Power frequency magnetic field interference resistant loop and single-phase intelligent electric meter

Abstract

The invention provides an anti-power-frequency magnetic field interference loop and a single-phase intelligent ammeter, the anti-power-frequency magnetic field interference loop comprises a diverter structure, the diverter structure comprises a manganese copper piece and a hollow conductive piece, and the diverter structure is used for generating mutually counteracted induced electromotive forces in a power-frequency magnetic field environment; the pins of the manganin piece and the hollow conductive piece are fixedly welded at corresponding positions on a printed circuit board, and the direction of a target magnetic field is perpendicular to the cross section of the manganin piece and the contour section of the hollow conductive piece; the cross section of the manganese-copper piece is parallel to the profile cross section of the hollow conductive piece, and the distance between the cross section and the profile cross section is smaller than a preset distance; the target magnetic field direction is a magnetic field direction corresponding to the power frequency induced electromotive force. According to the invention, mutual offset induced electromotive forces can be generated in a power frequency magnetic field, manganese-copper sampling signals are prevented from being interfered, meanwhile, the production automation degree and efficiency are improved, the process is simplified, the cost is reduced, and the development period is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smart meters, and particularly relates to an anti-power-frequency magnetic field interference circuit and a single-phase smart meter. BACKGROUND

[0002] In order to improve the anti-interference performance of an electric energy meter, relevant standards require that, when a voltage circuit applies 1.15 times the nominal voltage and a current terminal is open, a magnetic field is applied to three vertical planes of the electric energy meter in a specific power-frequency magnetic field environment (0.5 mT power-frequency magnetic field), and within 20 times the starting time, the test output of the electric energy meter should not generate more than one pulse. The existing shunt manganese-copper structure adopts a brazing connection to sample a soft wire, but there are problems such as low production automation, high labor cost, poor product quality consistency, and the like, and the sampling soft wire is not fixed, and transportation vibration can cause displacement of the sampling soft wire, thereby affecting the anti-power-frequency magnetic field function of the shunt.

[0003] At present, by directly welding a sampling hard needle on the surface of the manganese copper and reasonably arranging the sampling hard needle, the generated electromotive force signals are positively and negatively offset, so that the anti-interference purpose is achieved. However, this technology needs to be configured with at least two hard needles with complex shapes, which increases the material cost and manufacturing complexity, and the hard needle shape and spatial layout design are complex, which leads to a long development cycle.

[0004] Therefore, there is an urgent need for an anti-power-frequency magnetic field interference circuit and a single-phase smart meter to solve the above problems. SUMMARY

[0005] In view of the problems in the prior art, the present application provides an anti-power-frequency magnetic field interference circuit and a single-phase smart meter.

[0006] The present application provides an anti-power-frequency magnetic field interference circuit, comprising a shunt structure, wherein: The shunt structure comprises a manganese copper piece and a hollow conductive piece, for generating mutually offset induced electromotive forces in a power-frequency magnetic field environment; The pin of the manganese copper piece and the hollow conductive piece are fixedly welded on corresponding positions on a printed circuit board, and the target magnetic field direction is perpendicular to the cross section of the manganese copper piece and the profile section of the hollow conductive piece; the cross section of the manganese copper piece is parallel to the profile section of the hollow conductive piece, and the distance therebetween is less than a preset distance; and the target magnetic field direction is the magnetic field direction corresponding to the power-frequency induced electromotive force.

[0007] According to the anti-power-frequency magnetic field interference circuit provided by the present application, the hollow conductive piece is a U-shaped needle component.

[0008] According to the anti-power frequency magnetic field interference circuit provided by the application, the cross section of the manganese-copper piece is determined based on the area between the positive and negative pins of the manganese-copper piece; the pins of the manganese-copper piece are connected with the open ends of the U-shaped needle component, and the open ends are connected with the corresponding pads on the printed circuit board, respectively.

[0009] According to the anti-power frequency magnetic field interference circuit provided by the application, the first pad and the second pad are cross-connected through the internal wiring of the printed circuit board, wherein the first pad is the pad corresponding to the pin of the manganese-copper piece on the printed circuit board; and the second pad is the pad corresponding to the open end of the U-shaped needle component on the printed circuit board.

[0010] According to the anti-power frequency magnetic field interference circuit provided by the application, the anti-power frequency magnetic field circuit further comprises a U-shaped needle size optimization sub-circuit, wherein: The U-shaped needle size optimization sub-circuit comprises a sample U-shaped needle and a size optimization circuit board, and the open end of the sample U-shaped needle is connected with the rotating shaft on the top of the size optimization circuit board.

[0011] According to the anti-power frequency magnetic field interference circuit provided by the application, before the pin of the U-shaped needle component is connected with the second pad, the pin at the bottom of the size optimization circuit board is connected with the second pad through a wire, wherein the U-shaped needle size optimization sub-circuit is used to adjust the included angle between the profile cross section of the sample U-shaped needle and the target magnetic field direction through the rotating shaft, and the height of the U-shaped needle component is determined based on the induced power corresponding to each included angle.

