Digital non-contact AC voltage sensor and voltage measurement method

Abstract

The invention provides a digital non-contact alternating-current voltage sensor and a voltage measuring method, the sensor comprises an open-type alternating-current voltage probe, a sensing assembly based on the capacitive voltage dividing principle in the probe converts high voltage on a wire into a first voltage analog signal, and an external grounding shielding layer provides anti-interference protection. Signals output by the probe are sent to the signal acquisition module, a signal conditioning circuit in the signal acquisition module firstly filters, blocks and amplifies the signals, and second voltage analog signals easier to process are generated. And then, the main control unit integrated with an analog-to-digital converter converts the signal into a digital sampling value, and finally, the communication unit outputs a measurement result in a digital signal form. According to the sensor, through non-contact measurement and full-digital processing, safe and convenient alternating current high voltage detection is realized, and stable and anti-interference digital signals can be output.

Description

Technical Field

[0001] This invention belongs to the field of power monitoring technology, specifically relating to a digital non-contact AC voltage sensor and a voltage measurement method. Background Technology

[0002] Routine monitoring, equipment maintenance, and fault diagnosis of power systems are crucial for ensuring the safe and stable operation of the power grid. Among these, accurate measurement of AC voltage at line or equipment terminals is a fundamental and frequent operation. Existing voltage measurement technologies, especially in the field of non-contact measurement, while avoiding the risks of direct physical contact with high-voltage conductors, still face the challenge of balancing ease of operation with measurement accuracy in practical applications.

[0003] Currently, most non-contact voltage probes on the market adopt a closed ring structure. While this type of probe provides good electromagnetic shielding and ensures high measurement accuracy, its enclosed structure also brings inherent limitations. When measuring installed cables, operators must first disconnect the circuit, then disconnect one end of the cable from the terminal block, pass it through the closed aperture of the probe, complete the measurement, and then reconnect it. This process is not only cumbersome and time-consuming, but more importantly, the power-off operation will interrupt the normal operation of equipment or systems, potentially causing unnecessary economic losses. In certain continuous production or critical power supply situations where power outages are not permitted, this type of probe is unsuitable. Summary of the Invention

[0004] This invention provides a digital non-contact AC voltage sensor and a voltage measurement method to solve the above-mentioned technical problems.

[0005] In a first aspect, the present invention provides a digital non-contact AC voltage sensor, comprising:

[0006] An open-type AC voltage probe has an openable clamping structure for non-contactly accommodating the conductor under test inside it; the open-type AC voltage probe contains a sensing component based on the principle of capacitive voltage division, which converts the high voltage on the conductor under test into a first voltage analog signal; the open-type AC voltage probe also includes a grounding shielding layer that covers the outside of the sensing component.

[0007] A signal acquisition module, wherein the input terminal of the signal acquisition module is connected to the output terminal of the open-type AC voltage probe;

[0008] The signal acquisition module includes:

[0009] The signal conditioning circuit is used to receive the first voltage analog signal and perform filtering, DC blocking and amplification processing on the first voltage analog signal to generate a second voltage analog signal;

[0010] The main control unit integrates an analog-to-digital converter to convert the second voltage analog signal into digital sampled values;

[0011] The communication unit, connected to the main control unit, is used to output the measurement results processed by the main control unit in the form of digital signals.

[0012] Optionally, the signal conditioning circuit includes a first signal processing channel and a second signal processing channel;

[0013] When the signal conditioning circuit receives the first voltage analog signal, the first voltage analog signal is simultaneously input to the first signal processing channel and the second signal processing channel.

[0014] The first signal processing channel is configured with a first amplification factor to process signals within a first preset voltage range;

[0015] The second signal processing channel is configured with a second amplification factor, which is different from the first amplification factor, and is used to process signals within a second preset voltage range;

[0016] The main control unit adaptively selects the channel data corresponding to the effective measurement range for processing based on the output signals of the first signal processing channel and the second signal processing channel.

