A pre-embedded sensor wireless power supply system and method based on steel bar eddy current regulation

Abstract

This invention relates to the field of wireless power transmission technology and discloses a wireless power supply system and method for embedded sensors based on eddy current control of reinforcing steel mesh. Addressing the problem that when the transmitting coil moves to a specific symmetrical position, the induced eddy currents in adjacent reinforcing steel loops cancel each other out on the common reinforcing steel, forming an eddy current zero-crossing point, leading to a sudden drop in output power or even power interruption, the system includes a transmitting section and a receiving section. The transmitting section includes a DC power supply, two parallel high-frequency inverters, two compensation networks, and two mutually decoupled transmitting coils with a preset spatial offset distance. The receiving section includes a receiving coil fixed to the common reinforcing steel of adjacent reinforcing steel loops, a receiving compensation capacitor, a rectifier filter circuit, and a load. The system also includes a controller that dynamically switches the phase difference between the drive signals of the two high-frequency inverters between at least two preset phase states during the movement of the transmitting coil relative to the reinforcing steel loop, maintaining the synthesized eddy current on the common reinforcing steel in a non-zero state.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and more specifically, to a wireless power supply system and method for pre-embedded sensors based on eddy current control of steel mesh. Background Technology

[0002] In structural health monitoring systems for large civil infrastructure projects such as tunnels, sensors are typically embedded in reinforced concrete within the walls to detect key parameters such as temperature, humidity, and stress. Providing continuous and stable power to these sensor nodes, which are permanently embedded in the concrete, is a critical constraint determining system reliability. Traditional battery power is limited by its range and difficult to replace, while wired power faces risks such as complex wiring and susceptibility to aging and short circuits. Inductive wireless power supply technology, with its contactless operation and low maintenance costs, has become an effective solution for powering embedded sensors. In practical applications, the transmitting coil is usually mounted on the robotic arm of the inspection vehicle, replenishing the power to the embedded sensors during the vehicle's dynamic inspection as it moves along the tunnel.

[0003] However, the dynamic wireless power supply system for embedded sensors faces a severe challenge: the complex array of reinforcing bars within concrete not only creates a shielding effect but also causes dynamic changes in the coupling position due to the movement of the transmitting coil. This results in eddy currents induced in adjacent reinforcing bar loops exhibiting equal amplitude and phase at specific locations. At this point, the eddy currents on the common reinforcing bars at the location of the receiving coil cancel each other out, forming an "eddy current zero-crossing point." The appearance of an eddy current zero-crossing point means there is no effective excitation at that location, preventing the embedded sensor from acquiring energy, leading to a sudden drop in instantaneous power and a significant reduction in the system's average output power. Existing single-coil transmitting structures have a fixed magnetic field direction, making it difficult to eliminate the eddy current zero-crossing point problem during dynamic processes through magnetic field manipulation. Therefore, a wireless power supply solution for embedded sensors that can dynamically control the distribution of eddy currents in the reinforcing bars, eliminate eddy current zero-crossing points, and improve transmission power is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem of sudden drop in output power or even power interruption caused by the cancellation of eddy currents in adjacent steel bar circuits on the common steel bar when the transmitting coil moves to a specific symmetrical position during the dynamic wireless power supply of pre-embedded sensors.

[0005] To achieve the above objectives, the present invention employs the following technical means:

[0006] This invention provides a wireless power supply system for embedded sensors based on eddy current control of steel mesh, including a transmitting part and a receiving part;

[0007] The transmitting section includes a DC power supply. First high-frequency inverter Second high-frequency inverter First compensation network, second compensation network, first transmitting coil Second transmitting coil The first high-frequency inverter With the second high-frequency inverter Connected in parallel to the DC power supply The first high-frequency inverter The first transmitting coil is driven by the first compensation network. The second high-frequency inverter The second transmitting coil is driven by the second compensation network. The first transmitting coil With the second transmitting coil They are mutually decoupled and have a preset offset distance in space;

[0008] The receiving section includes a receiving coil. Receiver compensation capacitor rectifier filter circuit and load The receiving coil It is fixedly installed on the common reinforcing bar of two adjacent reinforcing bar loops;

[0009] The system also includes a controller configured to: [display a signal at the first transmitting coil] and the second transmitting coil During the movement relative to the steel reinforcement loop, the first high-frequency inverter... With the second high-frequency inverter The phase difference between the driving signals dynamically switches between at least two preset phase states, so that the synthetic eddy current on the common reinforcing bar remains in a non-zero state.

