Topology Optimization of Ferromagnetic Core in Wireless Charging Systems with EMI shielding

The ferromagnetic material (power ferrite) is one of the most crucial and the heaviest component in high-power Wireless Charging Systems (WCS). Optimizing the design of this ferromagnetic core can increase the power density of the WCS system while simultaneously reducing the eddy current losses at the metallic regions used for EMI shielding. In this paper, the analytical expression for hole sensitivity is derived for topology optimization of ferromagnetic material in an eddy current based WCS system with multiobjective functions. The first being maximization of mutual inductance and the second being minimization of eddy loss in the EMI shields. The empirically derived sensitivity for minimizing the eddy loss is first validated for a standalone eddy current system consisting of a current carrying winding, ferromagnetic material and a metallic shield in their vicinity. Further, a linear combination of derived sensitivity expressions are applied to a standard WCS system consisting of transmitter and receiver coils with ferromagnetic materials and EMI shielding to optimize both the magnetic coupling as well as the eddy loss.