Wireless power supply system and wireless power supply method for train windshield monitoring system

Abstract

The invention relates to the field of wireless power transmission, provides a wireless power supply system and a wireless power supply method for a train windshield monitoring system, and aims to solve the problem of unstable power supply caused by position deviation of a coupling mechanism of the wireless power supply system due to train operation vibration and windshield deformation. The high-frequency inverter circuit is configured to convert direct current into high-frequency alternating current and output square-wave voltage through a full-bridge inverter circuit topology; the magnetic coupling mechanism comprises a transmitting coil and a receiving coil, is attached to the two sides of rubber shed cloth of a train windshield, adopts a square coil structure and is wound by a litz wire to reduce high-frequency skin effect loss; the compensation network adopts an LCC-S type compensation topology, forms resonance with the magnetic coupling mechanism, provides constant voltage output and adapts to a vibration environment; the rectifier is configured to convert the alternating current induced by the receiving coil into direct current so as to supply power to a monitoring sensor load in the windshield; and the flexible soft magnetic sheets serve as magnetic shielding structures and are arranged on the two sides of the transmitting coil and the receiving coil.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission and provides a wireless power supply system and a wireless power supply method for a train windshield monitoring system. Background Art

[0002] As the operating speed of my country's high-speed trains continues to increase, the mechanical environment of the various connecting components at the ends of train vehicles has become more complex, and the requirements for various indicators during train operation have also become more stringent. As a critical soft connection between the various carriages of a high-speed train, the windshield inside the train is subject to severe vibration and deformation when the train moves at high speeds or traverses some harsh curves. The characteristic parameters of its air pressure variation and structural vibration are of great significance to the stability and safety of high-speed train operation, as well as the comfort of passengers on board. To ensure the stability and safety of train operation, the air pressure variation and structural vibration characteristics at different locations inside the train windshield are monitored in real time. The various characteristic parameters are analyzed and fitted with the occurrence patterns of abnormal air pressure changes and the range of air pressure changes on the train windshield, so as to predict and resolve potential safety risks during EMU operation in real time.

[0003] 1. Prior art related to the present invention

[0004] The transmitter of the wireless power supply system is mainly a high-frequency inverter. A high-frequency inverter is a power electronic device that converts DC power into high-frequency AC power. Then it is connected to the compensation network and transmits power through the transmitting coil. The schematic diagram of the high-frequency inverter and its effect on converting DC voltage to AC voltage are shown in the figure. Figure 1 As shown in the figure, the controller switches the four switches Q1, Q2, Q3, and Q4 on and off, converting the DC voltage into a square-wave AC voltage. In wireless charging systems, the high-frequency inverter at the transmitter is the core component for efficient energy transmission.

[0005] 2. Prior Art II Related to the Present Invention

[0006] The magnetic coupling device in the wireless power supply system is the core component for wireless power transmission. Its performance directly determines the energy transmission efficiency, power capacity and system stability. The magnetic coupling device is mainly composed of a transmitting coil and a receiving coil to achieve medium-distance contactless transmission of power. Figure 2 , which is a schematic diagram of the magnetic coupling device.

[0007] Disadvantages of the second prior art

[0008] The coupling mechanism is a crucial component of wireless power systems, enabling power transmission from the primary to the secondary side. Its physical parameters, such as self-inductance, mutual inductance, and internal impedance, have a crucial impact on the power and efficiency of wireless power transmission. The self-inductance and mutual inductance of traditional magnetic coupling devices vary significantly with relative position. In environments like high-speed train windshields, these are subject to significant interference from deformation and vibration, leading to unstable power supply to the monitoring system and resulting in monitoring anomalies.

[0009] 3. Prior Art 3 Related to the Present Invention

[0010] Compensation network technical solution. Wireless power systems are essentially loosely coupled transformers, with significant leakage inductance between the transmitting and receiving coils, resulting in significant energy loss as reactive power. The compensation network introduces a resonant network composed of capacitors and inductors, creating resonance with the transmitting and receiving coils of the magnetic coupling mechanism, adjusting the system's operating frequency to near the resonant point. This results in a low-impedance system, significantly reducing reactive power losses and boosting energy transmission efficiency to over 80% to 90%.

