Achieving Low Magnetic Flux Density and Low Electric Field Intensity for a Loosely Coupled Inductive Wireless Power Transfer System

Zhu, Guangqi; Lorenz, Robert D.

doi:10.1109/tia.2018.2860959

Cited by 18 publications

(9 citation statements)

References 20 publications

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“…This research focuses on increasing the quality factor and the optimal number of turns are not eventually considered for maximum power efficiency operation. A general design procedure to find electrical parameters by a theoretical analysis for maximum coil-to-coil efficiency has been proposed [32]. However, this research assumes that the size and shapes of the Tx and Rx coils are symmetrical, i.e., physical dimension and the number of turns.…”

Section: Introductionmentioning

confidence: 99%

Optimal Number of Turns Design of the IPT Coils for Laptop Wireless Charging

et al. 2021

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The coil design of the inductive power transfer (IPT) for a transmitter (Tx) and receiver (Rx) is crucial to determine the performance of the IPT. Considering core loss and copper loss of the Tx and Rx coils, which are major loss terms of the whole IPT system, determination of the winding turns for the Tx and Rx coils becomes a key factor for maximum power transfer design of the IPT coils. In this paper, an optimal turns design of IPT coils for laptop wireless charging applications with a maximum power transfer efficiency is proposed. Under a specific design requirement of IPT, optimal turns of the Tx and Rx coils N1,op and N2,op can be determined by the proposed IPT coil design procedure with a finite-element-method (FEM) based simulation analysis. From the results of the coil design by the proposed IPT coil design methodology, N1,op and N2,op for maximum power efficiency, and input DC voltage Vdc for the target load power can be found by the proposed coil design procedure. The 40W prototypes of the two symmetry and asymmetry IPT coils for laptop wireless charging were fabricated, and verified by simulation and experiments. To separately verify the core and copper loss of the IPT coils, a resistance model and Steinmetz equation-based methods were comparatively evaluated, and it was found that they matched well at a core temperature condition of below 40 o C. The results showed that the total weight and the thickness of the Tx and Rx coils as well as the maximum power efficiencies of 95.1% and 96.8% for the symmetry and asymmetry cases were obtained by the proposed IPT coil design procedure, which becomes a practical solution for the laptop wireless charging coil design. INDEX TERMS Wireless power transfer (WPT), inductive power transfer (IPT), coil design, optimal turns design, laptop wireless charging, maximum power transfer efficiency.

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Section: Introductionmentioning

confidence: 99%

Optimal Number of Turns Design of the IPT Coils for Laptop Wireless Charging

et al. 2021

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“…To improve the WPTS's efficiency, two compensation topologies named LC/S [4] and LC/CL [5] were proposed, the number of the coil turns, and the quality factor of the coils was optimized as well in [6]- [7]. Moreover, the performances of the square and circular coils in WPTS were investigated in [8], and the superiority of the square coil in improving system efficiency was revealed [8].…”

Section: Introductionmentioning

confidence: 99%

Determining the Optimal Range of Coupling Coefficient to Suppress Decline in WPTS Efficiency Due to Increased Resistance With Temperature Rise

Zhao

Wang

Eldeeb

et al. 2020

IEEE Open J. Ind. Electron. Soc.

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The continuous operation of the wireless power transfer system (WPTS) under high-frequency switching activity might cause a temperature rise in various system's components. That temperature rise might increase the resistance of the primary and secondary coils, which will lead to a significant decline in the system's efficiency. To address this problem at the design stage, we investigate the optimal range of the coupling coefficient that suppresses the efficiency drop due to the increasing resistance of the WPTS components. The proposed optimal range of the coupling coefficient can also ensure the output power requirements of the WPTS. Using four different WPTSs, the determination method for the optimal range of coupling coefficients under different system operational frequencies was developed and implemented. A 3-kW resonant experimental prototype WPTS was designed and built to validate the proposed coupling coefficients experimentally. The experimental results show that the optimized coupling range successfully suppressed the efficiency decline resulting from the increasing resistance caused by temperature rise. INDEX TERMS Wireless power transfer system (WPTS), efficiency, temperature rise, optimal coupling coefficient.

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“…Moreover, the design of coil radius also can influence on transfer distance. The average radius was adopted in refs [17]- [19]. The effects of inductive parameters and nearby electromagnetic fields on coils with two different radii were analyzed [17].…”

Section: Introductionmentioning

confidence: 99%

“…The Q-factors of coils were derived and analyzed for enhancing the transfer distance [18]. The effects of coil radius and transfer distance on transfer efficiency, magnetic and electric field distributions were also investigated [19]. The outside radius was considered in [20], [21].…”

Section: Introductionmentioning

confidence: 99%

“…The selfinductance, impedance, quality factor and coupling coefficient at different coil radii were calculated at a fixed transfer distance of 10 cm [21]. Refs [17], [19] and [21] studied the coil radius, nevertheless, most of the research only focused on the resonant frequency of kHz rather than MHz. The symmetrical structure was deeply studied [20].…”

Section: Introductionmentioning

confidence: 99%

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Influences of Coil Radius on Effective Transfer Distance in WPT System

et al. 2019

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The improvement of effective transfer distance is significant for wireless power transfer (WPT) via coupled magnetic resonances, with coil radius being the most important influencing factor. To study the relationship between effective transfer distance and coil radius, a model of WPT is established at first. Based on analyses of circuit and magnetic field, the influencing factors for effective transfer distance are obtained. Second, the models of WPT are constructed using software COMSOL, and the influences of Tx and Rx coil radius on the effective transfer distance are studied in detail. In addition, they are not proportional and the coil impedance is the most important factor. On this basis, a coil design method is proposed. Finally, an experiment device was built, and experimental results were well consistent with the theoretical analysis, showing the rationality and effectiveness of the proposed method.

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Achieving Low Magnetic Flux Density and Low Electric Field Intensity for a Loosely Coupled Inductive Wireless Power Transfer System

Cited by 18 publications

References 20 publications

Optimal Number of Turns Design of the IPT Coils for Laptop Wireless Charging

Optimal Number of Turns Design of the IPT Coils for Laptop Wireless Charging

Determining the Optimal Range of Coupling Coefficient to Suppress Decline in WPTS Efficiency Due to Increased Resistance With Temperature Rise

Influences of Coil Radius on Effective Transfer Distance in WPT System

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