[0010] In the above scheme, the first compensation network includes a first compensation inductor. First compensation capacitor and the first primary compensation capacitor The first high-frequency inverter One of the output terminals is connected to the first compensation inductor Then connect the first compensation capacitor respectively. one end and the first primary compensation capacitor One end, the first compensation capacitor The other end and the first high-frequency inverter The other output terminal is connected to the common ground, and the first primary compensation capacitor The other end is connected to the first transmitting coil One end, the first transmitting coil The other end connects to public land;

[0011] The second compensation network includes a second compensation inductor. Second compensation capacitor Second primary compensation capacitor The second compensation network and the second transmitting coil The connection method between the first compensation network and the first transmitting coil The connection methods between them are the same.

[0012] In the above scheme, when the system operating angular frequency is The reflected inductance of the receiving system is At that time, the first compensation network, the second compensation network, and the receiving resonant circuit satisfy the following set of resonance matching equations:

[0013]

[0014] Under the aforementioned resonance conditions, the first transmitting coil current and the second transmitting coil current satisfy:

[0015]

[0016] in, The output voltage value of the DC power supply. The output voltage pulse width angle of the first high-frequency inverter H1 is [missing information]. The output voltage pulse width angle of the second high-frequency inverter H2 is denoted as .

[0017] In the above scheme, the synthetic eddy current on the common reinforcing steel bar Satisfies the superposition theorem:

[0018]

[0019] in, and The steel reinforcement circuit is respectively connected to the launching side. and the aforementioned reinforcing bar circuit Coupled vortices; the coupled vortices and Solve based on the following system of coupled equations:

[0020]

[0021]

[0022] in, , The rebar circuits are respectively The aforementioned reinforcing bar circuit The equivalent impedance; The equivalent impedance of the receiving circuit; For the reinforcing bar circuit With the aforementioned reinforcing bar circuit Mutual intuition between them; The mutual inductance between the steel reinforcement circuit and the receiving coil Ls; , The first transmitting coil The second transmitting coil With the aforementioned reinforcing bar circuit Mutual intuition; , The first transmitting coil The second transmitting coil With the aforementioned reinforcing bar circuit Mutual intuition; , The first transmitting coil The current, the second transmitting coil The current;

[0023] The receiving coil loop current satisfy:

[0024]

[0025] System output power:

[0026] ;

[0027] The controller changes the first transmitting coil. The current and the second transmitting coil The phase vector sum of the currents makes the synthesized mutual inductance Keep non-zero values, where , , This ensures that the resultant eddy currents on the common reinforcing bars are not zero, thereby maintaining the system's output power. Continuous output.

[0028] In the above scheme, the receiving coil It consists of two semi-toroidal magnetic cores and Litz wire wound around the semi-toroidal magnetic cores, with an air gap between the two semi-toroidal magnetic cores. The receiving coil One end is connected to the receiving compensation capacitor One end of the receiving coil The other end and the receiving compensation capacitor The other end is connected to the two input terminals of the rectifier and filter circuit, and the output terminal of the rectifier and filter circuit is connected to the load. .

[0029] In the above scheme, the first transmitting coil and / or the second transmitting coil The DDQ type coil structure is adopted, including an upper DD type sub-coil and a lower Q type sub-coil; the bottom of the transmitting coil is attached to a ferrite core, and the transmitting coil is wound with Litz wire; the first transmitting coil With the second transmitting coil Natural decoupling is achieved by adjusting the relative positions.

[0030] In the above scheme, the at least two preset phase states include and When the phase difference At that time, the first transmitting coil The current and the second transmitting coil The currents are in phase, and the synthesized mutual inductance ;

[0031] When the phase difference At that time, the first transmitting coil The current and the second transmitting coil The current is out of phase, the composite mutual inductance ;in , .

[0032] The present invention also provides a phase modulation method for the system, comprising the following steps:

[0033] Step S1: Connect the first high-frequency inverter Output voltage pulse width angle and the second high-frequency inverter Output voltage pulse width angle All are fixed as ;

[0034] Step S2: Real-time monitoring of the first high-frequency inverter DC input current and the second high-frequency inverter DC input current Calculate the sum of the two. ;

[0035] Step S3: Obtain the phase difference respectively Total DC input current at time and the phase difference Total DC input current at time ,Compare and Size;

[0036] Step S4: If Then the controller controls the second high-frequency inverter. The drive signal and the first high-frequency inverter Phase difference between drive signals Keep as ;like Then the controller controls the second high-frequency inverter. The drive signal relative to the first high-frequency inverter Phase shift of the drive signal ;

[0037] Step S5: In the first transmitting coil and the second transmitting coil During the movement of the carrier, steps S2 to S4 are repeated to achieve dynamic switching of the phase difference.

