US Patent 10903694 Wireless power transmission device

A coil structure for wireless power transmission is provided. The coil structure comprises: a primary resonance coil wound in a spiral shape around a centripetal point; a primary induction coil, which supplies power to the primary resonance coil in a nonconnected state with an input or output terminal of the primary resonance coil and is wound in a spiral shape on a substantially same plane around a substantially same centripetal point as the centripetal point; a switch configured to be parallel with the primary resonance coil so as to control the ON and OFF of an operation of the primary resonance coil; and a capacitor coupled to the primary resonance coil so as to form a magnetic resonance with the primary resonance coil.