[0012] According to the anti-power frequency magnetic field interference circuit provided by the application, the rotating shaft is connected with a stepping motor through a transmission structure, and the stepping motor is used to drive the rotating shaft to adjust the included angle between the profile cross section of the sample U-shaped needle and the target magnetic field direction according to a preset stepping angle.

[0013] According to the anti-power frequency magnetic field interference circuit provided by the application, the height of the U-shaped needle component is calculated based on the target included angle and the height of the sample U-shaped needle, wherein the target included angle is the included angle corresponding to the induced power smaller than the starting power.

[0014] According to the anti-power frequency magnetic field interference circuit provided by the application, when it is determined that there are multiple target included angles, the height of the U-shaped needle component is calculated based on the target included angle corresponding to the power positive-negative jump and the height of the sample U-shaped needle in multiple target included angles.

[0015] The application further provides a single-phase intelligent electric meter comprising the anti-power frequency magnetic field interference circuit. The anti-power frequency magnetic field interference loop is used for generating mutual cancellation induced electromotive force in a power frequency magnetic field environment.

[0016] The anti-power frequency magnetic field interference loop and the single-phase intelligent electric meter provided by the application are characterized in that: the shunt structure is composed of a manganese copper piece and a hollow conductive piece, and the pins of the two are fixedly welded on the corresponding positions of the printed circuit board. When the power frequency magnetic field is perpendicular to the area enclosed by the hollow conductive piece and the manganese copper piece, mutual cancellation induced electromotive force can be generated in the power frequency magnetic field, so that the manganese copper sampling signal is immune to interference, and the production automation degree and efficiency are improved, the process is simplified, the cost is reduced, and the development cycle is shortened. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 The structure diagram of the anti-power frequency magnetic field interference loop provided by the application is shown in the figure. Figure 2 The structure diagram of the manganese copper piece provided by the application is shown in the figure. Figure 3 The installation position diagram of the U-shaped needle size optimization sub-circuit provided by the application is shown in the figure. Figure 4 The left view of the U-shaped needle size optimization sub-circuit provided by the application is shown in the figure. Figure 5 The angle change diagram of the U-shaped needle in the U-shaped needle size optimization sub-circuit provided by the application is shown in the figure. Figure 6 The structure diagram of the single-phase intelligent electric meter provided by the application is shown in the figure. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the application more clear, the technical solutions in the application will be described clearly and completely in the following combined with the drawings in the application. Obviously, the described embodiments are some embodiments of the application, not all embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0020] The existing intelligent electric meter generally adopts manganese copper shunt for current sampling. However, the current manganese copper shunt will generate induced electromotive force under the action of power frequency magnetic field, resulting in no-load false metering. The prior art mainly improves the anti-power frequency magnetic field interference ability of the manganese copper shunt by the following two methods: Method one: the manganese copper structure of the traditional shunt generally adopts the welding mode, and is connected to the printed circuit board through the sampling flexible wire. Since the welding, thermoplastic tube sleeving and tightening of the sampling flexible wire are all manual operations, there are problems such as low production automation, high labor cost and difficult to guarantee the consistency of product quality. Moreover, the sampling flexible wire is not fixed, and the transportation vibration may cause the displacement of the sampling flexible wire, thereby affecting the function of the shunt against the power frequency magnetic field. The traditional flexible wire welding process has been unable to meet the design requirements of the single-phase intelligent meter.

[0021] Method two: the existing technology directly welds the sampling hard needle on the surface of the manganese copper, and reasonably arranges the spatial position of the hard needle on the manganese copper, so that the area enclosed by the manganese copper and the sampling hard needle generates a positive and negative mutual cancellation of the electromotive force signal in the power frequency magnetic field, thereby achieving that the sampling signal of the manganese copper is not disturbed by the external power frequency magnetic field. However, this scheme needs to be configured with at least two hard needles with complex shapes, which increases the material cost and manufacturing complexity, and the complex shape and spatial layout design of the hard needle lead to a long development cycle.

[0022] In view of the problems existing in the prior art, the present application provides an anti-power frequency magnetic field interference loop of a single-phase intelligent meter, which only needs to be welded with a hollow conductive piece (such as a U-shaped needle) to form an area enclosed with a manganese copper piece, so that the induced electromotive force generated in the power frequency magnetic field is realized to be positive and negative, thereby achieving that the sampling signal of the manganese copper piece is not disturbed by the external power frequency magnetic field, improving the degree of automation and efficiency of production, simplifying the process, reducing the cost, and shortening the development cycle.

