The Study On The New Control Strategy Of Z Source Inverter

Research status on the Z source inverter and some control strategies are reviewed in Chapter 1 first.An abnormal operating state of the traditional Z source inverter is analyzed in Chapter 2, and the causes and the drawback of the state is discussed in detail. In order to overcome the drawback of the traditional Z source inverter, a modified Z source inverter is introduced. The principle of the modified Z source inverter is presented. The validity of the modified Z source inverter is verified by simulation and experiment results.The DC link close-loop control strategy of Z source inverter is presented in Chapter 3. At first, a small-signal model of Z source inverter DC link is proposed. Then the close loop control circuit designs of both the Z source capacitor voltage and the input voltage peak are presented in detail . Simulation and experiment results verify the validity of the proposed close loop control strategy.In Chapter 4, the output voltage control strategy of the Z source inverter is presented. At first, the modeling of the inverter part is introduced. After that, the control strategy of the traditional voltage source inverter is introduced. Then, the instantaneous voltage feedback control circuit of the Z source inverter with an inner loop of the output filter inductor current (double close loop) is designed. The validity of the double close loop control strategy is verified by simulation and experiment results.In Chapter 5, some new hardware techniques adopted in a 20kW prototype are presented. This chapter focuses on the auxiliary power supply design, the drive and protection circuit designs, and the 3D structure design of the prototype.At last, the research work of this thesis is summarized and the future research tasks are given.