A low-profile dynamic multi-load constant-voltage output wireless power transmission system

Abstract

This invention discloses a low-profile dynamic multi-load constant voltage output wireless power transmission system, belonging to the field of power transmission technology. It includes a transmitter, multiple coplanar repeater coils, multiple receivers, and a tuning capacitor. The transmitter is driven by a half-bridge or full-bridge inverter circuit with a working frequency of 100kHz, used to output high-frequency inverter voltage. The half-bridge inverter circuit outputs a square wave voltage with an amplitude of [missing value]. By setting double-layer PC40 manganese-zinc ferrite boards on the upper and lower sides of the connection between adjacent coplanar repeater coils, the main coupling coefficient between adjacent coils is increased from 0.09 without ferrite to ≥0.2, and the system transmission efficiency is increased to ≥85%. Simultaneously, the transmitter, repeater coils, and receivers all adopt a planar coil structure with an overall height ≤20mm, allowing for embedding in thin carriers such as desktops, floors, and electric vehicle charging stations. This perfectly adapts to scenarios requiring a low profile, such as smart homes, offices, and electric vehicle charging, resolving the contradiction between low coupling efficiency and large profile size in traditional systems.

Description

Technical Field

[0001] This invention relates to the field of power transmission, specifically to a low-profile dynamic multi-load constant voltage output wireless power transmission system. Background Technology

[0002] Wireless power transfer (WPT) technology, as an emerging technology that enables energy transfer without physical contact, has shown broad application prospects in recent years in fields such as smart homes (e.g., wireless charging for desktops and wireless power supply for home appliances), electric vehicle charging stations (e.g., simultaneous charging of multiple parking spaces), implantable medical devices (e.g., wireless power supply for in-body sensors), and portable electronic devices (e.g., mass charging of mobile phones and tablets). Among these, the coplanar WPT system, due to its planar coil design, can be arranged along surfaces such as floors, ceilings, and desktops, effectively solving the drawbacks of traditional coaxial WPT systems, such as space occupation and poor aesthetics. It has become the preferred solution for multi-load scenarios—for example, in an office desktop scenario, the coplanar system can be embedded under the desktop to simultaneously power multiple devices such as laptops, mobile phones, and wireless headphones; in electric vehicle charging stations, coils can be arranged along the ground of the parking spaces to achieve simultaneous wireless charging of multiple vehicles.

[0003] However, existing coplanar WPT systems still have significant shortcomings in multi-load constant voltage output scenarios, making it difficult to meet practical application requirements:

[0004] 1. Poor adaptability to multiple loads and limited output modes: Most systems can only achieve constant voltage or constant current output on a single branch, and cannot provide independent constant voltage power supply for multiple loads with different needs at the same time. For example, patent CN111478458A relies on a DSP processor and compensation network to achieve constant current / constant voltage switching, but only supports single branch output. Although the literature "A Wireless Power Transfer System with Multiple Constant Current and Constant Voltage Outputs" can achieve multi-load output, it requires a complex coil design of "odd units in series and even units in parallel" to distinguish constant current / constant voltage modes, and cannot achieve constant voltage output for multiple loads individually, making it difficult to adapt to the needs of "multiple devices needing constant voltage charging" in smart home and office scenarios.

[0005] 2. Low coil coupling efficiency and large system profile: Traditional coplanar systems have weak magnetic coupling between adjacent coils (the main coupling coefficient is usually ≤0.1), resulting in low transmission efficiency (<70%). Some solutions improve coupling by increasing the number of coil turns, but this increases the system thickness (>30mm), destroying the "low profile" advantage and making it impossible to embed in thin carriers such as desktops and floors, thus limiting its application in smart home and portable device scenarios.

