Time-Varying Wireless Power Transfer Systems for Improving Efficiency

TL;DR

This paper proposes a time-varying approach to wireless power transfer that overcomes traditional efficiency-power tradeoffs, demonstrating both theoretically and experimentally that temporal modulation significantly enhances transfer efficiency and received power.

Contribution

It introduces a novel temporal modulation technique for inductive wireless power transfer systems, overcoming fundamental tradeoffs and improving efficiency and power transfer.

Findings

Threefold increase in efficiency demonstrated experimentally

Temporal modulation avoids the efficiency-power tradeoff

Theoretical analysis confirms efficiency improvements with optimal modulation

Abstract

Conventional wireless power transfer systems are linear and time-invariant, which sets fundamental limitations on their performance, including a tradeoff between transfer efficiency and the level of transferred power. In this paper, we introduce and study a possibility of temporal modulation for inductive wireless power transfer systems and uncover that this tradeoff is avoided as a consequence of varying the inductive coupling strength in time. Our theoretical analysis reveals that under the optimal modulation depth and phase, the time modulation can yield a substantial improvement in the WPT efficiency, while the received power at the load is also improved compared to the static WPT reference system. We experimentally demonstrate the concept with a low-frequency system and observe a threefold improvement in efficiency over the reference static counterpart. This technical capability reconciles the inherent tradeoff between the WPT efficiency and transferred power, paving the way for simultaneous advancements in both efficiency and delivered power.