An open-circuit faults diagnosis method for matrix converters based on DWT analysis of output current

A novel diagnosis method is proposed in this work which is designed to detect open-circuit faults that occur in the matrix converter topology. In the potential application range of this type of converters, increased reliability and fault tolerance of the drive system is required through its remedial operation in cases of partial failures. All these requirements indicate that a monitoring system that is able to timely detect the various possible failures is necessary. In this paper, the output current of the matrix converter is monitored and analyzed using the discrete wavelet transform (DWT) in order to detect partial or total open-circuit failures of the converter´s bidirectional switches. The main advantage of the proposed method is that it is based on the output current measurement in contrast to the output voltage measurement that is required by previously proposed methods. Thus, the proposed method can be integrated without additional costs into motor current signature analysis (MCSA) systems that are used to detect faults in induction machines (IM). The choice of the mother wavelet which is used in the DWT analysis as well as the choice of the window function are evaluated in this work. The case of rapid changes of the output phase currents corresponding to the operating conditions are also examined.