Overview Of Sensorless Control Methods Of PMSMs Using High Frequency Injection

This research is concerned with the development and analysis of sensorless control strategies for Permanent Magnet Synchronous Motors (PMSMs), with a particular emphasis on the critical zero- and low-speed operating regions. Specific focus is given to the challenges encountered at low speeds, where the back electromotive force (Back-EMF) is minimal, necessitating the utilisation of alternative methods for rotor position estimation. The three high-frequency injection (HFI) techniques, namely pulsating injection with a sinusoidal wave, rotating injection with a triangular wave and pulsating injection with a square wave, are subjected to a comprehensive analysis. The research methodology is based on a combination of simulation and experimental validation. A comprehensive simulation of the proposed algorithms was conducted to study their behaviour and robustness under a variety of operating conditions. The simulations yielded valuable insights that informed the subsequent implementation of the techniques on a physical PMSM test bench. The experimental measurements corroborated the efficacy of the pulsating and rotating HFI approaches for estimating rotor position and speed in the low-speed region, while also identifying areas that warrant further examination. The results demonstrate that the proposed sensorless control methods are capable of achieving reliable performance under challenging conditions, thereby providing a foundation for further advancements in the field. This work makes a contribution to the understanding and practical implementation of sensorless PMSM control, particularly in applications that require precise operation at low speeds.