[0017] Optionally, the sensor further includes a power supply module, the power supply module comprising:

[0018] The first-stage DC-DC conversion circuit is used to convert the external DC power supply into the first internal DC voltage;

[0019] The second-stage DC-DC conversion circuit is used to convert the first internal DC voltage into an operating voltage for supplying the main control unit and the signal conditioning circuit.

[0020] A voltage reference circuit is used to generate a reference voltage, which is supplied to the operational amplifier in the signal conditioning circuit as a bias voltage and to the analog-to-digital converter as a reference.

[0021] Secondly, the present invention also provides a digital non-contact AC voltage measurement method, characterized in that it is applied to a sensor comprising an open-type AC voltage probe and a signal acquisition module, wherein the open-type AC voltage probe is provided with a symmetrically divided first electrode segment and a second electrode segment, and the signal acquisition module integrates a main control unit and a communication unit, and the method comprises the following steps:

[0022] The test wire is non-contactly housed inside the open-type AC voltage probe. Based on the principle of capacitive voltage division, the probe synchronously senses and collects the first and second electrode segments to generate a first and second voltage analog signals related to the voltage of the test wire.

[0023] The main control unit converts the first and second analog voltage signals into first and second digital signals, and calculates the main amplitude signal representing the voltage amplitude and the position offset factor representing the radial position of the conductor under test in the probe based on the first and second digital signals.

[0024] If the absolute value of the position offset factor is less than or equal to the preset effective installation threshold, the installation status of the open-type AC voltage probe is determined to be valid. The main amplitude signal and the position offset factor are used as inputs, and the compensated voltage measurement value is obtained by querying the two-dimensional correction model preset in the main control unit and calculating.

[0025] The compensated voltage measurement value is output to the outside through the communication unit.

[0026] Optionally, the step of calculating the main amplitude signal characterizing the voltage amplitude and the position offset factor characterizing the radial position of the conductor under test within the probe based on the first digital signal and the second digital signal includes the following steps:

[0027] The first digital signal and the second digital signal are summed to obtain the main amplitude signal representing the voltage amplitude.

[0028] The difference between the first digital signal and the second digital signal is obtained by performing a difference operation on the first digital signal and the second digital signal;

[0029] The position offset factor is obtained by normalizing the differential signal and the main amplitude signal.

[0030] Optionally, the method further includes the following steps:

[0031] If the absolute value of the position offset factor is greater than the effective installation threshold, the installation status of the open-type AC voltage probe is determined to be invalid.

[0032] Discard the main amplitude signal and the position offset factor calculated within the current acquisition period, and generate an alarm signal through the main control unit;

[0033] The alarm signal is output to the outside through the communication unit.

[0034] Optionally, the step of taking the main amplitude signal and the position offset factor as input, and obtaining the compensated voltage measurement value by querying the two-dimensional correction model preset in the main control unit and calculating it includes the following steps:

[0035] Using the main amplitude signal and the position offset factor as target coordinates, four adjacent reference grid points are located in the two-dimensional correction model preset in the main control unit;

[0036] Read the pre-stored reference voltage values ​​from the four reference grid points;

[0037] Based on the relative positional relationship between the target coordinates and the four reference grid points, a bilinear interpolation algorithm is used to perform weighted calculations on the four reference voltage values ​​to obtain the compensated voltage measurement value.

[0038] Optionally, the method further includes the following steps:

[0039] The open-type AC voltage probe receives a self-calibration trigger command when no test lead is present.

[0040] In response to the self-calibration trigger command, the system acquires the no-load signal generated by the first electrode segment and the second electrode segment, and converts it into a first baseline digital signal and a second baseline digital signal, respectively.

[0041] The first baseline digital signal and the second baseline digital signal are stored as baseline bias values, which are used to calibrate the first digital signal and the second digital signal.

