Power Decoupling Techniques in Power Conversion System in Battery Energy Storage Without Transformer

In order to eliminate the DC-side power pulsation of high-voltage direct-mounted battery storage systems, a bridge-arm multiplexed symmetrical half-bridge power decoupling structure is constructed to achieve decoupling control of the pulsating power. Firstly, the causes of pulsation power generation and the principle of decoupling control are described. Then, a virtual quadrature is constructed by applying the Second-Order-Generalized-Integrator and the mathematical model of power decoupling control in DQ coordinate system is obtained by coordinate transformation. On this basis, the corresponding passive controller is designed according to the passive control theory, and the power decoupling control strategy is proposed in combination with the pulsating voltage feedforward. Finally, a simulation model is established in PLECS, and the simulation results verify the effectiveness and correctness of the proposed power decoupling control strategy.