Multi-load wireless power transfer system based on high-order Anti-PT symmetry

Abstract

To provide a multi-load wireless power transfer system based on high-order Anti-PT symmetry and conveniently construct an effective Anti-PT non-Hermitian system by introducing a "W-shaped" anti-resonance mode into a basic WPT platform.SOLUTION: The "energy level attraction" of the anti-resonance mode is combined with the "energy level splitting" of the anti-resonance mode and the resonance mode, to study the "energy level pinning" effect of high-order Anti-PT symmetry. Considering the miniaturization and integration of devices, a "meta coil" is designed by using a "synthetic dimension", and used to construct a high-order Anti-PT symmetric system, thereby achieving multi-load efficient WPT. The new WPT technology based on the "energy level pinning" effect of high-order Anti-PT symmetry provides a good application research platform for enriching non-Hermitian physics.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the technical field of wireless power transmission, and in particular to a multi-load wireless power transmission system that achieves high efficiency and stability based on the "energy level pinning" effect of anti-resonant states in a high-order anti-parity-time (Anti-PT) symmetric system. [Background technology]

[0002] Wireless Power Transfer (WPT) is a technology that uses electromagnetic waves to transmit power directly from a power source to a load. It has opened up a new approach for people to use electricity, and has important application value in any scenario that requires high-degree of freedom in power supply, such as the home appliance industry, industrial automated workshops, and artificial intelligence platforms. However, traditional WPT is largely limited by the transmission distance. Researchers have discovered that magnetic resonance WPT can realize high-efficiency energy transmission over medium distances by using the near-field coupling effect between two resonant coils (where the coupling strength decreases exponentially with the increase in coil distance), thereby promoting the widespread development of non-radiative magnetic resonance WPT. Nevertheless, magnetic resonance WPT has the most prominent drawback that it is difficult to simultaneously achieve high efficiency and high stability of energy transmission. In the case of strong coupling (small spacing between resonant coils), high transmission efficiency can be ensured, but the operating frequency is split by the near-field coupling. Therefore, when the spacing between the sending end resonant coil and the receiving end resonant coil changes, the optimal operating frequency of the system will shift, and the stability of the device will be further reduced. On the other hand, in the case of weak coupling (large spacing between resonant coils), the stability of the operating frequency can be ensured, but the transmission efficiency is significantly reduced. Therefore, how to achieve stable energy transmission while maintaining high transmission efficiency of the system is currently an irreconcilable contradiction in medium- to long-distance WPT. To solve this problem, researchers have proposed to use a frequency tracking circuit to constantly change the operating frequency of the system, obtain the most efficient frequency through scanning, and then switch to the optimal operating frequency to ensure high-efficiency WPT. This solution can achieve high transmission efficiency, but the frequency scanning and tracking circuit of the system not only increases the structural complexity of the equipment, but also places higher requirements on the performance of circuit elements, so that the complex circuit matching network still has limitations in many application scenarios.

[0003] In recent years, the remarkable progress of non-Hermitian physics has provided new support in principle for modern WPT innovation. Researchers have applied the parity-time (PT) symmetry in non-Hermitian physics to WPT systems to realize robust WPT that adaptively tracks the optimal operating frequency of the system through nonlinear circuits. Although the solution is limited by the core element of the operational amplifier, making it difficult for the system's maximum power to reach 10W or more, it provides suggestions for exploring new research perspectives from new physical principles and further promotes the emergence of new technologies and new devices. At present, WPT technology based on frequency tracking circuits and nonlinear effects has gradually solved the problem of locking the optimal operating frequency of WPT, but the stability performance of the entire system is still low due to the high sensitivity to the complex circuits and nonlinear elements inside the device. In addition, how to realize stable and highly efficient WPT with long distances, high power transmission / receiving end area ratio, and multiple loads is still an important scientific challenge that is waiting to be solved as soon as possible. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the above scientific challenges, this invention proposes a "W-shaped" anti-resonance structure for the first time. By introducing the anti-resonance mode into the basic WPT platform, an effective non-Hermitian system of anti-parity-time (Anti-PT) can be easily constructed. The "energy level attraction" of the anti-resonance mode is combined with the "energy level splitting" of the anti-resonance mode and the resonance mode to investigate the "energy level pinning" effect due to the higher-order Anti-PT symmetry. [Means for solving the problem]

