Control Method on Photovoltaic Inverter Decoupling Circuit with Electrolytic Capacitor-Less

For the problem of the power imbalance between the AC side and DC side of the two-stage single-phase photovoltaic grid-connected inverter, an active power decoupling circuit control method is proposed. While stabilizing the bus voltage, the long-life film capacitors with small capacitance and high stability are used to replace large electrolytic capacitors with poor reliability. Combined with the law of power conservation, the instantaneous energy stored in the decoupling circuit is equal to the energy of the second fluctuation on the output side of the inverter, and the power decoupling can be achieved to calculate the control reference value required by the decoupling circuit. The calculation process of the decoupling circuit parameters and the design process of the controller are given. For a suitable closed-loop control method, the small signal modeling is presented and voltage current double closed-loop control strategy is proposed. Based on the design parameters, an experimental prototype with a power of 1 kW is produced. The experimental results verified the effectiveness of the proposed active power decoupling control strategy.