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This paper presents a nonlinear capacitive WPT system that automatically compensate for the coupling variation between the transmitter and receiver in a capacitive wireless power transfer (WPT) system with no active circuitry. The system is capable of minimizing the output power variation at a fixed operating frequency of13 MHz as the coupling distance varies. A constant output power is achieved over a wide range of coupling capacitance variation in comparison to the conventional capacitive wireless power transmission circuits. Such an approach is attractive for biomedical implants employing a capacitive WPT system. 

This paper presents a nonlinear capacitive WPT system that automatically compensate for the coupling variation between the transmitter and receiver in a capacitive wireless power transfer (WPT) system with no active circuitry. The system is capable of minimizing the output power variation at a fixed operating frequency of13 MHz as the coupling distance varies. A constant output power is achieved over a wide range of coupling capacitance variation in comparison to the conventional capacitive wireless power transmission circuits. Such an approach is attractive for biomedical implants employing a capacitive WPT system. 

Conventional linear resonant wireless power trnnsfer (WPT) systems suffe1· from a significant pe1•formance degrndation as the coupling factor between the translnit and receive coils varies. In this paper, the performance of a new WPT circuit that takes the advantage of nonlinear resonant circuit is investigated. It employs passive nonlinear resonators in both the trnnslnitter and receiver sides to regulate the output power without using any active or control circuitry, frequency tuning or complicated coil configurntions. A 60 W nonlinear WPT prototype circuit working at 1.5 MHz is designed, fab1icated and compared with a silnilal'ly designed linear \VPT circuit. The nonlinem· \VPT circuit is capable of maintaining almost a constant output power while the distance between the coils changes from 6 cm to 15 cm, a significant performance improvement as compared to the linear WPT circuit tested under the same conditions. 

Near-field resonant-based wireless power transfer (WPT) technology has a significant impact in many applications ranging from charging of biomedical implants to electric vehicles (EVs). The design of robust WPT systems is challenging due to its position-dependent power transfer efficiency (PTE). In this paper, a new approach is presented to address WPT's strong sensitivity to the coupling factor variation between the transmit and receive coils. The introduced technique relies on harnessing the unique properties of a specific class of nonlinear resonant circuits to design position-insensitive WPT systems that maintain a high PTE over large transmission distances and misalignments without tuning the source's operating frequency or employing tunable matching networks, as well as any active feedback/control circuitry. A nonlinear-resonant-based WPT circuit capable of transmitting 60 W at 2.25 MHz is designed and fabricated. The circuit maintains a high PTE of 86% over a transmission distance variation of 20 cm. Furthermore, transmit power and PTE are maintained over a large lateral misalignment up to ±50% of the coil diameter and angular misalignment up to ±75°. The new design approach enhances the performance of WPT systems by significantly extending the range of coupling factors over which both load power and high PTE are maintained.