Single-transmit dual-receive co-loaded wireless power transfer system based on inverse PT symmetry

Abstract

This invention discloses a single-transmitter, dual-receiver, shared-load wireless power transfer system based on anti-PT symmetry, belonging to the field of wireless power transfer circuit and control technology. The system includes a transmitting device and a receiving device; the transmitting device includes an inverter drive circuit and a transmitting coil, and the receiving device includes two receiving coils, a rectifier circuit, and a shared load; the inverter drive circuit converts the input DC power into AC power to excite the transmitting coils. By constructing an equivalent non-Hermitian coupling relationship that satisfies anti-PT symmetry characteristics under the configuration of receiving-side parameters and the action of the shared-load network, the system has a stronger tolerance to changes in the coupling coefficient: compared to traditional PT-WPT systems, this invention can maintain high transmission efficiency and output capability under weak coupling conditions, avoiding significant efficiency degradation as coupling weakens; under strong coupling conditions, it reduces the critical coupling threshold, expanding the coupling range that can maintain efficient transmission without active tuning. Compared to a three-coil PT system, this invention also uses a three-coil structure, but the system design is simpler, the applicable coupling range is wider, and the application scenarios are broader.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission circuit control technology, and more specifically to a single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry. Background Technology

[0002] In recent decades, Wireless Power Transfer (WPT) technology has experienced rapid and widespread development due to its high reliability, convenience, and security. However, most WPT solutions are inherently sensitive to transmission distance and structural disturbances, making them difficult to adapt to different application scenarios. When faced with system parameter disturbances, such as changes in coil coupling or component parameter drift, energy transmission stability deteriorates, easily leading to efficiency drops or even failure to supply power normally. When there are disordered disturbances within the structure, such as minor layout deviations or environmental interference, transmission performance fluctuates significantly, resulting in insufficient robustness.

[0003] In addition, most existing WPT systems use omnidirectional transmission, which causes electrical energy to radiate into the surrounding space. This results in energy waste in areas outside the target receiving device and can easily cause electromagnetic interference to surrounding electronic devices, further reducing transmission efficiency.

[0004] Moreover, existing WPT systems require complex active tuning to adjust transmission distance or switch loads, such as manually changing circuit parameters and frequently switching frequencies. This is cumbersome and inefficient, and cannot automatically maintain optimal power transmission over a wide range of distances, resulting in a significant reduction in efficiency in practical applications.

[0005] In addition, the existing WPT system basically lacks proactive capabilities. The transmitter cannot accurately obtain the status of each load and can only blindly broadcast energy, which can easily lead to overcharging and overcurrent of some loads and cannot prioritize charging devices in urgent need. It lacks intelligent and refined management. Summary of the Invention

[0006] The technical problem to be solved by this invention is: how to achieve stable power transmission with multiple receivers under a simple single inverter framework by using the concept of non-Hermitian parameter balancing, and provides a single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution: The present invention includes a transmitting device and a receiving device, wherein the transmitting device includes an inverter drive circuit and a transmitting coil, and the receiving device includes two receiving coils, a rectifier circuit and a load. The inverter drive circuit converts the input DC power into AC power and connects to the transmitting coil to transmit wireless power. The two receiving coils are used to receive the wireless power transmitted by the transmitting coil and are connected to the same load through the rectifier circuit. The two receiving coils are arranged independently in space to avoid direct mutual inductance.

[0008] Furthermore, the system also includes a transmitter compensation network, which includes a main capacitor connected to the inverter drive circuit and the transmitter coil, forming a natural resonant frequency with the transmitter coil to transmit wireless power.

[0009] Furthermore, the system also includes a first compensation network and a second compensation network at the receiving end. The first compensation network at the receiving end includes a tuning capacitor C2, and the second compensation network at the receiving end includes a tuning capacitor C3. The tuning capacitors C2 and C3 are respectively connected to two receiving coils and are connected to the rectifier circuit.

[0010] Furthermore, the inductance of both receiving coils is equal to the inductance of the transmitting coil.

[0011] Furthermore, the system also includes a filter network, which includes a filter capacitor C4 connected in parallel across the load.

