New Electro-Thermal Model for a Multichip Power Module Used in a Motor Drive

In this paper, we develop an analytical electro-thermal model for a power module with multiple heat sources. This model is applied on a motor drive power converter mounted on its air-cooled heatsink. It offers fast calculations of the junction temperature, taking into account the self-heating and the cross coupling effect. The calculations are based on averaged power losses obtained from the expression of the duty cycle, and analytical expressions of the system thermal impedances, which are measured by fast optical fiber temperature sensors. The model results are finally validated based on experimental measurements, which are carried out on a motor test set up at one operating point of the power converter, when the THI-PWM switching technique is used.