Bidirectional Capacitive Wireless Power Transfer for Energy Balancing in Modular Robots

A modular approach to the complex robotic systems is desireable due to advantages such as ease of development, reconfigurability, and re-usability. Powering these dynamic structures while maintaining ease of assembly and versatile form-factor is a challenge. One promising solution is to exchange energy between modules which each have a small battery. Performing this exchange of energy using mechanical connections is not only unreliable but also limits the reconfigurability of the modules. In this paper, we present a bidirectional capacitive wireless power transfer scheme for energy balancing between different robot modules. A modified CMCDE topology is also presented to make the power transfer resilient to the changes in the robot dimensions. The concept is verified by demonstrating 20 W of power transfer between two modules at 13.56 MHz achieving a dc-dc efficiency of 79 % that is resilient to the changes in the track length.