### Abstract

A coil with a high quality factor (Q) is desired to obtain a high efficiency for inductive power transfer (IPT). Q is proportional to the coil inductance and operating frequency, while inversely proportional to the coil resistance which increases with the raising of the frequency. An optimized frequency exists to obtain the maximum efficiency. Eddy currents and resulting AC resistance in Litz-wire coils are attributed to magnetic field. Especially, the induction component of the AC resistance is approximately proportional to the squared magnetic field where the coil exposed to. FEA simulations are conducted and surface integral method are employed to obtain the squared field. Additionally, the volume integral method is proposed to evaluate the overall effect of the field on the induction resistance. The optimized frequency for maximum efficiency is obtained based on the squared field calculation and resulting AC resistance evaluation. Sample prototype coils are manufactured to verify the resistance analysis methods. An IPT system is built employing these coils. Experiments show that the IPT system obtains the highest efficiency at frequencies closed to the predicted optimized ones

Original language | English (US) |
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Journal | IEEE Transactions on Power Electronics |

DOIs | |

State | Accepted/In press - May 21 2018 |

### Fingerprint

### Keywords

- Atmospheric modeling
- Bars
- Ferrites
- Immune system
- induction acresistance
- Inductive power transfer
- Litz-wire
- Magnetic fields
- optimized frequency
- proximity effect
- Resistance
- skin effect
- Spirals

### ASJC Scopus subject areas

- Electrical and Electronic Engineering

### Cite this

*IEEE Transactions on Power Electronics*. https://doi.org/10.1109/TPEL.2018.2839626

**Frequency Optimization for Inductive Power Transfer Based on AC Resistance Evaluation of Litz-wire.** / Liu, Jiangtao; Deng, Qijun; Czarkowski, Dariusz; Kazimierczuk, Marian K.; Zhou, Hong; Hu, Wenshan.

Research output: Contribution to journal › Article

*IEEE Transactions on Power Electronics*. https://doi.org/10.1109/TPEL.2018.2839626

}

TY - JOUR

T1 - Frequency Optimization for Inductive Power Transfer Based on AC Resistance Evaluation of Litz-wire

AU - Liu, Jiangtao

AU - Deng, Qijun

AU - Czarkowski, Dariusz

AU - Kazimierczuk, Marian K.

AU - Zhou, Hong

AU - Hu, Wenshan

PY - 2018/5/21

Y1 - 2018/5/21

N2 - A coil with a high quality factor (Q) is desired to obtain a high efficiency for inductive power transfer (IPT). Q is proportional to the coil inductance and operating frequency, while inversely proportional to the coil resistance which increases with the raising of the frequency. An optimized frequency exists to obtain the maximum efficiency. Eddy currents and resulting AC resistance in Litz-wire coils are attributed to magnetic field. Especially, the induction component of the AC resistance is approximately proportional to the squared magnetic field where the coil exposed to. FEA simulations are conducted and surface integral method are employed to obtain the squared field. Additionally, the volume integral method is proposed to evaluate the overall effect of the field on the induction resistance. The optimized frequency for maximum efficiency is obtained based on the squared field calculation and resulting AC resistance evaluation. Sample prototype coils are manufactured to verify the resistance analysis methods. An IPT system is built employing these coils. Experiments show that the IPT system obtains the highest efficiency at frequencies closed to the predicted optimized ones

AB - A coil with a high quality factor (Q) is desired to obtain a high efficiency for inductive power transfer (IPT). Q is proportional to the coil inductance and operating frequency, while inversely proportional to the coil resistance which increases with the raising of the frequency. An optimized frequency exists to obtain the maximum efficiency. Eddy currents and resulting AC resistance in Litz-wire coils are attributed to magnetic field. Especially, the induction component of the AC resistance is approximately proportional to the squared magnetic field where the coil exposed to. FEA simulations are conducted and surface integral method are employed to obtain the squared field. Additionally, the volume integral method is proposed to evaluate the overall effect of the field on the induction resistance. The optimized frequency for maximum efficiency is obtained based on the squared field calculation and resulting AC resistance evaluation. Sample prototype coils are manufactured to verify the resistance analysis methods. An IPT system is built employing these coils. Experiments show that the IPT system obtains the highest efficiency at frequencies closed to the predicted optimized ones

KW - Atmospheric modeling

KW - Bars

KW - Ferrites

KW - Immune system

KW - induction acresistance

KW - Inductive power transfer

KW - Litz-wire

KW - Magnetic fields

KW - optimized frequency

KW - proximity effect

KW - Resistance

KW - skin effect

KW - Spirals

UR - http://www.scopus.com/inward/record.url?scp=85047601373&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85047601373&partnerID=8YFLogxK

U2 - 10.1109/TPEL.2018.2839626

DO - 10.1109/TPEL.2018.2839626

M3 - Article

JO - IEEE Transactions on Power Electronics

JF - IEEE Transactions on Power Electronics

SN - 0885-8993

ER -