Robust Open-Switch Fault Diagnosis of Bidirectional DC/DC Converters Based on Extended Kalman Filter With Multiple Corrections

Open-switch fault of power transistors is a common problem in bidirectional DC/DC converter, which can cause considerable property loss and personal safety risk. However, the traditional model-based fault diagnosis methods mainly focus on the rapidity and rarely consider the parameter change of bidirectional DC/DC converter, which is poor in robustness. Therefore, this paper proposes a robust open-switch fault diagnosis method for bidirectional DC/DC converters in a hybrid energy storage system (HESS) based on extended Kalman filter (EKF) with multiple corrections, where the measured currents on the battery side and the supercapacitor side are used to correct the observed currents obtained by EKF until the residuals between the observed values and the measured values are less than the set correction thresholds, thus avoiding the influence of the parameter variations. The open-switch fault detection is achieved by judging whether the correction times of the currents on the battery side and the supercapacitor side exceed the maximum correction times. The open-switch fault location is achieved through judging whether the corrected value on the fault side exceeds the set correction threshold. The proposed method is validated through simulation and experimental studies. Both the results show the robustness of fault diagnosis for bidirectional DC/DC converter.