[0006] 3. Poor load dynamics and weak expansion capability: The position of the receiving coil (RX) of the existing system is fixed and cannot be dynamically connected / removed. If a load is removed, it is easy to cause voltage fluctuations (>15%) in the remaining loads, or even cause system resonance imbalance. Moreover, when expanding a new load, the overall coil layout and compensation circuit need to be redesigned, and "segment-by-segment expansion" cannot be achieved. For example, when adding a parking space in an electric vehicle charging station, the original coil structure needs to be disassembled, resulting in high maintenance costs.

[0007] 4. Complex compensation circuit and low reliability: In order to achieve constant voltage output, most solutions rely on complex closed-loop regulation circuits (such as patent CN110429691A, which requires switching the conduction mode of the high-frequency inverter module switching transistor), which not only increases hardware costs, but is also susceptible to electromagnetic interference, leading to regulation failure. This poses safety hazards in industrial, medical and other scenarios with high reliability requirements. Summary of the Invention

[0008] The purpose of this invention is to provide a low-profile dynamic multi-load constant voltage output wireless power transmission system to solve the problems of existing power transmission methods mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: including a transmitter, multiple coplanar repeater coils, multiple receivers, and a tuning capacitor;

[0010] The transmitter is driven by a half-bridge or full-bridge inverter circuit, operating at a frequency of 100kHz, and is used to output high-frequency inverter voltage. The half-bridge inverter circuit outputs a square wave voltage with an amplitude of [missing value]. The full-bridge inverter circuit outputs a square wave voltage with an amplitude of 2. ;

[0011] The coplanar repeater coil includes at least one auxiliary repeater coil and at least one passive repeater coil. Double-layer PC40 manganese-zinc ferrite plates are installed on both the upper and lower sides of the connection point between adjacent coplanar repeater coils. The main coupling coefficient between adjacent coils is... ≥0.2, the cross-coupling coefficient between non-adjacent coils is negligible compared to the main coupling coefficient;

[0012] The receiving end (RX) can be dynamically placed in the voltage regulation area above the coplanar repeater coil to provide power to the load, and the output voltage across the receiving end (RX) satisfies the formula: , ( The system's operating angular frequency, For mutual inductance between APR and RX, For APR coil current, For tuning capacitors, (where the load resistance is the Nth RX), the voltage is related to Other The load resistance value is irrelevant;

[0013] The tuning capacitor, together with the transmitting coil, the coplanar repeater coil, and the receiving coil, constitutes an LCR series resonant circuit, and each resonant circuit satisfies the resonance condition. The system's operating angular frequency, For coil inductance, (for the tuning capacitor), so that each resonant circuit resonates at 100kHz;

[0014] As a further preferred embodiment of this technical solution: the system consists of N charging segments, where N≥1;

[0015] When N=1, the charging section consists of a transmitter (TX), one auxiliary relay coil (APR), and one receiver (RX), and the circuit matrix equation satisfies:

[0016] ;

[0017] ( The equivalent loss resistance of the coil. For coil and Mutual feeling, For coil current, (This refers to the output voltage of the inverter circuit).

[0018] When N>1, the first charging segment consists of a transmitter (TX), an auxiliary repeater coil (APR), and a receiver (RX). The remaining N-1 charging segments each consist of a pair of passive repeater coils (PRR) and auxiliary repeater coils (APR) and a receiver (RX). When adding a new charging segment, only the "PRR-APR" pair and the corresponding RX need to be added. The circuit matrix equation only expands the corresponding dimension and does not affect the voltage output of the existing charging segment.

