A new high-frequency AC link three-phase four-wire power electronic transformer

In this paper, a new three-phase four-wire high-frequency AC link matrix converter is discussed, and the topology of conventional matrix converter is modified with an additional transformer for three-phase four-wire electronic power distribution application. The proposed approach accomplishes high output voltage transfer ratio which is more than unity, galvanic isolation between both voltage sources and higher power density by employing a high-frequency transformer into the intermediate stage of the dual bridge matrix converter. It has a bidirectional power flow capability, controllable input source displacement power factor and lower harmonic distortion on both input and output sides. Furthermore, with three dimensional space vector PWM (313 SVPWM) and modified control strategy, the input and output currents may keep low harmonic distortion under unbalanced input voltage or variable three-phase four-wire unbalanced loads. The proposed approach is a competitive solution to the electronic power transformer. Experimental results of a three-phase four-wire 220/380V 5KVA 50Hz electronic power transformer system based on DSP controller are presented and shown to demonstrate the advantages of the proposed system.