[0023] Figure 1 The structure diagram of the anti-power frequency magnetic field interference loop provided by the present application can be referred to Figure 1 The present application provides an anti-power frequency magnetic field interference loop, which comprises a shunt structure, wherein: The shunt structure comprises a manganese copper piece 101 and a hollow conductive piece 102, which are used to generate mutually cancelled induced electromotive forces in a power frequency magnetic field environment; Wherein, the pins of the manganese copper piece 101 and the hollow conductive piece 102 are fixedly welded on the corresponding positions on the printed circuit board 103, and the target magnetic field direction is perpendicular to the cross section of the manganese copper piece 101 and the profile section of the hollow conductive piece 102; the cross section of the manganese copper piece 101 is parallel to the profile section of the hollow conductive piece 102, and the distance is less than a preset distance; the target magnetic field direction is the magnetic field direction corresponding to the power frequency induced electromotive force.

[0024] On the basis of the above embodiment, the hollow conductive piece 102 is a U-shaped needle component.

[0025] In the present application, the shunt structure mainly consists of two parts: a manganese copper piece 101 (which can be referred to Figure 1(Front view) and hollow conductive element 102 (see reference) Figure 1 The left view shows a U-shaped needle component. The manganese copper component 101, as the core element for current sampling, is widely used in current detection in electricity meters due to its low resistivity and high stability. In this invention, the manganese copper component 101 is designed with a specific shape (e.g., a straight line) to ensure effective cooperation with the hollow conductive component 102.

[0026] The hollow conductive element 102, as a key component for anti-interference, together with the manganese-copper element 101, forms a closed loop. In this invention, the shape and position of the hollow conductive element 102 are determined by calculation to ensure that mutually canceling induced electromotive forces are generated under a specific magnetic field direction. For example, the hollow conductive element 102 can also be a semi-circular hollow structure, a rectangular hollow structure, etc. The following embodiments of this invention are mainly described using a U-shaped needle component.

[0027] Specifically, the hollow conductive element 102 is fixed on the printed circuit board 103 parallel to the cross-section of the manganese copper element 101 (i.e., the sampling portion of the manganese copper element 101). Further, this invention is described with the target magnetic field direction as the Y-axis, meaning it aims to cancel interference present in the smart meter along the Y-axis.

[0028] For reference Figure 1 As shown, the power frequency magnetic field in the Y-axis direction is perpendicular to the cross-section of the manganese copper component 101 and the outline cross-section of the hollow conductive component 102. This arrangement ensures that the effective projected area of ​​the cross-section of the manganese copper component 101 and the outline cross-section of the hollow conductive component 102 in the X-axis and Z-axis directions approaches zero. This invention achieves this by precisely controlling the relative position and spacing between the hollow conductive component 102 and the manganese copper component 101, so that when an external power frequency magnetic field (i.e., the target magnetic field direction) is applied in these directions, the induced electromotive force generated is also extremely small because the projected area is almost zero.

[0029] In this invention, the pins of the manganese copper component 101 and the hollow conductive component 102 are fixedly soldered to corresponding positions on the printed circuit board 103. This hard-connection method not only improves the automation and efficiency of production, but also simplifies the process, reduces costs, and enhances product consistency and reliability.

[0030] The present application is based on Faraday's law of electromagnetic induction (ε = -dΦ / dt), the induced electromotive force in a closed circuit is proportional to the rate of change of magnetic flux through the circuit. By optimizing the structure layout of the shunt, the U-shaped needle loop and the manganese copper piece produce mutual offset induced electromotive force in a certain magnetic field direction (such as the Y-axis direction), thereby achieving the purpose of anti-interference. Among them, the magnetic flux Φ = B·S·sinθ, B is the magnetic induction intensity, S·sinθ is the effective projection area in the magnetic field direction, and θ is the angle between the magnetic field direction and the plane. For example, when the X-axis and Z-axis direction magnetic field is applied, through the Figure 1 The product structure layout shown can be seen that θ tends to 0°, and the effective area is 0 (that is, the projection area in the X-axis and Z-axis direction of the magnetic field is 0); when the Y-axis direction magnetic field is applied, θ tends to 90°, and the effective area is S, at this time, only need to confirm whether the induced electromotive force generated in the Y-axis direction is in a reasonable range.

[0031] Further, according to the standard conditions, the smart meter needs to be immersed in the Y-axis direction, and the magnetic field environment with a magnetic induction intensity of 0.5mT (400A / m); the voltage circuit applies 1.15 times the nominal voltage, and the current circuit has no current; within 20 times of the starting time, the test output of the smart meter should not generate more than one pulse. The calculation formula of the starting time τ (unit: s) is: Among them, k represents the number of pulses output by the smart meter per kilowatt hour, with the unit of imp / kWh; represents the nominal voltage, with the unit of V; represents the starting current, with the unit of A.