[0042] Optionally, the two-dimensional correction model is generated through the following steps:

[0043] The actuator moves the wire under test inside the open-type AC voltage probe to multiple preset radial position points;

[0044] At each radial position point, multiple standard voltage values ​​are applied to the conductor under test using a standard voltage source;

[0045] At each calibration point consisting of a radial position point and a corresponding standard voltage value, a set of calibration main amplitude signals and calibration position offset factors are calculated.

[0046] Establish a mapping relationship between the standard voltage value and the corresponding set of calibration main amplitude signals and calibration position offset factors;

[0047] The mapping relationship is solidified into a two-dimensional correction model and preset in the main control unit.

[0048] Optionally, outputting the compensated voltage measurement value to the outside via the communication unit includes the following steps:

[0049] Multiple compensated voltage measurements are acquired within a continuous measurement cycle;

[0050] Store multiple compensated voltage measurements into a data buffer queue;

[0051] A moving average digital filtering algorithm is applied to the data in the data buffer queue to generate the final filtered voltage measurement value.

[0052] The final voltage measurement value is encapsulated into a data frame conforming to a predetermined communication protocol, and the data frame is sent to an external device through the communication unit.

[0053] The beneficial effects of this invention are:

[0054] By combining a unique open-type AC voltage probe with a signal acquisition module featuring a built-in intelligent algorithm, safe, convenient, and high-precision voltage measurement of AC conductors is achieved without disconnecting the electrical circuit. The open-type clamping structure of the probe greatly simplifies the on-site installation process, avoiding the power outage losses and operational complexities associated with traditional closed-type probes. The internally integrated grounding shielding layer, especially the permalloy material layer included in the preferred design, provides excellent electromagnetic shielding for the sensing components, effectively suppressing external noise interference in complex industrial environments and ensuring the purity of the acquired signal. The multi-channel parallel processing circuitry within the signal acquisition module amplifies the signal in segments for different voltage ranges, ensuring excellent measurement linearity and resolution across a wide dynamic range from 50V to 500V. The core control unit not only handles data acquisition and conversion but also actively identifies and compensates for potential measurement errors introduced by the uncertainty of the relative position of the probe and the conductor, fundamentally solving the technical pain point that the accuracy of traditional open-type sensors is easily affected by the installation method. Attached Figure Description

[0055] Figure 1 This is a schematic diagram illustrating an application scenario of a digital non-contact AC voltage sensor in one embodiment of this application.

[0056] Figure 2 This is a schematic diagram of the structure of an open-type AC voltage probe in one embodiment of this application.

[0057] Figure 3 This is a schematic block diagram of the complete structure of a digital non-contact AC voltage sensor in one embodiment of this application.

[0058] Figure 4 This is a schematic diagram showing the connection between the signal acquisition module and the power supply module in one embodiment of this application.

[0059] Figure 5This is a flowchart illustrating a digital non-contact AC voltage measurement method in one embodiment of this application. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0061] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0062] This invention provides a digital non-contact AC voltage sensor, such as... Figure 1 As shown, in typical industrial applications, digital non-contact AC voltage sensors can be easily deployed on the conductors under test within a distribution cabinet. Measurement data is transmitted in real-time to terminal devices via an RS485 communication bus, enabling remote online monitoring of the field voltage. The sensor's physical structure primarily consists of an open-type AC voltage probe and a signal acquisition module. These two components work together to form a complete link from physical signal capture to digital information output.

[0063] Reference Figure 2The core feature of the probe lies in its open-type design. This closable clamping structure allows operators to easily attach the probe directly to the primary conductor being measured without needing to power off or disconnect the circuit. This design fundamentally solves the pain points of traditional closed-type sensors, which require wire threading, resulting in cumbersome operation, time-consuming and labor-intensive processes, and potential production interruptions. The probe contains a sensing component based on the principle of capacitive voltage division, which is crucial for converting high-voltage to low-voltage signals. Specifically, when the primary conductor is placed inside the probe, an equivalent capacitance network consisting of an input coupling capacitor C1 and a reference capacitor C2 is formed between the conductor, one or more sensing electrodes inside the probe (shown as voltage divider rings), and the probe's internal reference ground. The high voltage U1 on the measured conductor is divided on this capacitance network, thereby inducing a first voltage analog signal U2 on the sensing electrodes that is proportional to U1 but has a much smaller amplitude.

