The Circuit Theory Behind Coupled-Mode Magnetic Resonance-Based Wireless Power Transmission

By Mehdi Kiani, Maysam Ghovanloo. IEEE Transactions on Circuits and Systems Part 1: Regular Papers, 2012

418 citations recorded by the source corpus.

Inductive coupling is a viable scheme to wirelessly energize devices with a wide range of power requirements from nanowatts in radio frequency identification tags to milliwatts in implantable microelectronic devices, watts in mobile electronics, and kilowatts in electric cars. Several analytical methods for estimating the power transfer efficiency (PTE) across inductive power transmission links have been devised based on circuit and electromagnetic theories by electrical engineers and physicists, respectively. However, a direct side-by-side comparison between these two approaches is lacking. Here, we have analyzed the PTE of a pair of capacitively loaded inductors via reflected load theory (RLT) and compared it with a method known as coupled-mode theory (CMT). We have also derived PTE equations for multiple capacitively loaded inductors based on both RLT and CMT. We have proven that both methods basically result in the same set of equations in steady state and either method can be applied for short- or midrange coupling conditions. We have verified the accuracy of both methods through measurements, and also analyzed the transient response of a pair of capacitively loaded inductors. Our analysis shows that the CMT is only applicable to coils with high quality factor (Q) and large coupling distance. It simplifies the analysis by reducing the order of the differential equations by half compared to the circuit theory.

Subfields: Electrical and Electronic Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/3aac012af3a16b0f1704b426dc0545c1d54a4332

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Electrical and Electronic Engineering

1. S. R. Hui
2. Wenxing Zhong
3. Chi Kwan Lee
4. Zhenshi Wang
5. Chuang Wang
6. Yang He
7. Jian Zhang
8. Xinmei Yuan

In Mechanical Engineering

1. S. R. Hui
2. Zhenshi Wang
3. Chuang Wang
4. Yang He
5. Jian Zhang
6. Chi Kwan Lee
7. Xinmei Yuan
8. Xuezhe Wei

Citations in the corpus

• A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize Efficiency and Extractable Power (2015, background): “This study focuses on a circuit-based model, but it is worth noting that there exist different other possibilities to model WPT systems [13], [25], [26].”
• A Critical Review of Recent Progress in Mid-Range Wireless Power Transfer (2014, methodology): “While the coupled mode theory is used in [27], several references [33], [34], [36] have transformed the analysis using electric circuit theory, which is easily understood by electrical engineers.”
• Comparative Analysis of Two-Coil and Three-Coil Structures for Wireless Power Transfer (2017, methodology): “For midrange coupling conditions, it has been proven that both coupled-mode theory and circuit theory basically result in the same set of equations in the steady state and that either method can be applied [35]–[37].”
• Nonlinear Parity-Time-Symmetric Model for Constant Efficiency Wireless Power Transfer: Application to a Drone-in-Flight Wireless Charging Platform (2019, background): “The CMT models of the two topologies have the similar formulation when high quality factor and weak coupling are satisfied [21], [22].”
• A Critical Review of Wireless Power Transfer via Strongly Coupled Magnetic Resonances (2014, methodology): “reducing the order of the differential equations by half compared to CT [18].”