[0019] As a further preferred embodiment of this technical solution: the size of the double-layer PC40 manganese-zinc ferrite plate is adapted to the connection area of ​​adjacent coplanar relay coils, which is used to enhance the magnetic coupling between adjacent coils, so that the main coupling coefficient of adjacent coils is increased by at least 2 times compared with that without the ferrite plate; without the ferrite plate, the coupling coefficients of adjacent coils k12=k24=0.09, k13=k34=0.015, k23=0.22, after setting the ferrite plate, k12 and k24 increase to ≥0.2, and the cross coupling coefficients of non-adjacent coils k13, k34, and k14 change ≤0.01, which can still be ignored;

[0020] As a further preferred embodiment of this technical solution: the receiving end (RX) can move within a range of ±20mm above the coplanar relay coil. During the movement, due to mutual inductance... The output voltage fluctuation caused by the change satisfies: To maintain constant voltage output characteristics;

[0021] As a further preferred embodiment of this technical solution: when any one or more receivers (RX) are removed from the system, the voltage of the remaining RX satisfies the formula: Because the dimension of the circuit matrix equation is reduced but the main coupling parameters remain unchanged, voltage fluctuations... And the system transmission efficiency ( For RX output power, (TX input power);

[0022] As a further preferred embodiment of this technical solution: the transmitting end (TX) coil, the coplanar relay coil, and the receiving end (RX) coil all adopt a planar coil structure, with the coils arranged along the surface of the planar carrier, and the overall height of the system ≤20mm;

[0023] And the inductance Li and tuning capacitance Ci of each coil satisfy At resonance, the circuit exhibits pure resistive characteristics with no reactive power loss.

[0024] As a further preferred embodiment of this technical solution: in the LCR series resonant circuit, when the system operating frequency reaches the resonant frequency... At that time, the imaginary part of each element in the circuit matrix equation is 0, that is... At this point, the current in each coil is determined only by the resistance and mutual inductance, further improving the stability of the output voltage;

[0025] As a further preferred embodiment of this technical solution: in the circuit matrix equation, the normalized frequency... The normalized current of the m-th resonator Main coupling coefficient Normalization analysis can verify that each RX voltage is independent of the normalization frequency x and the load resistance.

[0026] As a further preferred embodiment of this technical solution: the load resistance of the receiving end (RX) It can vary within the range of 10Ω-50Ω. When the load changes, because... and The changes cancel each other out, and the output voltage fluctuation satisfies: To maintain a stable constant voltage output;

[0027] As a further preferred embodiment of this technical solution: by adding a "passive repeater coil (PRR) - auxiliary repeater coil (APR)" pair and the corresponding receiver (RX), the system can be expanded to support simultaneous power supply of more than 5 RXs; after expansion, the dimension of the circuit matrix equation increases synchronously, but the voltage equations corresponding to each RX still satisfy the requirements. All RXs independently achieve constant voltage output without interfering with each other.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. In this invention, a segmented design of "transmitter (TX) - repeater coil (APR / PRR) - receiver (RX)" is used, combined with an LCR series resonant circuit (satisfying the resonance condition). ), so that the output voltage of each receiver (RX) satisfies the formula This voltage is independent of its own load resistance (within the range of 10Ω-50Ω) and other RX loads. For example, in an office desktop scenario, it can simultaneously power a laptop (19V constant voltage), a mobile phone (5V constant voltage), and a wireless headset (3.7V constant voltage), and each device can work independently without interfering with each other, thus solving the problem of the single multi-load output mode of the existing system.

[0030] 2. In this invention, by setting double-layer PC40 manganese-zinc ferrite plates on the upper and lower sides of the connection between adjacent coplanar relay coils, the main coupling coefficient of adjacent coils is increased from 0.09 without ferrite to ≥0.2, and the system transmission efficiency is increased to ≥85%. At the same time, the transmitting end, relay coil, and receiving end all adopt planar coil structure with an overall height of ≤20mm. It can be embedded in thin carriers such as desktops, floors, and electric vehicle charging piles, perfectly adapting to scenarios that require "low profile" such as smart homes, offices, and electric vehicle charging, and solving the contradiction between "low coupling efficiency" and "large profile size" in traditional systems.

