Research On Photovoltaic System Based On Z-source Inverter

Contradiction between the depletion of traditional energy sources and the demand of increased energy has led to more attention to the development and utilization of new energy. Naturally, as a clean, green renewable energy, solar energy has gained people's popularity, and photovoltaic power generation has become one of the important research areas. At present, the traditional voltage-source inverter and current-source inverter are widely used in power electronic conversion devices of the photovoltaic generation system.However, both of the two kinds of topology have some inherent theoretical flaws, for example, additional DC/DC boost or buck converter is needed, the switches of the upper and lower bridge leg can not be in shoot-through states or open states simultaneously. These shortcomings will increase the cost of photovoltaic power generation system, reducing conversion efficiency, causing the output AC voltage waveform distortion, and even affect the industry process of photovoltaic power generation.To solve this problem, a novel topological structure-Z source inverter was used, and the photovoltaic system was developed and designed with the core of this inverter. Firstly, the article analyses the circuit structures and shortcomings of the traditional inverters, on this basis, the topology, operation principle and the frequently-used modulation strategy were presented in details. It is found that during to the addition of shoot-through signals, the switching times of Z-source inverter are greatly increased by up to 2 times, resulting in increased switching losses. As a result, the modulation strategy of injecting non-sinusoidal into reference voltage is presented in this paper and analyzed using the power electronics simulation software PSIM. Compared with the traditional simple boost modulation strategy, the switching times are reduced by 50% and switching loss is greatly decreased. In addition, the modulation index M is increased from 1 to 2/3^1/2. Correspondingly, the DC voltage utilization is increased and the voltage stresses of switching devices are reduced.On the basis of the above theoretical analysis, experimental platform of photovoltaic power generation system based on Z-source inverter was set up, adopting TI's Digital Signal Processor TMS320LF2407A as the central process unit, and the software part and hardware part are both designed and debugged. For comparison analysis, the photovoltaic power generation system with the modulation strategy of simple boost control and injecting non-sinusoidal into reference voltage are both carried out related research. Consistent with simulations and experiments to verify that when using the modulation strategy of injecting non-sinusoidal into reference voltage, the photovoltaic power generation system based on Z-source inverter has the following advantages:the harmonics in the output waveforms of the inverter are decreased, switching losses are Significantly reduced and The output performance of photovoltaic power generation system are improved.