[0032] In the present application, the test requires that within 20 times of the starting time, the test output of the smart meter should not generate more than one pulse, that is, the induced power generated by the smart meter in the 0.5mT environment P should be less than the starting power , and the calculation formula of the starting power (unit: W) is: Since the target magnetic field direction is perpendicular to the cross section of the manganese copper piece 101 and the profile section of the hollow conductive piece 102, this design ensures that when the external power frequency magnetic field is applied along this direction, the spatial layout advantage between the hollow conductive piece and the manganese copper piece can be maximized to produce the best anti-interference effect. At the same time, the cross section of the manganese copper piece 101 and the profile section of the hollow conductive piece 102 are kept parallel, and the distance is less than a preset distance, to further optimize the anti-interference performance.

[0033] ​​In practical applications, the anti-power frequency magnetic field interference loop is integrated into a single-phase smart meter. During testing, the smart meter is immersed in a power frequency magnetic field environment with a specific direction and intensity (e.g., Y-axis direction, magnetic induction intensity of 0.5 mT), while applying specified voltage and current conditions. By monitoring the number of test output pulses of the smart meter, it can be verified whether its anti-interference performance meets the standard requirements. In addition, through the application of automated test fixtures and high-efficiency parameter tuning tools, the optimal U-shaped needle height and angle parameters can be quickly determined, further shortening the development cycle and reducing costs.

[0034] The anti-power frequency magnetic field interference loop and single-phase smart meter provided by the present application have a shunt structure composed of a manganese copper piece and a hollow conductive piece. The pins of the two are fixedly welded to the corresponding positions on the printed circuit board. When the power frequency magnetic field is perpendicular to the area enclosed by the hollow conductive piece and the manganese copper piece, it can generate mutual cancellation of induced electromotive force in the power frequency magnetic field, so that the manganese copper sampling signal is not disturbed, while improving the degree of automation and efficiency of production, simplifying the process, reducing costs and shortening the development cycle.

[0035] On the basis of the above embodiment, the cross section of the manganese copper piece is determined based on the area between the positive and negative pins of the manganese copper piece; the pins of the manganese copper piece and the open end of the U-shaped needle component are respectively connected to the corresponding pads on the printed circuit board.

[0036] In the present application, the cross section of the manganese copper piece is defined by the area between its positive and negative pins. In a smart meter, the manganese copper piece serves as a key element for current sampling, and its two ends are usually provided with pins (positive and negative) for connection with other parts in the circuit. The area between the two pins, i.e., the part of the manganese copper piece that actually participates in current conduction, is defined as the cross section of the manganese copper piece. The shape and size of this cross section have a direct impact on the resistance characteristics of the manganese copper piece, which in turn affects the accuracy of current sampling. Figure 2 The structure diagram of the manganese copper piece provided by the present application can be referred to Figure 2 The positive pin 2011 and the negative pin 2022 in the cross section 201 of the manganese copper piece are respectively connected to the corresponding pads on the printed circuit board. This connection method can be realized by using existing welding process, ensuring stable and reliable electrical connection between the manganese copper piece and the printed circuit board. During the welding process, parameters such as welding temperature, time and soldering amount need to be controlled to avoid damage to the manganese copper piece or the printed circuit board, while ensuring the mechanical strength and electrical performance of the welding points.

[0037] In the present application, the U-shaped needle component is a key component of the anti-interference loop, and its open end is designed to be connected with the pad on the printed circuit board. The shape and spatial layout of the U-shaped needle component can ensure that the induced electromotive force generated by the manganese copper piece can be offset in the power frequency magnetic field environment, thereby achieving the anti-interference effect. Specifically, in the present application, the open end of the U-shaped needle component is fixed on the corresponding pad of the printed circuit board by welding or other reliable connection methods. This connection method needs to ensure the stability of the electrical connection between the U-shaped needle component and the printed circuit board, while maintaining the relative position accuracy of the U-shaped needle component on the printed circuit board, so as to play the best anti-interference role in the magnetic field environment.

[0038] In practical application, the manganese copper piece and the U-shaped needle component are connected with the pads on the printed circuit board through their respective pins and open ends to form a complete anti-interference loop, which not only ensures the stability of the electrical connection, but also facilitates automated production and quality control. In order to further improve the anti-interference performance, the layout of the manganese copper piece and the U-shaped needle component on the printed circuit board needs to be optimized. The present application can ensure the best anti-interference effect in a specific magnetic field direction by precisely controlling the relative position and distance between the two. At the same time, factors such as the interlayer structure and wiring method of the printed circuit board also need to be considered to reduce the influence of electromagnetic interference on the circuit performance. In the present application, the sampling point pad of the manganese copper piece and the pad of the U-shaped needle component are connected through the internal wiring of the printed circuit board, so that in the target magnetic field direction (such as the Y-axis direction in the figure) Figure 1 , the U-shaped needle component and the manganese copper piece generate mutually offset induced electromotive forces.

[0039] On the basis of the above embodiment, the first pad and the second pad are cross-connected by the internal wiring of the printed circuit board, wherein the first pad is the pad corresponding to the pin of the manganese copper piece on the printed circuit board; and the second pad is the pad corresponding to the open end of the U-shaped needle component on the printed circuit board.

