Research On Single-Phase Inverters With Zero Low Frequency Input Current Ripple

As renewable energy,the development and utilization of solar energy is helpful to ease the current energy crisis and environmental problems.Photovoltaicn(PV)power generation is an important way to use solar energy.As an important link in the photovoltaic power generation system,PV inverter plays a key role in the efficiency,reliability,life and other aspects of the whole system.In the photovoltaic power generation system,the PV module output is the DC power,while the instantaneous output is pulsating power.In order to balance the input and output power,usually in the DC side parallel large capacity electrolytic capacitor to decouple the power pulsation,thus ensuring the input side does not contain low frequency current ripple components.However,the life of the electrolytic capacitor is limited,thus limiting the life of the inverter system.Therefore,how to reduce the required capacitance of the decoupling capacitor,which can be used thin film capacitor,making the inverter system greatly extended life.In this paper,the development of photovoltaic power generation and inverter is introduced in detail,and then some methods to suppress low frequency current ripple are analyzed.To solve this problem,a novel single-phase inverter with zero input low frequency current ripple is proposed in this paper.For the new single-phase inverter,two improved single-phase inverters are proposed.In these three single-phase inverters,the isolated step-up converter is constructed by embedding the auxiliary circuit in the flyback converter,and then the power ripple is completely transferred to the decoupling capacitor,eventually eliminating the low frequency ripple components in the input current.In this paper,the working principle of the inverter and the design of the key parameters is described in detail,and verified by the MATLAB simulation software.An experimental prototype is also set up to verify one of the improved single-phase inverters.The experimental results verify the feasibility of this improved single-phase inverter.The last chapter summarizes the major results of the work and offers suggestions for future work.