Current-Based Resonant Power Delivery with Multi-Cycle Switching for Extended-Range Inductive Power Transmission

A current-based resonant power delivery (CRPD) technique with multi-cycle switching has been presented that enables efficient inductive power transmission at large distances. Unlike the conventional inductive link, in which the receiver (Rx) LC-tank is utilized as a voltage source, the proposed CRPD switches the Rx LC-tank for several cycles in a novel fashion to utilize it as a current source. Therefore, the voltage across the load (R-{L}) can be significantly higher than the Rx LC-tank voltage. This eliminates the need for DC-DC charge pumps or AC-DC voltage multipliers, which require several capacitors and diodes. In CRPD, the energy is first stored in the Rx coil by shorting the Rx LC-tank for several power carrier cycles. At the peak of Rx coil current, the coil energy is then transferred to R-{L} for a quarter of the power carrier cycle. The circuit theory behind CRPD has been developed and verified with simulation results. A proof-of-concept CRPD was also characterized in measurements to demonstrate its feasibility. In measurements, CRPD was capable of achieving the DC voltage of 3.1 V across an R-{L} of 100 \text{k}\Omega, by switching the Rx LC-tank at 50 kHz with an AC voltage amplitude of 1 V across the Rx coil at the operation frequency of 1 MHz. Moreover, compared to a conventional inductive link followed by a passive rectifier, to achieve a minimum DC voltage of 2.8 V across an R-{L} of 100 \text{k}\Omega the proposed CRPD extended the range from 7 cm to 13 cm for the same voltage across the transmitter coil.