[0064] like Figure 2 As shown, to ensure measurement accuracy and anti-interference capabilities, the sensing component is completely encased in a grounded shielding layer, i.e., the shielding cover shown in the figure. This grounded shielding layer is electrically connected to the circuit ground of the signal acquisition module, forming a Faraday cage structure, which effectively isolates external electric field noise from the internal sensing capacitor. To further enhance anti-interference performance in industrial environments with more complex electromagnetic conditions, a preferred embodiment of the present invention adds a permalloy material layer to the grounded shielding layer. Permalloy, as a soft magnetic material with extremely high permeability and low coercivity, provides a low magnetic reluctance path for electromagnetic interference such as power frequency magnetic fields, thereby bypassing it from the sensitive sensing component and achieving precise electromagnetic shielding of the sensing head. This provides a solid physical guarantee for obtaining a pure first voltage analog signal.

[0065] The input terminal of the signal acquisition module is connected to the output terminal of the open-type AC voltage probe, responsible for receiving the first analog voltage signal, processing it, and converting it into a digital output. (Refer to...) Figure 3 Specifically, after the first analog voltage signal is input from the probe to the signal acquisition module, it first enters a signal conditioning circuit. The function of this signal conditioning circuit is to perform a series of necessary preprocessing steps on the first analog voltage signal to generate a second analog signal suitable for subsequent digital acquisition. These preprocessing steps typically include: first, filtering through an RC filter network to remove noise and interference components above the power frequency; then, DC blocking through a DC blocking capacitor to eliminate any possible DC bias in the signal, ensuring that only pure AC signal components are processed; finally, amplification by the core operational amplifier, because the signal sensed from the probe is usually very weak and must be sufficiently amplified to be effectively recognized by the analog-to-digital converter.

[0066] To achieve high-precision measurements over a wide voltage range (e.g., 50V to 500V), the signal conditioning circuit of this invention preferably employs a multi-channel parallel processing design. For example... Figure 4 and Figure 5 As shown, the signal conditioning circuit includes at least two parallel signal processing channels: a first signal processing channel and a second signal processing channel. The signal input from the probe, after initial filtering and DC blocking, simultaneously enters these two channels. The core of each channel is an operational amplifier, such as op-amp A and op-amp B in the figure. The circuit topologies of these two channels can be identical, but their key parameter, the amplification factor, is set to different values ​​through different resistor configurations. For example, the first signal processing channel (with op-amp A as its core) is configured with a first amplification factor, which is relatively high and specifically designed for accurately measuring signals in lower voltage ranges (e.g., 50V-150V); while the second signal processing channel (with op-amp B as its core) is configured with a second amplification factor, which is lower and used to prevent signal saturation distortion when measuring higher voltage ranges (e.g., 150V-500V). The two second analog signals (Vout1 and Vout2) generated after amplification by these two channels are simultaneously sent to the main control unit (MCU).

[0067] In this embodiment, the main control unit can be a high-performance microcontroller. The main control unit integrates an analog-to-digital converter (ADC) to convert the two input analog signals into digital sampled values. The firmware program of the main control unit analyzes the digital sampled values ​​of these two channels in real time, uses an intelligent algorithm to determine the measurement range of the current voltage being measured, and adaptively selects the channel data corresponding to the effective measurement range for processing. After completing all digitization calculations, the main control unit obtains an accurate voltage measurement result. Finally, this measurement result is sent to the communication unit, which is connected to the main control unit and is responsible for outputting the processed measurement result as a digital signal. In this embodiment, the communication unit is a RS-485 module.