[0038] In the above scheme, the carrier is a detection vehicle, and the first transmitting coil and the second transmitting coil The robotic arm is installed at the end of the detection vehicle; as the detection vehicle moves along a preset path, the robotic arm causes the first transmitting coil to... and the second transmitting coil Maintaining a preset height and fixed posture, and close to the wall surface where the pre-embedded steel reinforcement loop is located; in step S5, the controller repeatedly executes steps S2 to S4 at a preset sampling period.

[0039] The present invention also provides a method for designing the transmitting coil of the system, comprising the following steps:

[0040] Step S1: Input design parameters, including DC power supply voltage. Operating frequency First compensating inductor Second compensation inductor Equivalent parameters of rebar circuits, mutual inductance between rebar circuits Mutual inductance between the reinforcing steel and the receiving coil Receiver coil self-inductance Receiver compensation capacitor Load resistance and target average power ;

[0041] Step S2: Set the initial number of turns , and initial decoupling offset distance , in steps Increase The first transmitting coil under the current number of turns is obtained through simulation. Maximum mutual inductance between the steel reinforcement circuit and the rebar circuit and the second transmitting coil Maximum mutual inductance between the steel reinforcement circuit and the rebar circuit Determine whether it satisfies If the conditions are not met, then the first transmitting coil is added. number of turns The simulation is then repeated until the conditions are met, with the current number of turns fixed. ;

[0042] Step S3: Connect the first transmitting coil and the second transmitting coil Place in the starting position , in steps Move to the destination At each displacement point, the mutual inductance parameter matrix between the transmitting coil and each steel reinforcement circuit is obtained through simulation. , ;

[0043] Step S4: At each displacement point, calculate the phase difference according to the mutual inductance parameter matrix. and the phase difference The combined eddy current on the common reinforcing bars at that time Select the synthetic eddy current The phase with the larger amplitude is taken as the optimal phase difference at that displacement point. Based on the optimal phase difference The corresponding synthetic eddy current The receiving coil is calculated using the following formula. loop current :

[0044]

[0045] Then calculate the output power at this displacement point using the following formula:

[0046]

[0047] express The complex conjugate;

[0048] Then calculate the output power at this displacement point using the following formula:

[0049]

[0050] Step S5: Determine if the condition is met. , Let represent the target average power; if not satisfied, then let . , Reset Then return to step S2 to redesign; if satisfied, proceed to step S6;

[0051] Step S6: Output the current number of turns , and decoupling offset distance As the final design solution.

[0052] Because the present invention employs the above-mentioned technical means, it has the following beneficial effects:

[0053] I. Effectively eliminates eddy current zero-crossing points during dynamic processes, expanding the effective power supply range. This invention detects the characteristics of the DC-side input current and dynamically switches the phase of the high-frequency current in the two transmitting coils in real time, changing the phase distribution of the synthetic magnetic field. This avoids the mutual cancellation of eddy currents on the target steel bar where the receiving coil is located, ensuring that the pre-embedded sensor always receives a continuous energy supply during the movement of the detection vehicle. (Effectively eliminating eddy current zero-crossing points in dynamic processes and ensuring power supply continuity: Considering the dynamic fluctuations of mutual inductance parameters during the movement of the detection vehicle and the difficulty in accurately measuring the external relative position, in order to solve the technical problem of power supply interruption caused by the mutual cancellation of eddy currents in adjacent steel bar circuits at specific symmetrical positions, this invention combines the independent driving of dual transmitting coils with a dynamic phase switching method based on the comparison of the total DC input current (steps S2 to S4). If only a dual-coil structure is used, the system cannot adapt to changes in the external position; if only the phase switching function is used, it is difficult to determine the accurate switching timing when position feedback is lacking. In the combined scheme of this invention, steps S2 and S3 directly map the complex external spatial magnetic field coupling state using the magnitude of the total DC current inside the system, providing a precise triggering basis for the phase switching in step S4. The combination of the two produces a synergistic effect of adaptively controlling the external spatial magnetic field based on the internal electrical parameters of the system. This synergistic effect not only eliminates the need for any external position sensors, but also actively rotates the synthetic magnetic field vector from an electromagnetic mechanism perspective, breaking the eddy current cancellation state and completely eliminating dynamic eddy current zero-crossing points.)