[0005] The technical solutions adopted in the present invention are as follows:

[0006] A multi-load wireless power transmission system based on high-order Anti-PT symmetry, comprising: constructing a third-order Anti-PT symmetry WPT system by combining a W-type anti-resonance structure and a Lorentz resonance structure; and for the W-type anti-resonance structure, + =ω0+Δ and ω - =ω0-Δ is iγ, where Δ represents the detuning amount, and the coupling coefficient between the resonant mode ω0 in the W-type antiresonant structure and the resonant structure is κ.

[0007] The equation of motion for the system is:

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[0011] Furthermore, without loss of generality, we first assume that γ=1, in which case, for different coupling strengths κ, the locations where system modes merge correspond to exclusion points for the non-Hermitian system.

[0012] Furthermore, based on equation (1), the transmission efficiency of a WPT system with third-order Anti-PT symmetry using a W-type anti-resonance structure and a Lorentz resonance structure is expressed by the following equation:

[0013]

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[0014] In the formula, S 2+ represents the signal output from the resonant structure, TIFF0007630855000007.tif19150 represents the signal input from the anti-resonance structure. A0 represents the amplitude of the resonance structure, and A + and A - represents the amplitude of the detuned mode of the antiresonant structure, and at a fixed operating frequency ω = ω0, the transmission efficiency of the system is always η = 4γ / 4γ = 1.

[0015] Furthermore, the method further includes the steps of designing an anti-resonant transmitting coil ATC using a planar superstructure coil, and then matching it with the receiving coil RC to construct a compact third-order Anti-PT symmetric WPT system.

[0016] Furthermore, the radii of the ATC and RC are denoted by R and r, respectively. When R is fixed at 15 cm, the near-field coupling coefficient between the ATC and RC decreases exponentially with the increase in the area ratio of the power transmitting / receiving terminals, κ0 = 159.55e -0.72R / r It becomes.

[0017] Furthermore, when the bypass capacitor is used as the equivalent circuit diagram of the ATC with the composite dimension and the AC power supply voltage is U=-I1Z, the Kirchhoff equation of the ATC can be expressed as follows:

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[0020] Furthermore, the method further includes the step of proposing a synthesized third-order Anti-PT symmetric WPT system and assuming that L3=L, C3=C, and R=Z, in which the Kirchhoff equation of the system is expressed as follows:

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[0025] The beneficial effects of the technical solution described in the present invention are as follows:

[0026] Compared with traditional resonant WPT, anti-resonant WPT has higher safety (i.e. lower standby power loss), stability, transmission efficiency and flexibility. Considering the miniaturization and integration of devices, the present invention adopts "synthetic dimension" to design a "super-structure coil" and uses it to construct a high-order Anti-PT symmetry system, further realizing high-efficiency WPT with multiple loads. The proposed novel WPT technology based on the "energy level pinning" effect of high-order Anti-PT symmetry not only provides a good application research platform for the enrichment of non-Hermitian physics, but also opens up new approaches for near-field applications such as resonant imaging, wireless sensing, photon routing, etc., which break through the traditional resonant mechanism. [Brief description of the drawings]

