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 Pulse Width Modulation (SHEPWM) is implemented. Under low switching frequency, considering 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, switching-angle-fitting-based delay compensation with an improved phase locked loop (IPLL) is designed to eliminate the position estimation error. Finally, a 3.7-kW IPMSM sensorless drive platform is used to verify the effectiveness of the proposed strategy.