基于子模组工况分析的模块化多电平储能系统开路故障诊断方法

These curity and reliability of DC converter in energy storage system are directly related to the normal operation of the system. By the analysis on fault operation conditions of half bridge sub-module in modular multilevel DC-DC converter (MMDDC), this paper proposes a fast-open circuit diagnostic method, which can be used under a wide super capacitor voltage range. According to different voltages endured by the lower arm under normal and fault conditions, a simple hardware detection circuit and a concise diagnosis algorithm built in FPGA are hence employed. The detection circuit is responsible for detecting the operating conditions of sub-module in real time, while the diagnosis algorithm accomplishes the final diagnosis using detection results and drives signals in a short time. The design principle of the proposed method and the selection principle of the key parameters are provided in detail. The proposed method avoids complex mathematical calculations and is easy to be implemented. Finally, the proposed diagnostic method is verified experimentally based on a scale down MMDDC energy storage prototype.