A simple sensorless control strategy for IPMSM in 1 MW flywheel energy storage system

Abstract

In recent decades, the flywheel energy storage system (FESS) has developed rapidly. Field oriented control is a core technology in the control of the interior permanent magnet synchronous motor (IPMSM), which is usually selected as the flywheel motor. The rotor angle and the speed of the IPMSM are important variables in the field oriented control. In industrial applications of the large-capacity FESS, however, the speed sensor could be unreliable due to the external interference and hence it is difficult to obtain the precise values of those two variables. In this paper, a simple sensorless control strategy is proposed in order to evade the measurement of the rotor angle and the speed. The proposed strategy is divided into two parts in accordance with the flywheel's speed and an angle estimation method based on the back electromotive force (back-EMF) is adopted after the starting of the flywheel. In the proposal, the rotor position can be estimated accurately during the system's whole operation period, including the charging status, the discharging status and the standby status, and the continuous information of the rotor angle and the speed can be obtained. The proposed sensorless control strategy is analyzed theoretically, and experiments are conducted on a 1MW FESS. The experimental results verify the effectiveness of the proposed strategy.