Experimental Characterization of the Predictive Thermal Behaviour Model of a Surface-Mounted Soft Magnetic Composite Inductor
Résumé
The latest low-profile high-power inductors, used in DC-DC converters to power an assortment of applications, are going endlessly smaller and submitted to larger amount of current.
This surface-mounted magnetic component is commonly constructed using a wound copper coil which is over-moulded in a Soft Magnetic Composite (SMC) based on an iron-resin material mixture.
The performances of that high-power density device depend closely on the coupled interaction of magnetic phenomenon, joule effect and thermal behaviour, which is difficult to apprehend at board level simulation. Thus, the present study highlights the electromagnetic phenomena encountered by SMC inductor devices and their influence on the temperatures of the iron-based core and copper-based coil.
In order to better characterize the behaviour of high-power inductor devices, a set of coupled electromagnetic and thermal simulations were performed on the case of an industrial demonstration electronic board. Consequently, the influence of surrounding active electronic components upon the acceptable temperature rise of the inductor parts has been investigated.
The numerical simulations were completed by electrical characterizations and thermal measurements on the test vehicle for various operating conditions with the purpose to establish a more realistic thermal model of the inductor device.
The agreement of the fine detailed model with experiment results is quite relevant: the divergence is lower than 10%.
Further, for minimizing the expensive meshing of the finely detailed simulations and the computation time, a novel concept of compact thermal model for inductor device, based on DELPHI methodology, was used. The deducted two-heating-source DELPHI-style model adequately correlates the physical behaviour of all heat paths of the inductor device, our purpose.