Research on Energy Storage Interface Circuit and Its Control Principle Based on the L-LLC Resonant Bidirectional DC-DC Converter

Aiming at the low operating efficiency and poor dynamic response of energy storage interface circuit for flexible interface of connecting microgrid to power grid, the principle of PI or PID and optimal trajectory hybrid control based on the L-LLC resonant bidirectional DC-DC converter (L-LLC BDC) is proposed. It realize zero-voltage switching and zero-current switching for input switches and output rectifiers respectively, besides, it not only significantly reduce the computational complexity and further increase switching frequency, but also improve dynamic response of the converter remarkably. Using state-plane analysis, the operation status and characteristics of L-LLC-BDC are described in detail, based on that, the control system of the energy storage interface circuit is designed. In view of the principle of PI or PID and optimal trajectory hybrid control based on the L-LLC-BDC, the simulation shows that the correctness of theoretical analysis and the superiority of dynamic response and the operation performance of flexible interface of connecting microgrid to power grid is guaranteed.