[0012] Furthermore, in the system, the magnetic coupling between the transmitting coil and the receiving coil forms a real coupling channel, and the common load network forms a virtual coupling channel, resulting in equivalent virtual coupling between the two receiving branches. The common load network includes a rectifier circuit, a filter network, and a load. By adjusting the detuning parameters on the receiving side and the equivalent gain / loss parameters of the common load branch at the operating frequency, the system satisfies the anti-PT symmetry condition. After the two receiving resonant branches merge into the same load branch through the rectifier circuit and the filter network, the rectifier circuit and the filter network present an equivalent impedance to the AC side that is related to the amplitude and phase relationship of the branch current, thereby introducing an off-diagonal coupling term between the receiving resonant branches. The coupling term is represented by an imaginary part, which, together with the real coupling from the transmitting end to the receiving end, determines the system characteristic spectrum, making the system as a whole exhibit non-Hermitian coupling characteristics.

[0013] Furthermore, the system also includes a control and adjustment unit for synchronizing the frequency of the transmitting coil with the anti-PT symmetric operating state of the system through frequency synchronization and phase adjustment.

[0014] Furthermore, the resonant frequencies of the two receiving coils satisfy: w1 = w0 + Δ, w2 = w0 - Δ, where, This is the detuning amount generated by the corresponding tuning capacitors. w0 represents the resonant frequency of the transmitting end, and w1 and w2 represent the detuning frequencies of the two receiving ends, respectively. At that time, the system is in an anti-PT symmetric operating state. , Mutual inductance coefficient, Where L is the operating frequency, L is the coil inductance, and the tuning capacitors C2 and C3 can change their capacitance in real time according to the change of distance, so that they always maintain a constant value despite the change of distance. .

[0015] Furthermore, the system adjusts the virtual coupling term by regulating the load of the receiving branch and the inductance of the receiving coil, thereby enabling dynamic migration of the system between different operating points and maintaining the stability of energy transmission and the balance of power distribution.

[0016] Furthermore, the coupling coefficient between the two receiving coils is negligible, while the coupling coefficient between the transmitting coil and the two receiving coils is variable and opposite.

[0017] The present invention has the following advantages over the prior art:

[0018] 1. Simple structure and unified control unit

[0019] The entire system requires only one transmitter inverter to control and achieve ZPA to keep the transmitter resonant, which greatly simplifies the system structure and reduces hardware costs and control complexity.

[0020] 2. Automatic power balancing and strong robustness

[0021] Through the virtual coupling and anti-PT balancing mechanism formed by the shared load network, the system can automatically adjust the detuning when the coupling coefficient and coil distance change, so as to achieve power self-balancing and stable transmission and adapt to different working distances and load conditions.

[0022] 3. High efficiency and wide coupling operating range

[0023] Anti-PT balancing suppresses the power attenuation problem of traditional systems under weak coupling, enabling the system to maintain high efficiency and low ripple output over a wider coupling range, and making the energy transfer characteristics more stable.

[0024] 4. Easy to implement in engineering and industrial applications

[0025] Each part of this invention can be composed of conventional inductors, capacitors, rectifiers and control modules, without the need for special materials or complex matching structures, and is suitable for fields such as multi-terminal wireless power supply and sensor wireless charging.

[0026] 5. When the distance between the receiving coil and the transmitting coil changes, capacitors C2 and C3 can adaptively change in real time, making the system more intelligent and convenient. Attached Figure Description

[0027] Figure 1 This is the overall equivalent circuit structure diagram of the single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry in this embodiment of the invention;

[0028] Figure 2 This is a circuit topology diagram of a single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry in an embodiment of the present invention;

[0029] Figure 3 This is a graph showing the relationship between the real part of the normalized eigenvalues ​​and the normalized coupling strength in an embodiment of the present invention;

[0030] Figure 4 This is a graph showing the relationship between the imaginary part of the normalized eigenvalues ​​and the normalized coupling strength in an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram illustrating the process of outputting voltage and current in phase by a full-bridge inverter in an embodiment of the present invention.

[0032] Figure 6 This is an equivalent diagram of capacitor C2 and capacitor C3 in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the control strategy for capacitors C2 and C3 in an embodiment of the present invention. Detailed Implementation

[0034] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0035] like Figure 1 , Figure 2 As shown, this embodiment provides a technical solution: a single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry, which mainly includes a transmitter, two receivers, a compensation and shared-load network, and a control and regulation unit.

