System Architecture, Design, and Optimization of a Flexible Wireless Charger for Renewable Energy-Powered Electric Bicycles

Wireless power transmission (WPT) is one of the breakthroughs in effortless electric vehicle (EV) charging technology. Different types of wireless charger topologies were proposed and implemented to meet various constraints like power transfer efficiency, wireless transfer distance, and misalignment tolerance. Yet the coupling separation and the transfer efficiency are still underdeveloped for contactless charging of medium- and low-power EVs like e-cycles and e-scooters. For achieving the high-distance WPT in the vehicles which are prone to misalignment issues, series-series (SS) compensated WPT is used. The conventional SS-compensated WPT uses a voltage-fed converter for the power conversion. But the combination of these topologies allows reverse current flow in the system, which will affect the transfer efficiency and life span of the source. To prevent this, a reverse blocking diode or a current-fed converter can be used. Though the reverse current problem can be solved, these approaches seem to reduce the power transfer efficiency further. This article tries to optimize the current-fed converter-based SS-WPT to achieve higher coupling separation, higher power transfer efficiency, and higher misalignment tolerance than the conventional designs. To achieve this, the input inductor of the current-fed converter and the primary coil of the SS-WPT are tuned without affecting the magnetic resonance condition. The transfer efficiency was found to be 94% at a coupling separation of 200 mm, which is 20% more than the conventional voltage source inverter-based, renewable energy-powered SS-WPT charging efficiency. After proving the concept in prototype design, the results are validated by testing the same in a real-time electric cycle.

Automated summary

The study aimed to optimize the current-fed converter-based SS-WPT topology to improve transfer efficiency and coupling separation while avoiding reverse current problem. After experimental validation, the transfer efficiency reached 94%, which is 20% higher than traditional designs, at a coupling separation of 200mm.