An improved multi-layer PCB winding and circuit design for universal contactless charging platform

Contactless battery charging platform is an emerging technology that brings safety, reliability and convenience to low-profile charging applications. In this paper, an improved three-layer circular coil array PCB winding is proposed, which can generate the near-uniform magnetic field over a specific operation area. Moreover, an optimal circuit design procedure is developed to maintain the approximately constant output voltage, regardless of the magnetic coupling variation. The coil structure is analyzed with finite-element simulation and verified with EMC scanner test results. Measurements and experiments are further carried out to confirm the almost uniform magnetic coupling and validate the circuit design procedure. The design proposed in this paper is well adaptable to a universal battery charging platform.