[0054] Second, it significantly improves the average transmission power of the system. By employing the dual-transmitter coil phase dynamic switching strategy of this invention, the eddy currents on the target steel reinforcement where the receiving coil is located are always kept at a high level. (Significantly improves the average transmission power of the system in complex rebar arrays: Considering the electromagnetic shielding effect generated by the pre-embedded rebar array and the tendency for multiple transmitting coils to cross-couple, in order to solve the technical problem of low average output power of dynamic wireless power supply systems, this invention combines the spatial natural decoupling design of transmitting coils (step S2) with the optimal phase difference matching of each dynamic displacement point (step S4). Simple coil decoupling can only eliminate cross-interference and reactive circulating current at the transmitting end, but cannot directly improve the energy pickup at the receiving end. This invention achieves complete decoupling of the two coils through step S2, providing a physical basis for the independent and lossless control of the two sets of high-frequency magnetic fields in step S4; and then, in conjunction with step S4, utilizes the symmetry of the rebar mesh to dynamically match and maximize the phase difference of the synthesized eddy currents. The deep combination of the two produces a synergistic effect of converging eddy currents using the structural characteristics of the rebar array itself. This effect transforms the obstruction of the magnetic field by the rebar mesh into an effective superposition of eddy currents, keeping the synthesized eddy currents on the common rebar at a high level, thereby significantly improving the average transmission power of the system throughout the entire dynamic range.) Attached Figure Description

[0055] Figure 1 This is a schematic diagram illustrating the application of the system of the present invention;

[0056] Figure 2 A schematic diagram of the topology of a pre-embedded sensor dynamic wireless power supply system based on dual-transmitting coil phase modulation is provided in an embodiment of the present invention.

[0057] Figure 3 This is a schematic diagram of the transmitting coil structure provided in an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of the steel reinforcement network and receiving coil structure of the present invention;

[0059] Figure 5 A control flowchart for a phase switching method based on dual transmitting coils provided in an embodiment of the present invention;

[0060] Figure 6 A flowchart illustrating the design and optimization of the number of turns of dual transmitting coils provided in an embodiment of the present invention;

[0061] Figure 7 This is a graph showing the output power of the BP and DDQ transmitting coils as a function of moving distance under a fixed phase difference condition in an embodiment of the present invention.

[0062] Figure 8 This is a graph showing the output power of the BP and DDQ transmitting coils changing with the moving distance after dynamic switching with optimal phase difference in this embodiment of the invention. Detailed Implementation

[0063] The embodiments of the present invention will be described in detail below. Although the present invention will be described and illustrated in conjunction with some specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, any modifications or equivalent substitutions made to the present invention should be covered within the scope of the claims of the present invention.

[0064] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art will understand that the present invention can be practiced without these specific details.

[0065] To address the issues of power reduction and power interruption caused by eddy current zero-crossing in dynamic wireless power supply systems for embedded sensors, this invention aims to provide a dynamic wireless power supply system and method for embedded sensors based on dual-transmitting coil phase control. By adjusting the current phase difference between the dual transmitting coils in real time, the eddy current distribution in the rebar array is controlled, effectively avoiding eddy current zero-crossing and improving the system's energy transmission stability and average output power in dynamic scenarios.

[0066] The pre-embedded sensor dynamic wireless power supply system and method of the present invention solves the eddy current zero-crossing problem in the dynamic transmission process from the underlying electromagnetic mechanism through phase modulation of dual transmitting coils. At the system transmitting end, a first high-frequency inverter and a second high-frequency inverter convert DC power into high-frequency AC power, which drives the first and second transmitting coils via an LCC compensation network. Let the pulse width angles of the output voltages of the first and second high-frequency inverters be respectively... and And if the lag phase difference between the second high-frequency inverter drive signal and the first high-frequency inverter drive signal is φ, then the fundamental vector of the AC voltage output by the two sets of inverters... and They are respectively represented as

[0067] (1)

[0068] (2)

[0069] When the system is in full resonance, the transmitting coil current exhibits constant current source characteristics, and its effective value of high-frequency excitation current is... and satisfy:

[0070] (3)

[0071] (4)

[0072] The high-frequency magnetic field generated by the transmitting coil induces eddy currents in the steel mesh embedded in the concrete. Among these, the two main steel loops adjacent to the receiving coil play a dominant role in energy transmission. and According to Kirchhoff's laws, the electromagnetic coupling relationship between the main steel reinforcement loop and the receiving loop can be described by the impedance matrix equation, i.e., the impedance of the main steel reinforcement loop. Inter-loop Mutual inductance between reinforcing bars and receiving coil And the mutual inductance between the transmitting end and the steel reinforcement circuit ( , , , Together, they determine the induced eddy currents in the steel reinforcement circuit. and Because the receiving coil is fixedly mounted on... and The combined eddy current on the common reinforcing bar 0 between the bars satisfy:

[0073] (5)

[0074] Receiver coil circuit current I R This is then generated by the synthetic eddy current excitation, satisfying...

