Research And Design Of Resonant Single Phase Inverter With Power Decoupling

Household photovoltaic inverter system has the inherent double-frequency problem due to the instantaneous power unbalance between DC and AC side.Such low frequency power will cause double-line frequency ripple on the input inductor and dc-link capacitors which will damage the input source and degenerates the output power quality.The double-line frequency ripple problem has attracted a lot of research attention and should be treated seriously.This paper first analyzes the mechanism of low-frequency ripple and its harm to the power generation system,and summarizes the advantages and disadvantages of the existing solutions.A single-phase photovoltaic grid-connected inverter(DC-AC)low-frequency ripple suppression method based on buck/Boost active power decoupling control method is proposed.Based on the type of single-phase push-pull DC-AC inverter,further study on the basic principle of active power decoupling control,the design of active power decoupling control algorithm,using power semiconductor devices to circuit redistribution of energy storage component,the shift of low-frequency power ripple,eliminate the output DC voltage ripple,thereby significantly reducing demand for capacitor capacity,can use thin film capacitor optimizing the overall performance.A two-level inverter scheme with soft switching function is designed,and the scheme is analyzed in detail and its parameters are designed.The active power decoupling circuit uses independent closed loop control,and the inverter uses current feedforward double closed loop P+PI control.A two-stage inverter and DC bus active power decoupling converter model was built using PSIM,and a hardware test platform was also built to test the control algorithm.The simulation and experimental show that the active decoupling control method of the single-phase grid-connected inverter and the active decoupling circuit proposed in this paper are effective,which can obviously reduce the voltage ripple of the DC bus,improve the output voltage quality obviously,and provide some theoretical and technical guidance for the overall performance improvement of the new energy power generation system.