Fault detection and location of open-circuited switch faults in matrix converter drive systems

Matrix converter based electric vehicles can be effectively applied to military vehicles due to weight and volume reduction as well as high temperature operation with no dc-bus capacitors fragile in a harsh environment. For successful applications for military vehicle areas, satisfactory reliability issues have to be incorporated into the matrix converter drives. This paper proposes a fault diagnostic technique for detecting and locating open-circuited faults in switching components of matrix converter drive systems. In this paper, the fault-mode behaviors of the matrix converter are, in detail, explored under the open-circuited switch fault conditions. Based on the investigated knowledge of the converter behaviors, the proposed scheme enables the matrix converter drive to detect and exactly identify power switches in which open-circuited faults have occurred. The proposed fault diagnostic algorithm is based on monitoring nine voltage errors assigned to nine bi-directional switches of the matrix converter. The voltage error signals are constructed with simple comparison of measured input and output voltages. In case that any of bi-directional switches are associated with open-circuited switch faults, the dedicated voltage error signals rise over a certain threshold value, which can be possible to detect a fault occurrence and locate the faulty switch. Since the developed diagnostic method requires no construction of reference output voltages from the pulsewidth modulation (PWM) reference signals, it can be implemented with simple and robust features. Verification results are presented to demonstrate the feasibility of the proposed technique.