Optimized Design of a Wireless Charger Prototype for an e-Scooter

Abstract

Individual mobility vehicles are revolutionizing transportation in the urban environment. Among them, e-scooters are one of the fastest growing vehicles. However, these vehicles have some drawbacks such as incompatibility among different chargers or reduced autonomy, which especially affects e-scooters rental. Wireless charging is presented as a solution to these drawbacks since it allows the batteries to be charged without user intervention. This paper addresses the design process and implementation details related to a magnetic-resonance charger for an e-scooter. In contrast to the previous works, we present a comprehensive approach that addresses the design of the coil topology, the dimensions of the ferrite tiles, the definition of the gap and the optimised control for a CC-CV charge. The main contribution of the work is the consideration of all these issues jointly while we also take into account the vehicle’s materials and structure for an accurate design and implementation. The dimensions of the vehicle impose a strong restriction on the coil design. Therefore, a detailed analysis about the location of the secondary and primary coils in a real e-scooter is executed with Ansys Maxwell. The study about the geometries of ferrite tiles is also performed considering the particularities of this type of vehicle. This study led to an optimal solution for the coil geometries and ferrite placement that minimizes the costs. The proposed system has been validated with the implementation of a real prototype of 100 W, to which a CC-CV control has been incorporated to achieve a safe charge for different battery states. The control can be easily adapted for a wide range of e-scooters. In this way, the use of this type of chargers on public installations can be maximized.

Keywords

• Wireless power transfer
• coil design
• e-scooter
• ferrite layout
• CC-CV control
• magnetic field