[0040] In the present application, cross-connection refers to connecting the corresponding pads of two different elements on the printed circuit board through internal wiring in a non-linear (i.e. cross) manner. The main purpose of this connection method is to optimize the current path in the power frequency magnetic field environment, so that the manganese copper piece and the U-shaped needle component generate mutually offset induced electromotive forces, thereby achieving the anti-interference effect.

[0041] Specifically, the first pad is the corresponding connection point of the manganese-copper piece pin on the printed circuit board. As the core element of current sampling, the pin of the manganese-copper piece is responsible for leading the current signal in and out of the manganese-copper piece. When designing the printed circuit board, a specific pad position will be allocated for each pin of the manganese-copper piece, and these pads are connected to other circuit elements through the internal wiring of the printed circuit board. In this invention, the first pad is specifically the pad of the positive or negative pin of the manganese-copper piece on the printed circuit board.

[0042] The second pad is the corresponding connection point of the open end of the U-shaped needle component on the printed circuit board. As a key part of the anti-interference loop, the open end of the U-shaped needle is designed for electrical connection with the printed circuit board. When designing the printed circuit board, a specific pad position will also be allocated for the open end of the U-shaped needle, and this pad is connected to the manganese-copper piece or other circuit elements through the internal wiring of the printed circuit board. In this invention, the second pad is specifically the pad of the open end of the U-shaped needle on the PCB.

[0043] Further, during the manufacturing process of the printed circuit board, the first pad (the pad corresponding to the manganese-copper piece pin) and the second pad (the pad corresponding to the open end of the U-shaped needle) are cross-connected through the internal wiring of the printed circuit board. This cross-connection method involves interlayer wiring of a multi-layer printed circuit board to ensure the optimization of the current path and the maximization of the anti-interference effect.

[0044] Through this cross-connection method, when an external power frequency magnetic field is applied to the printed circuit board, the manganese-copper piece and the U-shaped needle component will generate mutual cancellation of induced electromotive force. Since their current paths are crossed, the two induced electromotive forces will cancel each other out, thereby reducing the impact on the metering performance of the smart meter. This anti-interference design is particularly suitable for smart meter applications in complex electromagnetic environments, and can significantly improve the anti-interference ability and metering accuracy of the smart meter.

[0045] On the basis of the above-mentioned embodiments, the anti-power frequency magnetic field loop further comprises a U-shaped needle size optimization sub-circuit, wherein: The U-shaped needle size optimization sub-circuit comprises a sample U-shaped needle and a size optimization circuit board, and the open end of the sample U-shaped needle is connected to the rotating shaft on the top of the size optimization circuit board. Before the pin of the U-shaped needle component is connected to the second pad, the pin on the bottom of the size optimization circuit board is connected to the second pad through a wire, wherein the U-shaped needle size optimization sub-circuit is used to adjust the included angle between the profile cross section of the sample U-shaped needle and the target magnetic field direction through the rotating shaft, and determine the height of the U-shaped needle component based on the induced power generated by each included angle.

[0046] Figure 3The installation position diagram of the U-shaped needle size optimization sub-circuit provided by the present application can refer to Figure 3 As shown in the figure, before the U-shaped needle component is welded on the printed circuit board, the U-shaped needle size optimization sub-circuit 301 can be temporarily welded on the second pad through a wire. Figure 4 The left view of the U-shaped needle size optimization sub-circuit provided by the present application can refer to Figure 4 As shown in the figure, in the present application, the sample U-shaped needle 401 in the U-shaped needle size optimization sub-circuit is a U-shaped needle model with adjustable height and open end, which is used to simulate the function of the actual U-shaped needle component in the magnetic field. The open end of the sample U-shaped needle 401 is designed to be connected with the rotating shaft 4021 on the top of the size optimization circuit board 402, so as to adjust the included angle with the direction of the magnetic field.

[0047] The size optimization circuit board 402 is a special circuit board, which is provided with a rotating shaft 4021 on the top for connecting the open end of the sample U-shaped needle 401, and is provided with pins on the bottom for connecting with the second pad (i.e. the corresponding pad of the U-shaped needle component on the printed circuit board) through a wire. In addition, the size optimization circuit board 402 can be integrated with a stepping motor control circuit, an induced power measurement circuit, etc. inside, so as to realize automatic testing and data processing.

[0048] Before the pins of the U-shaped needle component are connected with the second pad, the present application first connects the pins on the bottom of the size optimization circuit board 402 with the second pad through a wire. In this way, the sample U-shaped needle 401 forms an electrical connection with the circuit of the smart meter to be tested through the size optimization circuit board 402, so that the anti-power frequency magnetic field loop is first assembled with the U-shaped needle size optimization sub-circuit before the U-shaped needle component is installed, to optimize the size of the U-shaped needle component. Then, the rotating shaft 4021 on the top of the size optimization circuit board 402 can be used to accurately adjust the included angle θ between the profile section of the sample U-shaped needle 401 and the direction of the target magnetic field. This step determines the size and direction of the induced electromotive force generated by the U-shaped needle in the magnetic field.

