Three-phase-four-wire Inverter Used in Large Capacity Programmable Harmonic Current Generator

The large capacity harmonic current generator based on three-phase-four-wire configuration uses four-leg converter as its main circuit. So it is different from the traditional small capacity linear current source. The whole equipment can output steady harmonic current include the selective order harmonic (below 25(th) order), reactive current and unbalanced current. Besides, dynamic change process of harmonic current can also be accurately simulated by the equipment. The output harmonic current can be set by communicating with computer or the EPROM. The harmonic current generator can be applied to testing electrical measurement equipment or debugging the harmonic current elimination equipments. This paper firstly introduces the operation principle and main circuit; and then analyzes the control circuit structure and presents one control method with voltage feedforward control and the output current DFT feedback control; lastly the simulation results and the experiment results based on 50kVA harmonic current generator are given in this paper. The results of the simulation and experiment verify the good performance of the device even though for the large capacity.