[0031] 3. In this invention, the receiving end (RX) can move freely within ±20mm above the relay coil, with voltage fluctuation ≤10%. When 1-2 RXs are removed, the voltage fluctuation of the remaining RXs is ≤10%, and the system efficiency remains ≥85%. For example, in a smart home scenario, users can remove a fully charged mobile phone at any time, while the remaining laptops and headphones still maintain a stable constant voltage power supply. In addition, new charging sections can be expanded by adding "PRR-APR" relay pairs, supporting simultaneous power supply to more than 5 loads without redesigning the overall circuit. For example, when adding parking spaces to an electric vehicle charging station, only "PRR-APR" coil groups need to be spliced, significantly reducing expansion costs and solving the problems of poor load dynamics and weak expansion capabilities in existing systems.

[0032] 4. In this invention, constant voltage output is achieved through a pure circuit topology design (segmented coil + LCR resonance), eliminating the need for a DSP processor, closed-loop regulation circuit, or switching transistor mechanism. This reduces the number of electronic components by 60% and lowers the risk of failure due to electromagnetic interference. Simultaneously, the standardized design of the coil structure and ferrite board reduces hardware costs by 30%. Furthermore, maintenance only requires replacing a single "PRR-APR" repeater pair or RX, without disassembling the entire system. This offers significant advantages in high-reliability scenarios such as industrial and medical applications, solving the problems of complex compensation circuits and low reliability in existing systems. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a circuit model of a low-profile dynamic multi-load constant voltage output wireless power transmission system according to the present invention.

[0034] Figure 2 This is a top view of the low-profile dynamic multi-load constant voltage output wireless power transmission system of the present invention.

[0035] Figure 3 The magnetic field distribution of a coplanar four-coil structure in a low-profile dynamic multi-load constant voltage output wireless power transmission system of the present invention, in both cases with and without a double-sided ferrite plate.

[0036] Figure 4 The ADS simulation circuit diagram and model diagram of a three-load system of a low-profile dynamic multi-load constant voltage output wireless power transmission system according to the present invention are shown below.

[0037] Figure 5 The figure shows the ADS voltage simulation results of a low-profile dynamic multi-load constant voltage output wireless power transfer system according to the present invention.

[0038] Figure 6 The ADS simulation circuit diagram and model diagram of a low-profile dynamic multi-load constant voltage output wireless power transmission system for removing one of the loads according to the present invention are shown below.

[0039] Figure 7 The figure shows the ADS voltage simulation results of a low-profile dynamic multi-load constant voltage output wireless power transfer system according to the present invention.

[0040] Figure 8 The ADS simulation circuit diagram and model diagram of a low-profile dynamic multi-load constant voltage output wireless power transfer system with two loads removed are provided for this invention.

[0041] Figure 9 The figure shows the ADS voltage simulation results of a low-profile dynamic multi-load constant voltage output wireless power transfer system according to the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example

[0044] Please see Figures 1-9 As shown, the present invention provides a low-profile dynamic multi-load constant voltage output wireless power transmission system technical solution: including a transmitter, multiple coplanar repeater coils, multiple receivers and tuning capacitors;

[0045] The transmitter is driven by a half-bridge or full-bridge inverter circuit, operating at a frequency of 100kHz, and is used to output high-frequency inverter voltage. The half-bridge inverter circuit outputs a square wave voltage with an amplitude of [missing value]. The full-bridge inverter circuit outputs a square wave voltage with an amplitude of 2. ;

[0046] The coplanar repeater coil includes at least one auxiliary repeater coil and at least one passive repeater coil. Double-layer PC40 manganese-zinc ferrite plates are installed on both the upper and lower sides of the connection point between adjacent coplanar repeater coils. The main coupling coefficient between adjacent coils is... ≥0.2, the cross-coupling coefficient between non-adjacent coils is negligible compared to the main coupling coefficient;

[0047] The receiving end (RX) can be dynamically placed in the voltage regulation area above the coplanar repeater coil to provide power to the load, and the output voltage across the receiving end (RX) satisfies the formula: , ( The system's operating angular frequency, For mutual inductance between APR and RX, For APR coil current, For tuning capacitors, (where the load resistance is the Nth RX), the voltage is related to Other The load resistance value is irrelevant;

[0048] The tuning capacitor, together with the transmitting coil, the coplanar repeater coil, and the receiving coil, constitutes an LCR series resonant circuit, and each resonant circuit satisfies the resonance condition. The system's operating angular frequency, For coil inductance, (For tuning capacitors), so that each resonant circuit resonates at 100kHz.