[0049] Further, the electric energy meter assembled with the above anti-power frequency magnetic field interference loop is placed in a magnetic field of 0.5 mT in the Y-axis direction, and a voltage of 1.15 Un is applied (open circuit current). Figure 5 The angle change diagram of the U-shaped needle when the U-shaped needle size optimization sub-circuit provided by the present application is running can refer to Figure 5 As shown in the figure, the included angle θ of the sample U-shaped needle 401 is accurately rotated by a stepping motor, and each adjustment of an angle (such as 1° step) is paused, and the real-time induced power P is read. The induced power P can be obtained by reading through the MTS test software through a Bluetooth or RS485 interface.

[0050] Further, after scanning the required angle range (e.g. 0° to 90°), the inductive power P data corresponding to each angle θ is derived. By analyzing these data, the angle θ with the smallest absolute value of inductive power P (closest to zero) is selected min , which represents the direction in which the U-shaped needle generates the smallest induced electromotive force under the magnetic field condition. Then, according to the geometric relationship, the height H of the U-shaped needle required by the actual electric energy meter can be calculated by the formula H = L sin(θ min ), where L is the height of the sample U-shaped needle 401, and θ min is the angle between the sample U-shaped needle 401 and the magnetic field. Finally, the U-shaped needle with the standard size closest to the calculated value H is selected as the final solution.

[0051] On the basis of the above embodiment, the rotating shaft is connected to the stepping motor through a transmission structure, and the stepping motor is used to drive the rotating shaft to adjust the included angle between the profile section of the sample U-shaped needle and the target magnetic field direction according to a preset stepping angle.

[0052] In the present application, the stepping motor serves as a power source to convert an electric pulse signal into precise angular displacement or linear displacement. The rotation angle is accurately controlled by inputting the number of pulses, and higher resolution can be achieved by combining subdivision driving technology. Acceleration, deceleration and stopping can be completed in a short time, which is suitable for frequent start-stop scenarios. In the U-shaped needle optimization process, the stepping motor drives the rotating shaft by a preset stepping angle (e.g. 1° step) to gradually adjust the included angle between the sample U-shaped needle and the magnetic field.

[0053] In the present application, the rotation of the stepping motor is transmitted to the rotating shaft through a transmission structure, and deceleration, torque increase or change of motion direction can be achieved. When the U-shaped needle size optimization sub-circuit is temporarily welded on the second pad and powered on, the stepping motor driver receives the controller instructions to reset the rotating shaft to the initial angle (e.g. 0°). The initial position is confirmed by the limit switch or encoder feedback to ensure the accuracy of the subsequent adjustment reference. Then, the driver outputs pulses at a preset speed, and the stepping motor drives the rotating shaft to rotate to the target angle through the transmission structure. After reaching the target angle, the motor enters the holding mode, and the rotor is locked by high current to prevent the U-shaped needle from deviating due to vibration or external force. After the inductive power measurement is completed, the next adjustment is performed. All angles are automatically traversed through program control, which shortens the optimization period (from several hours to 3 minutes), thereby quickly determining the height of the U-shaped needle component.

[0054] On the basis of the above embodiment, the height of the U-shaped needle component is calculated based on the target included angle and the height of the sample U-shaped needle, wherein the target included angle is the included angle corresponding to the inductive power smaller than the starting power.

[0055] In the present application, the height of the U-shaped needle component refers to the vertical dimension of the U-shaped needle component actually applied in the equipment such as smart meters, and the design needs to meet the requirement of resisting power frequency magnetic field interference. The height directly affects the induced electromotive force generated by the U-shaped needle component in the magnetic field, and further determines the sensitivity of the equipment to the magnetic field.

[0056] The height of the sample U-shaped needle refers to the adjustable height model used in the optimization process of the U-shaped needle component, and the height can be pre-set (for example, the height of the sample U-shaped needle = the height limit of the meter shell - safety gap, and the safety gap is 2 mm). The sample U-shaped needle can be adjusted by rotation to simulate the actual effect of the U-shaped needle component of different heights.

[0057] In the present application, the target angle refers to the angle (θ) between the sample U-shaped needle and the direction of the magnetic field when the induced power P is less than the starting power threshold of the equipment (i.e. the minimum power at which the equipment is not disturbed by the magnetic field and misoperates). min At this time, the interference is minimized and the magnetic resistance performance is optimal.

[0058] In an embodiment, the determination process of the target angle is specifically described. First, the smart meter equipped with the sample U-shaped needle is placed in the target magnetic field (such as 0.5 mT power frequency magnetic field), and the rated voltage (1.15Un) is applied, and the current is open circuit. Then, the sample needle is rotated by a stepping motor, and the angle θ is adjusted step by step with a pre-set step angle (such as 1° / step), and the real-time induced power P is measured after each step. By covering the range of 0°-90°, the induced power P corresponding to each θ is recorded.

