PV Power Generation System Based On Quasi-Z Source Inverter

Photovoltaic(PV) power generation is one of the most prospective new energy source, and the power converter play a key role in PV power generation system, it's reliability, efficiency and expense are important to the whole system. The output of PV battery varies a lot under different conditions, so the system needs extra DC/DC convertor to keep the output stable. However, the DC/DC convertor will increase the cost, reduce the efficiency, also the traditional voltage-source inverter may appear shoot-through state and reduce the system operation reliability, while introducing the dead band will cause output waveform distortion.This thesis analyzes a novel inverter-the quasi-Z-source inverter (QZSI), it has only once power transformation, but can boost/buck the input voltage to meet the wide variation of PV battery output. Without extra DC/DC convertor of double stage system or large scale inverter of one stage system, QZSI can reduce the cost and the number of power device. Shoot-through state is allowed in QZSI can prevent the circuit from damaging to enhance system reliability and the output current waveform will be improved because there is no dead band. So the QZSI is ideal for PV power generation.In this thesis, the working principle, average state-space and small-signal model of QZSI have been analyzed. The unique SPWM and SVPWM modulation strategies based on QZSI are introduced also the traditional simple step-up simple SPWM modulation based on Z-sourse inverter is modified to meet the whole system control strategy of QZSI also it has been achieved by sorfware based on DSP. This thesis mainly focuses on the QZSI with energy storage battery based on the PV power system. Simulation results show the validity of proposed structure and control strategy. The structure and control strategy of grid-connected QZSI with battery PV power generation system also has been analyzed and simulation results show the validity of this system proposed. At last a prototype QZSI has been designed and the PV power system with battery based on independent PV power generation systems experiment platform is built. Experiment results verify the validity of the theoretical analysis, the prototype QZSI and the PV Power Generation System with battery based on QZSI.