This paper presents a reactive power analysis for an EV wireless power transfer (WPT) system based on magnetomotive force (MMF) and magnetic circuit analysis, in which the MMF magnitude and phase are deliberately designed to improve power transfer efficiency. The proposed analysis clarifies the relations among the MMF magnitude, MMF phase, and reactive power requirement of the pad. Unlike the conventional designs that prefix the compensation network topology and rely solely on circuit analysis, the proposed approach incorporates magnetic circuit-based insight into the system design. Experimental results show that, for the same WPT pad geometries, the highest efficiency was observed near the region of minimum pad reactive power. The methodology is validated across various air gap conditions, confirming its applicability to practical EV WPT systems and providing a basis for comprehensive system design guidelines.
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