Research On Three-to-One-Phase Quasi-Z Source Matrix Converter

Matrix converter has been paid widespread attentions by scholars at home and abroad because of its many advantages, and recently has become one of the hot spots in the field of power electronics. However, the current research mainly focused on three-to-three-phase form, rarely involves the three-to-one-phase matrix converter. With the rapid development of new energy technologies, single-phase power supply with high-quality is needed in more and more industrial applications, so it is very important to study three-to-one-phase matrix converter. But traditional three-to-one-phase matrix converter has low voltage gain, its input currents are distorted, and output is sensitive to grid disturbances. All of these defects have seriously limited its application in industrial practice. This thesis is devoted to solve these problems in the traditional three-to-one-phase matrix converter.Firstly, three-to-one-phase Quasi-Z source direct matrix converter and three-to-one-phase Quasi-Z source indirect matrix converter are proposed, which insert Quasi-Z source into three-to-one-phase direct matrix converter and three-to-one-phase indirect matrix converter, respectively. By using the unique characteristics of the Quasi-Z source circuit, the shortcomings of low voltage gain and poor anti-interference ability are overcomed.Secondly, by inserting shoot-through vector into the modulation method of traditional three-to-one-phase matrix converter, the dual voltage modulation method is proposed for three-to-one-phase Quasi-Z source direct matrix converter, as well as pace vector modulation method for three-to-one-phase Quasi-Z source indirect matrix converter.Thirdly, in order to solve the distortion of the input current, analytic models of input current are built for three-to-one-phase Quasi-Z source direct matrix converter and three-to-one-phase Quasi-Z source indirect matrix converter, respectively. The paramenter design method of Quasi-Z source is studied. It is found that the input current can be sinusoidal by designing the parameters of the Quasi-Z source. However, a larger Quasi-Z source parameter is needed when the output frequency is low, which results in a low power factor for the system.Fourthly, to solve the distortion of the input current when the output frequency is low, a new three-to-one-phase Quasi-Z source indirect matrix converter with power compensation is proposed. A predictive power control method is proposed for this converter. Simulation results verify the sinusoidal input current can be obtained by using this modulation method.Finally, the experimental platform is built, which uses DSP and CPLD as control unit. A series of experiments were carried out on the proposed three-to-one-phase Quasi-Z source direct matrix converter. The results show that the proposed converter and the model are correct.