Sliding Mode Observer-Based Robust Switch Fault Diagnosis of Bidirectional Interleaved Converters for Energy Storage System

Reliable operation of the DC-DC power converter interfaced with the energy storage system is vital for many mission-critical applications, where a reliable fault diagnosis is essential. In this paper, a robust switch open-circuit fault diagnosis method based on sliding mode observer is proposed and then applied to a bidirectional interleaved buck/boost converter for the energy storage system. It uses the sliding mode observer to generate the residual, which is then sent to the evaluation module to make the fault decisions. Thanks to the robustness of the sliding mode control algorithm, the generated residual decouples the uncertainties and disturbances with the switch faults. Therefore, it shows strong immunity to the circuit parameter uncertainties and load disturbances. Furthermore, as the diagnosis variables, namely, the inductor currents, are within the closed-loop control system, the extra sensors are not needed. The effectiveness and robustness of the proposed fault diagnosis method have been demonstrated by both the simulation and experimental results.