[0027] Other characteristics, objects and advantages of the present application will become more apparent on reading the detailed description of the non-limiting examples which follow, with reference to the drawings in which: [Figure 1] A valid third-order Anti-PT symmetric non-Hermitian system is shown, in which (a) is the energy transfer model of the coupling between the "W-type" anti-resonance structure and the Lorentz resonance structure, (b) is the real (solid line) and imaginary (dashed line) parts of the eigenfrequencies of the system at different coupling strengths κ, and (c) is the equivalent three-energy level model of the valid third-order Anti-PT symmetric non-Hermitian system. [Diagram 2] The equivalent circuit model of an effective third-order Anti-PT symmetric non-Hermitian system is shown in Fig. 1. In the figure, (a) is a circuit model of an individual ATC, and (b) is a circuit model of an ATC and an RC combined. [Diagram 3] This shows the change in the coupling strength between the ATC and RC in accordance with the transmitting / receiving end area ratio in a third-order Anti-PT symmetric WPT system constructed with a "superstructure coil". [Figure 4] The real (a) and imaginary (b) parts of the system's natural frequency are shown for different transmitting / receiving end area ratios R / r, where the solid and dashed lines represent WPT systems corresponding to ATC and RTC, respectively. [Diagram 5]A comparison of the transmission efficiency of WPT systems compatible with ATC and RTC is shown. [Figure 6] This shows the use of a WPT system incorporating ATC for multi-load energy transmission, in which (a) and (b) are the transmission efficiency of the system when load A is moved, (c) and (d) are a comparison of the transmission efficiency with two identical loads, and (e), (f), and (g) are a comparison of the transmission efficiency with two different loads. [Figure 7] A comparison of standby power loss in WPT systems compatible with ATC and RTC is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The present application will be described in more detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are merely for the purpose of interpreting the relevant invention, and do not limit the invention. It should also be noted that, for the sake of convenience, only parts related to the invention are shown in the drawings.

[0029] It should be noted that, unless contradictory, the embodiments and features in the embodiments in the present application can be combined with each other. The present application will be described in detail below by examples with reference to the drawings.

[0030] 1. Explanation of the solution principle This invention proposes to construct a third-order Anti-PT symmetric WPT system by combining a “W-type” anti-resonance structure with a Lorentz resonance structure, and the corresponding physical model is shown in Figure 1(a). For the “W-type” anti-resonance structure, there are two detuned modes ω + =ω0+Δ and ω - The coupling coefficient between =ω0-Δ is iγ, where Δ represents the detuning amount. The coupling coefficient between the resonant mode ω0 in the "W-type" anti-resonant structure and the resonant structure is κ. The equation of motion for the system shown in FIG. 1(a) can be expressed as follows:

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[0034] Based on equation (1), the transmission efficiency of the WPT system with third-order Anti-PT symmetry based on the “W-type” anti-resonance structure and the Lorentz resonance structure can be expressed as follows:

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[0036] II. Experimental steps and results In the experiment, the present invention proposes to design an anti-resonance transmitter coil (ATC) using a planar "super-structure coil", and then match it with a receiver coil (RC) to build a compact WPT system with third-order anti-PT symmetry, as shown in Figure 3. The radii of the ATC and RC are denoted by R and r, respectively. When R=15cm is fixed, Figure 3 shows that the near-field coupling coefficient of the ATC and RC decreases exponentially with the increase of the transmitting / receiving end area ratio, κ0=159.55e -0.72R / r The lumped constant circuit element part of the "super-structure coil" is shown in Figure 3, where the power signal is input to the system from the "+" and "-" on the left side of the circuit board. L2 attached to the circuit board represents the distributed inductor provided by the Litz wire, and L1 and C i (i=0,1,2) represent lumped constant inductors and capacitors, respectively.

