Magnetic design considerations to improve nonlinear characteristics of inductively coupled power transfer systems

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Description/Abstract

Purpose – This study seeks to apply finite element analysis to study the proximity effect in amulti-pickup inductively coupled power transfer system, quantify the effect and propose improved pick-up configurations. Design/methodology/approach – A mixture of approximate analytical formulae and accurate finite-element simulations has been used as a tool for qualitative and quantitative analysis. Simplified consideration of magnetic flux paths aids understanding, whereas detailed numerical computation provides reliable performance prediction. Findings – It is shown that a multi-pickup formation of conventional E-pickups may lead to power loss due to negative coupling between neighbouring pickups and that the phenomenon is nonlinear. Thus, two novel configurations for multi-pickup systems have been proposed, an alternately-directed Z-pickup and a spilt-type E-pickup, both showing improved linearity, increased total power and more efficient use of ferromagnetic material. Research limitations/implications – The investigation aimed mainly at the electromagnetic performance, while economic issues will still need to be addressed. Practical implications – The proposed pick-up configurations may be very helpful in systems where improved performance is needed but space or configuration limitations restrict or eliminate the possibility of using other designs. Originality/value – The finite-element aided magnetic field simulation has proved invaluable in achieving difficult design objectives. The combination of a simplified analytical approach and detailed numerical analysis has provided a reliable tool for accomplishing improved designs.