Automatic Frequency Tuning with Power-Level Tracking System for Wireless Charging of Electric Vehicles

Gao, Yuqing; Zhou, Chenxi; Zhou, Ji; Huang, Xiaoyan; Yu, Dunshan

doi:10.1109/vppc.2016.7791622

Cited by 5 publications

(8 citation statements)

References 6 publications

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“…Strongly coupled regime is very advantageous in wireless power transfer; because, M-independent efficiency means that one can transfer a constant power even if the distance between the loops varies. To realize that, one needs to set up a frequency-tuned system like those that have recently been proposed in several works [18][19][20][21]. However, the distance range over which efficiency is constant is limited to a critically coupling distance (d critical ).…”

Section: Simulation Resultsmentioning

confidence: 99%

A Circuit Model-Based Analysis of Magnetically Coupled Resonant Loops in Wireless Power Transfer Systems

Sis¹

2018

Electrica

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Magnetically coupled resonant loops can be represented by a lumped element circuit model. Each parameter in the lumped element model can be expressed as a function of loop geometry and the separation between the loops; therefore, the geometry can be systematically changed, and the power transfer efficiency of the coupled loops can be predicted. This paper presents a simulation-based efficiency analysis for wireless power transfer systems utilizing magnetically coupled resonant loops. The behavior of power transfer efficiency is studied for various loop geometry parameters, and the simulation results are presented in detail. These results clearly show that there is a trade-off between peak efficiency and critical coupling distance, both of which depend on the loop size, frequency of operation, and source-load impedances. To verify the accuracy model, two identical circular loops are fabricated and measured, and the measurement results agree well with the model.

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Section: Simulation Resultsmentioning

confidence: 99%

A Circuit Model-Based Analysis of Magnetically Coupled Resonant Loops in Wireless Power Transfer Systems

Sis¹

2018

Electrica

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“…This problem may be partially sidestepped in some applications by varying the excitation frequency [4][5][6], but this may not be permissible due to band allocation restrictions. Even I if the excitation frequency can change enough to compensate for detuning of the transmitter, this approach transfers the tuning problem to the receiver, which in reality may be more challenging.…”

Section: Introductionmentioning

confidence: 99%

“…With a high Q factor, the tuning circuitry must remain functional with potentially large voltages (from a few V to kV) and currents (mA to many A) even with relatively modest excitation voltages. A conventional technique for inductive power systems is to use multiple external capacitors, typically with binary weighted values, selected by means of large solid-state switches [4,7], or even electromechanical relays. The number of selectable capacitor elements needed depends on the Q factor, component tolerances, and the impact of environmental effects (which can include detuning due to ferromagnetic elements as well as temperature).…”

Section: Introductionmentioning

confidence: 99%

A Self-Tuning Resonant-Inductive-Link Transmit Driver Using Quadrature Symmetric Delay Trimmable Phase-Switched Fractional Capacitance

Kennedy

Bodnar

Lee

et al. 2018

IEEE J. Solid-State Circuits

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The efficiency of inductively-coupled power transfer systems is increased when high-Q inductor-capacitor circuits are used, maximising the magnetic field strength at the transmitter for a given drive amplitude. Such circuits require precise tuning to compensate for environmental effects and component tolerances which modify the resonant frequency. A single zero-voltageswitched fractional capacitance may be used to accurately tune the circuit to resonance, reducing implementation costs compared to classical tuning techniques. However, integration onto a chip presents challenges which must be addressed, such as operating with large voltage excursions and compensating for high-voltage driver delays.We describe here the operation of a self-tuning LC resonant circuit driver using a symmetrically-switched fractional capacitance. An architecture for a fully integrated system for operation at 75kHz-2.6MHz is presented. Implemented in a 0.18µ µ µ µm 1.8V-50V CMOS/LDMOS technology, the integrated circuit uses high voltage interfaces for capacitance switching and sampling inputs, and includes digital phase trimming to compensate for propagation delays in large driver devices. Correct operation of the self-tuning functionality is verified across the available frequency range, with results presented for static and dynamic tuning responses.

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“…Various system-level solutions have been proposed for compensating the output power reductions due to coupling variations [5][6][7][8][9][10][11][12][13][14][15]. Tunable impedance-matching circuits, or so-called impedance-tuned systems, may be utilized to match the source and load resistances to varying input and output impedances seen toward the transmit and receive coils, respectively [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Impedance-tuned systems utilize tunable lumped components and a control unit. Frequency-tuned systems are also proposed by researchers to deliver a constant power to the load against varying coupling between the coils [11][12][13][14][15]. One can maintain an almost-constant output power at strongly coupled regime if the radio frequency (RF) source frequency is tuned to either one of the two resonance frequencies, which are known as even-and odd-mode frequencies (f even and f odd ).…”

Section: Introductionmentioning

confidence: 99%

A Cross-Shape Coil Structure for Use in Wireless Power Applications

Sis

Orta

2018

Energies

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This paper presents a novel coil structure employing two parallel-connected subunit rectangular coils. The structure is based on the fact that the rectangular coils are less sensitive to misalignment along its longer side. Therefore, two identical subunit rectangular coils are vertically-oriented to one another and connected in parallel to form a cross-shape coil. The cross-shape coils have the advantage of better misalignment tolerance as compared to circular and square coils with similar footprints at the cost of an increased wire usage. Electromagnetic simulations and experiments on various small-sized coils are performed to verify the advantages of the proposed coil structure. Based on the simulation and measurement results, cross-shape coils exhibit not only better tolerance to misalignment, but also smaller self-inductance values resulting in larger coupling coefficients as compared to square and circular coils. A large cross-shape coil pair consisting of 100 × 70 cm subunit rectangles are fabricated with copper tubes and utilized in a frequency-tuned wireless power transfer system. When coils are separated by 17 cm, a near constant efficiency of more than 89% up to 15 cm misalignment along xor y-directions and 13 cm along diagonal direction is obtained in the frequency-tuned system.

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Automatic Frequency Tuning with Power-Level Tracking System for Wireless Charging of Electric Vehicles

Cited by 5 publications

References 6 publications

A Circuit Model-Based Analysis of Magnetically Coupled Resonant Loops in Wireless Power Transfer Systems

A Circuit Model-Based Analysis of Magnetically Coupled Resonant Loops in Wireless Power Transfer Systems

A Self-Tuning Resonant-Inductive-Link Transmit Driver Using Quadrature Symmetric Delay Trimmable Phase-Switched Fractional Capacitance

A Cross-Shape Coil Structure for Use in Wireless Power Applications

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