[0037] As shown in Figure 3, the bypass capacitor is used as the equivalent circuit diagram of the "synthetic dimension" ATC. When the AC power supply voltage is U=-I1Z, the Kirchhoff equation of the ATC can be expressed as follows:

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[0040] Considering the coupling structure of ATC and RC shown in Figure 3, the present invention proposes a WPT system with a synthesized third-order Anti-PT symmetry. To simplify the system, we assume that L3 = L, C3 = C, and R = Z. In this case, the Kirchhoff equation of the system can be expressed as follows:

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[0045] As can be seen from equation (4), the third-order Anti-PT symmetric non-Hermitian system can realize energy transmission independent of coupling strength, i.e., it can realize high-efficiency WPT at different transmitting / receiving end area ratios. When choosing L=98μH, C=5.1nF, and Z=50Ω, the real and imaginary parts of the eigenvalues ​​of the system obtained with the change of RC radius are shown in Fig. 4, respectively. As can be seen, the eigenfrequency ω0=226 in real terms alone does not depend on the radius of RC, which provides an effective approach for high-efficiency WPT at different transmitting / receiving end area ratios. In particular, when the radius ratio of ATC and RC satisfies R / r=2.41, the eigenvalues ​​merge at the EP1 position. For convenience of comparison, a resonant transmitter coil (RTC) is used instead of the ATC, as shown by the dashed line in Fig. 4, to provide the phase diagram of the conventional resonant WPT with the same parameters. As can be seen from the figure, for conventional resonant WPT, when the radius ratio of RTC and RC meets R / r=1.7, the eigenvalues ​​merge at the EP1 position. When the radius ratio exceeds this critical value, the system's eigenfrequency is no longer real, and the transmission efficiency is significantly reduced. Also, as can be seen from Figure 4, the EP of the effective third-order Anti-PT symmetrical WPT system appears under the condition of a larger radius ratio than that of conventional resonant WPT.

[0046] Compared with the conventional resonant WPT system, the transmission efficiency of the synthesized anti-resonant system is shown in Figure 5. The calculation and measurement results of the RTC (ATC) WPT system are represented by solid lines (dashed lines) and five-pointed stars (circles), respectively. As can be seen from the figure, for the resonant WPT system, considering different radius ratio conditions, it is necessary to track the optimal operating frequency. However, when the anti-resonant Anti-PT symmetric WPT system is introduced, its operating frequency is always fixed at ω0 = 226 kHz. Meanwhile, the transmission efficiency of the Anti-PT symmetric WPT is relatively stable, but in the resonant WPT system, when the radius ratio R / r is larger than 2.4, the transmission efficiency drops sharply. As can be seen by comparing with the transmission efficiency in Figure 5, such an Anti-PT symmetric WPT system with a real natural frequency that is not related to the radius ratio is a high-efficiency WPT solution with a high transmitting / receiving end area ratio without frequency tracking.

[0047] The present invention proposes various multi-load WPTs by utilizing the high-efficiency WPT with high transmitting / receiving end area ratio realized by the Anti-PT symmetric WPT system. First, for the planar coil structure with a helix structure, the magnetic field distribution inside is uniform. Figure 6(a) shows the coupling strength between the transmitting coil and the receiving coil measured by moving the load A at different distances in the z direction. According to the results, when the RC is moved, the coupling strength between the transmitting coil and the RC is almost constant at all times, so the transmission efficiency becomes independent of the position of the RC. The dashed line and the circle in Figure 6(b) respectively represent the theoretically calculated and experimentally measured values ​​of the transmission efficiency when the RC is moved from 0 cm to 8 cm along the z direction in the third-order Anti-PT symmetric WPT system when the corresponding radius ratio is R / r=6 (coupling strength is κ0=5.1kHz). As a control group, the theoretical and experimentally calculated values ​​of the transmission efficiency of the resonant WPT system with the same parameters are represented by a solid line and a five-pointed star. When comparing a third-order Anti-PT symmetric WPT system incorporating an ATC with a resonant WPT system incorporating an RTC, it was found that the third-order Anti-PT symmetric WPT system can achieve a significant improvement in transmission efficiency at a high transmitting / receiving end area ratio.