[0049] In this embodiment, the system consists of N charging segments, where N≥1;

[0050] When N=1, the charging section consists of a transmitter (TX), one auxiliary relay coil (APR), and one receiver (RX), and the circuit matrix equation satisfies:

[0051] ;

[0052] ( The equivalent loss resistance of the coil. For coil and Mutual feeling, For coil current, (This refers to the output voltage of the inverter circuit).

[0053] When N>1, the first charging segment consists of a transmitter (TX), an auxiliary repeater coil (APR), and a receiver (RX). The remaining N-1 charging segments each consist of a pair of passive repeater coils (PRR) and auxiliary repeater coils (APR) and a receiver (RX). When adding a new charging segment, only the "PRR-APR" pair and the corresponding RX need to be added. The circuit matrix equation only expands the corresponding dimension and does not affect the voltage output of the existing charging segment.

[0054] In this embodiment, the size of the double-layer PC40 manganese-zinc ferrite plate is adapted to the connection area of ​​adjacent coplanar relay coils to enhance the magnetic coupling between adjacent coils, thereby increasing the main coupling coefficient of adjacent coils by at least 2 times compared to when there is no ferrite plate. When there is no ferrite plate, the coupling coefficients of adjacent coils are k12=k24=0.09, k13=k34=0.015, and k23=0.22. After setting the ferrite plate, k12 and k24 increase to ≥0.2, and the cross coupling coefficients of non-adjacent coils k13, k34, and k14 change by ≤0.01, which can still be ignored.

[0055] Specifically, the receiving end (RX) can move within a range of ±20mm above the coplanar relay coil. During the movement, due to mutual inductance... The output voltage fluctuation caused by the change satisfies: To maintain constant voltage output characteristics.

[0056] In this embodiment, when any one or more receivers (RX) are removed from the system, the voltage of the remaining RX satisfies the formula: Because the dimension of the circuit matrix equation is reduced but the main coupling parameters remain unchanged, voltage fluctuations... And the system transmission efficiency ( For RX output power, (TX input power).

[0057] Specifically, the transmitting (TX) coil, coplanar repeater coil, and receiving (RX) coil all adopt a planar coil structure, with the coils arranged along the surface of the planar carrier, and the overall system height ≤20mm;

[0058] And the inductance Li and tuning capacitance Ci of each coil satisfy At resonance, the circuit exhibits pure resistive characteristics with no reactive power loss.

[0059] In this embodiment, in the LCR series resonant circuit, when the system operating frequency reaches the resonant frequency... At that time, the imaginary part of each element in the circuit matrix equation is 0, that is... At this point, the current in each coil is determined only by the resistance and mutual inductance, further improving the stability of the output voltage.

[0060] Specifically, in the circuit matrix equation, the normalized frequency The normalized current of the m-th resonator Main coupling coefficient Normalization analysis can verify that each RX voltage is independent of the normalized frequency x and the load resistance.

[0061] In this embodiment, the load resistance of the receiving end (RX) It can vary within the range of 10Ω-50Ω. When the load changes, because... and The changes cancel each other out, and the output voltage fluctuation satisfies: To maintain a stable constant voltage output.

[0062] Specifically, by adding a "passive repeater coil (PRR) - auxiliary repeater coil (APR)" pair and the corresponding receiver (RX), the system can be expanded to support simultaneous power supply of more than 5 RXs; after expansion, the dimension of the circuit matrix equation increases synchronously, but the voltage equations corresponding to each RX still satisfy the requirements. All RXs independently achieve constant voltage output without interfering with each other.

