An Improved Sensorless Control of IPMSM Based On Pulsating High-Frequency Signal Injection With Less Filtering for Rail Transit Applications

A pulsating high-frequency signal injection-based low-speed sensorless control of interior permanent magnet synchronous motor (IPMSM) using a conventional stationary reference frame low-pass filter (LPF) may experience a phase delay. Similarly, the heterodyning process may exhibit time delay and bandwidth restriction. Thus, an improved approach with a single high-pass filter in a stationary reference frame is proposed. The rotor position error is extracted from the high-frequency current using the sign of sine of the injected signal considering the phase shift. Consequently, the estimated reference frame LPF in the heterodyning process and the delay compensator for a stationary reference frame LPF-based approach are discarded. A phase-shift tracking observer (PSTO) independent of position error is included. Meanwhile, an online d-axis high-frequency current amplitude estimation is adopted to normalize the effect of d-axis inductance variation. The comparative study with a stationary reference frame LPF and the heterodyning process has shown that the proposed self-sensing strategy delivers an excellent speed sensorless control performance. Thanks to the online d-axis current amplitude estimation, the impact of d-axis inductance variation on speed-position identification has been improved. The proposed self-sensing strategy has been validated using MATLAB simulation and Hardware-in-the-loop (HIL) with TMS320F28335 digital signal processor considering rail transit applications.