MLD-Based Thermal Behavior Analysis of Traction Converters Under Faulty Conditions

The existing thermal behavior analysis mainly focuses on the normal condition of converter but lacks investigation in the cases of faulty condition and modulation strategy switching. This further leads to inaccuracy and incomprehensive thermal management. In order to address this issue, in this article, a mixed-logical-dynamic (MLD)-based electrothermal model is proposed for a fast observation of the thermal behavior of power devices within converters under both normal case and open-circuit (OC) fault cases. It also has the advantage of applicability to various modulation strategies. To be specific, the switching-logic-mixed (SLM) and transition-logic-mixed (TLM) variables are first defined to analyze the generating conditions of power loss in power modules, where the power loss models considering the normal and OC fault cases are built, after which the MLD-based electrothermal model is established to calculate the junction temperature of power modules, which will be used to obtain the thermal behaviors of converters. Finally, under various OC fault cases, the thermal behavior of traction converters is analyzed by hardware-in-the-loop (HIL) real-time simulation test. The HIL-based results show that the proposed model can be used to analyze the thermal behaviors under various scenarios in real time, which can further offer guidance for thermal management under faulty conditions.