[0011] The windshield is constantly squeezed during train operation. To ensure stable energy transmission, the constant voltage output "LCC-S" compensation topology with a certain anti-drift effect was selected as the technical solution for the compensation network of this system. The "LCC-S" compensation network is a new type of wireless power transmission technology with great advantages in transmission efficiency and transmission distance. The circuit form of this compensation network is as follows Figure 3 As shown. P , L S The diagram below shows the transmitter and receiver coils. The capacitors and inductors on the left are the transmitter compensation network, while the capacitors and inductors on the right are the receiver compensation network.

[0012] 4. Prior Art 4 Related to the Present Invention

[0013] The receiving device of the wireless power supply system is mainly a rectifier. The rectifier is a key component of the wireless power supply system, responsible for converting the AC power induced by the receiving coil into DC power for the load to use. Commonly used rectifier circuits include controlled rectifier circuits and uncontrolled rectifier circuits. Considering the circuit volume and cost, and simplifying the control method, this system uses an uncontrolled rectifier circuit to achieve power conversion. Figure 4 As shown. in It represents the input AC voltage, and U0 represents the output DC voltage after rectification by the rectifier. Summary of the Invention

[0014] The purpose of the present invention is to solve the problem of unstable power supply caused by position deviation of the coupling mechanism of the wireless power supply system caused by train running vibration and windshield deformation.

[0015] In order to achieve the above-mentioned purpose, the present invention adopts the following technical means:

[0016] The present invention provides a wireless power supply system for a train windshield monitoring system, comprising:

[0017] a high-frequency inverter circuit configured to convert direct current into high-frequency alternating current and output a square wave voltage through a full-bridge inverter circuit topology;

[0018] A magnetic coupling mechanism includes a transmitting coil and a receiving coil, which are attached to both sides of the rubber tarpaulin of the train windshield to achieve contactless transmission of electrical energy through magnetic field coupling. The transmitting coil and the receiving coil adopt a square coil structure and are wound with Litz wire to reduce high-frequency skin effect losses.

[0019] a compensation network, adopting an LCC-S type compensation topology, configured to form resonance with the magnetic coupling mechanism, provide a constant voltage output and adapt to the vibration environment during train operation;

[0020] a rectifier configured to convert the alternating current induced by the receiving coil into direct current to supply power to a windshield interior monitoring sensor load;

[0021] It also includes a flexible soft magnetic sheet as a magnetic shielding structure. The flexible soft magnetic sheet is arranged on both sides of the transmitting coil and the receiving coil to increase the coil self-inductance and mutual inductance parameters and suppress parameter fluctuations caused by vibration.

[0022] In the above solution, the flexible soft magnetic sheet serves as the transmitting end magnetic core and the receiving end magnetic core.

[0023] In the above solution, the square coil structure of the transmitting coil and the receiving coil has an outer side length of 50 mm and an inner side length of 20 mm, and the number of winding turns is 15.

[0024] In the above solution, the flexible soft magnetic sheet is a square soft magnetic sheet, wherein the side length of the transmitting end soft magnetic sheet is 52 mm, and the side length of the receiving end soft magnetic sheet is 48 mm, so as to optimize the magnetic field coupling efficiency and anti-offset capability.

[0025] In the above solution, the system operates at a frequency of 200kHz. Higher frequencies allow for smaller coils (though the windshield's structure precludes the use of larger coils), but this increases skin effect and interference susceptibility. This solution opts for 200kHz to accommodate the thin windshield's structure, requiring the simultaneous introduction of litz wire and flexible magnetic shielding.

[0026] In the above scheme, the compensation network includes a transmitter compensation circuit and a receiver compensation circuit. The receiver compensation circuit includes a capacitor and a receiving coil self-inductance in series resonance, so that the system operates in a resonant state, the input impedance is purely resistive, and the output voltage satisfies the following relationship:

[0027]

[0028] Among them U o is the output voltage, M is the mutual inductance value, U s is the input voltage, L1 is the transmitter compensation inductor, w is the operating angular frequency, I P is the transmitting coil current.

[0029] In the above solution, the size of the magnetic shielding piece at the transmitting end is larger than the outer diameter of the transmitting coil, and the size of the magnetic shielding piece at the receiving end is smaller than the outer diameter of the receiving coil.

[0030] In the above solution, the connection relationship of the LCC compensation unit at the transmitting end is:

[0031] The output end of the high-frequency inverter circuit is connected in sequence to the series compensation inductor L1 and the parallel compensation capacitor C1;

[0032] The parallel compensation capacitor C1 and the series compensation capacitor C p With the transmitting coil L P in parallel;

[0033] In the compensation unit of the receiving end S, the series compensation capacitor C s Directly with the receiving coil L s After connecting in series, they are connected to the rectifier circuit.

