All-Detuned Three-Coil Configuration for Advantages in Inductive Power Transfer Systems

Zirui Yao, Shiying Luo, Xuan Wei, Zhuhaobo Zhang, Guanxi Li, Xiangwei Shen, Ni Zhang, Philip T. Krein, Hao Ma

Research output: Contribution to journalArticlepeer-review


In inductive power transfer systems, some applications require working at higher power levels, transferring power with longer air gaps, and meeting geometric constraints. Many situations will decrease system coupling and affect performance. In this article, a three-coil configuration based on an all-detuned design is proposed to optimize the overall coupling and system efficiency. Primary and tertiary coils of the proposed topology are mounted on the same side. The three coil resonances in the proposed system, as extra degrees of freedom, do not match the switching frequency or each other. The key objectives of the proposed all-detuned design are to achieve a constant current output and unity power factor based on an equivalent two-coil circuit model; maximize the overall coupling coefficient to reduce the switching frequency or coil inductances by selecting a suitable tertiary resonant frequency; and optimize efficiency to be superior to those in a conventional two-coil system by minimizing coil currents. A 1-kW prototype has been prepared to verify the method. For example, when the main coupling coefficient is only 0.077, dc-dc efficiency of the proposed method ranges from 90.2% to 91.2% over a 2:1 load range, while that of the conventional two-coil system does not exceed 90%.

Original languageEnglish (US)
Pages (from-to)11870-11884
Number of pages15
JournalIEEE Transactions on Power Electronics
Issue number10
StatePublished - Oct 1 2023


  • Couplings
  • Impedance
  • RLC circuits
  • Reactive power
  • Resonant frequency
  • Switching frequency
  • Topology
  • all-detuned design
  • constant current
  • equivalent resonance
  • inductive power transfer system
  • low coupling
  • three-coil power transfer
  • unity power factor
  • All-detuned design
  • inductive power transfer (IPT) system

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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