An Improved SoC Balance Control Method for Low-Voltage DC Microgrids

The low-voltage DC microgrid is an important form of smart power supply system to realize the DC load of terminal users. In order to solve the problem of inconsistent state of charge (SoC) of each energy storage unit in DC microgrids, an improved SoC balancing method is proposed for low-voltage DC microgrids on the customer side. The method can realize SoC balancing and load current sharing in both charging and discharging process, while the bus voltage deviation can be in a small range. Meanwhile, the control system does not need the output current sampling and interconnection communication among each energy storage unit, which reduces the design cost of the system. Secondly, the curve method is proposed to analyze the dynamic characteristics of the system operation process according to the curve characteristics of SoC function, and the system stability analysis is given based on the small signal model. Finally, the hardware experimental platform is built to verify the correctness and feasibility of the proposed method.