Inductive Power Transfer System With Self-Calibrated Primary Resonant Frequency

Inductive power transfer (IPT) is a commonly employed technique for wirelessly supplying power to implantable medical devices. A major limit of this approach is the sensitivity of the inductive link to coupling factor variations between transmitting and receiving coils. We propose in this paper a new method for compensating these variations and improving the inductive link efficiency. The proposed technique is based on a mechatronic module that dynamically tunes the primary resonant capacitor value in order to maintain the resonance state of the IPT system. The module is able to maintain resonance state for apparent primary inductance range at least from 0.5 to 5 μH using a high capacitance resolution of 0.032 pF. Experimentations conducted on a 13.56MHz IPT system showed a 65% higher power transfer compared to a traditional IPT system.