A Buck Type Multi-Input Distributed Generation System With Parallel-Timesharing Power Supply

This paper proposes the circuit structure, topological family and energy management control strategy (EMCS) of a Buck type multi-input distributed generation system (DGS) with parallel-timesharing power supply. Also, the power supply modes (PSMs) and their smooth transition, as well as the control loops and multiple duty cycles expression are studied. The circuit structure is composed of a Buck type single-stage multi-input inverter and a single-stage isolated battery charging/discharging converter, with their outputs parallel-connected on the AC side. The topological family includes full-bridge etc. 3 types of circuit. By comparing the load power and the total generated multi-input sources power, the proposed EMCS achieves real-time control of charging/discharging converter's power flow and the system's smooth transition among different PSMs. The proposed "variable inductances equivalent method" regards the output filter inductor as the parallel connection of two virtual inductances, based on which the small signal model of multi-input inverter is established and the corresponding control loops are designed. Experimental results of a 3kVA laboratory prototype have shown that the proposed circuit topology has a good performance of high conversion efficiency, low distortion of output voltage, and galvanic isolation among load, multi-input sources and battery, etc.