[0059] Further, all angles θ of which the induced power P is less than the starting power threshold are screened out, and the smallest absolute value angle is the target angle θ min . Then, according to the trigonometric function, the relationship between the actual U-shaped needle height H and the sample U-shaped needle L, the target angle θ min is: H=L·sin(θ min ); In the present application, according to the calculated actual U-shaped needle height H, the closest specification is selected from the standard size library (such as 0.1 mm interval), thereby significantly reducing the magnetic field sensitivity.

[0060] On the basis of the above embodiment, when multiple target angles are determined to exist, the height of the U-shaped needle component is calculated based on the target angle at which the power jumps positively and negatively and the height of the sample U-shaped needle.

[0061] In the present application, the target angle refers to the angle (θ) between the sample U-shaped needle and the direction of the magnetic field when the induced power P is less than the starting power threshold of the smart meter. In theory, there may be multiple target angles that satisfy this condition, and the optimal solution needs to be further screened.

[0062] In the present application, when the sample U-shaped needle is rotated to a certain angle, the induced power jumps from a positive value to a negative value, or vice versa. This phenomenon indicates that the interaction between the U-shaped needle and the magnetic field reaches a dynamic equilibrium point, at which the induced power is closest to zero and the anti-interference performance is optimal. The power data when the sample U-shaped needle is rotated to each angle can be referred to Table 1: Table 1 Power data Due to the nonlinear relationship between the U-shaped needle induced power and the included angle, there can be multiple θ that make P < 0.22W (such as 58°, 59° and 61° in Table 1 meet the condition), and the angle of the induced power closest to zero (i.e. the power positive-negative jump point) needs to be identified from multiple target included angles to minimize magnetic field interference. When P changes from positive to negative (or negative to positive), mark the current angle as θ jump (such as 61°). This point corresponds to the phase jump of induced electromotive force, indicating that the coupling direction of the U-shaped needle and the magnetic field is reversed, and the interference energy is minimized. Finally, θ jump is selected as the optimal height, and the relationship between the height L of the sample U-shaped needle and the height H of the U-shaped needle used by the final smart meter is H = L • sin(θ jump ). According to the above geometric relationship, based on θ jump (such as 61°), the optimal height is calculated as 24.05mm, and a U-shaped needle with a height of 24mm is finally selected.

[0063] In an embodiment, a single-phase smart meter is taken as an example for illustration: the shunt structure is composed of a manganese copper piece and a single U-shaped needle component. The sampling part of the manganese copper piece is designed as a straight line to ensure that the overall projection area of the manganese copper piece and the U-shaped needle component in the X-axis and Z-axis directions approaches zero (which can be referred to as shown in Figure 1 ). The U-shaped needle component is parallel to the manganese copper piece and is welded to the printed circuit board, and the manganese copper piece welding point and the U-shaped needle component welding point are connected through the internal wiring of the printed circuit board.

[0064] In this embodiment, the single-phase smart meter has a nominal voltage of 220V, an output pulse number per kilowatt-hour k of 1000imp / kWh, a turning current of 0.5A, and a starting current of 0.04 , i.e. the starting current is 0.02A, and the calculated starting time τ is 819s, and the starting power is 0.22W. In addition, the single-phase smart meter shell material in the embodiment has a height limit H=29.5mm, and the height of the sample U-shaped needle is selected as L=27.5mm, that is, the height limit H of the single-phase smart meter shell material minus a safety gap of 2mm, the single-phase smart meter is installed on the U-shaped needle size optimization sub-circuit, immersed in a magnetic field environment with a magnetic induction intensity of 0.5mT (400A / m) in the direction of the power frequency magnetic field of the Y-axis; the voltage circuit applies an alternating voltage of 253V; the current is zero. Through the Bluetooth connection of the single-phase smart meter, real-time data acquisition is facilitated.

[0065] Then, the sample U-shaped needle in the U-shaped needle size optimization sub-circuit is controlled to rotate by a stepping motor, and the scanning angle (0° to 90°) is stepped at 1° / s (each step stops for 1s to read the real-time power). The application collects data (which can be referred to as Table 1) through the MTS system, although it is less than 0.22W, that is, qualified, but the U-shaped needle size optimization sub-circuit can read the induced power of the full height to find the position closest to the induced power of 0 (that is, the closest cancellation value when the power jumps positively and negatively), such as the angle θ of 61° selected in Table 1 as the optimal height min , combined with the height L of the sample U-shaped needle, the final U-shaped needle height H used by the electric meter is calculated as L•sin(θ min ).

