Scheme for Transcutaneous Energy Transfer Applications

A key feature of future active implants will include wireless transcutaneous energy transfer (TET). A novel closed-loop control scheme is presented here for coupled resonant tank circuits that is capable of providing stable and maximally efficient power transfer under various load and disturbance conditions as well as for varying implants. The control algorithm consists of four cascaded control loops using capacitance, frequency, and voltage as the primary control variables. The innermost, D, control loop uses the primary side voltage to control the secondary side current. The C-loop uses the excitation frequency to set the optimal working point for the TET system and the secondary side tank behavior.

The secondary side tank may either act as voltage or current source dependent upon the frequency setting of the primary side. The TETs transfer function is shaped by setting the primary capacitance in the B-control loop, determining the performance and transmission efficiency. The exact positioning of primary and secondary coils is determined by an online measurement of the mutual inductance M. In this paper, the D-control loop has been both simulated and realized, for the A–C loops a proof of concept is shown.