On-Site Estimation of Thermal Resistance Degradation of Double-Sided Cooling (DSC) Power Modules Under Power Cycling Conditions

Double-sided cooling (DSC) power modules are increasingly used due to their superior cooling capability and low parasitic inductance. However, the DSC modules have multiple interconnections for heat dissipation, so it is challenging to accurately monitor the thermal resistance degradation of each interconnection under power cycling conditions. An estimation method considering the self-heating and thermal coupling effects of DSC power modules is proposed based on a traditional lumped resistor-capacitor (RC) thermal impedance network. The proposed method combining a recursive least squares (RLSs) algorithm with a thermal network model can well evaluate the thermal resistance of each interconnection and their variations on-site during power cycling tests. The lifetime of DSC power modules for power cycling tests could be overestimated if using the 20% increment in overall thermal resistance of DSC modules as a failure criterion.