On-line diagnosis for rectifier open circuit faults and input voltage unbalance based on the output DC voltage

Power electronics converter systems (PECS) are significant corner stones in enormous variety of industrial applications, including smart grids and variable speed drives. One of the factors that assist to improve such systems is the study of their fault mode behaviors. Besides that, the open circuit (O-C) faults in the PECS do not trigger the standard protection systems in the converter but rather cause system malfunction. Therefore, the O-C fault diagnoses become critical for PECS. This paper presents an on-line fault diagnostic algorithm for O-C faults of the power switches in the rectifier circuit, as well as the identification of the unbalance input voltage to the rectifier. The proposed techniques are based solely on the measurements of the output DC voltage of the rectifier; so, they avoid any additional sensors or hardware in comparison with the previous researches. The experimental evaluations for the proposed algorithms are implemented using a coupled DC motor with AC synchronous generator scheme, and demonstrate the effectiveness and the robustness of the proposed diagnostic algorithms in this paper.