[0068] In this embodiment, the sensor also includes a power supply module. The power supply module includes a first-stage DC-DC converter circuit, such as a TPS54302 chip, responsible for stepping down a wide-range external DC power supply (e.g., 12V) to a stable first internal DC voltage (e.g., 4.2V). This first internal DC voltage is then fed into a second-stage DC-DC converter circuit, such as a TPS63802 chip, for finer voltage conversion, further converting it into a lower-noise operating voltage (e.g., 3.3V) required by the system core. This operating voltage directly supplies the main control unit and the digital section of the signal conditioning circuit. However, for high-precision analog circuits, an absolutely accurate reference is also required. Therefore, the power supply module also integrates a voltage reference circuit, such as a dedicated voltage reference chip AZ31LAN. This circuit uses a relatively stable 3.3V operating voltage as input to generate a highly stable reference voltage (e.g., 3.0V) with minimal temperature drift and extremely low noise. This reference voltage has a crucial dual function: on the one hand, it is supplied as a bias voltage to the operational amplifier in the signal conditioning circuit, ensuring that the amplification process of the analog signal will not drift due to power fluctuations; on the other hand, it is also directly connected to the ADC reference pin of the main control unit MCU as a reference during analog-to-digital conversion, fundamentally guaranteeing the final accuracy of the entire measurement link.

[0069] Figure 5 This is a flowchart illustrating a digital non-contact AC voltage measurement method in one embodiment. Figure 5 The illustrated digital non-contact AC voltage measurement method is applied to a sensor comprising an open-type AC voltage probe and a signal acquisition module. The open-type AC voltage probe internally has symmetrically divided first and second electrode segments. The signal acquisition module integrates a main control unit and a communication unit. It should be understood that, although... Figure 5 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 5 At least some steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps. For example Figure 5 As shown, the digital non-contact AC voltage measurement method disclosed in this invention specifically includes the following steps:

[0070] S101. The wire to be tested is non-contactly housed inside an open-type AC voltage probe. Based on the principle of capacitive voltage division, the probe synchronously senses and acquires a first voltage analog signal and a second voltage analog signal related to the voltage of the wire to be tested through the first electrode segment and the second electrode segment.

[0071] The core principle of this method involves non-contactly housing the conductor under test within the open-type AC voltage probe. This is achieved by utilizing the capacitive coupling effect between the alternating electric field surrounding the conductor and the symmetrically arranged sensing electrodes within the probe. In practice, the operator opens the probe's clamping structure, places the conductor inside, and then closes it. The conductor, along with the independent first and second electrode segments inside, forms input coupling capacitors. The magnitudes of these two capacitors differ depending on the radial position of the conductor relative to the two electrode segments. To accurately capture this instantaneous state, the main control unit performs strict synchronous sampling of the voltages induced on the two electrode segments under the same clock pulse, thereby generating two time-corresponding first and second voltage analog signals.

[0072] S102. The main control unit converts the first voltage analog signal and the second voltage analog signal into a first digital signal and a second digital signal, and calculates the main amplitude signal representing the voltage amplitude and the position offset factor representing the radial position of the conductor under test in the probe based on the first digital signal and the second digital signal.

[0073] The main control unit processes the two acquired analog signals. First, its integrated analog-to-digital converter (ADC) samples and quantizes the first and second analog voltage signals, converting them into a first digital signal Va and a second digital signal Vb, respectively, suitable for computation. Then, the firmware within the main control unit performs parallel calculations on these two digital signals according to a preset algorithm to decouple the information. One specific implementation calculates the main amplitude signal Vs and the position offset factor Pf using the following formula:

[0074]

[0075] Among them, Vs mainly reflects the overall intensity of the measured voltage, while Pf, through normalization, eliminates the influence of the voltage amplitude itself and becomes a dimensionless index that is only related to the relative position of the conductor.

[0076] S103. If the absolute value of the position offset factor is less than or equal to the preset effective installation threshold, the installation status of the open-type AC voltage probe is determined to be valid. The main amplitude signal and the position offset factor are used as inputs, and the compensated voltage measurement value is obtained by querying the preset two-dimensional correction model in the main control unit and performing calculations.

