Thermal analysis of a multi-chip Si/SiC-power module for realization of a bridge leg of a 10 kW Vienna rectifier

For realizing a three-phase 400 V/sub AC//800 V/sub DC/ 10 kW unity power factor PWM (Vienna) rectifier system a novel Si/SiC multi-chip power semiconductor modules (IXYS VUM26B) facilitating switching frequencies up to 500 kHz is employed. Direct water cooling of the modules base plates does significantly reduce the size of the cooling system. As the heat flow is directly from the power module into the water the cooling system can be realized using non-metal heat sink what does reduce common-mode EMI emissions. In this paper it is shown how the time behavior of the power module semiconductor junction temperatures over a mains period can be calculated with high accuracy by combining simple thermal equivalent circuits and stationary thermal simulations of the cooling system. Furthermore, the determination of the switching losses by circuit simulation based on experimental data is discussed and the power transistor and power diode junction temperatures are investigated for different operating points of the rectifier system.