[0034] The present invention also provides a wireless power supply method for a train windshield monitoring system, which is applied to the wireless power supply system, comprising:

[0035] The transmitting coil and the receiving coil are fixed at corresponding positions inside and outside the windshield bellows respectively;

[0036] The system resonant state is maintained by the LCC-S type compensation network, so that the receiving end outputs a constant voltage characteristic;

[0037] A flexible magnetic shielding layer is used to suppress the fluctuation of magnetic coupling parameters caused by train vibration.

[0038] This invention addresses the issue of unstable power supply in wireless power systems caused by coupling mechanism position offsets through system-level optimization design, targeting the special operating conditions of train windshield monitoring systems (such as high-frequency vibration, windshield deformation, and metal interference). A detailed analysis is as follows:

[0039] 1. The present invention adopts a square coil structure as a technical means of the magnetic coupling mechanism to solve the problem of fluctuations in the self-inductance and mutual inductance parameters of the coupling mechanism caused by vibration and deformation of the train windshield, thereby achieving the effect of improving the stability of the magnetic field coupling.

[0040] During operation, the train windshield is forced to vibrate in three dimensions and bend and deform, causing the coupling coils attached to both sides of the rubber tarpaulin to deform. The self-inductance and mutual inductance parameters of traditional circular coils are prone to significant changes in this environment, affecting the efficiency of power transmission. The present invention adopts a square coil structure (outer side length 50mm, inner side length 20mm, wound 15 turns), which has a larger initial mutual inductance value under the same spatial dimensions compared to circular coils, and when bent and deformed (such as 90° bending), its self-inductance and mutual inductance parameter change rate is lower. This is because the geometric structure of the square coil provides a more uniform magnetic field distribution and a larger effective coupling area, which can better adapt to the expansion, contraction and rotational torsion of the windshield and reduce parameter drift. As a result, the magnetic field coupling is more stable, avoiding power supply interruptions or fluctuations caused by vibration, and ensuring that electric energy is continuously and efficiently transmitted to the receiving end.

[0041] 2. The present invention solves the energy loss problem caused by the skin effect under high-frequency working conditions by adopting the technical means of using Litz wire to wind the transmitting coil and the receiving coil, thereby achieving the effect of improving the energy transmission efficiency of the system.

[0042] In a high-frequency working environment of 200kHz, the current is concentrated on the surface of the conductor (skin effect), which causes the AC resistance of the traditional single-strand conductor to increase and generate additional losses. The present invention uses a multi-strand twisted Litz wire (single-strand wire diameter 0.05mm, 200 strands) to wind the coil. Its structure significantly reduces the high-frequency AC resistance by dispersing the current path. The twisted design of the Litz wire increases the effective surface area of ​​the conductor, reduces eddy current loss, and makes the current distribution more uniform. As a result, under the excitation of the square wave voltage output by the high-frequency inverter circuit, the ohmic loss of the coil is reduced, and more electrical energy is converted into effective magnetic field energy rather than heat energy, thereby improving the overall transmission efficiency from the transmitting end to the receiving end and supporting the stable operation of the monitoring sensor load.

[0043] 3. The present invention solves the problems of metal support structure interference and parameter fluctuation in a vibration environment by arranging flexible soft magnetic sheets on both sides of the coil as a magnetic shielding structure, while increasing the self-inductance and mutual inductance parameters, thereby achieving the effect of enhancing the system's anti-interference ability and parameter stability.

[0044] The train windshield environment has supporting structures such as metal aluminum frames, which are prone to eddy current effects and weaken magnetic field coupling; at the same time, vibration causes the coil position to shift, causing fluctuations in self-inductance and mutual inductance. The present invention uses a flexible rubber soft magnetic sheet (relative magnetic permeability 20-100) as a magnetic shielding layer. The transmitting end size (52mm) is slightly larger than the outer diameter of the coil, and the receiving end size (48mm) is slightly smaller than the outer diameter of the coil. The flexible material is made of a composite of ferrite magnetic powder and rubber. It can be bent to adapt to the deformation of the windshield. Compared with the rigid ferrite core, it can effectively suppress parameter changes caused by vibration. The soft magnetic sheet increases the magnetic permeability of the coil's magnetic circuit, strengthens the magnetic field concentration, reduces leakage magnetic field and external metal interference; at the same time, its elastic properties buffer the vibration impact and keep the self-inductance and mutual inductance relatively constant. As a result, the system maintains high coupling efficiency in a dynamic environment and avoids fluctuations in the power supply voltage due to external factors.

