Coil enhancements for high efficiency wireless power transfer applications

Sampath, J.P.K.; Alphones, Arokiaswami; Vilathgamuwa, D.M.; Ong, Alex; Bac, Nguyen, Xuan

doi:10.1109/iecon.2014.7048933

Cited by 16 publications

(6 citation statements)

References 17 publications

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“…As a result, the current is induced by induction therein, and a rectifier is then used to convert the AC-induced current to DC to charge the battery [23]. Figure 2 shows the equivalent circuit model using lumped parameter model when using a series-series (SS) compensation topology [24]. In the figure, I 1 , R 1 , C 1 , and L 1 are the primary side current, resistance, capacitance, and inductance, respectively, and I 2 , R 2 , C 2 , and L 2 are the corresponding parameters on the secondary side, M is the mutual inductance between the primary and secondary coils, and V in , R s , and R L are the HF power source, the power source internal resistance, and the load resistance, respectively.…”

Section: The Wpt System For Charging Evsmentioning

confidence: 99%

Core Structure and Electromagnetic Field Evaluation in WPT Systems for Charging Electric Vehicles

Elnail

Huang

Xiao³

et al. 2018

Energies

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The electromagnetic field (EMF) in a wireless power transfer (WPT) system needs to couple inductively between the primary and the secondary coils through a large air gap, thus giving the system a loosely coupled characteristic. Therefore, magnetically permeable material must be employed to improve the coupling and reduce leakage magnetic flux. However, adding an iron core increases the weight and introduces core loss as a new factor. In this paper, a WPT system model using a lumped circuit model is introduced. Moreover, the relationship between the relative permeability and the coupling coefficient in addition to the core amount (core thickness) and core loss are discussed. Three cores structure named: pot, slotted, and shaped bars cores are investigated using finite element method (FEM) software. Inspired by the investigation results, a new core structure using optimum shaped bars is proposed, the EMF level for reducing core loss in high-power transfer systems and in order to mitigate the EMF exposure to humans is intensively evaluated. The proposed core succeeded in reducing EMF and core loss by about 44% and 30%, respectively. The FEM software and physical prototype were used to validate the proposed optimum core structure. Results showed that 3.5 kW power transferred through a 20 cm air gap with 96% system efficiency(coil-coil).

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Section: The Wpt System For Charging Evsmentioning

confidence: 99%

Core Structure and Electromagnetic Field Evaluation in WPT Systems for Charging Electric Vehicles

Elnail

Huang

Xiao³

et al. 2018

Energies

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“…Design parameters of coils depicted in Table I are chosen to obtain highest quality factor for the selected footprint area [15]. Mutual inductance between circular spiral/helical coils can be calculated using filament method [16].…”

Section: A Designing Coil Shapesmentioning

confidence: 99%

Optimization of double spiral metamaterial for wireless power transfer

Sampath

Alphones

Vilathgamuwa

2015

2015 9th International Conference on Power Electronics and ECCE Asia (ICPE-ECCE Asia)

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Metamaterials (MMs) have been proposed to improve the performance of wireless power transfer (WPT) systems. However, optimization of WPT systems with MM using complex electromagnetic analytical methods and slow finite element simulation methods have become increasingly tedious. A simple analytical approach using equivalent circuit method to optimize WPT systems with MMs is proposed in this paper. A Double spiral metamaterial (DSM) is introduced and analyzed using the proposed approach. Furthermore, a detailed optimization process is presented considering system level performance indices (efficiency and transferred power) and application level requirements (transfer distance, maximum misalignment and probability of alignment). A novel figure-of-merit is introduced to achieve better compromise between system level performance indices and application level requirements. The proposed optimization strategy is validated with the experimental results.Index Terms -Wireless power transfer, metamaterial, efficiency optimization, Figure-of-merit.

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“…Some studies have found that output power is maximized in the critical coupling condition [11,12]. Other works have studied maximizing system efficiency [13,14]. It is possible to minimize the loss and maximize the coupling coefficient by designing a magnetic coupling system with high-quality factor [13].…”

Section: Introductionmentioning

confidence: 99%

“…It is possible to minimize the loss and maximize the coupling coefficient by designing a magnetic coupling system with high-quality factor [13]. Another way to gain high efficiency is to reduce proximity effect losses by increasing the separation between coil turns or increasing the number of the turns within the given area [14]. The other studies have increased the transferring distance or improved efficiency by increasing the number of coils [15,16].…”

Section: Introductionmentioning

confidence: 99%

Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

2020

Electronics

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This paper analyzes the output voltage of an inductive wireless power transfer (WPT) depending on coupling conditions. When the optimum efficiency and maximum output power are obtained, it is called critical coupling, so the receiving coil and the transmitting coil should be separated by a certain distance. When the distance between the transmitting coil and receiving coil is very short, it is called over coupling, and output power decreases with the optimal operating state of the critical coupling condition. To design the entire circuit system for the inductive WPT depending on the coupling condition, it is beneficial to analyze the output voltage according to a load variation, an input voltage, and an operating frequency. Therefore, the output voltage depending on the coupling condition in the inductive WPT is analyzed in this paper. The output voltage gain in critical coupling condition is greater than one and is not affected by a load variation by a series LC resonant operation. The reduced output power in an over coupling condition can be recovered by a series LLC resonant operation. In addition, the output voltage gain is almost one and is affected by the load variation in the over coupling condition. A 5W prototype is implemented with the wireless power consortium standard coils and experimental results are shown to verify theoretical analysis and operation.

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Coil enhancements for high efficiency wireless power transfer applications

Cited by 16 publications

References 17 publications

Core Structure and Electromagnetic Field Evaluation in WPT Systems for Charging Electric Vehicles

Core Structure and Electromagnetic Field Evaluation in WPT Systems for Charging Electric Vehicles

Optimization of double spiral metamaterial for wireless power transfer

Output Voltage Analysis of Inductive Wireless Power Ttransfer with Series LC and LLC Resonance Operations Depending on Coupling Condition

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