Research On The Mechanism Of Common Mode Voltage In Matrix Converter

Compared with the AC-DC-AC type of power of converters, as one type of general power converter, MC (Matrix Converter) can realize n phase to m phase voltage conversion and provide sinusoidal output voltages with varying amplitude and frequency, while drawing sinusoidal input currents with unity power factor. This converter can render bi-directional power flow and need no energy storage components except small AC filters for elimination of switching ripples. The MC function is different by changing the control algorithm as rectifier, inverter, converter, etc. Moreover, four-quadrant operation without power grid pollution is achievable. Due to above mentioned characteristic, MC attracts many researchers'interests to investigate on power conversion by means of different new technical issues.An introduction is given, which includes the background, purpose and meaning of research work, the configuration of MC and matrix converter's control methods. The principles and the equivalent AC-DC-AC topology of MC, and the SPWM strategy is analyzed and modulated. The characteristic of SPWM is that the control is simple, the control switch function needn't completed math reasoning and calculation, the output line voltages of converter meet sinusoidal rule, and the output frequency can be modulated. Simulations and experiments are used to identify its feasibility.According to the mechanism of CMV ( Common Mode Voltage ) generated by MC and the restraining principle, the magnitude, waveforms and harmonic spectrum of CMV were investigated in details, and the essences of CMV are presented. CMV of different switch states of SPWM is analyzed and simulated. A new three level control strategy to reduce the maximum CMV is presented, which can eliminate CMV, restrain its adverse effects in effect, and the output line voltage tends to be more like sine wave. Simulations and experiments are used to identify its validity and availability.In the end, by comparing several SPWM control strategies, it's obviously high level can restrain CMV. The output line voltage tends to be more like sine wave, and it can eliminate CMV in evidence, which can do some theory instruction to eliminating CMV, which establishes basics for MC's more researches.