[0045] 4. The present invention solves the problem of unstable output voltage caused by load changes and vibrations by adopting the technical means of LCC-S compensation topology, achieving the effect of providing constant voltage output and adapting to the train operating environment.

[0046] The vibration of the train windshield causes the mutual inductance M of the coupling mechanism to change. The traditional compensation topology is prone to cause output voltage fluctuations, affecting the power supply of the sensor load. The present invention adopts an LCC-S compensation network, in which the transmitter includes a series compensation inductor L1, a parallel compensation capacitor C1 and a series compensation capacitor C P , the receiving end is the series compensation capacitor C s With the receiving coil L s Resonance. In the resonant state, the system input impedance is purely resistive, the reflected impedance is only related to the mutual inductance, and the output voltage U o According to the formula U o =(MU s ) / L1, where U s is the input voltage, L1 is a fixed inductor value. o Independent of load changes, only dependent on mutual inductance M and input voltage U s When vibration causes M to fluctuate, the constancy of L1 buffers the change and maintains U o At the same time, the LCC-S structure adapts to a wide range of offsets, ensuring that the system still operates at the resonant point when the windshield is squeezed or deformed, providing a constant voltage DC output to ensure continuous and reliable power supply for the monitoring sensors.

[0047] In summary, this invention achieves system-level optimization for multiple constraints on train windshields through the synergistic effect of the aforementioned technical approaches: the square coil maximizes contact area to resist misalignment, the Litz wire suppresses high-frequency losses to improve efficiency, the flexible soft magnetic sheet compensates for vibration to stabilize parameters, and the LCC-S topology maintains a constant output voltage to adapt to load variations. This solves the problem of unstable power supply and provides an efficient and reliable solution for powering sensors in enclosed environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a high frequency inverter;

[0049] Figure 2 It is a magnetic coupling device;

[0050] Figure 3 To compensate the network;

[0051] Figure 4 It is an uncontrolled rectifier circuit;

[0052] Figure 5 Equivalent model of windshield monitoring power supply system;

[0053] Figure 6 is the equivalent circuit topology based on the LCC-S compensation network;

[0054] Figure 7 This is a CRH3 folding canopy windshield, with (a) the overall structure, (b) the schematic diagram of the folding canopy section, and (c) the actual folding canopy section.

[0055] Figure 8 This is a schematic diagram of the placement of the coupling mechanism;

[0056] Figure 9 Comparison of square coils and circular coils. (a) Schematic diagram of an equivalent square coil, (b) Schematic diagram of an equivalent circular coil, and (c) the effect of coil bending on square and circular coils.

[0057] Figure 10 The ferrite rigid core (left) and the rubber soft magnetic sheet (right);

[0058] Figure 11 Diagram of the overall system for wireless power supply for windshield monitoring.

[0059] 1- Grounding cable, 2- Leaf spring, 3- Leaf spring seat assembly, 4- Grounding busbar, 5- Pedal bracket, 6- Pedal, 7- Floor covering fabric, 8- Mounting frame, 9- Double-layer corrugated awning, 10- Windshield hanging ring plate, 11- Windshield awning cavity, 12- Fixed end, 13- Canopy fabric, 14- Metal aluminum frame, 15- Support rod;

[0060] A1-transmitter coil, A1-1-transmitter compensation coil, A1-2-transmitter magnetic core, A1-3-transmitter shielding aluminum plate;

[0061] A2-receiving end coil, A2-1-receiving end shielding aluminum plate, A1-2-receiving end magnetic core. DETAILED DESCRIPTION

[0062] The following is a detailed description of the embodiments of the present invention. Although the present invention will be described and illustrated in conjunction with certain specific embodiments, it should be noted that the present invention is not limited to these embodiments. On the contrary, modifications or equivalent substitutions of the present invention are intended to fall within the scope of the claims of the present invention.

[0063] In addition, in order to better illustrate the present invention, numerous specific details are given in the following detailed description. It will be understood by those skilled in the art that the present invention can also be implemented without these specific details.

