Design a Wireless Power Transfer System with Variable Gap Applied to Left Ventricular Assist Devices

In order to solve the problem of low efficiency and short transmitting distance of WPT in implantable medical applications, this paper presents a WPT system with switchable match network. The main coupling mechanism is analyzed, which is a novel 2-coil system with 90mm outer diameter of primary spider-web coil and 65mm outer diameter of secondary spider-web coil. Meanwhile, the range of load impedance is calculated to ensure the Pi match network. Related simulation and experiments are carried out and the results show that at 6.78MHz frequency, the proposed system could achieve up to 180mm transmitting distance, a constant output 16.8V voltage with transmitting efficiency up to 78% through the switch able Pi match network.