Comprehensive Modeling of Magnetoinductive Wave Devices for Wireless Power Transfer

Sandoval, Fralett Suarez; Moazenzadeh, Ali; Wallrabe, Ulrike

doi:10.1109/tpel.2017.2779606

Cited by 12 publications

(6 citation statements)

References 14 publications

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“…Publicly introduced by Kurs et al [23], multi-coil systems with additional resonant coils within the transmission interface can enhance WPT efficiency, as also suggested by RamRakhyani et al [24] or Kiani et al [25]. The additional resonators can either be classified as impedance transformer, in which impedance matching is realized by placing the resonators directly on top of transmitter and receiver coil [7], or as magneto-inductive waveguide, in which the effective distance between the WPT coils is reduced, hence increasing the efficiency [26].…”

Section: A Related Workmentioning

confidence: 86%

Efficient Wireless Power Transfer With Capacitively Segmented RF Coils

et al. 2020

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Wireless power transfer systems have been widely applied in the field of portable and implantable devices, featuring contact-free and reliable energy supply. Novel implant systems, such as brain-computer interfaces, impose the challenges of strong miniaturization and operation under loosely coupled conditions. Therefore, maximizing power transfer efficiency while decreasing the size of transmitter and receiver structures becomes a central research question. This paper presents a unified design strategy of modeling, analyzing and optimizing planar spiral coils with integrated capacitive elements, so-called capacitively segmented coils, for operation in wireless power transfer interfaces. It mathematically analyzes and experimentally verifies that the combination of capacitive coil segmentation, increased operational frequencies and geometrical coil optimization can be used to establish wireless power transfer links with comparatively high efficiency, small size and limited detuning effects in lossy dielectric environments. The paper embraces the formulation and verification of a broadband analytical link model based on partial element equivalent circuits, which is subsequently used to determine dominant coupling and loss mechanisms and to optimize the coils' geometries for high efficiency. Moreover, an extended analysis shows how the capacitive coil segmentation can effectively suppress dielectric losses and non-uniform current distributions by canceling the inductive contribution of every coil segment at the frequency of operation. Utilizing these methods, an exemplary 40.68 MHz wireless power link with a 30 mm primary and a 10 mm secondary coil is designed and evaluated: With a maximum efficiency of up to 31 % in biological tissue at 20 mm separation distance, it features efficiency levels which are up to ten times higher and a specific absorption rate which is up to five times lower compared to non-segmented systems. When operated at 150 MHz in air, efficiency levels are up to 1.5 times higher than in state-of-the-art systems of the same size.

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Section: A Related Workmentioning

confidence: 86%

Efficient Wireless Power Transfer With Capacitively Segmented RF Coils

et al. 2020

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“…In case of battery charging applications, the array is fed by a voltage source inverter, whereas the receiver is connected to a typical battery charger load, composed of a matching network, a rectifying and filtering stage, a DC/DC converter, and the battery. A further degree of freedom is obtained with the addition in the last cell of the array of a termination load

z_{T}

, which can be adjusted to maximize the transfer efficiency, as described in Sandoval et al 15 In order to optimize the efficiency, the modulation of the termination impedance proposed in Sandoval et al 16 can be implemented, making it possible to assume similar operating conditions for each position of the receiver. The analysis can be carried out considering the fundamental components of current and voltage, which can be treated as phasors at the resonant angular frequency

ω_{0} = 2 π f_{0}

.…”

Section: Resonator Array For Iptmentioning

confidence: 99%

“…In these systems, the power travels from the source to the load through the relay coils at the expense of an increased sensitivity to the mismatch between the input and output side impedances, 12,13 which reflects also on the magnetic near‐field distribution 14 . Solutions to this problem have been proposed in Sandoval et al, 15,16 making arrays of resonators an increasingly viable option for both consumer electronics and industrial applications. Notwithstanding, a feasible implementation of relay coil assisted IPT systems requires that parameters such as voltage gain and impedance are taken into account.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10][11] In these systems, the power travels from the source to the load through the relay coils at the expense of an increased sensitivity to the mismatch between the input and output side impedances, 12,13 which reflects also on the magnetic near-field distribution. 14 Solutions to this problem have been proposed in Sandoval et al, 15,16 making arrays of…”

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confidence: 99%

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Two‐port network compact representation of resonator arrays for wireless power transfer with variable receiver position

