IPMSM Sensorless Control for Zero- and Low-Speed Regions Under Low Switching Frequency Condition Based on Fundamental Model

In the high-power traction system, such as rail transit, the switching frequency is relatively low. The bandwidth of the current controller and the frequency of the injected signal are both limited under low switching frequency, which hinders the sensorless control of interior permanent magnet synchronous motor (IPMSM) in the zero- and low-speed regions. This article presents an IPMSM sensorless control for zero- and low-speed regions under low switching frequency conditions based on the fundamental model. The position can be estimated from the estimated virtual back electromotive force (EMF) with sinusoidal current injection. An internal model control (IMC) and a vector PI (VPI) control are designed to solve the problem of current controller bandwidth limitation. The multiple adaptive filters (AFs) based on the second-order second-order generalized integrator (SO-SOGI) are designed to eliminate the harmonics related to the injection frequency and the fundamental frequency in the stationary frame (SF) to improve the control performance. Meanwhile, the proposed sensorless control strategy is extended from the SF to the rotating frame (RF), which is easier to implement. The rotor position and speed are estimated by a third-order supertwisting extended state observer. The effectiveness of both proposed strategies is verified by experiments.