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Maximising power transfer efficiency (PTE) in resonant inductive power transfer (IPT) systems requires strong coupling between transmitter and receiver coils. In applications where system constraints yield a weak inductive link (e.g.: significant distance between coils.) or there is a requirement for a specific power level, then geometrically optimising the coils can enhance inductive linkage. To achieve this, a novel coil design method has been presented which provides maximum efficiency for both strongly-and loosely-coupled inductive links. A parameter (i.e.: Strong Coupling Factor.) has been introduced to assist the design procedure. Discussed results from a practical 1.06 MHz inductive link, developed using the proposed design method, show that with proper selection of strong coupling factor (e.g.: C = 220.) the designed coil geometry can provide maximum PTE of 86%, which is in close correlation (≈ 3%) with theoretical analysis using MATLAB. Index Terms-Wireless power transfer (WPT), inductive power transfer (IPT), resonant coupling, electromagnetic induction, near-field communication.

A design technique for optimizing resonant coils and the energy transfer of inductive links. IEEE transactions on microwave theory and techniques [online], Early Access.

This paper proposes a new controller for power regulation in dual active bridge (DAB) DC−DC converter based on a new scheme that tracks minimum RMS current to ensure minimum losses. The proposed controller is based on an implementation of perturb and observe (P&O) tracking method that enables minimum current point tracking (MCPT) at any desired level of active power transfer and DC voltage ratio. The P&O is embedded in a closed loop control scheme which simultaneously regulates active power in DAB converter. The nonlinear I-V characteristic of DAB presents the basis for this proposed controller and the rationale of using P&O algorithm. The proposed controller does not require complex non-linear converter modelling and is not circuit parameter dependent. Design procedure of the proposed controller is presented, and extensive simulation is carried out using MATLAB/Simulink to validate effectiveness of the proposed MCPT closed loop controller. An experimental prototype also substantiates the results achieved.

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