[0048] Next, considering a situation involving n identical loads A (coupling between the loads may be neglected), the Kirchhoff equation for the system can be written as:

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[0052] Finally, we also considered the problem of selective allocation of transmission efficiency under the multi-load condition of a WPT system with ATC. A ≠Z B), the transmission efficiency ratio of the two loads can be expressed by the following formula:

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[0054] Focusing on safety and energy saving, it is very meaningful to maintain the low energy output of the system when the system is in an idle state. In the conventional WPT solution, the idle power loss is always a difficult problem to solve. However, in the Anti-PT symmetric system built in anti-resonance mode, such limitations can be effectively overcome. Compared with the conventional resonant WPT system, the standby power loss of the Anti-PT symmetric WPT system is as shown in FIG. 7. The calculation results and measurement results of the WPT system corresponding to ATC and RTC are represented by solid lines and symbols, respectively. As can be seen from the figure, the idle power loss of the Anti-PT symmetric WPT system near the operating frequency is obviously smaller than that of the conventional resonant WPT, which is useful for intermittent wireless charging and has higher safety in practical use. The advantages of the multi-load wireless power transmission system based on the high-order Anti-PT symmetry proposed in the present invention are as follows:

[0055] 1. The high-order Anti-PT symmetric WPT system constructed in the “W” type anti-resonance mode has real eigenvalues ​​and has high transmission efficiency.

[0056] 2. By combining the "energy level attraction" of the antiresonance mode with the "energy level splitting" of the antiresonance mode and the resonance mode, the "energy level pinning" effect due to higher-order Anti-PT symmetry was investigated, which ensured the locking of the frequency of energy transmission and high stability.

[0057] 3. The "superstructure coil" with anti-resonance mode has a simple structure and the coil size is equivalent to that of a conventional resonant coil.

[0058] 4. The transmission efficiency of the high-order Anti-PT symmetric WPT system is highly robust against near-field coupling strength, and can achieve a high transmitting / receiving end area ratio and highly efficient energy transmission for multiple loads.

[0059] The above is merely a description of the preferred embodiment and the technical principles utilized in this application. Those skilled in the art should understand that the scope of the invention of this application is not limited to the technical solution of the specific combination of the above technical features, and also includes other technical solutions constituted by any combination of the above technical features or their equivalent features without departing from the spirit of the invention, such as, for example, replacing the above features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. A multi-load wireless power transmission system based on high-order Anti-PT symmetry, comprising: constructing a third-order Anti-PT symmetric WPT system by coupling a W-type anti-resonance structure with a Lorentz resonance structure; and for the W-type anti-resonance structure, two detuned modes ω ＋ =ω ０ +Δ and ω － =ω ０ The coupling coefficient between −Δ is iγ, where Δ represents the detuning amount, and the resonant modes ω in the W-type antiresonant structure and the resonant structure ０ The coupling coefficient between is κ, The equation of motion for the system is: [0010] In the formula, γ ｊ and Γ ｊ (j=+,-,0) are resonant modes a ｊ = A ｊ e －ｉωｔ represents the radiation loss and the intrinsic loss, and κ ± represents the near-field coupling strength between the antiresonance and resonance structures, 【number】 represents the electromagnetic wave input to the antiresonant structure from the outside, and γ ＋ = γ － = γ ０ / 2=γ, κ ＋ = κ － Considering = κ, the system specific loss Γj ＋ =Γ － =Γ ０ = 0 is ignored, non-reflective condition 【number】 Taking this into consideration, the dynamics equation of the system can be expressed as follows: [0025] In this case, the effective Hamiltonian of the system is expressed as follows: [0030] In the formula, ω ０ represents the center frequency of the resonant and antiresonant systems, Δ represents the frequency detuning of the antiresonant structure, κ represents the coupling strength between the antiresonant and resonant structures, and γ represents the radiation loss of the two detuning modes in the antiresonant structure. From equation (3), it is found that the non-Hermitian system satisfies the third-order Anti-PT symmetry condition (PT)H(PT) －１ = pH ＊ It is confirmed that P = -H is satisfied, and the center of symmetry of the system is ω ０ The system according to claim 1,

2. Without loss of generality, we first assume that γ = 1, in which case, at different coupling strengths κ, the locations where system modes merge correspond to the exclusion points of the non-Hermitian system.

