Review of Sensorless Control Technology for Flywheel Energy Storage PMSM

Abstract

Sensorless control of the Permanent Magnet Synchronous Motor (PMSM) is a key technology for achieving high efficiency and reliable operation in Flywheel Energy Storage Systems (FESS). This review focuses on sensorless control techniques suitable for the wide speed range and high dynamic response of FESS, covering methods for zero/low-speed, medium/high-speed, and full-speed operation. First, the fundamentals of sensorless control for FESS motors (mainly PMSM) are analyzed, and the principles and advantages of high-frequency signal injection methods in the zero/low-speed range are compared, along with their limitations in standby and startup scenarios of the flywheel. Second, recent advances in model-based methods-such as sliding mode observers and model reference adaptive systems-for the medium/high-speed range are elaborated. By comparing the strengths and weaknesses of each method under charging, discharging, and standby conditions, targeted improvement strategies are summarized, and a full-speed sensorless control strategy tailored to the FESS PMSM is proposed. Finally, future trends are discussed in the context of practical FESS applications, including online parameter identification, fault-tolerant control, and the integration of intelligent algorithms.