Core-Shared-Repeater (CSR) Coil Scheme for Low EMI and Efficient WPT System in Ultra-Thin Digital TV

In this paper, we propose and analyze an ultra-thin digital TV wireless power transfer (WPT) system. We suggest core-shared-repeater (CSR) coils to get higher performance in terms of coil to coil wireless power transfer efficiency (PTE) and lower electromagnetic interference (EMI). However, it is difficult to achieve higher PTE and lower EMI level due to 50 cm long air-gap, low operating frequency, and compact size of the transmitter (Tx) and receiver (Rx) structures. Therefore, we have proposed two core-shared-repeater (CSR) coils, which are placed on a ferrite core of the Tx coil. The CSR coils are used to confine the leakage magnetic flux from the Tx and transfer to the Rx coils. Furthermore, two CSR coils can be utilized to reduce the 3rd current harmonic by applying a resonant frequency of the CSR coils slightly smaller than three times of operating frequency. Using the proposed WPT system, we improved the coil to coil PTE from 61.8% to 83.9% and reduced the 3rd Rx current harmonic by 19.16 dB scale.