Abstract：This paper proposes a three-phase quasi-Z-source grid-connected inverter with strong boost ability and three kinds of simple boost modified space vector modulation (SVM) strategies. Two existing kinds of modified SVMs were used as the simple boost modulation. The characteristics of the inverter with five kinds of simple boost modified SVM strategies were deeply investigated and compared, including the switching losses of the inverter bridge and the impedance network diode, the loss of the energy storage inductor, the current ripples of the energy storage inductor and the filter inductor, and total harmonic distortion (THD) of output grid-connected current. It is concluded that the overall performance of the inverter is the best with the simple boost modified SVM that has four shoot-through segments between active vectors and traditional zero vectors. The quasi-Z-source grid-connected inverter is composed of a large boost ratio quasi-Z-source impedance network and a three-phase inverter. The simple boost modified SVM strategy has many advantages, such as fully utilizing zero vector action time, low switching loss and voltage stress, strong boost capability. The feasibility of the inverter and the correction of theory analysis were verified by the experiments. It lays a key technical foundation on new energy grid-connected power generation systems such as photovoltaic, wind.
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2018, Vol. 33 
