Optimisation analysis of coil configuration and circuit model for asymmetric wireless power transfer system

Wang, Sheng-Ming; Hu, Zhenzhong; Chen, Rong; Lu, Conghui; Xiong, Tingting; Chen, Junfeng; Liu, Minghai

doi:10.1049/iet-map.2017.0539

Cited by 14 publications

(17 citation statements)

References 27 publications

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“…As seen, for coupling coefficients smaller than k = 0.15, the transferred power is low at f / f s due to the weak coupling between the coupled coils. For coupling coefficients larger than k = 0.15, the transferred power at f / f s is also low due to the frequency splitting phenomenon [11,20,23,24]. While this phenomenon is happening, as a result of impedance matching problem in short coil-coil distance (in the strongly coupled region), the maximum power is transferred at splitting frequencies instead of the natural resonant frequency f s [16].…”

Section: Tracking Maximum Efficiency Point During Variations In Coil-mentioning

confidence: 99%

Dual‐objective control strategy for maximum power and efficiency point tracking in wirelessly powered biomedical implanted devices

Esfahani

Madani

Niroomand

2019

IET Microwaves, Antennas & Propagation

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Wireless charging is widely considered as a safe and reliable way for powering biomedical implants, as it avoids problems like surgical infection. Wireless power transfer (WPT) systems are desired to work efficiently against variations in coil–coil distance or output load. On the other hand, to maintain the maximum overall efficiency of the WPT system, the high frequency (HF) power amplifier, used to feed WPT system, must operate at optimal zero‐voltage switching (ZVS) condition. In this paper, an automated dual‐objective control strategy adaptive to variations in coil–coil distance or output load is proposed which ensures both targets of tracking maximum power point and operating at optimal ZVS condition by adjusting operating frequency and duty‐cycle of switching voltage of HF power amplifier, respectively; that is while there have been few studies which have addressed both the two targets. To evaluate the effectiveness of the proposed strategy, a PCB prototype, operating at 800 kHz, is fabricated. Experimental results, demonstrating the proposed strategy increases transferred power from 23 mW to about 45 mW, are in good agreement with theoretical predictions. Additionally, while implanting the receiver coil in a real biological tissue, experiments show only 2% of degradation in power transfer efficiency as well as no frequency shift.

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Section: Tracking Maximum Efficiency Point During Variations In Coil-mentioning

confidence: 99%

Dual‐objective control strategy for maximum power and efficiency point tracking in wirelessly powered biomedical implanted devices

Esfahani

Madani

Niroomand

2019

IET Microwaves, Antennas & Propagation

View full text Add to dashboard Cite

show abstract

“…The values of the above changes are due to the coil impedance, and the changes in the number of turns and pitch deeply affect the coil impedance and quality factor [21], [23]. To give a more accurate conclusion, the coil impedance is calculated at 6.78 MHz without tuning, and the results are shown below.…”

Section: Simulation Of the Number Of Turns And The Pitchmentioning

confidence: 99%

“…In [22], a design and optimization method for the small coil used in implantable medical devices was proposed. An optimizable coil configuration and a circuit model were proposed to increase the transfer distance [23].…”

Section: Introductionmentioning

confidence: 99%

Maximizing Transfer Distance for WPT via Coupled Magnetic Resonances by Coupling Coils Design and Optimization

et al. 2020

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The technology of wireless power transfer via coupled magnetic resonances (CMR-WPT) has a good transfer performance in the ''middle range'', but it is far from satisfying the application requirements in practice. To achieve a longer transfer distance, coils are usually complicatedly designed, making the system unwieldy and costly. Based on the intuitive and easily adjustable coil parameters, a design and optimization method was proposed in this paper, which can realize the minimum size coil that meets the requirements at 6.78 MHz. First, an equivalent model of the CMR-WPT system was developed, and the influences of coil parameters on the effective transfer distance and power transfer efficiency (PTE) were analyzed, indicating that the effective transfer distance and PTE were not always proportional to the coil radius, the number of turns or the pitch. Then, the coil impedance and the quality factor of different coils were calculated. In addition, the influence degree of coil parameters on the transfer performance was also compared using variable control. Finally, an experimental platform was built, and experimental results agreed well with the simulation results. INDEX TERMS Coupled magnetic resonances, design and optimization, coil parameters, effective transfer distance, power transfer efficiency.

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“…In the near‐field techniques, compared with the traditional inductively coupled scheme, magnetic resonant coupling wireless power transfer (MRC‐WPT) has been a hot research area due to its longer transfer distance 3 . Thus, it is applied in various applications such as implanted biomedical devices, portable electronics, and electric vehicle charging system 4–6 …”

Section: Introductionmentioning

confidence: 99%

Operating characteristics of four‐coil magnetic resonant coupling wireless power transfer under different resonant states

Wang

Zhang

et al. 2020

Circuit Theory & Apps

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In wireless power transfer, the transfer efficiency decreases with the increase of the transfer distance. To improve the power transfer performance, the operating characteristics of a conformal coplanar four-coil magnetic resonant coupling wireless power transfer system are investigated and analyzed under four different resonant states. Based on the complete equivalent circuit model, the transmission coefficient and the input impendence are calculated. The performance of the systems operated under four resonant states is studied and compared. Also, the origin of the difference is specifically analyzed. The simulation results indicate that the wireless power transfer system operated under State 1, the state where the compensated serial capacitance makes the coils work at the frequency of the maximum Q-factor, shows the most excellent transfer characteristic among the four resonant states. The transmission coefficient can be well maintained above 0.8 within the transfer distance of 30 cm. Experiment has been carried out for validation, and the result indicates that more power can be delivered to the load for the system operated under State 1. K E Y W O R D S operating characteristics, resonant state, transmission coefficient, wireless power transfer 1 | INTRODUCTION Wireless power transfer has received a great deal of attention as it provides a possibility to deliver energy without power lines. A variety of wireless power transfer techniques have been developed, which are based either on near-field or farfield electromagnetic coupling. 1,2 Previous studies have demonstrated that higher power transfer efficiency can be obtained via the near-field techniques than the far-field approaches. In the near-field techniques, compared with the traditional inductively coupled scheme, magnetic resonant coupling wireless power transfer (MRC-WPT) has been a hot research area due to its longer transfer distance. 3 Thus, it is applied in various applications such as implanted biomedical devices, portable electronics, and electric vehicle charging system. 4-6 Generally, most MRC-WPT systems are featured with two coils. It has been revealed in other studies 7-9 that the transfer performance of the two-coil system deteriorates with the increase of the transfer distance due to the weakened magnetic coupling. To extend the transfer distance, MRC-WPT systems with repeaters positioned between transmitting and receiving coils have been investigated. 10-15 Nevertheless, the transmission efficiency

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Optimisation analysis of coil configuration and circuit model for asymmetric wireless power transfer system

Cited by 14 publications

References 27 publications

Dual‐objective control strategy for maximum power and efficiency point tracking in wirelessly powered biomedical implanted devices

Dual‐objective control strategy for maximum power and efficiency point tracking in wirelessly powered biomedical implanted devices

Maximizing Transfer Distance for WPT via Coupled Magnetic Resonances by Coupling Coils Design and Optimization

Operating characteristics of four‐coil magnetic resonant coupling wireless power transfer under different resonant states

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