Thermal coupling analysis for a multi-chip paralleled IGBT module in a doubly fed wind turbine power converter

Thermal coupling between adjacent IGBT or diode chips is the result of non-uniform temperature distribution in a multi-chip IGBT module. This affects the junction temperatures and hence the total power loss predicted for the module. The study first investigates the impact of thermal coupling effect on the junction temperatures through finite element method (FEM), and then develops a thermal coupling impedance model to represent such effect. The effect is shown to reduce with the distance exponentially. The model result agrees well with test. The validated model is then used to predict the junction temperature swings during operational power cycling in a DFIG wind turbine, showing the difference between the rotor and grid side converters. The model presented and the results obtained may be important for reliability evaluation and condition monitoring in the wind turbine power converters as well as in other multi-chip paralleled power electronic systems