Time-Efficient Integrated Electrothermal Model for a 60-kW Three-Phase Bidirectional Synchronous DC–DC Converter

This article introduces an accurate and fast electrothermal model to calculate power loss and junction temperature of power electronic devices in a three-phase dc-dc converter, and to simulate converter dynamics during a simulated drive cycle. The proposed electrothermal model calculates power loss and junction temperature by representing the three-phase dc-dc converter dynamics within a drive cycle using a three-phase state-space average model. The three-phase state-space average model is modified to represent converter dynamics when one or two phases are off, in addition to the phase transition dynamics. The existing electrothermal models can either represent converter dynamics but are too slow for long simulations like drive cycles, or they reduce the simulation time at the expense of junction temperature accuracy. Furthermore, the existing electrothermal models in the literature are for inverters and single-phase dc-dc converters. The proposed electrothermal model combines the advantages of fast simulation time with accurate estimation of junction temperature. The power loss calculated by the proposed method is verified by a switching Simulink/PLECS model, and the mosfet temperature estimation is validated experimentally using a 60-kW three-phase bidirectional boost converter under steady-state conditions and a custom drive cycle. The efficiency of the three-phase converter is measured experimentally and compared with the efficiency calculations from the proposed electrothermal model.