Influential Factors on Switch Power Losses of a Buck Converter: A Reliability Approach

Abstract

Over the past several decades, with expanding utilization of power electronic devices, attention to the lifetime and reliability has become more momentous than before. Furthermore, different parameters can affect the reliability of devices. For this reason, a comprehensive assessment of influential factors needs to be conducted. In this paper, the switch power losses as the most significant factor in the reliability evaluation are studied. The simulation of the considered DC-DC buck converter was carried out using Matlab/Simulink. The results illustrate that the increase of switching frequency and the input voltage level leads to an increased switch power losses, whereas the opposite is true for the modulation index. Additionally, the results from the analysis conducted on three levels of output powers clarify that the power losses increases by higher output power, but the increasing rate is almost constant. However, the rising ratio of the power losses follows a downward trend with the increase of modulation index. A Gaussian function is able to model the junction temperature of the examined IGBT with an acceptable accuracy. This model can eliminate the need for additional calculations when new conditions for a buck converter are defined. The results obtained from this study confirmed that different criteria such as selecting the appropriate type of IGBT module must be considered for circuit design with reduced switching losses and longer lifespan.