A Novel Current Control Method Based on Dual-Mode Structure Repetitive Control for Three-Phase Power Electronic Load

The test platforms of motor driver are relatively expensive, high energy consumption, complex mechanical structure, and not readily available. A three-phase power electronic load of simulated permanent magnet synchronous motor is used to eliminate the risk associated with the performance testing of motor driver, without complex mechanical system. This equipment not only can simulate a variety of load characteristics, but also has the ability to recover energy with little loss and high power factor. In this work, a novel current tracking control strategy based on dual-mode structure repetitive control (DMRC) is proposed to improve the tracking accuracy of alternating current. Compare to control strategy operated in the d-q coordinate system, the proposed control strategy can direct track sine wave commands on the stationary α-β coordinate system, which is easier to implement with fewer intermediate coordinate transformation in practice. An inductor-capacitor-inductor (LCL) filter is used to interface the voltage source converter (VSC) and the tested inverter in the three-phase electronic load system. Adjusting the odd-harmonic gain and even-harmonic gain of DMRC controller can effectively suppress the current harmonics. Furthermore, the comparative evaluation of DMRC, repetitive control and conventional PI control is conducted to verify the superiority of DMRC at different AC voltage frequency of tested inverter. The simulation has been carried out on three-phase power electronic load. As a result, the proposed method can achieve low total harmonic distortion (THD) (<1.8%) of AC current, It can provides nearly 20% reduction of THD in phase current when compared with PI controller.