Space-vector based current control of permanent-magnet synchronous motor/generator drive applied to flywheel energy storage system

This paper develops a 5kW permanent-magnet synchronous motor/generator (PMSM/G) drive applied to flywheel energy storage system (FESS). The higher power density, compact structure and high torque generating capabilities of the PMSM make it suitable for the applications in flywheel energy storage systems, electric vehicles, air-conditioners and micro-grid systems. To develop the PMSM/G drive for charging and discharging the flywheel, the dynamic model is established in advance. According to the derivation of the proposed space-vector based feed-forward current control scheme, the PMSM/G parameters including back-EMF constant, winding inductance and winding resistance are required. The parameter estimation of the PMSM is completed via experimental tests. The proposed current control algorithm can be implemented in both motor mode and generator mode. In addition, the switching times of the three-phase full-bridge power switched in the PMSM/G drive are decreased to reduce the switching losses. The digital control of the PMSM/G drive system is fulfilled by the microcontroller. To verify the driving performance of the PMSM/G drive, some experimental results are measured. This PMSM/G drive can be operated at different rotational speeds and output powers.