用于钒电池组自启动的双级高频隔离变流器
Two-stage DC/DC converter with a high frequency transformer used in a vanadium battery self-startup

钒电池启动时需先为电解液循环系统供电，待电堆主闸自动闭合后电池才能正常充放电。但是，钒电池在严重缺电时电堆的初始电动势较低，与循环系统的恒压供电值相差较大，所以，当电堆主闸自动闭合时变流器与电池间会产生较大的冲击电流。针对上述问题，该文提出了一种双级型高频隔离变流器及其控制方法，实现了高频隔离并网钒电池组在自启动过程中的冲击电流抑制，并通过电池参数测定避免了变流器限流控制时循环系统由于电压过低导致自启动失败的现象。最后通过5kW钒电池样机自启动实验，验证了所提出拓扑的可行性及控制方法的有效性。
Abstract：The self-startup of a vanadium battery consists of the following steps. Firstly, the electrolyte circulation system is started. After the main switch is closed to connect the cell stack with the converter, the conventional charging and discharging operations are then started. However, the voltage difference can be extremely large between the electrodes in the stack and the required input voltage in the circulation system, especially when the stack is at low capacity. This large voltage difference will lead to a large current transient between the converter and the vanadium battery. Thus, when the converter is using current limit control, the circulation system input voltage should be carefully selected to avoid self-startup failure. This paper presents a two-stage DC/DC converter with a high frequency transformer for the vanadium battery self-startup process with its control principle. A self-startup test with a 5 kW vanadium battery module showed that the converter worked during the self-startup and charge/discharge processes.