Modelling of a Planar Magnetic Component for PCB-Integration

Abstract: The trend toward the electrification of functionalities magnifies the part played by power electronic converters, which are continuously expected to deliver more power, at a lower cost, in a smaller volume and always with a high reliability. To this end, high switching frequency integrated converters, and especially Printed-Circuit-Board (PCB) –integrated devices, could embody an interesting paradigm. This however raises new challenges, in particular regarding the need for low-profile, planar, components. This study focuses on a structure of magnetic component made of a PCB placed between two plates of ferro- or ferri-magnetic material. Concentric spirals are printed on the PCB to form the winding(s) of the device. The plates of magnetic material decrease the reluctance of the magnetic path, whilst improving the Electro-Magnetic Compatibility (EMC) of the device by acting as a magnetic shield. A multi-physical modelling of this structure is described in this report. Both the magneto-static and magneto-dynamic are characterised, the electrostatics of the device is estimated, expressions of the core and copper losses are derived, thermal is assessed and some considerations on EMC are drawn.  Finally, a prototype is manufactured and characterised. The measured results are confronted with those obtained using Finite Elements Analysis (FEA) and the derived modelling. An ideality factor is introduced as an estimator of the correlation between the results simulated using FEA and those of the modelling. It appears that, in the somewhat restricted domain of interest, the correlation is satisfying. As for the physical measurements, they differ from the calculated and simulated results mostly due to the limited accuracy of the modelling and to the chosen dimensioning not being ideal enough for the derived modelling to give proper results.