Power transfer efficiency for distance-adaptive wireless power transfer system

Seo, Dong-Geun; Ahn, Seong‐Hyeop; Kim, J.-H.; Lee, W.-S.; Khang, Seung-Tae; Chae, Soo-Chang; Yu, Jong‐Won

doi:10.23919/ropaces.2018.8364249

Cited by 12 publications

(11 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, coupled WPT approaches are limited in the distance achieved. In addition, at very close separations, magnetic resonance WPT systems are prone to over-coupling and require reconfigurable tuning circuitry for re-tuning the coils in over-coupling and under-coupling regions [23,24].…”

Section: Wpt: the Existing Approachesmentioning

confidence: 99%

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

2020

View full text Add to dashboard Cite

Achieving a wireless power transfer (WPT) link insensitive to separation is a key challenge to achieving power autonomy through wireless-powering and wireless energy harvesting over a longer range. While coupled WPT has been widely used for near-field high-efficiency WPT applications, the efficiency of the WPT link is highly sensitive to separation and alignment, making it unsuitable for mobile systems with unknown or loose coupling such as wearables. On the other hand, while ultra-high frequency (UHF) and microwave uncoupled radiative WPT (0.3–3 GHz) enables meters-long separation between the transmitter and the receivers, the end-to-end efficiency of the WPT link is adversely limited by the propagation losses. This work proposes radiative WPT, in the 6.78 MHz license-free band, as a hybrid solution to separation-independent WPT, thus mitigating the losses associated with coil separation. Resonant electrically small antennas were fabricated using embroidered textile coils and tuned using L-matching networks, for wearable WPT. The antenna’s efficiency and near-fields have been evaluated numerically and experimentally. The proposed WPT link achieves a stable forward transmission of S 21 > − 17 dB and S 21 > − 28 dB, independent of coil separation on the XZ and XY planes respectively, in a 27 m 3 volume space. The presented approach demonstrates the highest WPT link efficiency at more than 1-m separation and promises higher end-to-end efficiency compared to UHF WPT.

show abstract

Section: Wpt: the Existing Approachesmentioning

confidence: 99%

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

2020

View full text Add to dashboard Cite

show abstract

“…A better system performance needs a high level of Q [10]. When the frequency of the resonance circuit is fixed, the quality factor Q will increase with the increasing value of L r .…”

Section: Cross Coil Structure In the Transmittermentioning

confidence: 99%

“…Their system efficiency can reach 90.2%; however, the transmitter in [9] is spherical, which may need an additional support structure in the practice application. In order to increase the distance of the misaligned WPT system, a repeating coil has been used in the system [10,11]; however, the repeats cannot be applied in some situation. The magnetic field shaping technique is also used in [12], but there are three independent power supplies in their system, which increases system complexity.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling and Experimental Analysis of Three-Dimensional Cross Coil Structure for Misaligned Wireless Power Transfer System

Song¹,

An²,

Li³

et al. 2020

PIER C

View full text Add to dashboard Cite

The coaxiality of the transmitter and receiver has a significant impact on the efficiency in a wireless power transfer system. In order to keep high system efficiency, a novel coil structure is studied in this paper. Several plane coils are crossed to make up a three-dimensional coil structure in the transmitter, which will make sure the system in the state of strong magnetic field coupling. In the theory part, the magnetic field equation of different relationships between transmitter and receiver is deducted in detail. In the simulation part, the performance of the three-dimensional coil structure has been studied. The simulation results show that the new coil structure can generate a rotating magnetic field, and the rotating magnetic field will keep the system in the state of the strong magnetic field coupling in the simulation model. In the experimental part, the three-dimensional coil structure has been compared to a plane coil structure. The experimental results show that the efficiency of the three-dimensional coil structure is increased above 10% in the misalignment situation. The simulated and experimental results show that the new three-dimensional coil structure has a better performance in the misalignment situation than the plane coil structure in a wireless power transfer system.

show abstract

“…Recently, various techniques have been reported to extend the effective range of wireless power transfer. For instance, distance-adaptive wireless power transfer systems have been demonstrated based on novel adaptive matching techniques [ 1 , 2 , 3 ], by over-coupling the coils [ 4 ], or by utilizing compensating capacitors [ 5 ]. Although these methods have demonstrated their potential with an efficiency of as high as 80% for a distance of 50% (relative to the largest coil dimension) between the Tx and Rx coils, the effect is limited to cases where the two coils are well, if not perfectly, aligned.…”

Section: Introductionmentioning

confidence: 99%

Compensation for Lateral Misalignment in Litz Wire Based on Multilayer Coil Technology

Chang

Lim

Lee

2021

Sensors

View full text Add to dashboard Cite

This study applies a multilayer coil technology that can compensate for a decrease in transfer efficiency due to a lateral misalignment in a practical 100 kHz-band wireless power transfer system and validates its effect on the efficiency of compensation. The effectiveness is investigated using coils fabricated with Litz wires. Three-turn rectangular assistant coils 22.4 × 45.3 mm2 in size were stacked on a five-turn circular primary coil with a diameter of 45.3 mm in a 2 × 1 array. Transfer efficiency between two such coils was measured by producing lateral misalignment, while maintaining the vertical distance between the Tx and Rx coils at 7 mm. The experimental results showed that the transfer efficiency was compensated by approximately 46.1%P maximum in a misalignment state of 30 mm, which corresponded to 67% of the maximum size of the coil, compared to the transfer efficiency of the structure, in which the multilayer coil was not applied. Furthermore, transfer efficiency was compensated by 37.6%P, even in an asymmetric system in which the multilayer structure was applied only to the Tx coil, thereby confirming an excellent multilayer coil technology effect on compensation for lateral misalignment in practical cases.

show abstract

Power transfer efficiency for distance-adaptive wireless power transfer system

Cited by 12 publications

References 5 publications

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

Separation-Independent Wearable 6.78 MHz Near-Field Radiative Wireless Power Transfer using Electrically Small Embroidered Textile Coils

Modeling and Experimental Analysis of Three-Dimensional Cross Coil Structure for Misaligned Wireless Power Transfer System

Compensation for Lateral Misalignment in Litz Wire Based on Multilayer Coil Technology

Contact Info

Product

Resources

About