[0064] Based on the actual working conditions of the windshield monitoring sensor in the train, the present invention compares various traditional power supply methods for the sensor and proposes a method in this scenario that uses magnetic coupling wireless power supply technology to place coupling mechanisms on the inside and outside of the windshield surface respectively, so as to transmit energy from the external transmitting device of the windshield to the internal receiving device of the windshield, so as to achieve the goal of effectively obtaining energy from the power supply car and transmitting it to the internal monitoring sensor of the windshield through the wireless power supply system during the driving process.

[0065] Analyze and determine the optimal installation position of the coupling mechanism, and design a coupling mechanism suitable for the environment from aspects such as coil material, shape, size, magnetic shielding structure material, etc.

[0066] A circuit equivalent model based on magnetic field wireless power supply technology was established and analyzed. The "LCC-S" compensation circuit topology was selected as the compensation mechanism of the system, and the power supply mode of the monitoring sensor was designed.

[0067] 1. Overall technical solution

[0068] The schematic diagram of the equivalent model of the overall windshield monitoring power supply system is as follows: Figure 5 As shown in the figure, it mainly consists of a high-frequency inverter circuit, a transmitting coil and a receiving coil (magnetic coupling mechanism), a compensation network, a rectifier, and power supply for the sensor load and communication module. The energy transmitting board is powered by the train's onboard industrial frequency AC power supply. After rectification, it is converted into a high-frequency AC voltage through a high-frequency inverter. This voltage flows through the compensation circuit topology into the transmitting coil to generate a high-frequency induced magnetic field. The receiving coil induces energy in the high-frequency magnetic field and outputs high-frequency electricity. This voltage flows through the compensation circuit in the energy receiving board to the rectifier device to output DC power. This DC power is then sent to load components such as monitoring sensors to ensure the stable operation of the entire monitoring system.

[0069] like Figure 6The overall system circuit diagram is shown below. The high-frequency inverter utilizes a full-bridge inverter circuit topology. After setting the dead time, two pairs of switching transistors alternately conduct, converting electrical energy into an AC square wave voltage that is then fed into the resonant network. The windshield is constantly squeezed during train operation. To ensure stable energy transmission, a constant-voltage output "LCC-S" compensation topology with a certain degree of anti-offset performance was selected as the compensation network for this system. When the system reaches resonant state, energy transmission efficiency is maximized, and electrical energy is transmitted to the receiving end via a magnetic coupling mechanism. The AC voltage generated by the receiving device is converted into DC voltage by a rectifier bridge composed of diodes at the rear to power the system.

[0070] 2. Technical solution of magnetic coupling mechanism in windshield bellows environment

[0071] The core components consist of a transmitter, receiver, and magnetic core material. The transmitter coil is typically wound with Litz wire to reduce high-frequency skin effect losses. The receiver coil should be symmetrical or compatible with the transmitter coil, taking into account space constraints and the mutual inductance M with the transmitter coil. The choice of magnetic core material directly affects magnetic field coupling efficiency, energy loss, and system stability.

[0072] Selection of the location of the coupling mechanism: The folding awning windshield structure targeted by the present invention is as follows: Figure 7 As shown in (a).

[0073] During high-speed train operation, the windshield inside the train is forced to vibrate due to the vortices and pressure pulsations in the annular cavity between the inner and outer windshields. Furthermore, when the train turns, the interaction between structural components exerts tensile and compressive forces on the windshield bellows structure from both sides of the train. At this point, the windshield bellows structure, a hybrid rigid-flexible structure, experiences three-dimensional vibrations, including expansion, contraction, and rotational torsional variations.

[0074] Due to the eddy current effect of metal in the electromagnetic field, if there is a metal obstacle between the transmitting coil and the receiving coil, the wireless transmission effect of the power will be greatly affected, and even the power cannot be transmitted. Therefore, the coupling coil must be attached to both sides of the rubber awning. Figure 8 shown.

[0075] Coil Material Selection: Because the system operates at a 200kHz frequency, high-frequency currents can cause significant skin effect. Litz wire (200 strands) with a single-strand diameter of 0.05mm was selected. Its multi-strand twisted structure effectively reduces AC resistance and losses, while its cross-sectional area meets the current-carrying requirements with a safety margin of 2 times (0.7A operating current).