[0063] Working principle or structural principle: After the system starts up, the transmitter (TX) is driven by a half-bridge or full-bridge inverter circuit, outputting a 100kHz high-frequency square wave voltage (half-bridge output amplitude). Full bridge output amplitude 2 ); tuning capacitor The TX coil, relay coil (APR / PRR), and RX coil respectively form an LCR series resonant circuit, according to the resonance condition. Each coil circuit resonates at 100kHz, at which point the circuit exhibits purely resistive characteristics. There is no reactive power loss, laying the foundation for efficient energy transmission;

[0064] When the TX coil is energized, it generates an alternating magnetic field, which transfers energy to the first auxiliary relay coil (APR) through "main coupling." The double-layered PC40 manganese-zinc ferrite plate at the junction of adjacent coils acts as a "magnetic line bridge," increasing the main coupling coefficient between TX and APR from 0.09 to ≥0.2, and more than doubling the magnetic flux utilization rate. The APR then transfers energy through mutual inductance (…). Energy is transferred to the corresponding receiver (RX) to power the load. In multi-charging-segment expansion scenarios (N>1), the first APR transfers energy to the next APR through a passive repeater coil (PRR) (forming a "PRR-APR" repeater pair), which then powers the new RX. Since the cross-coupling coefficient between non-adjacent coils (such as k13, k14) is ≤0.01, which is much smaller than the main coupling coefficient, cross-interference can be ignored, and each charging segment works independently, achieving "segment-by-segment expansion".

[0065] According to Kirchhoff's laws, the system circuit matrix equation is: When the system is in resonance = The imaginary part of the equation is 0, and the current in each coil is determined only by the resistance and mutual inductance. At this time, the voltage across RX satisfies: Since the coil structure is fixed, (Mutual inductance between APR and RX) (APR coil current) For tuning capacitors, all are constants, therefore With load resistance It doesn't matter, even With the voltage varying within the range of 10Ω-50Ω, or with some RX removed, the voltage fluctuation of the remaining RX is still ≤10%, achieving independent constant voltage output for multiple loads;

[0066] When the RX moves dynamically (within ±20mm range), Slight variations occur, but due to the enhanced coupling effect between the system's resonant characteristics and the ferrite plate, voltage fluctuations can be controlled to ≤10%. When all loads are removed or the system is shut down, the TX coil current drops to zero, the resonance between each relay coil and the RX coil terminates, the system returns to its initial state, and waits for the next startup.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0068] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art, inspired by this description, design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the scope of protection of this invention.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-profile dynamic multi-load constant voltage output wireless power transfer system, characterized in that: It includes a transmitter, multiple coplanar repeater coils, multiple receivers, and tuning capacitors; The transmitter is driven by a half-bridge or full-bridge inverter circuit, operating at a frequency of 100kHz, and is used to output high-frequency inverter voltage. The half-bridge inverter circuit outputs a square wave voltage with an amplitude of [missing value]. The full-bridge inverter circuit outputs a square wave voltage with an amplitude of 2. ; The coplanar repeater coil includes at least one auxiliary repeater coil and at least one passive repeater coil. Double-layer PC40 manganese-zinc ferrite plates are installed on both the upper and lower sides of the connection between adjacent coplanar repeater coils. The main coupling coefficient between adjacent coils is... ≥0.2, the cross-coupling coefficient between non-adjacent coils is negligible compared to the main coupling coefficient; The receiving end (RX) can be dynamically placed in the voltage regulation area above the coplanar repeater coil to provide power to the load, and the output voltage across the receiving end (RX) satisfies the formula: , ( The system's operating angular frequency, For mutual inductance between APR and RX, For APR coil current, For tuning capacitors, (where the load resistance is the Nth RX), the voltage is related to Other The load resistance value is irrelevant; The tuning capacitor, together with the transmitting coil, the coplanar repeater coil, and the receiving coil, constitutes an LCR series resonant circuit, and each resonant circuit satisfies the resonance condition. The system's operating angular frequency, For coil inductance, (For tuning capacitors), so that each resonant circuit resonates at 100kHz.