[0066] The application only uses a single U-shaped needle and a manganese copper piece to form an anti-magnetic field interference loop, realizes anti-interference through precise spatial layout (such as |S_x|, |S_z|<0.1mm², so that the X-axis / Z-axis projection area ≈0) and circuit cross connection (ΔV≤±2μV, so that the induced electromotive force of the Y-axis is in opposite phase and is cancelled out). And, develop an automatic test tool (that is, a U-shaped needle size optimization sub-circuit), integrate a high-precision stepping motor (±0.1°) to control angle scanning, combine the MTS system to collect induced power in real time, and apply an algorithm to quickly lock the angle θ min with the best cancellation effect and the corresponding optimal U-shaped needle height H, greatly shorten the development and adjustment period (typical time <180s), and reduce the material cost.

[0067] Figure 6 The structure diagram of the single-phase smart meter provided by the application is shown in Figure 6 The application provides a single-phase smart meter, which comprises the anti-power frequency magnetic field interference loop 601 described in the above embodiments, and the anti-power frequency magnetic field interference loop 601 is used to generate mutual cancellation of induced electromotive force in a power frequency magnetic field environment.

[0068] The single-phase intelligent electric meter provided by the application is composed of a manganese copper piece and a U-shaped needle component, and the pins of the two are fixedly welded on the corresponding positions of a printed circuit board. When a power frequency magnetic field is perpendicular to the area enclosed by the U-shaped needle and the manganese copper piece, the induced electromotive force generated in the power frequency magnetic field can be counteracted, so that the manganese copper sampling signal is not disturbed, and the production automation degree and efficiency are improved, the process is simplified, the cost is reduced, and the development cycle is shortened.

[0069] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A loop for immunity to power frequency magnetic fields, characterized in that, The shunt structure comprises a manganese-copper piece and a hollow conductive piece, and is used to generate mutual cancellation of induced electromotive force in a power frequency magnetic field environment. The pin of the manganese-copper piece and the hollow conductive piece are fixedly welded to corresponding positions on a printed circuit board, and a target magnetic field direction is perpendicular to a cross section of the manganese-copper piece and a profile section of the hollow conductive piece; the cross section of the manganese-copper piece is parallel to the profile section of the hollow conductive piece, and the distance between the cross section and the profile section is less than a preset distance; and the target magnetic field direction is a magnetic field direction corresponding to a power frequency induced electromotive force. The hollow conductive piece is a U-shaped needle component.

2. The anti-power-frequency magnetic field interference loop according to claim 1, characterized in that, The cross section of the manganese-copper piece is determined based on a region between a positive pin and a negative pin of the manganese-copper piece; and the pins of the manganese-copper piece and the open ends of the U-shaped needle component are respectively connected to corresponding pads on the printed circuit board.

3. The anti-power-frequency magnetic field interference loop according to claim 2, characterized in that, The first pad and the second pad are cross-connected by internal wiring of the printed circuit board, wherein the first pad is a pad corresponding to the pin of the manganese-copper piece on the printed circuit board, and the second pad is a pad corresponding to the open end of the U-shaped needle component on the printed circuit board.

4. The anti-power-frequency magnetic field interference loop of claim 3, wherein, The anti-power frequency magnetic field loop further comprises a U-shaped needle size optimization sub-circuit, wherein:

5. The anti-power-frequency magnetic field interference loop of claim 4, wherein, The U-shaped needle size optimization sub-circuit comprises a sample U-shaped needle and a size optimization circuit board, and the open end of the sample U-shaped needle is connected to a rotating shaft at the top of the size optimization circuit board. Before the pin of the U-shaped needle component is connected to the second pad, the pin at the bottom of the size optimization circuit board is connected to the second pad through a wire, wherein the U-shaped needle size optimization sub-circuit is used to adjust an included angle between the profile section of the sample U-shaped needle and the target magnetic field direction through the rotating shaft, and determine the height of the U-shaped needle component based on induced power corresponding to each included angle.

6. The anti-power-frequency magnetic field interference loop of claim 5, wherein, The rotating shaft is connected to a stepping motor through a transmission structure, and the stepping motor is used to drive the rotating shaft to adjust the included angle between the profile section of the sample U-shaped needle and the target magnetic field direction according to a preset stepping angle.

7. The anti-power-frequency magnetic field interference loop of claim 6, wherein, The height of the U-shaped needle component is calculated based on a target included angle and the height of the sample U-shaped needle, wherein the target included angle is an included angle corresponding to induced power that is less than starting power.

8. The anti-power-frequency magnetic field interference loop of claim 6, wherein, When it is determined that there are multiple target included angles, the height of the U-shaped needle component is calculated based on a target included angle at which power jumps from positive to negative and the height of the sample U-shaped needle.

9. The anti-power-frequency magnetic field interference loop of claim 8, wherein, The anti-power frequency magnetic field interference loop comprises any one of claims 1 to 9, wherein:

10. A single phase smart meter, characterized by, The anti-power frequency magnetic field interference loop is used to generate mutual cancellation of induced electromotive force in a power frequency magnetic field environment. ​

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