An Application Of Z-Source Inverter As A Grid-connected Power Conditioner

Research status on the Z source inverter as a grid-connected power conditioner and some control strategies are reviewed in Chapter 1 first.The DC link close-loop control strategy of Z source inverter is presented in Chapter 2. At first, a small-signal model of Z source inverter DC link is proposed. Then the close loop control circuit design of the Z source capacitor voltage is presented in detail. Simulation and experiment results verify the validity of the proposed close loop control strategy.In Chapter 3, the output current 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 with LCL filter as a grid-connected power conditioner is introduced. Then, A novel grid-connected strategy with zero steady-state error is developed in this paper. A more practical quasi-PR controller is used and a step by step design procedure is proposed based on theoretical analysis. The validity of the close loop control strategy is verified by simulation and experiment results.In Chapter 4, some new hardware techniques adopted are presented. This chapter focuses on the auxiliary power supply design, the drive and protection circuit designs. After that, the flow charts of DSP are presented. This chapter focuses on soft start program, a digital phase locked loop control program and the PWM production program. The experiment results are given in the end.At last, the research work of this thesis is summarized and the future research tasks are given.