Resonant topology design method for implantable wireless power transfer system

Abstract

Abstract The variable load and coil distance of implantable wireless power transfer system lead to unsteady output voltage, and resonant topology for wireless power transfer system is likely to solve this issue. But existing topologies are unable to meet the demands of implantable wireless power transfer system in practice. This paper presented a method to design resonant topologies for implantable wireless power transfer system in detail and proposed a series of topologies. Wireless power transfer systems based on the proposed topologies can achieve load‐independent output voltage. The output voltage is not constrained by the parameter of coils and its load‐independent feature is irrelevant to the coupling coefficient. Besides, a simple output voltage estimation method can be implemented on the transmitting side to monitor output voltage accurately. The characteristics of proposed implantable wireless power transfer systems are compared and the most attractive resonant topology named LCC/PS topology is pointed out. The proposed implantable LCC/PS wireless power transfer system has high power transfer efficiency from 60% to 76.9% at a coil distance of 5 cm when the load varies from 500 to 2500 Ω. An experimental setup is built and its working frequency is 6.78 MHz. The experimental results with acceptable tolerance show the accuracy of theoretical analysis and the excellent performance of the resonant topologies.

Keywords

• Power electronics, supply and supervisory circuits
• Prosthetics and orthotics
• Wireless power transmission