[0036] The transmitter drives the transmitting coil through a high-frequency inverter circuit, generating an alternating magnetic field in space. Two receiving coils are located within the magnetic field's influence region. Through magnetic coupling and induced voltage, energy is received and combined for output via their respective compensation networks, rectification networks, and a shared load network. The system as a whole adopts a single transmitter structure, capable of stably supplying power to multiple receivers simultaneously.

[0037] The two receiving coils are arranged independently in space to avoid direct mutual inductance, thus ensuring that virtual coupling is generated only by the shared load path and AC reflection effect.

[0038] Specifically, the wireless power transmission system in this embodiment includes a transmitting device and a receiving device;

[0039] The launching device includes:

[0040] Inverter drive circuit, used to convert input DC power into AC power;

[0041] The main capacitor C1 is electrically connected to the inverter drive circuit;

[0042] The main capacitor switch is used to control the connection and disconnection of the main capacitor C1 with the inverter drive circuit.

[0043] The transmitting coil L1 is connected to the main capacitor C1 and the inverter drive circuit, and is used to form an inherent resonant frequency f0 with the main capacitor C1 to transmit wireless power.

[0044] The receiving device includes:

[0045] Tuning capacitors C2 and C3 are connected to receiving coils L2 and L3, respectively;

[0046] Both tuning capacitors C2 and C3 include: capacitor C a and capacitor C b Switching transistors Q5 and Q6.

[0047] A rectifier circuit is used to convert received alternating current (AC) into direct current (DC).

[0048] Load R L It is connected to the rectifier circuit to consume DC power for charging and to generate virtual coupling;

[0049] A load switch is used to control the connection and disconnection of the load from the rectifier circuit.

[0050] Filter capacitor C4;

[0051] The outputs of the two receiving branches are connected to the same load via a rectifier circuit and filter capacitor C4, forming a common load path.

[0052] The receiving coils L2 and L3 are electrically connected to the tuning capacitors C2 and C3 and the rectifier circuit, respectively, to form a detuned frequency with the tuning capacitors C2 and C3 to receive the wireless energy transmitted by the transmitting coil L1.

[0053] II. Working Principle

[0054] The core mechanism of the system is the inverse PT balancing structure.

[0055] (1) The magnetic coupling between the transmitting and receiving coils forms a "real coupling" channel;

[0056] (2) The shared load network (including rectification, filtering and load) forms a "virtual coupling" channel, so that there is an equivalent virtual coupling between the two receiving branches;

[0057] (3) By adjusting the receiver side detuning and equivalent gain / loss, the system can meet the anti-PT condition, thereby achieving automatic power balancing and robust power transfer of multiple branches.

[0058] (4) When the receiving branch is combined with the common load, the phase difference of its AC current will be reflected to the AC side through the rectification and filtering network, forming an equivalent virtual coupling. This virtual coupling and the real coupling together determine the characteristic spectrum of the system, making the whole exhibit non-Hermitian characteristics.

[0059] (5) When the detuning amount Δ and the virtual coupling term γ satisfy a certain proportional relationship, the system enters the anti-PT balance region. At this time, the power is automatically distributed between the two receiving branches to achieve stable output. Even if the coupling coefficient or load changes, the system can maintain stable power transmission.

[0060] (6) When the distance changes, the coupling coefficient also changes. The tuning capacitor is controlled by controlling the conduction phase angle of the switching transistor to maintain the desired coupling coefficient. This condition. The switched capacitor is constructed by connecting MOSFETs Q5 and Q6 in series. By controlling the conduction angle of the MOSFETs, the charging and discharging time of the capacitor is indirectly controlled. This control can indirectly adjust the amount of charge stored in the capacitor, thus effectively presenting different capacitance values. When current Ia flows in, the current is split into Ib and Ic, which flow into Ca and Q5 respectively. The charging and discharging of Ca is controlled by controlling Q5. When current Ia flows out, the charging and discharging of Ca is controlled by controlling Q6.

[0061] III. Hardware Components

[0062] (1) Transmitter module

[0063] It includes an inverter circuit, a compensation network, and a transmitting coil.

[0064] The inverter circuit can be a full-bridge structure, driven by the control and regulation unit to generate high-frequency current.