2. The low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 1, characterized in that: The system consists of N charging segments, where N≥1; When N=1, the charging section consists of a transmitter (TX), one auxiliary relay coil (APR), and one receiver (RX), and the circuit matrix equation satisfies: ； ( The equivalent loss resistance of the coil. For coil and Mutual feeling, For coil current, (This refers to the output voltage of the inverter circuit). When N>1, the first charging segment consists of a transmitter (TX), an auxiliary repeater coil (APR), and a receiver (RX). The remaining N-1 charging segments each consist of a pair of passive repeater coils (PRR) and auxiliary repeater coils (APR) and a receiver (RX). When adding a new charging segment, only the "PRR-APR" pair and the corresponding RX need to be added. The circuit matrix equation only expands the corresponding dimension and does not affect the voltage output of the existing charging segment.

3. The low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 2, characterized in that: The dimensions of the double-layer PC40 manganese-zinc ferrite plate are adapted to the connection area of ​​adjacent coplanar relay coils to enhance the magnetic coupling between adjacent coils, thereby increasing the main coupling coefficient of adjacent coils by at least 2 times compared to when there is no ferrite plate. When there is no ferrite plate, the coupling coefficients of adjacent coils are k12=k24=0.09, k13=k34=0.015, and k23=0.

22. After setting the ferrite plate, k12 and k24 increase to ≥0.2, and the changes in the cross coupling coefficients of non-adjacent coils k13, k34, and k14 are ≤0.01, which can still be ignored.

4. The low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 3, characterized in that: The receiving end (RX) can move within a range of ±20mm above the coplanar repeater coil. During the movement, due to mutual inductance... The output voltage fluctuation caused by the change satisfies: To maintain constant voltage output characteristics.

5. A low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 4, characterized in that: When any one or more receivers (RX) are removed from the system, the voltage of the remaining RX satisfies the formula: Because the dimension of the circuit matrix equation is reduced but the main coupling parameters remain unchanged, voltage fluctuations... And the system transmission efficiency ( For RX output power, (TX input power).

6. The low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 5, characterized in that: The transmitting (TX) coil, coplanar repeater coil, and receiving (RX) coil all adopt a planar coil structure, with the coils arranged along the surface of the planar carrier, and the overall height of the system ≤20mm; And the inductance Li and tuning capacitance Ci of each coil satisfy At resonance, the circuit exhibits pure resistive characteristics with no reactive power loss.

7. A low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 6, characterized in that: In the LCR series resonant circuit, when the system operating frequency reaches the resonant frequency... At that time, the imaginary part of each element in the circuit matrix equation is 0, that is... At this point, the current in each coil is determined only by the resistance and mutual inductance, further improving the stability of the output voltage.

8. A low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 7, characterized in that: In the circuit matrix equation, the normalized frequency The normalized current of the m-th resonator Main coupling coefficient Normalization analysis can verify that each RX voltage is independent of the normalized frequency x and the load resistance.

9. A low-profile dynamic multi-load constant voltage output wireless power transmission system according to claim 8, characterized in that: The load resistance of the receiving end (RX) It can vary within the range of 10Ω-50Ω. When the load changes, because... and The changes cancel each other out, and the output voltage fluctuation satisfies: To maintain a stable constant voltage output.

10. A low-profile dynamic multi-load constant voltage output wireless power transfer system according to claim 9, characterized in that: By adding a "passive repeater coil (PRR) - auxiliary repeater coil (APR)" pair and the corresponding receiver (RX), the system can be expanded to support simultaneous power supply of more than 5 RXs; after expansion, the dimension of the circuit matrix equation increases synchronously, but the voltage equations corresponding to each RX still satisfy the following conditions. All RXs independently achieve constant voltage output without interfering with each other.

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