Resonant inductive power transfer for an E-bike charging station

This paper presents the design and the experimental tests of an E-bike 300-W battery charger for a cyclo-station based on wireless power technology. In particular, a series resonant inductive power converter with an E-geometry magnetic core topology is proposed. A mathematical model is developed and a performance analysis is conducted to determine the voltage transfer function, maximum power transfer capability, efficiency for different air-gaps (1–3 cm), and misalignments (0.5–1.5 cm). Also, it is performed analytical and experimental investigations of the minimum and maximum relative frequency points of active input power and efficiency in order to determine how these points changed as the resistance load varied. The results of the analyses indicated that the maximum frequency points of active input power are different from the maximum frequency points of efficiency and the zero-frequency points of reactive input power. This means that maximum power transfer and efficiency conversion are not obtained in correspondence with the resonant frequency. For this purpose, it is conducted a wide frequency characterization of 30–50 kHz around the designed resonant frequency of 40 kHz. An iterative electrical and magnetic design procedure is proposed based on 3D finite element analysis. Simulation and experimental results are presented for a full-sized prototype. The design of the E-bike battery charger is validated in terms of rated input voltage and output power for different air-gap configurations.