[0075] (6)

[0076] The final average power output of the system is

[0077] (7)

[0078] According to electromagnetic theory, the power received at the receiving end is proportional to the difference in the combined mutual inductance M. diff The square of, where

[0079] (8)

[0080] When the transmitting coil moves dynamically with the detection vehicle, the mutual inductance parameter fluctuates dynamically due to changes in their relative spatial positions; at specific symmetrical positions, [the following will occur]. ,lead to and The induced eddy currents in the middle have equal amplitudes and opposite phases, thus canceling each other out, which is the phenomenon of "eddy current zero crossing" that causes a sudden drop in power.

[0081] To overcome this technical deficiency, this invention proposes to fix the inverter pulse width angle. This allows the transmitter to inject a high-frequency magnetic field of maximum amplitude into space; simultaneously, the phase difference φ of the inverter drive signal is used as a dynamic control variable. When the phase difference π is changed, eddy currents are induced in the steel reinforcement circuit. and The phase will change synchronously, thus forcing the vector superposition state of the two sets of eddy currents on the common reinforcing bar bar0 to undergo rotational transfer in polar coordinates. By sampling and comparing the total input current on the DC side of the inverter in real time, the controller performs optimal switching between specific phase difference states (such as φ=0 and φ=π), forcibly changing the phase distribution characteristics of the spatial synthetic magnetic field to ensure the mutual inductance difference. Always stay away from zero. This control strategy maintains the synthetic eddy current. Always in the maximum vector superposition state, it ultimately realizes continuous, high-power wireless energy transmission of the pre-embedded sensor during dynamic power supply.

[0082] like Figure 1 As shown, the pre-embedded sensor dynamic wireless power supply system of the present invention mainly serves scenarios such as tunnel structure health monitoring in practical applications. The system's receiving coil is pre-arranged within the steel reinforcement mesh inside the tunnel wall and surrounds the sensor, while the transmitting coil, serving as the energy transmitter, is installed at the end of the robotic arm of the track inspection vehicle. During the vehicle's inspection operation, the robotic arm extends the transmitting coil to a position close to the wall surface, maintaining it at the same height and with a fixed posture, and it slowly moves horizontally following the inspection vehicle. During this process, high-frequency alternating current is injected into the transmitting coil to excite a high-frequency magnetic field. Energy is then continuously transferred to the receiving coil through magnetic field coupling, inducing eddy currents in the steel reinforcement mesh of the pre-embedded environment. Finally, a power conversion circuit provides a stable power supply to the pre-embedded sensor.

[0083] like Figure 2 As shown in the system topology diagram, this invention mainly consists of a transmitting section and a receiving section. The transmitting section includes two independently driven high-frequency inverters, both connected in parallel to a 60V DC voltage source. The system operates at a frequency f of 250kHz, with a system angular frequency of ω = 2πf. The output of the first high-frequency inverter is connected to the first compensation inductor. First compensation capacitor and the first primary compensation capacitor The LCC compensation network is constructed. Specifically, the inverter output passes through a 10.66μH compensation inductor. Then, it was connected to a compensation capacitor of 38.88nF. and a 3.14nF primary compensation capacitor One end is connected, which then drives the first transmitting coil with a self-inductance of 130μ. The second transmitting circuit uses the exact same topology connection method, and its compensation inductor... Compensation capacitor and primary compensation capacitor The voltages were set to 10.7 μH, 38.5 nF, and 2.16 nF, respectively, to drive a second transmitting coil with a self-inductance of 190 μ. Based on this system topology, the primary-side transmitting coil exhibits excellent constant current source characteristics, and its effective value of high-frequency excitation current is... and It is directly determined by the pulse width angle of the inverter output voltage, and satisfies the following relationship:

[0084] (9)

[0085] (10)

[0086] like Figure 3 As shown, to achieve flexible magnetic field modulation and eliminate cross-coupling between transmitting coils, the transmitting end preferably employs a multi-coil structure, such as a BP coil or a DDQ coil, capable of natural decoupling through adjustment of relative positions. In specific implementations, the external dimensions of the transmitting coil are set to 150mm × 300mm to match the dimensions of the adjacent reinforcing bar circuit. Its body is wound with 0.05mm × 825 strands of Litz wire, and a 2mm thick PC40 ferrite core is bonded to the bottom. To further reduce the insulation voltage requirements at the receiving end, this embodiment preferably uses a DDQ type coil, with a 22-turn DD-type sub-coil on the upper layer and a 16-turn Q-type sub-coil on the lower layer. Research has verified that this DDQ structure can reduce the peak induced voltage at the receiving end by approximately 25.7% while maintaining the same average transmission power, significantly improving system safety.

