Modelling of power electronics converters by using the incidence matrix approach

Abstract

This paper deals with the failure diagnosis for the power electronics converters. During the operation, power electronics converters are exposed to the different faults caused by wear, stress and unpredicted events. This is manifested as an output terminal short-circuit or open terminals. Such inadequate operation modes cause different failures inside the converters. The semiconductor elements can be destroyed in two ways, the transistor (IGBT or MOSFET) inside the one leg can be short circuited or can act as open terminals. Both types of fault are undesirable and cause that the converter's output does not produce the desired voltages and, thus, cannot supply the load adequately. Converter operation can be described by using a differential equations-based model, with consideration of the triggering pulses that have impact on the equations' coefficients. Using the incidence matrix approach, the modelling of converter can be automated and the model can be calculated in real-time. In a real converter control unit, input voltage, output voltages and currents are measured and the triggering pulses are calculated, so all of this information can be used as inputs for calculation of our model and comparison with our model. When variables of interest differ between the calculated model and real converter, there is some fault present in the real converter and it can be identified using some diagnostic technique. In the first step, the verification of the converter modelled by the new incidence matrix approach was verified by comparison with the converter modelled by the Matlab-Simscape SimPowerSystem library.