Compact thermal modelling can provide useful tools for electronic systems designers. Indeed, the generation of simplified but accurate thermal models enables to reduce the number of 3D thermal simulations with high complexity and expensive computation time. Another benefit is the possibility for device manufacturers to provide systems suppliers with extended datasheets in the form of Compact Thermal Model (CTM) without revealing the device structure or used materials. The CTM can be applied to multi-chips systems and it is auto-adaptive to boundary conditions change. In this paper, CTM methodology is defined for an efficient power module structure with double side cooling. The extracted CTM is used to investigate cooling pump defects in the design phase of the inverter. The results are compared with a 3D thermal model using Computational Fluid Dynamics software (6SigmaET).