[0087] like Figure 4 As shown, in the receiving section, the pre-embedded steel bar array uses 12mm diameter HRB400 steel bars, welded into a grid pattern with horizontal and vertical spacing of 15cm. The receiving coil is fixed to two adjacent main steel bar loops ( and The receiving coil is located on the common reinforcing bar (bar0) between the two semi-hollow cylindrical ferrite cores. A 2mm air gap is left between the two semi-cylindrical ferrite cores, and 20 turns of Litz wire are wound around the outside. The receiving coil has a self-inductance of 70.8μH. With a 10.1nF receiving compensation capacitor The series circuit forms a resonant network, which is then rectified by a diode bridge to form a 30Ω DC load. Power supply. In this structure, the core of energy pickup at the receiving end lies in the induced eddy currents on the common reinforcing bar bar0. According to the superposition theorem, the resultant eddy currents on this target reinforcing bar... satisfy:

[0088] (11)

[0089] in and These are the launch side and the steel reinforcement circuit. and Coupled eddy currents. When the transmitting coil moves to a specific symmetrical position, if the mutual inductance of the two coils is equal, it will lead to... and The amplitudes are equal but the phases are opposite, thus completely canceling each other out and triggering a "zero-crossing point of the eddy current," causing a sharp drop in power.

[0090] like Figure 5 As shown in the control flowchart, to eliminate this "eddy current zero-crossing" problem, this invention implements a real-time dynamic phase switching control strategy. During control execution, the output voltage pulse width angles of the two high-frequency inverters are first adjusted. and Both are fixed at π to ensure the transmitter outputs the maximum magnitude magnetic field into space. Subsequently, the DC-side input current of the first and second inverters is monitored in real time via hardware circuitry, and the total current of both is calculated. The controller compares the magnitude of the total current under different phase difference states (such as when the phase difference between two sets of drive signals is φ=0 and φ=π), and automatically selects the phase difference value that maximizes the total DC current for real-time switching. This dynamic optimization mechanism can forcibly break the phase difference as the detected vehicle's displacement changes. and The offset state effectively eliminates the eddy current zero-crossing point of the reinforcement loop throughout the entire horizontal movement range.

[0091] like Figure 6 As shown in the flowchart of the turns design, and in conjunction with the above hardware configuration and control strategy, this invention provides a method for designing and optimizing the number of turns of the transmitting coil. In the initial design phase, the input DC power supply voltage is first determined. Operating frequency f, first compensation inductor Second compensation inductor Equivalent parameters of rebar circuit , , , Mutual inductance between steel reinforcement circuits Mutual inductance between the reinforcing bar and the receiving coil Receiver coil self-inductance and compensation capacitor Load resistance Target average power Establish basic data. Set the initial number of turns for the dual transmitting coils and adjust the decoupling offset distance between the two coils. Finite element simulation is used to determine whether the maximum mutual inductance between the two coils meets the decoupling requirements. If not, the parameters are fine-tuned in 1mm increments and the simulation is repeated until natural decoupling is achieved and the position parameter is fixed. Based on this, the transmitting coil is simulated from its initial position. Move to the destination The entire process is analyzed, and the dynamic mutual inductance parameter matrix is ​​extracted at each displacement point. The instantaneous output power is calculated using the aforementioned phase switching strategy. Finally, the actual average transmission power of the system is calculated by integrating the output power over the entire moving range. It satisfies:

[0092] (12)

[0093] If the average power Failed to meet the set target requirements Then, the number of turns of the transmitting coil is increased synchronously, and the above decoupling judgment and power verification iterative process is repeated until the optimal number of turns that meets the power constraint and has no cross coupling is finally determined and the final scheme is output.