[0065] The compensation network is used to make the transmitter resonate near the operating frequency, ensuring effective energy coupling.

[0066] (2) Receiver module

[0067] It includes two independent receiving coils, each with its own compensation network and rectifier unit.

[0068] Both receiving coils are coupled to the transmitting coil, but there is no direct magnetic flux coupling between them.

[0069] Each receiving branch is rectified and output to the common load bus to achieve energy convergence.

[0070] The tuning capacitor control unit enables adaptive changes in the tuning capacitor.

[0071] (3) Shared load network

[0072] It consists of a DC load and optional filter components.

[0073] The shared load is both an energy convergence point and a path for the formation of virtual coupling.

[0074] Its voltage and current fluctuations are reflected through AC side coupling, which adjusts the power distribution characteristics of the system.

[0075] (4) Control and regulation unit

[0076] It is responsible for monitoring the voltage and current at the transmitting end and the power at the receiving end.

[0077] By adjusting the inverter phase shift or modulation signal, the equivalent admittance at the transmitter can be changed, thus achieving zero phase at the transmitter.

[0078] IV. System Performance and Operating Characteristics

[0079] (1) Wide coupling stability

[0080] Even when the coupling coefficient varies over a large range, this system can still maintain stable energy transmission and high-efficiency output.

[0081] (2) Automatic efficiency adjustment

[0082] The power of the two receiving branches can achieve self-balancing in the absence of communication. As the load changes or displacement is adjusted, efficiency is maintained by regulating the detuning.

[0083] (3) Receiver detuning adjustability

[0084] The tuning capacitor at the receiver is controllable and its detuning can be flexibly adjusted according to the scenario. This feature enables the system to operate efficiently in different application scenarios.

[0085] The theoretical derivation of this invention mainly revolves around Hamiltonian and coupled-mode theory. Coupled-mode theory is a mathematical model for analyzing energy transfer between two resonants, which can intuitively reflect the mode of energy transfer. This invention designs a resonant wireless power transfer system. When the input frequency is equal to the natural frequency of the transmitting coil, the transmitting coil resonates, generating a maximum magnetic field, which couples to the receiving coil, causing the receiving coil to also detune, thereby transferring energy to the load. In the receiving coil, each receiving coil detunes with its respective tuning capacitor; the degree of detuning is determined by the coupling coefficient. The Hamiltonian for a single transmitter, dual receivers, and shared load is discussed in the following formulas.

[0086] First, analyze the circuit topology and then list Kirchhoff's voltage laws:

[0087] (1)

[0088] according to , , We can obtain:

[0089] (2)

[0090] in, It is the detuning caused by the tuning capacitor.

[0091] (3)

[0092] Formula (3) is the Hamiltonian, where , This is because the two receiving coils are reversed; It is the transmitting end; It's from the receiving end. This also represents the virtual coupling caused by shared load. It is a load. This is the negative resistance at the transmitting end. (The first and third rows represent the two receiving ends, and the second row represents the transmitting end.)

[0093] Solve for its eigenvalues ,get:

[0094] (4)

[0095] Let the detuning quantity be... Substituting into equation (4), we can obtain:

[0096] (5)

[0097] Therefore, the three eigenvalues ​​(relative) The offset is , We can obtain:

[0098] (6)

[0099] From formula (6), we can obtain:

[0100] when When, and when the system is in a strongly coupled region, the three roots form a real center. With symmetrical real roots on both sides, real frequency splitting occurs. For example... Figure 3 As shown.

[0101] when At that time, all three were This is the EP point, the frequency bifurcation point.

[0102] when When, and when the system is in a weakly coupled region, a real root is obtained. With a pair of conjugate complex roots, such as Figure 4 As shown. Compared to the PT system, when Furthermore, when the system is in the weakly coupled region, real roots exist, while PT systems do not have real roots, thus causing a sharp drop in efficiency. The presence of real roots can mitigate the frequency drop problem when the system is in the weakly coupled region.

[0103] like Figure 5 The diagram shown illustrates the process of outputting in-phase voltage and current in a full-bridge inverter according to this invention. DC The input is a DC voltage. Under the self-oscillating control strategy, the control circuit acquires the output current signal and performs a zero-crossing comparison, outputting two sets of complementary PWM waves, where Q1 and Q4 have the same waveform, and Q2 and Q3 have the same waveform. Finally, under the action of the inverter circuit, the phase difference between the voltage and current at the output port is always 0.

