Improved thermal couple impedance model and thermal analysis of multi-chip paralleled IGBT module

With the development of large capacity variable speed constant frequency wind turbines, wind power converters with the multi-chip paralleled insulated gate bipolar transistor (IGBT) modules are widely used as an energy flow interface, a valid junction temperature calculation is vital considering the multichip electro-thermal influences, because thermal analysis is of great significance in terms of safe operation and reliability for the wind power converter. Focusing on the multi-chip thermal coupling effects, this paper proposes an improved thermal couple impedance model for a real multi-chip IGBT module in the power converter of a 2MW doubly fed induction generator (DFIG) wind turbine. First, the steady state junction temperature and thermal coupling profiles are analyzed by using finite element method (FEM). Second, by introducing into the equivalent thermal couple impedance matrix, an improved electro-thermal model is derived. Finally, junction temperatures of chips in different position are calculated by using the improved thermal coupling impedance model, and the results are further compared with those of the traditional thermal model and real tested case temperatures of the 2MW DFIG. Results show that the improved thermal model is much more valid than the traditional model for the thermal analysis of the multi-chip paralleled power module in the wind turbine power converter, and junction temperatures of the chips in non-edge position could be higher and this should be carefully considered in design and operational management control.