Sandrolini

Simonazzi

Barmada

et al. 2022

Circuit Theory & Apps

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This paper presents an equivalent circuit characterization of an array of resonators for wireless power transfer (WPT) applications. These apparatuses are composed of magnetically coupled resonant coils acting as a transmitter which feeds a receiver coil that can be placed over them at any position, allowing the tolerance of the system to the receiver misalignment to be dramatically enhanced. This advantage makes resonator arrays a suitable solution for both low-and high-power applications. The latter usually involve battery charging, with the resonator array acting as a transformer stage, ensuring galvanic isolation. An equivalent two-port network can be defined for any receiver position, allowing the array to be treated as a traditional transformer. Thereby, the simulation of the system can be simplified, as it is required in the design steps of a converter and control strategy. Analytical expressions of the two-port network parameters are proposed for arrays of any size and length. The formulas have been numerically and experimentally validated.battery charging, circuit modeling, inductive power transfer, resonator array, transformer, wireless power transfer | INTRODUCTIONIn the last decade, wireless power transfer (WPT) systems have become a convenient and reliable solution in many applications, ranging from powering portable electronic devices to automatic machines and electric vehicle (EV) charging. [1][2][3] These apparatuses offer many advantages, as the ability of operating in difficult environments or the possibility to transfer power to moving loads. The size and weight of high-power batteries can be reduced by more frequent charging, which can be dramatically eased by wireless chargers. Several different technologies have been proposed in literature for both stationary and dynamic charging. [4][5][6] For high-power transfer, among near-field WPT technologies, inductive power transfer (IPT) is largely employed. One of its major limits is the misalignment between the transmitter and receiver apparatuses, which dramatically affects the efficiency and the transferred power. In order to improve the tolerance to the misalignment, arrays of magnetically coupled resonating L-C circuits (also referred as relay coils) can be used, which represent a very cheap solution since only few passive electronic components are required. [7][8][9][10][11] In these systems, the power travels from the source to the load through the relay coils at the expense of an increased sensitivity to the mismatch between the input and output side impedances, 12,13 which reflects also on the magnetic near-field distribution. 14 Solutions to this problem have been proposed in Sandoval et al, 15,16 making arrays of

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“…It basically consists of magnetically coupled resonant coils arranged to form a one-dimensional array [11] and an external resonant coil coupled to one or more array cells. Resonator arrays are mainly devoted to very-low-power systems, especially for consumer electronics applications, as discussed in [12][13][14][15], but more recently, they have also been considered for high-power applications [16], where the coils and compensation networks deserve specific attention [17,18]. The possibility of using resonator arrays to detect objects was also explored in [19][20][21], where the interaction between metallic objects or tags and the resonator array was exploited.…”

Section: Introductionmentioning

confidence: 99%

Resonator Arrays for Linear Position Sensors

Simonazzi

Sandrolini

Mariscotti

2023

JLPEA

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A contactless position sensor based on an array of magnetically coupled resonators and an external single coil cell is discussed for both stationary and dynamic applications. The simple structure allows the sensor to be adapted to the system in which it is installed and can be used to detect the positions of objects in motion that bear an external resonator coil that does not necessitate a supply. By exploiting the unique behaviour of the array input impedance, it is possible to identify the position of the external resonator by exciting the first array cell with an external voltage source and measuring the resulting input current. The system is robust and suitable for application in harsh environments. The sensitivity of the measured input impedance to the space variation is adjustable with the definition of the array geometry and is analysed. Different configurations of the array and external resonator are considered, and the effects of various termination conditions and the resulting factor of merit after changing the coil resistance are discussed. The proposed procedure is numerically validated for an array of ten identical magnetically coupled resonators with 15 cm side lengths. Simulations carried out for a distance of up to 20 cm show that, with a quality factor lower than 100 and optimal terminations of both the array and external coil, it is possible to detect the position of the latter.

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Comprehensive Modeling of Magnetoinductive Wave Devices for Wireless Power Transfer

Cited by 12 publications

References 14 publications

Efficient Wireless Power Transfer With Capacitively Segmented RF Coils

Efficient Wireless Power Transfer With Capacitively Segmented RF Coils

Two‐port network compact representation of resonator arrays for wireless power transfer with variable receiver position

Resonator Arrays for Linear Position Sensors

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