Wireless Power Transfer With Zero-Phase-Difference Capacitance Control

Iguchi, Shunta; Yeon, Pyungwoo; Fuketa, Hiroshi; Ishida, Koichi; Sakurai, Takayasu; Takamiya, Makoto

doi:10.1109/tcsi.2015.2388832

Cited by 22 publications

(17 citation statements)

References 23 publications

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“…Open state had the highest transfer efficiency of about 70% in short distance, but the efficiency decreased rapidly away from the main coil, as shown in Figure . Short state had got higher efficiency 59% around the middle distance and the efficiency decreased slowly, but the efficiency is low in short distance because of splitting . We were able to get optimized efficiency, the average of 54% from 5 cm to 40 cm in the MR‐WPT system, by switching states.…”

Section: Measurement and Analysismentioning

confidence: 86%

“…Impedance matching is one of them and the best key factor of MR‐WPT system; it creates strong resonance and a better resonance transfer power, but the resonation is being split when rx is closed by tx. Researchers approached various ways, such as designing a resonator, changing capacitance or inductance , and aligning load coil with the main coil. Some researchers attempted to transfer power far away using extra coils, called repeaters, which keep resonance even at a longer distance.…”

Section: Introductionmentioning

confidence: 99%

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Efficiency optimization using reconfigurable resonators for MR‐WPT in laptop computers

Lee

Kang

Jung

2016

Micro & Optical Tech Letters

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In this paper, magnetic resonant wireless power transfer (MR‐WPT) was studied, which is being raised for mobile devices, to improve transfer efficiency. We utilized an array of resonators, which is reconfigurable with pin‐diode. It showed that the transfer efficiency can be optimized by controlling the status (Open/Short‐mode) of the resonators along the transfer distance. The resonators were flat, with small size and characteristics suitable to design mobile devices. The transfer efficiency of the system was increased by 12%, averaging in transfer distance from 5 cm to 40 cm, and maintained higher than 30% in 40 cm distance. It is digitally controlled with pin‐diodes in the practical mobile devices such as laptop, cell phone, and tablet PC. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:3000–3003, 2016

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Section: Measurement and Analysismentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Efficiency optimization using reconfigurable resonators for MR‐WPT in laptop computers

Lee

Kang

Jung

2016

Micro & Optical Tech Letters

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“…In this paper, a number of these issues related to WPT systems are discussed in detail. Other issues, such as impedance matching (which will be discussed in brief in Section 3) and control methods [83,84], will not be discussed for the sake of brevity.…”

Section: Benchmark Of the Research Workmentioning

confidence: 99%

Magnetically Coupled Resonance WPT: Review of Compensation Topologies, Resonator Structures with Misalignment, and EMI Diagnostics

2018

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Magnetically coupled resonance wireless power transfer systems (MCR WPT) have been developed in recent years. There are several key benefits of such systems, including dispensing with power cords, being able to charge multiple devices simultaneously, and having a wide power range. Hence, WPT systems have been used to supply the power for many applications, such as electric vehicles (EVs), implantable medical devices (IMDs), consumer electronics, etc. The literature has reported numerous topologies, many structures with misalignment effects, and various standards related to WPT systems; they are usually confusing and difficult to follow. To provide a clearer picture, this paper aims to provide comprehensive classifications for the recent contributions to the current state of MCR WPT. This paper sets a benchmark in order to provide a deep comparison between different WPT systems according to different criteria: (1) compensation topologies; (2) resonator structures with misalignment effects; and, (3) electromagnetic field (EMF) diagnostics and electromagnetic field interference (EMI), including the WPT-related standards and EMI and EMF reduction methods. Finally, WPT systems are arranged according to the application type. In addition, a WPT case study is proposed, an algorithm design is given, and experiments are conducted to validate the results obtained by simulations.

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“…Therefore, it is important to eliminate frequency detuning by using a certain control strategy. Many methods to deal with this problem are reported in previous works, including frequency tracking [7-9], impedance matching (IM) [10,11] and compensation capacitor tuning [12][13][14]. In [8], a phase-locked-loop (PLL) controller is applied to the primary side.…”

mentioning

confidence: 99%

“…However, this method has no effect on the secondary side. In [14], adjustable capacitors are applied to both sides. However, this control strategy should use wireless communication, which increases the complexity of control and cost.In this paper, a novel dual-side independent switched capacitor control strategy for MCR-WPT systems with coplanar coils is proposed.…”

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confidence: 99%

Dual-Side Independent Switched Capacitor Control for Wireless Power Transfer with Coplanar Coils

et al. 2018

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The transfer coils of traditional Magnetic Coupling Resonant Wireless Power Transfer (MCR-WPT) systems are generally arranged coaxially. Coplanar coils can be an alternative scheme that can save more space in some applications, such as mobile phone wireless charging. However, the inductances of coplanar coils are sensitive to foreign objects, which leads to a reduction in transfer efficiency and output power. A MCR-WPT system with coplanar coils and its control strategy are proposed in this paper. First, the characteristic of the mutual inductance and the magnetic field distribution between the coplanar coils are analyzed. A formula to calculate mutual inductance between the coplanar coils is proposed in this part. Secondly, the effect of inductance offset and frequency detuning on transfer efficiency and output power are analyzed. Then, the control strategy to eliminate frequency detuning is proposed. The proposed method implements switched capacitor to take place of constant compensation capacitor. The equivalent capacitance of switched capacitor is adjusted when the frequency detuning occurred. Thus, the inherent frequency of the resonant tank tracks the source frequency all the time. Since the switched capacitor of each side is controlled based on the quantity of their own, the control process is independent and does not require wireless communication. The complexity and the cost of the system are reduced. At the end of the article, the veracity of mutual inductance formula and the effectiveness of the proposed control strategy are verified by experiments. The experimental coils are placed in in an environment full of interference. The inductances of the coils are reduced from 224 µH to about 214 µH. The transfer efficiency and output power of MCR-WPT system with closed-loop control are higher than the one without control. At a distance of 5 cm from edge to edge, the transfer efficiency is 76.37% under the proposed control and 72.21% under no control. The output power is 285.66 W under the proposed control and 271.37 W under no control.field distribution are different from the coaxial ones. There are some works that have analyzed the mutual inductance of coils with lateral misalignment [5] or with angular azimuth misalignment [6]. However, there is no research on the MCR-WPT system with coplanar coils. This kind of coils arrangement has been neglected before.Inductances of coils are very sensitive to external interferences. For instance, ferrite cores are used frequently in the design of coils to improve the mutual inductance. However, ferrite cores can change the distribution of the magnetic field [7]. Thus, the inductances of coils will vary significantly with misalignment. Metal objects outside coils can also cause the instability of inductances. Meanwhile, the capacitances of compensation capacitors in the MCR-WPT system may be affected by temperature, frequency, bias voltage, etc. Therefore, the inherent frequency of the resonant tanks consisting of an inductor and compensation capacitor is changed accor...

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Wireless Power Transfer With Zero-Phase-Difference Capacitance Control

Cited by 22 publications

References 23 publications

Efficiency optimization using reconfigurable resonators for MR‐WPT in laptop computers

Efficiency optimization using reconfigurable resonators for MR‐WPT in laptop computers

Magnetically Coupled Resonance WPT: Review of Compensation Topologies, Resonator Structures with Misalignment, and EMI Diagnostics

Dual-Side Independent Switched Capacitor Control for Wireless Power Transfer with Coplanar Coils

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