Diagnosis of open-circuit faults in matrix converters

This paper presents a new diagnostic technique, known as the modulated error voltages (MEV), for the diagnosis of open-circuits faults in the power switches of matrix converters. The proposed technique is based on the monitoring of nine modulated output error voltages, each one associated to a bidirectional switch of the converter. For each output phase, an error voltage is calculated and subsequently modulated by the gate signals of each one of the three bidirectional switches connected to that specific phase. Each modulated signal is subsequently averaged over a certain period of time. If at the end of this averaging period the obtained value is higher than a threshold limit, it will trigger the indication of an open-circuit fault in the power switch associated to the monitored signal. By using the MEV it is possible to concurrently detect and locate open-circuit faults, independently of the type of load of the matrix converter or its operating conditions, namely amplitude and frequency of the output voltages, both in steady-state and transient regimes. Moreover, the MEV allows to speed up the diagnostic process when compared to other diagnostic techniques, and can easily deal with the presence of multiple faults occurring simultaneously.