Switching Angle Fitting-Based Delay Compensation With IPLL for IPMSM Sensorless Drives Under SHEPWM

In the medium- and high-speed range of rail-transit applications, to maximize utilization of the dc bus voltage and optimize the induced harmonic performance, selective harmonic elimination pulsewidth modulation (SHEPWM) is implemented. Under low switching frequency, considering a further reduction in the calculation delay effect, a switching-angle fitting (SAF) method is proposed with delay compensation in SHEPWM. In addition, the conventional phase-locked loop (PLL) cannot guarantee position extraction accuracy under acceleration and deceleration conditions, and the delayed estimated position increases the input error of the PLL. Then, SAF-based delay compensation with an improved PLL (IPLL) is designed to eliminate the position estimation error. Finally, a 3.7-kW interior permanent magnet synchronous machine (IPMSM) sensorless drive platform is used to verify the effectiveness of the proposed strategy.