Boosting the Efficiency: Unconventional Waveform Design for Efficient Wireless Power Transfer

TLDR

Wireless power transfer has traditionally used single‑carrier continuous‑wave signals, with most efficiency improvements focused on circuit design, but recent work has explored waveform design—including multisines, OFDM, chaotic, harmonic, UWB, ICW, and white‑noise signals. The article reviews waveform techniques for wireless power transfer, focusing on multisines/multicarrier, harmonic, and chaotic signals. The authors present a theoretical explanation and experimental evidence of efficiency gains, detail receiver‑side circuit design, and describe efficient transmission architectures that emphasize spatial power combining. Signals with high peak‑to‑average power ratio improve efficiency over continuous‑wave signals, as supported by theoretical explanations and experimental results.

Abstract

Traditionally, wireless power is delivered through single-carrier, continuous-wave (CW) signals. Most research efforts to enhance the efficiency of wireless power transfer systems have been confined to the circuit-level design. However, in recent years, attention has been paid to the waveform design for wireless power transmission. It has been found that signals featuring a high peak-to-average power ratio (PAPR) can provide efficiency improvement when compared with CW signals. A number of approaches have been proposed, such as multisines/multicarrier orthogonal frequency division multiplex (OFDM) signals, chaotic signals, harmonicsignals, ultrawideband (UWB) signals, intermittent CW (ICW) signals, or white-noise signals. This article reviews these techniques with a focus on multisines/multicarrier signals, harmonic signals, and chaotic signals. A theoretical explanation for efficiency improvement is provided and accompanied by experimental results. Circuit design considerations are presented for the receiver side, and efficient transmission architectures are also described with an emphasis on spatial power combining.