Fault diagnosis of open and short-circuit faults in a parallel multi-cell converter based on sliding mode observer

This paper presents an observer-based diagnosis approach of open and short-circuit switch faults in a parallel multi-cell converter composed of three buck type converters. Motivated by its convergence qualities in a finite time and its robustness to external uncertainties and disturbances, a first-order sliding mode switched observer is used in residual generation. The residuals are then compared to a fixed threshold to obtain the different faults signatures. The selected residual evaluation function provided more information about residual signals which allowed the isolation and identification of the faults. Taking into account the hybrid behavior of the studied system, this method ensures both the detection and the identification of the fault, and eventually, the isolation of the faulty switch in the case of single and multiple faults. Moreover, it provides a fast diagnosis and thus allows a timely intervention to reconfigure the system and ensure safety and continuity of operation. The performance of the proposed approach is established by numerical simulations.