Closed-Loop Control for Cascaded Bidirectional Buck+Boost Converter with A Low-Loss Modulaiton Strategy

Compared with the traditional centralized battery energy storage system, the resident battery energy storage system has the advantages of high flexibility, high control granularity and high efficiency. Focus on this resident application, the bidirectional non-insolated DC-DC converter directly connected to battery modules is the key components. For the optimization of the conversion efficiency, the low-loss modulation strategy with PWM plus phase shift is analyzed considering the zero-voltage switching (ZVS) conditions and loss distribution. On this basis, the constant voltage control scheme in both step-down and step-up modes are proposed under the restriction of ZVS constraints. The experimental results show the feasibility and effectiveness of theoretical analysis, modulation strategy and control scheme.