified. The experimental results show that the proposed method can improve the position estimation precision during the fast CR transition, which can be effectively applied in SSM.