A Multi-Transmitter Configuration for High-Safety Wireless Power Transfer Applications

A multi-transmitter configuration made by an array of passive resonant elements placed in the proximity of the driver coil for inductive Wireless Power Transfer applications is presented. The array is able to significantly decrease the electric field level produced by the fed loop at the operative frequency of 6 MHz, thus reducing the potentially dangerous radiation over biological tissues (i.e., the Specific Absorption Rate, SAR). Nonetheless, the proposed arrangement preserves the same efficiency level of the simple driver-receiver system and it does not affect the useful working distance. Electromagnetic simulations have been performed to evaluate the SAR reduction and the efficiency levels achieved by the multi-transmitter configuration in comparison with the driver-receiver system. The proposed solution can be extremely useful in all the WPT applications in which the SAR exposure is a concern, such as automotive applications, biomedical implants and rechargeable devices.