Development of Electric Assisted Bicycle System using Wireless Charging System and Electric Double Layer Capacitor

Abstract

This paper presents a wireless charging system that utilizes an electric double layer capacitor (EDLC) as a power source for an electric assisted bicycle. The proposed system was optimized in terms of miniaturization. First, the minimum energy of the EDLC was evaluated. The results showed that the energy source in the proposed system can be smaller than that in the conventional system when the energy density of the EDLC is improved more than 1.52 times. Second, the coil of the wireless power transmission and the charger were analyzed. Short- and open-type coils of the same size were compared in experiments. The results showed that the short-type coil can be further miniaturized than the open-type coil at the same resonance frequency. Third, the volumes of the EDLC and converter were evaluated. The results showed that the volume of the boost type can be reduced by 30% compared to that of the buck type. Finally, in order to reduce the number of devices in the proposed system, the diode bridge rectifier was replaced with a three-phase inverter. This reduced the number of devices of the proposed system by one-third.