[0104] In summary, this invention features a novel three-coil structure that, compared to the PT-WPT system, achieves wide coupling in the weak coupling region as in the strong coupling region; and in the strong coupling region, it reduces the critical coupling condition, expanding the transmission advantage without active tuning. Ultimately, when When conditions are met, wide coupling is achieved across the entire range. Compared to a three-coil PT system, it also has a three-coil structure, but its system design is simpler and its application range is wider.

[0105] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A single-transmitter, dual-receiver wireless power transmission system based on anti-PT symmetry, characterized in that, The device includes a transmitting device and a receiving device. The transmitting device includes an inverter drive circuit and a transmitting coil. The receiving device includes two receiving coils, a rectifier circuit, and a load. The inverter drive circuit converts the input DC power into AC power and connects to the transmitting coil to transmit wireless power. The two receiving coils are used to receive the wireless power transmitted by the transmitting coil and are connected to the same load through the rectifier circuit. The two receiving coils are arranged independently in space to avoid direct mutual inductance.

2. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 1, characterized in that, The system also includes a transmitter compensation network, which includes a main capacitor connected to an inverter drive circuit and a transmitter coil, forming a natural resonant frequency with the transmitter coil to transmit wireless power.

3. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 2, characterized in that, The system also includes a first compensation network and a second compensation network at the receiving end. The first compensation network at the receiving end includes a tuning capacitor C2, and the second compensation network at the receiving end includes a tuning capacitor C3. The tuning capacitors C2 and C3 are respectively connected to two receiving coils and are connected to the rectifier circuit.

4. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 3, characterized in that, The inductance of both receiving coils is equal to the inductance of the transmitting coil.

5. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 3, characterized in that, The system also includes a filter network, which includes a filter capacitor C4 connected in parallel across the load.

6. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 5, characterized in that, In the system, the magnetic coupling between the transmitting coil and the receiving coil forms a real coupling channel, and the common load network forms a virtual coupling channel, resulting in equivalent virtual coupling between the two receiving branches. The common load network includes a rectifier circuit, a filter network, and a load. By adjusting the detuning parameters on the receiving side and the equivalent gain / loss parameters of the common load branch at the operating frequency, the system satisfies the anti-PT symmetry condition. After the two receiving resonant branches are combined into the same load branch through the rectifier circuit and the filter network, the rectifier circuit and the filter network present an equivalent impedance to the AC side that is related to the amplitude and phase relationship of the branch current, thereby introducing an off-diagonal coupling term between the receiving resonant branches. The coupling term is represented by an imaginary part, which, together with the real coupling from the transmitting end to the receiving end, determines the system characteristic spectrum, making the system as a whole exhibit non-Hermitian coupling characteristics.

7. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 6, characterized in that, The system also includes a control and adjustment unit, used to keep the resonant frequency of the transmitting coil consistent with the anti-PT symmetrical operating state of the system through frequency synchronization and phase adjustment.

8. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 7, characterized in that, The resonant frequencies of the two receiving coils satisfy: w1 = w0 + Δ, w2 = w0 - Δ, where, This is the detuning amount generated by the corresponding tuning capacitors. w0 represents the resonant frequency of the transmitting end, and w1 and w2 represent the detuning frequencies of the two receiving ends, respectively. At that time, the system is in an anti-PT symmetric operating state. , Mutual inductance coefficient, Where L is the operating frequency, L is the coil inductance, and the tuning capacitors C2 and C3 can change their capacitance in real time according to the change of distance, so that they always maintain a constant value despite the change of distance. .

9. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 8, characterized in that, The system adjusts the virtual coupling term by regulating the load of the receiving branch and the inductance of the receiving coil, thereby enabling dynamic migration of the system between different operating points and maintaining the stability of energy transmission and the balance of power distribution.

10. The single-transmitter dual-receiver shared-load wireless power transmission system based on anti-PT symmetry according to claim 9, characterized in that, The coupling coefficient between the two receiving coils is negligible, while the coupling coefficient between the transmitting coil and the two receiving coils is variable and opposite.

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