[0094] To further quantify the improvement effect of phase switching on output power, this embodiment tested the output power with a fixed phase difference (φ=0 and φ=π) and with the dynamic phase switching of the present invention (φ=π) as the transmitting coil moved horizontally from -300mm to +300mm. The output power of the receiver at that time. Figure 7 Experimental results show that for DDQ type dual-transmitter coils, when phase switching is not performed, the power curve shows a zero point at a specific location, leading to power interruption; for example... Figure 8 As shown, after adopting the phase switching method proposed in this invention, the power zero point is completely eliminated throughout the entire movement range, and the average output power is increased from 7.29W to 11.72W, an increase of 60.98%. Simultaneously, under different load conditions (e.g., 30Ω, 40Ω, 50Ω), the location of the switching point is determined solely by the mutual inductance difference. The fact that the method remains unaffected by load changes indicates its excellent load adaptability. This result fully verifies that the present invention, through dynamic phase control of dual transmitting coils, can effectively avoid eddy current zero-crossing and significantly improve the average transmission power and power supply continuity of the dynamic wireless power supply system.

Claims

1. A wireless power supply system for embedded sensors based on eddy current control of reinforcing mesh, characterized in that, Includes a sending section and a receiving section; The transmitting section includes a DC power supply. First high-frequency inverter Second high-frequency inverter First compensation network, second compensation network, first transmitting coil Second transmitting coil The first high-frequency inverter With the second high-frequency inverter Connected in parallel to the DC power supply The first high-frequency inverter The first transmitting coil is driven by the first compensation network. The second high-frequency inverter The second transmitting coil is driven by the second compensation network. The first transmitting coil With the second transmitting coil They are mutually decoupled and have a preset offset distance in space; The receiving section includes a receiving coil. Receiver compensation capacitor rectifier filter circuit and load The receiving coil It is fixedly installed on the common reinforcing bar of two adjacent reinforcing bar loops; The system also includes a controller configured to: [display a signal at the first transmitting coil] and the second transmitting coil During the movement relative to the steel reinforcement loop, the first high-frequency inverter... With the second high-frequency inverter The phase difference between the driving signals dynamically switches between at least two preset phase states, so that the synthetic eddy current on the common reinforcing bar remains in a non-zero state.

2. The system according to claim 1, characterized in that, The first compensation network includes a first compensation inductor. First compensation capacitor and the first primary compensation capacitor The first high-frequency inverter One of the output terminals is connected to the first compensation inductor Then connect the first compensation capacitor respectively. one end and the first primary compensation capacitor One end, the first compensation capacitor The other end and the first high-frequency inverter The other output terminal is connected to the common ground, and the first primary compensation capacitor The other end is connected to the first transmitting coil One end, the first transmitting coil The other end connects to public land; The second compensation network includes a second compensation inductor. Second compensation capacitor Second primary compensation capacitor The second compensation network and the second transmitting coil The connection method between the first compensation network and the first transmitting coil The connection methods between them are the same.

3. The system according to claim 2, characterized in that, When the system operating angular frequency is The reflected inductance of the receiving system is At that time, the first compensation network, the second compensation network, and the receiving resonant circuit satisfy the following set of resonance matching equations: Under the aforementioned resonance conditions, the first transmitting coil current and the second transmitting coil current satisfy: in, The output voltage value of the DC power supply. The output voltage pulse width angle of the first high-frequency inverter H1 is [missing information]. The output voltage pulse width angle of the second high-frequency inverter H2 is denoted as .

4. The system according to claim 1, characterized in that, The synthetic eddy current on the common reinforcing steel Satisfies the superposition theorem: in, and The transmitting side is respectively for the steel reinforcement circuit and the aforementioned reinforcing bar circuit Coupled vortices; the coupled vortices and Solve based on the following system of coupled equations: in, , The rebar circuits are respectively The aforementioned reinforcing bar circuit The equivalent impedance; The equivalent impedance of the receiving circuit; For the reinforcing bar circuit With the aforementioned reinforcing bar circuit Mutual intuition between them; The mutual inductance between the steel reinforcement circuit and the receiving coil Ls; , The first transmitting coil The second transmitting coil With the aforementioned reinforcing bar circuit Mutual intuition; , The first transmitting coil The second transmitting coil With the aforementioned reinforcing bar circuit Mutual intuition; , The first transmitting coil The current, the second transmitting coil The current; The receiving coil loop current satisfy: System output power: ； The controller changes the first transmitting coil. The current and the second transmitting coil The phase vector sum of the currents makes the synthesized mutual inductance Keep non-zero values, where , , This ensures that the resultant eddy currents on the common reinforcing bars are not zero, thereby maintaining the system's output power. Continuous output.