[0076] Choice of coupling coil shape: Both circular coils and square coils are suitable for the design of coupling mechanisms where the coils face each other for energy transmission, such as Figure 9As shown in the figure, using a circular coil with a wire diameter of 1mm and 15 turns, an outer diameter of 50mm and an inner diameter of 20mm, and a square coil with an outer side length of 50mm and an inner side length of 20mm as examples, the changes in the self-inductance and mutual inductance parameters of the coils under conformal bending are compared. It can be seen that under the same spatial dimension parameters, the self-inductance and mutual inductance values ​​of the square coil are greater than those of the circular coil. Furthermore, when the coil bends at a 90° angle, the self-inductance value of the square coil changes by 11.5%, while the self-inductance value of the circular coil changes by 12.1%. In a dual-coil structure, when the transmitting coil bends at an angle between 0 and 90°, the mutual inductance value of the square coil changes within 19.6%, while the mutual inductance value of the circular coil changes within 20.9%.

[0077] As the preceding analysis indicates, the windshield bellows structure is subject to constant three-dimensional low-frequency vibration during train operation, and the coupling coils attached to the bellows' sides also undergo dynamic bending deformation. When the coils are bent and deformed, the self-inductance and mutual inductance parameters of square and circular coils exhibit essentially the same change characteristics, with the square coil exhibiting slightly better parameter immunity than the circular coil. Furthermore, the mutual inductance of the square coil is greater than that of the circular coil within the same spatial dimensions. Therefore, the coupling coils in this paper adopt a square coil structure.

[0078] Magnetic shielding structure material selection and design: When designing a coupling mechanism, adding a magnetic shielding structure can increase the self-inductance and mutual inductance parameters of the coupling coil, thereby improving the wireless power transmission capability of the system. In addition, there are many metal support structures in the windshield bellows environment. In order to reduce or even isolate the impact of metal objects on the coupling mechanism, the coupling line is used in the special vibration environment of the windshield bellows. Therefore, this design uses a flexible rubber soft magnetic sheet as the magnetic shielding structure. Figure 10 As shown in the figure, compared to rigid ferrite cores, rubber soft magnetic sheets are flexible structures made of ferrite powder, rubber, and chlorinated polyethylene (CPE). They can be cut and bent according to design requirements. Although the relative magnetic permeability of rubber soft magnetic sheets is lower than that of traditional ferrite cores due to the support of multiple materials, their flexible and bendable properties are well suited for coupling mechanism design in the vibration environment of windshield bellows.

[0079] In the uniquely close transmission distance environment of a windshield bellows, adding soft magnetic sheets on both sides of the coupling coil not only increases the coil's self-inductance and mutual inductance parameters, but also significantly suppresses fluctuations in the coil's self-inductance and mutual inductance when the coil is bent. Conventional magnetic shielding structures are typically the same shape as the coil and are equal to or slightly larger in size. Therefore, this design uses square soft magnetic sheets measuring 52mm at the transmitting end and 48mm at the receiving end.

[0080] 3. Technical solution for compensation network

[0081] The equivalent circuits of the sending and receiving ends of the LCC-S compensation network are as follows: Figure 3 As shown. s is the input voltage, L P , L S are the transmitting and receiving coils of the magnetic coupling mechanism, R L is the load resistance, jwMI p The transmitting mechanism is equivalent to a voltage source on the receiving device, and the remaining inductance and capacitance work together to put the circuit in a resonant state.

[0082] Analyze the equation of the circuit model. When the system works in the resonant state, the compensation capacitor C at the receiving end is s =(C s2 +C s1 ) and coil self-inductance L S Series resonance, the equivalent resistance is R L , the reflected impedance Z of the power receiving end mapped to the transmitting end r for:

[0083]

[0084] From KVL, the input voltage is:

[0085]

[0086] Input impedance Z in for:

[0087]

[0088] Parallel compensation capacitor C f The voltage across the coil branch is equal to:

[0089]

[0090] Substituting the compensation element parameter relationship, we can get:

[0091]

[0092] Combined, the system output voltage U o for:

[0093]

[0094] Analysis of the above expressions reveals that when the system is fully resonant, the system input impedance is purely resistive. When the system input voltage is constant, the transmitting coil current is dependent solely on the resonant inductance L1 and the system operating frequency w. When the system is operating stably, the resonant inductance and operating frequency remain unchanged, and therefore the coil current remains unchanged. Even if coil coupling disappears and the mutual inductance reaches zero (no-load), the system remains operational without excessive current and circuit damage. Therefore, LCC-S wireless power transmission systems can operate in no-load conditions. When the load of the LCC-S resonant compensation network changes, the power receiving end exhibits constant voltage source characteristics, making it easier to achieve dynamic balance of the system output voltage.

