Free-Positioning Wireless Charging System for Small Electronic Devices Using a Bowl-Shaped Transmitting Coil

Kim, Jin-Wook; Kim, Do-Hyeon; Choi, Jeong‐Hee; Kim, Kwan-Ho; Park, Youngjin

doi:10.1109/tmtt.2015.2398865

Cited by 85 publications

(28 citation statements)

References 20 publications

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“…Taking the magnetic flux density of 5.9 mT at the two ends of the inner part as the expected value, the number of turns of the frustum coil can be designed to meet this expected magnetic flux density: In order to accurately determine the parameters of the frustum coil and exhibit the enhanced magnetic coupling effect, the simulated results of the magnetic flux density along the wok surface without and with the frustum coil were compared with the analytical results from Section 3, as shown in Figure 8. Particularly, the calculated lines were obtained by moving points mentioned in (20) and (23) along the wok's curved bottom. The slight discrepancy was mainly due to the inevitable magnetic field leakage, as well as the effect of the ferrite bars and aluminum shield.…”

Section: Computational Simulationmentioning

confidence: 99%

“…Moreover, the orthogonal receiving coil was implemented to improve the transfer efficiency under coil misalignment and achieve homogenous WPT for move-and-charge scenarios [19]. A WPT system with a bowl-shaped transmitting coil to charge small electronics such as hearing aids and an effective method to calculate the magnetic field in the air was proposed in [20]. Meanwhile, by adopting the MRC mechanism [21], selective induction heating can be achieved by regulating the operating frequency at different resonant frequencies [22].…”

Section: Introductionmentioning

confidence: 99%

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All-In-One Induction Heating Using Dual Magnetic Couplings

Han¹,

Chau²,

Wong³

et al. 2019

Energies

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This paper proposes and implements an all-in-one induction heating system, which can accommodate both pan-shaped and wok-shaped utensils. Traditionally, the pan is heated by a planar induction cooktop while the wok is heated by a curved induction cooktop. In this paper, both magnetic inductive coupling and magnetic resonant coupling are utilized to achieve excellent heating performance of the wok based on a planar primary coil. The key is to flexibly employ a detachable frustum coil for heating the wok. Specifically, the theoretical models of the proposed induction heating system with and without using the frustum coil are derived to analyze the proposed system. Computational simulation results of the magnetic and thermal fields of the proposed system are provided to elaborate the heating performance of the wok. A 1500 W prototype is designed and built. The calculated, simulated and experimental results are all in good agreement, which validate the feasibility of the proposed induction heating system well.

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Section: Computational Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

All-In-One Induction Heating Using Dual Magnetic Couplings

Han¹,

Chau²,

Wong³

et al. 2019

Energies

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“…The U-coil method attained an energy transfer efficiency that was 66% better than that of the two-coil method. Kim et al [16] presented a WPT system that utilizes a bowl-shaped transmitting coil (B-STxC) to charge small electronics, such as hearing aids and wearable electronic devices. They suggested three-coil WPT systems.…”

Section: Related Workmentioning

confidence: 99%

Single-Tube and Multi-Turn Coil Near-Field Wireless Power Transfer for Low-Power Home Appliances

et al. 2018

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Single-tube loop coil (STLC) and multi-turn copper wire coil (MTCWC) wireless power transfer (WPT) methods are proposed in this study to overcome the challenges of battery life during low-power home appliance operations. Transfer power, efficiency, and distance are investigated for charging mobile devices on the basis of the two proposed systems. The transfer distances of 1–15 cm are considered because the practicality of this range has been proven to be reliable in the current work on mobile device battery charging. For STLC, the Li-ion battery is charged with total system efficiencies of 86.45%, 77.08%, and 52.08%, without a load, at distances of 2, 6, and 15 cm, respectively. When the system is loaded with 100 Ω at the corresponding distances, the transfer efficiencies are reduced to 80.66%, 66.66%, and 47.04%. For MTCWC, the battery is charged with total system efficiencies of 88.54%, 75%, and 52.08%, without a load, at the same distances of 2, 6, and 15 cm. When the system is loaded with 100 Ω at the corresponding distances, the transfer efficiencies are drastically reduced to 39.52%, 33.6%, and 15.13%. The contrasting results, between the STLC and MTCWC methods, are produced because of the misalignment between their transmitters and receiver coils. In addition, the diameter of the MTCWC is smaller than that of the STLC. The output power of the proposed system can charge the latest smartphone in the market, with generated output powers of 5 W (STLC) and 2 W (MTCWC). The above WPT methods are compared with other WPT methods in the literature.

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“…In case of m = n, the self-inductance is calculated. If we consider a circular coil consists of many loops, for the ith loop with a radius r i and cross-sectional area of a i , the self-inductance can be given as follows [17]:…”

Section: Circuit Analysismentioning

confidence: 99%

“…Many studies have investigated coil structures that are used in a wide range of applications, such as flat coils, square coils, and coils with cores. Three-dimensional structures have also been discussed, for example, a bowl-shaped transmitter coil [17]. The three-dimensional resonant cavity has been discussed, offering an effective way of charging multiple devices simultaneously, such as devices implanted in a freely moving animal [18], charging a mobile phone and a watch [19], and LEDs [20].…”

Section: Introductionmentioning

confidence: 99%

Free Angular-Positioning Wireless Power Transfer Using a Spherical Joint

Houran

Yang

2018

Energies

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Many studies have investigated resonator structures and winding methods. The aims of this paper are as follows. First, the paper proposes an optimized winding model for a bio-inspired joint for a wireless power transfer (WPT) system. The joint consists of a small spherical structure, which rotates inside a hemispherical structure. The transmitter coil (Tx) is wound on the hemisphere structure, and the receiver coil (Rx) is wound on the small sphere. The power is transferred while rotating Rx over a wide range of angular misalignment. In addition, the algorithm design of the proposed winding method is given to get an optimized model. Moreover, the circuit analysis of the WPT system is discussed. Second, the magnetic field density is investigated considering a safety issue, which is linked to human exposure to electromagnetic fields (EMFs). Moreover, EMF mitigation methods are proposed and discussed in detail. Finally, the simulation results are validated by experiments, which have confirmed that the proposed winding method allows the system to rotate up to 85 degrees and achieve an efficiency above 86%. The proposed winding method for the WPT system can be a good technique for some robotic applications or a future replacement of the human joint.

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Free-Positioning Wireless Charging System for Small Electronic Devices Using a Bowl-Shaped Transmitting Coil

Cited by 85 publications

References 20 publications

All-In-One Induction Heating Using Dual Magnetic Couplings

All-In-One Induction Heating Using Dual Magnetic Couplings

Single-Tube and Multi-Turn Coil Near-Field Wireless Power Transfer for Low-Power Home Appliances

Free Angular-Positioning Wireless Power Transfer Using a Spherical Joint

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