Research On Ripple Eliminated Technology Of Single-phase Inverter Based On Flyback

With the widespread use of traditional fossil energy and the growing environmental problems,people are turning their attention to new clean renewable energy such as solar energy.Photovoltaic power generation is an extremely effective way to utilize solar energy,and photovoltaic inverters,as one of its key links,play a decisive role in the performance of the entire system.Currently,photovoltaic inverters are moving toward high reliability,long life and low cost.This paper mainly studies single-phase inverters that can achieve low-frequency current ripple rejection on the input side.The photovoltaic inverter output is usually connected to the grid or linear load,and the output power has low frequency pulsation.The PV module usually requires the inverter input power to be DC to achieve maximum power tracking,so there is a problem of instantaneous input and output power imbalance.For this reason,large-capacity electrolytic capacitors are usually connected in parallel at the input of the inverter or the intermediate bus of the multi-level inverter to balance the input power and output power,but the electrolytic capacitor has problems of large volume,low reliability,short life and the like.In order to enable the inverter to adopt a film capacitor of suitable price and volume,the capacitance of the capacitor needs to be greatly reduced.In this paper,we first study the working principle of a single-phase inverter using Buck-Boost auxiliary circuit to suppress the low-frequency current ripple on the input side,and analyze its working principle,and A converter control method different from active filtering technique is presented.The inverter realizes decoupling of input and output power by the auxiliary circuit,thereby ensures input DC power,output AC power,and is verified by simulation.The leakage inductance energy of the above inverter cannot be fed back,and there is an auxiliary inductance in the auxiliary circuit,which affects the power density.To this end,this paper proposes a single-phase inverter based on flyback conversion ripple cancellation,which improves the above-mentioned inverter,and adds an auxiliary circuit on the primary side of the transformer.The excitation inductance energy is corrected,and the pulsating power of twice the power frequency is passed through the auxiliary circuit,thereby realizing power decoupling and ensuring the input DC of the inverter.In this paper,the predictive current control strategy corresponding to the inverter is introduced in detail,and the relationship between the auxiliary capacitor voltage ripple and its capacitance is derived.The reference value of the capacitance value is given.At the same time,the design methods of other key parameters are also given.Based on the above basic concepts,this paper designs a prototype to verify the experimental results.The experimental results show that the proposed single-phase inverter based on flyback cancellation ripple is feasible.