[0095] 4. Beneficial effects brought by the technical solution of the present invention

[0096] For the first time, the actual working conditions inside the windshield were correlated with the train's operating status for fitting analysis, and effective monitoring of the interior of the windshield was proposed. In order to solve the problem of difficulty in powering the train windshield monitoring sensors, an application plan was proposed without destroying the environmental structure of the train windshield, providing a new approach to solving the problem of difficulty in powering sensors in closed environments that may exist in multiple fields such as railways and urban rail transit systems. Based on the internal environment of the train windshield and the characteristics of the sensor load conditions, the offset problem caused by misalignment of the coupling mechanism that may exist during train driving was analyzed. A simple control strategy for AC switching was designed, the topology of the hybrid compensation circuit was changed, and the shape of the magnetic core and coil of the coupling mechanism was optimized to form a complete wireless power supply system to provide stable power to various monitoring sensors inside the windshield, ensuring the normal operation of the windshield monitoring system.

Claims

1. A wireless power supply system for a train windshield monitoring system, characterized in that: include: a high-frequency inverter circuit configured to convert direct current into high-frequency alternating current and output a square wave voltage through a full-bridge inverter circuit topology; A magnetic coupling mechanism includes a transmitting coil and a receiving coil, which are attached to both sides of the rubber tarpaulin of the train windshield to achieve contactless transmission of electrical energy through magnetic field coupling. The transmitting coil and the receiving coil adopt a square coil structure and are wound with Litz wire to reduce high-frequency skin effect losses. a compensation network, adopting an LCC-S type compensation topology, configured to form resonance with the magnetic coupling mechanism, provide a constant voltage output and adapt to the vibration environment during train operation; a rectifier configured to convert the alternating current induced by the receiving coil into direct current to supply power to a windshield interior monitoring sensor load; It also includes a flexible soft magnetic sheet as a magnetic shielding structure. The flexible soft magnetic sheet is arranged on both sides of the transmitting coil and the receiving coil to increase the coil self-inductance and mutual inductance parameters and suppress parameter fluctuations caused by vibration.

2. The wireless power supply system according to claim 1, wherein: The square coil structures of the transmitting coil and the receiving coil have an outer side length of 50 mm and an inner side length of 20 mm, and the number of winding turns is 15.

3. The wireless power supply system according to claim 2, wherein: The flexible soft magnetic sheet is a square soft magnetic sheet, wherein the side length of the transmitting end soft magnetic sheet is 52 mm, and the side length of the receiving end soft magnetic sheet is 48 mm, so as to optimize the magnetic field coupling efficiency and anti-offset capability.

4. The wireless power supply system according to claim 1, wherein: The system operating frequency is 200kHz.

5. The wireless power supply system according to claim 1, wherein: The compensation network includes a transmitter compensation circuit and a receiver compensation circuit. The receiver compensation circuit includes a capacitor and a receiving coil self-inductance in series resonance, so that the system operates in a resonant state, the input impedance is purely resistive, and the output voltage satisfies the following relationship: Among them U o is the output voltage, M is the mutual inductance value, U s is the input voltage, L1 is the transmitter compensation inductor, w is the operating angular frequency, I P is the transmitting coil current.

6. The wireless power supply system according to claim 1, wherein: The size of the magnetic shielding piece at the transmitting end is larger than the outer diameter of the transmitting coil, and the size of the magnetic shielding piece at the receiving end is smaller than the outer diameter of the receiving coil.

7. The wireless power supply system according to claim 1, wherein: The connection relationship of the LCC compensation unit at the transmitting end is: The output end of the high-frequency inverter circuit is connected in sequence to the series compensation inductor L1 and the parallel compensation capacitor C1; The parallel compensation capacitor C1 and the series compensation capacitor C p With the transmitting coil L P in parallel; In the receiving end S compensation unit, the series compensation capacitor C s Directly with the receiving coil L s After connecting in series, they are connected to the rectifier circuit.

8. A wireless power supply method for a train windshield monitoring system, characterized in that The wireless power supply system according to any one of claims 1 to 7 comprises: The transmitting coil and the receiving coil are fixed at corresponding positions inside and outside the windshield bellows respectively; The system resonant state is maintained by the LCC-S type compensation network, so that the receiving end outputs a constant voltage characteristic; A flexible magnetic shielding layer is used to suppress the fluctuation of magnetic coupling parameters caused by train vibration.

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