5. The system according to claim 1, characterized in that, The receiving coil It consists of two semi-toroidal magnetic cores and Litz wire wound around the semi-toroidal magnetic cores, with an air gap between the two semi-toroidal magnetic cores. The receiving coil One end is connected to the receiving compensation capacitor One end of the receiving coil The other end and the receiving compensation capacitor The other end is connected to the two input terminals of the rectifier and filter circuit, and the output terminal of the rectifier and filter circuit is connected to the load. .

6. The system according to claim 1, characterized in that, First transmitting coil and / or the second transmitting coil The DDQ type coil structure is adopted, including an upper DD type sub-coil and a lower Q type sub-coil; the bottom of the transmitting coil is attached to a ferrite core, and the transmitting coil is wound with Litz wire; the first transmitting coil With the second transmitting coil Natural decoupling is achieved by adjusting the relative positions.

7. The system according to claim 1, characterized in that, The at least two preset phase states include and When the phase difference At that time, the first transmitting coil The current and the second transmitting coil The currents are in phase, and the synthesized mutual inductance ; When the phase difference At that time, the first transmitting coil The current and the second transmitting coil The current is out of phase, the composite mutual inductance ;in , .

8. A phase modulation method based on the system of claim 1, characterized in that, Includes the following steps: Step S1: Connect the first high-frequency inverter Output voltage pulse width angle and the second high-frequency inverter Output voltage pulse width angle All are fixed as ; Step S2: Real-time monitoring of the first high-frequency inverter DC input current and the second high-frequency inverter DC input current Calculate the sum of the two. ; Step S3: Obtain the phase difference respectively Total DC input current at time and the phase difference Total DC input current at time ,Compare and Size; Step S4: If Then the controller controls the second high-frequency inverter. The drive signal and the first high-frequency inverter Phase difference between drive signals Keep as ;like Then the controller controls the second high-frequency inverter. The drive signal relative to the first high-frequency inverter Phase shift of the drive signal ; Step S5: In the first transmitting coil and the second transmitting coil During the movement of the carrier, steps S2 to S4 are repeated to achieve dynamic switching of the phase difference.

9. The method according to claim 8, characterized in that, The carrier is a detection vehicle, and the first transmitting coil and the second transmitting coil The robotic arm is installed at the end of the detection vehicle; as the detection vehicle moves along a preset path, the robotic arm causes the first transmitting coil to... and the second transmitting coil Maintaining a preset height and fixed posture, and close to the wall surface where the pre-embedded steel reinforcement loop is located; in step S5, the controller repeatedly executes steps S2 to S4 at a preset sampling period.

10. A method for designing the transmitting coil of the system as described in claim 1, characterized in that, Includes the following steps: Step S1: Input design parameters, including DC power supply voltage. Operating frequency First compensating inductor Second compensation inductor Equivalent parameters of rebar circuits, mutual inductance between rebar circuits Mutual inductance between the reinforcing steel and the receiving coil Receiver coil self-inductance Receiver compensation capacitor Load resistance and target average power ; Step S2: Set the initial number of turns , and initial decoupling offset distance , in steps Increase The first transmitting coil under the current number of turns is obtained through simulation. Maximum mutual inductance between the steel reinforcement circuit and the rebar circuit and the second transmitting coil Maximum mutual inductance between the steel reinforcement circuit and the rebar circuit Determine whether the condition is met. ; If the condition is not met, then the first transmitting coil is added. number of turns The simulation is then repeated until the conditions are met, with the current number of turns fixed. ; Step S3: Connect the first transmitting coil and the second transmitting coil Place in the starting position , in steps Move to the destination At each displacement point, the mutual inductance parameter matrix between the transmitting coil and each steel reinforcement circuit is obtained through simulation. , ; Step S4: At each displacement point, calculate the phase difference according to the mutual inductance parameter matrix. and the phase difference The combined eddy current on the common reinforcing bars at that time Select the synthetic eddy current The phase with the larger amplitude is taken as the optimal phase difference at that displacement point. Based on the optimal phase difference The corresponding synthetic eddy current The receiving coil is calculated using the following formula. loop current : Then calculate the output power at this displacement point using the following formula: express The complex conjugate; Then calculate the output power at this displacement point using the following formula: Step S5: Determine if the condition is met. , Let represent the target average power; if not satisfied, then let . , Reset Then return to step S2 to redesign; if satisfied, proceed to step S6; Step S6: Output the current number of turns , and decoupling offset distance As the final solution.

Images