A Sensorless Control Method for Inertia Flywheel Coupler

The high penetration of renewable energy sources into power grids has intensified system frequency fluctuations. Flywheel energy storage technology offers a solution to enhance grid frequency stability. Within flywheel storage systems, precise control of the electromagnetic coupler linking the inertia flywheel and synchronous condenser is critical. Conventional speed-sensor-based control schemes suffers from high implementation costs and reliability limitation, while sensorless control techniques remain inadequately explored for zero and low slip speed operation of electromagnetic couplers. This paper proposes a novel high-frequency voltage injection method for sensorless position control of electromagnetic couplers in inertia flywheel systems. By optimizing injection voltage and signal processing process, the method improves angular position estimation accuracy. Specifically, a dual-loop speed-current control strategy is designed and implemented, tailored to the operational characteristics of electromagnetic couplers within a slip speed range of 0 - 300 rpm. Simulation results demonstrate that the proposed method achieves effective speed-sensorless control of electromagnetic couplers and improve the control performance compared with the traditional method.