Exact Analysis of Frequency Splitting Phenomena of Contactless Power Transfer Systems

Niu, Wangqiang; Chu, Jianxin; Gu, Wenjin; Shen, Aidi

doi:10.1109/tcsi.2012.2221172

Cited by 195 publications

(117 citation statements)

References 21 publications

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“…Frequency tracking is another solution to effectively transfer EM power in strong coupling region. WPT/MRC system implementing this method transfers EM power not at the fixed resonant frequency but at a varying optimal frequency and hence a series of complex control circuits are required in the WPT/MRC system, such as differential amplifier, phase compensator, phase-locked loop, and so on [11,19,27,28], which occupy specialized space and introduce additional power consumption. Reference [29] uses tunable impedance matching network to extend the range of the available transfer distance in both weak and strong coupling regions, but the network also needs control circuit to switch corresponding impedance matching channel according to the transfer distance.…”

Section: A Methods Of Using Nonidentical Resonant Coils For Frequency mentioning

confidence: 99%

A Method of Using Nonidentical Resonant Coils for Frequency Splitting Elimination in Wireless Power Transfer

Lyu

Meng

Yang

et al. 2015

IEEE Trans. Power Electron.

109

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In this paper, an efficient method is proposed to eliminate frequency splitting in nonradiative wireless power transfer via magnetic resonance coupling (WPT/MRC). In this method, two nonidentical resonant coils (NIRCs) are used as wireless power transmitter and receiver, respectively. According to the elliptic integral term in the analytical expression, the pole of the mutual inductance function with respect to transfer distance can be eliminated by using the two NIRCs, and hence over-coupling between transmitter and receiver with close transfer distance is avoided. Therefore, frequency splitting caused by over-coupling can be suppressed and stable output power can be achieved. The NIRCs are analytically calculated, numerically simulated and finally, fabricated and tested to verify the theory. All the calculated and experimental results show that frequency splitting is completely eliminated and uniform voltage across the load is achieved. Furthermore, lateral misalignment between the NIRCs barely introduces frequency splitting, and the suppression level of frequency splitting can also be controlled freely.  Index Terms-Frequency splitting, magnetic resonance coupling, nonidentical resonant coils, wireless power transfer (WPT)

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Section: A Methods Of Using Nonidentical Resonant Coils For Frequency mentioning

confidence: 99%

A Method of Using Nonidentical Resonant Coils for Frequency Splitting Elimination in Wireless Power Transfer

Lyu

Meng

Yang

et al. 2015

IEEE Trans. Power Electron.

109

View full text Add to dashboard Cite

show abstract

“…(a) For the feedback variable i 1 , the inverter flips when i 1 crosses zero, so the self-oscillating points are in coincidence with the middle resonant point or the splitting points, as shown in Figure 4a. Unfortunately, the middle resonant point with the frequency f res is unstable, and both of the odd and even splitting points [26] with the splitting frequencies f odd and f even are stable. Studies in [18][19][20] indicate that, in the close coupling 2-coil WPT systems, though the power at f res is smaller than the Energies 2016, 9, 491 6 of 16 one at f odd or f even , the efficiency is higher at f res .…”

Section: Analysis Of the Self-oscillating Feedback Methodsmentioning

confidence: 99%

Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer

Ren

Wen-an

2016

Energies

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Abstract:The synchronous tuning of the self-oscillating wireless power transfer (WPT) in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX) rather than the transmitter (TX) current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT system which use the TX current as the feedback variable.

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“…However, for coil-to-coil distances less than the critical coupling distance, twin output power peaks will occur on either side of the resonant frequency even if the primary and secondary circuits are perfectly tuned to the same frequency. This is the frequency splitting phenomenon and is explained in [20].…”

Section: Implementation Of the Soft-switching Techniques By Tuning Thmentioning

confidence: 98%

“…To simplify the calculation, R 1 and R 2 are assumed to be zero, then Equations (16) and (17) can be transformed into Equations (19) and (20).…”

Section: Implementation Of the Soft-switching Techniques By Tuning Thmentioning

confidence: 99%

Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems

Liu

Wang

et al. 2017

Energies

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Abstract:Increasing the resonant frequency of a wireless power transfer (WPT) system effectively improves the power transfer efficiency between the transmit and the receive coils but significantly limits the power transfer capacity with the same coils. Therefore, this paper proposes a coil design method for a series-series (SS) compensated WPT system which can power up the same load with the same DC input voltage & current but with increased resonant frequency. For WPT systems with higher resonant frequencies, a new method of realizing soft-switching by tuning driving frequency is proposed which does not need to change any hardware in the WPT system and can effectively reduce switching losses generated in the inverter. Eighty-five kHz, 200 kHz and 500 kHz WPT systems are built up to validate the proposed methods. Experimental results show that all these three WPT systems can deliver around 3.3 kW power to the same load (15 Ω) with 200 V input voltage and 20 A input current as expected and achieve more than 85% coil-system efficiency and 79% system overall efficiency. With the soft-switching technique, inverter efficiency can be improved from 81.91% to 98.60% in the 500 kHz WPT system.

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Exact Analysis of Frequency Splitting Phenomena of Contactless Power Transfer Systems

Cited by 195 publications

References 21 publications

A Method of Using Nonidentical Resonant Coils for Frequency Splitting Elimination in Wireless Power Transfer

A Method of Using Nonidentical Resonant Coils for Frequency Splitting Elimination in Wireless Power Transfer

Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer

Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems

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