Harmonics Influence Analysis on Current-Oversampling-based Position Estimation under Multi-mode PWM for IPMSM Sensorless Drives in Rail Transit Applications

Due to characteristics of direct drive and high efficiency, IPMSM is widely used in rail transit applications. In rail transit traction system, the electromagnetic environment is complex, and the position sensor is prone to damage, resulting in train operation failures. Because the implementation way has high dynamic performance and does not require additional signal injection, the rotor position estimation based on current oversampling is suitable for sensorless control in rail transit application. Currently, the optimized synchronous modulation used in traction inverter is selected harmonics elimination (SHE) PWM. However, different SHE modes result in varying harmonic components in the induced current, which leads to different current distortion levels and of reduce current over-sampling fitting accuracy. Finally, the rotor position estimation performance is deteriorated, which needs to be further analyzed and addressed in this work.