Modeling of electromagnetic interference shielding materials in wireless power transfer for board-to-board level interconnections

In this paper, we present the modeling of electromagnetic interference (EMI) shielding materials in wireless power transfer (WPT) for board-to-board level interconnections. The properties of the materials such as ferrite and metal can change the equivalent circuit of the spiral coil. The additional components due to the presence of the shielding material are expressed as a simple equivalent circuit model, of which the components are calculated using the analytic equations. It is verified that the results from the model show good correlation with the simulated results. In other words, the shielding material affects not only EMI shielding in WPT but also equivalent circuit model of the coil, hence the impedance curves of WPT can be changed. The impedance curves derived from the modeling are compared with the simulated results under 1GHz. From this modeling, we can estimate the impedance curves and the performance of WPT system.