3. Based on equation (1), the transmission efficiency of a WPT system with third-order anti-PT symmetry using a W-type anti-resonance structure and a Lorentz resonance structure is expressed by the following equation: [0045] In the formula, S ２＋ represents the signal output from the resonant structure, 【number】 represents the signal input from the antiresonance structure, and A ０ represents the amplitude of the resonance structure, A ＋ and A － represents the amplitude of the detuned mode of the antiresonant structure, and for a fixed operating frequency ω = ω ０ The multi-load wireless power transmission system based on high-order Anti-PT symmetry as claimed in claim 1, wherein the transmission efficiency of the system is always η=4γ / 4γ=1.

4. The multi-load wireless power transmission system based on high-order Anti-PT symmetry as claimed in claim 1, further comprising the step of designing an anti-resonant transmitting coil ATC using a planar superstructure coil, and then matching it with a receiving coil RC to construct a WPT system with third-order Anti-PT symmetry.

5. The radii of the ATC and RC are denoted by R and r, respectively. When R is fixed at 15 cm, the near-field coupling coefficient between the ATC and RC decreases exponentially with the increase in the area ratio of the power transmitting / receiving ends, κ ０ = 159.55e －０．７２Ｒ／ｒ The multi-load wireless power transmission system based on the high-order Anti-PT symmetry according to claim 4,

6. By using the bypass capacitor as the equivalent circuit diagram of the composite dimension ATC, the AC power supply voltage is U = -I １ In the case of Z, the Kirchhoff equation for ATC can be expressed as follows: [0050] In the formula I １ and I ２ respectively represent the currents along different directions, L 1 represents the inductance of the inductor of the lumped constant circuit, L 2 represents the inductance of the distributed inductor provided by the Litz wire, C i (i=0, 1, 2) represents the capacitance of the capacitor of the lumped constant circuit, respectively, -Z represents the source impedance, and due to the symmetry of the ATC structure, L １ = L ２ = L and C ２ = C １ and 1 / C=1 / C １ +1 / C ０ 、 【number】 Assuming that, a suitable approximation 【number】 The amplitude of the ATC structural mode is a ｎ = (-iL ｎ / ω)dI ｎ / dt (n=1, 2), and then equation (5) is rewritten as [006] The equivalent gain and effective coupling of the ATC structure are γ ０ =-Z / 2L and κ=1 / 2ωC ０ The multi-load wireless power transmission system based on the high-order Anti-PT symmetry according to claim 5, characterized in that L is obtained as

7. We propose a synthetic third-order Anti-PT symmetric WPT system and ３ = L, C ３ = C, R = Z, where the Kirchhoff equation for the system is: [0070] Here, M = ξL represents the combined mutual inductance of the ATC and TC, and ξ = -C / C ０ represents the coupling factor of different loads, and similarly to equation (6), the following kinetic equation of the coupled system of ATC and RC is obtained: [0080] Unitary transformation 【number】 Using a ３ = a ０ Then, the equation of motion can be expressed as follows: [0090] Δ=1 / 2ωC ０ L and γ ０ = -Z / 2L, the dynamic equation obtained from the Kirchhoff equation is expressed as follows: [0010] γ = γ ０ Define κ = -Δ / 2 and κ = -Δ / 2, and the effective Hamiltonian of the system is expressed by equation (3), and the system satisfies the Anti-PT symmetry condition (PT) H(PT) －１ = pH ＊ The multi-load wireless power transmission system based on high-order Anti-PT symmetry as claimed in claim 6, wherein P=-H is satisfied.

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