Research On Quasi-z-source For Single-phase Inverter

In the new energy power generation system, the traditional voltage source and currentsource inverter have the barriers like the range of application is small and the antijamming ability is weak. The Z-source inverter can realize the buck-boost ability and theability of shooting-through the phase legs which is performed by two-stage conversiontradionally, then improve the stability of the system. But the present Z-source inverter hasthe drawbacks of high capacitor voltage stress and huge inrush surge.Against the traditional Z-source inverter defect, the new Z-source inverter is analyzedin the thesis. Compared with the traditional Z-source inverter, it features lower voltageacross one of the capacitors. But the inverter also has the drawback of huge impact. Aquasi-z-source inverter is presented in the thesis. The new topology can reduce the voltageacross Z-source capacitors. The soft-start strategy for the new inverter is proposed to avoidthe impact. Thus it can improve the stability of the system.The system model of the inverter is established and transfer function is derived. Acontrol strategy with capacitor voltage plus feedback is investigated, so it can control ofthe voltage of the output. Double-frequency PWM is investigated, combined withquasi-z-source inverter’s characteristics, analysis and comparison of different modulationSPWM. Then propose a modified SPWM control strategy. Analyze the system state andthe parameter design rule is given.At last，the simulation and a prototype are built on and the experimental results aregiven. A experimental prototype is built up and verify the theoretical analysis bysimulation and experiment.