三电平双有源桥DC-DC变换器开路故障的故障诊断与容错方法

The three-level dual-active-bridge (TL-DAB) DC-DC converter is a promising bidirectional DC-DC converter for high-voltage and high-power systems. As the core component in electric vehicle (EV) battery charging systems, TL-DAB will gain wide applications due to its advantages of the capability of high voltage range, high power density, and easy control implementation. The reliability of TL-DAB is essential for the safe operation of the whole EV battery charging system. However, the open-circuit fault (OCF) in TL-DAB converters is a huge threat, leading to DC bias, overcurrent, and imbalanced electrical stress. To address these issues, fault detection and tolerant methods are supposed to be developed. In this article, a fault diagnosis method based on the central voltages of the bridge arms is proposed to locate the faulty switch quickly and accurately. Then, the corresponding fault-tolerant methods are proposed to reduce or remove the threats caused by single or multiple open-circuit faults and maintain a certain transmission power. A TL-DAB converter experimental platform is built to verify the correctness of the faulty mode analysis of TL-DAB converter and the effectiveness of the proposed fault detection and tolerant method.