双有源桥直流储能系统软开关优化控制

传统直流储能系统中电容器荷电状态(state of charge, SOC)的变化会导致直流变换器两端电压不匹配，使得功率器件无法处在软开关状态，从而增加了开关损耗。通过分析软开关控制与电容器SOC之间的关系，本文提出一种双有源桥(dual active bridge, DAB)直流储能系统软开关优化控制，实现储能系统在充放电过程中，各功率器件始终处在软开关状态，维持直流母线电压稳定，降低功率损耗。该方法将储能电容SOC变化引入DAB移相控制，确定SOC与移相角的定量关系，使直流变换器功率器件满足软开关条件。根据直流母线电压及储能系统充放电特性，设计恒压、恒流充电和恒压、恒功率放电控制方法。仿真与实验结果验证了所设计软开关优化控制方法的有效性。

Soft-switching Optimal Control for Dual Active Bridge DC Energy Storage System

The change of state of charge (SOC) for traditional DC energy storage system leads to the voltage mismatch of DC converter, which makes the power device unable to be in soft switching state and increases the switching losses. A soft switching optimal control method for dual active bridge (DAB) DC energy storage system is proposed in this paper by analyzing the relationship between soft switching control and capacitor SOC. The method can realize the soft switching state of power devices in the charging and discharging process for DC energy storage system, which keeps the stability of DC bus and reduces the power losses. The capacitor SOC is introduced into the phase shifting control of DAB by determining the relationship between SOC and phase shifting angles, which makes the converter power devices satisfy soft-switching conditions. According to the DC bus voltage and the charging and discharging characteristics of energy storage, the constant voltage, constant current charging and constant voltage and constant power discharging control method is designed. The simulation and experiment results verify the effectiveness of proposed soft switching optimal control method.