A new matrix type three-phase four-wire power electronic transformer

A new three-phase input, three-phase four-wire output, and with a high-frequency AC link matrix type convertor is discussed. The topology of the conventional matrix convertor is modified with an additional high-frequency 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 convertor. It has the same advantages as the conventional matrix convertor, such as bidirectional power flow capability, controllable input power factor and lower harmonic distortion on both input and output sides. Furthermore, with three dimensional space vector PWM (3D SVPWM) and modified control strategy, the input and output currents may keep low harmonic distortion under unbalanced input voltages 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.