A Simple and Reliable Approach to Stabilizing Output Voltage of A Wireless Power Transfer System for Active Implantable Medical Devices

In this paper, we present the insertion of a simple two-element network at the transmission (TX) of a wireless power transfer (WPT) system for active implantable medical devices (AIMDs). The network parameters are optimized to compensate for the changes of mutual-coupling between the TX and receiving (RX) and make the output voltage constant within a specific range. A theoretical condition is analytically derived, simulations and experiments are conducted to verify the effectiveness of the proposed system. The variation of the output voltage is kept at about 5% for both rotational and axial misalignments. The specific absorption rate (SAR) of the proposed system is also investigated for safety concerns. The result shows that the proposed system reduces SAR, and it is safe for wireless charging of AIMDs.