[0077] The absolute value of the calculated position offset factor Pf is compared with a preset effective installation threshold Pt within the main control unit. If |Pf| is less than or equal to Pt, the current probe installation status is determined to be within an effective and compensable range. At this point, the main control unit uses the calculated main amplitude signal Vs and the position offset factor Pf as two independent coordinate inputs to query a pre-calibrated two-dimensional correction model stored within it. This model stores the mapping relationship between different (Vs, Pf) combinations and the actual voltage value. By querying this model and performing interpolation and other calculations, a dynamically compensated voltage measurement value Vc can be obtained.

[0078] S104. Output the compensated voltage measurement value to the outside through the communication unit.

[0079] The final step in the entire intelligent measurement process is to output the compensated voltage measurement value Vc through the communication unit. The principle involves encapsulating the high-precision digital result obtained through complex calculations within the main control unit into a standardized data format and reliably transmitting it to external devices via a physical channel. In one specific implementation, the main control unit packages the final compensated voltage measurement value Vc into a complete data frame according to widely used industrial communication protocols such as Modbus. This data frame contains the core voltage data, along with the device address, function code, and a CRC code for error checking. Subsequently, the main control unit sends this data frame to the communication unit, such as an RS-485 transceiver chip, via its UART interface. This chip is responsible for converting the signal into a highly interference-resistant differential signal and outputting it externally via a twisted-pair cable.

[0080] In one embodiment, calculating the main amplitude signal characterizing the voltage amplitude and the position offset factor characterizing the radial position of the conductor under test within the probe based on the first digital signal and the second digital signal includes the following steps:

[0081] The first digital signal and the second digital signal are summed to obtain the main amplitude signal that represents the voltage amplitude.

[0082] The difference signal is obtained by performing a difference operation on the first digital signal and the second digital signal;

[0083] The position offset factor is obtained by normalizing the differential signal and the main amplitude signal.

[0084] In this embodiment, after the main control unit converts the analog signals from the two symmetrical electrode segments into a first digital signal Va and a second digital signal Vb, the primary calculation step is to sum these two digital signals. The principle behind this step is that when the tested conductor undergoes radial displacement within the probe, its coupling capacitance with one electrode segment increases (leading to signal enhancement), while its coupling capacitance with the other electrode segment decreases (leading to signal weakening). This inverse relationship ensures that the sum of the two signals remains relatively stable within a certain displacement range. Specifically, the arithmetic logic unit (ALU) of the main control unit executes a simple addition instruction to obtain the main amplitude signal Vs using the following formula: This initially reduces the measurement fluctuations caused by the uncertainty of the conductor position at the algorithm level, thus obtaining a preliminary measurement value that more stably reflects the true strength of the measured voltage than any single signal.

[0085] While acquiring the main amplitude signal, the difference between the first digital signal Va and the second digital signal Vb is calculated in parallel. This step aims to initially extract raw information directly related to the conductor's position offset. The principle is that the signal difference between the two symmetrical electrode segments directly reflects the degree and direction of the conductor's deviation from its geometric center. When the conductor is centered, Va and Vb are theoretically equal, with a difference of zero; when the conductor shifts to one side, the absolute value of the difference increases with the shift, and its sign indicates the direction of the shift. Specifically, the main control unit executes a subtraction instruction to obtain the differential signal Vd using the following formula: This makes the positional information implicit in the two signals explicit, generating an intermediate variable that can initially quantify the positional shift.

[0086] Finally, the differential signal Vd and the main amplitude signal Vs are normalized. This crucial step aims to completely eliminate the interference of the measured voltage amplitude on position determination, thereby obtaining a pure quantitative index that is only related to the relative position of the conductor. The principle is that dividing a position-related quantity (differential signal) by a quantity primarily related to voltage amplitude (main amplitude signal) eliminates the common amplitude influence. Specifically, the main control unit executes a division instruction to obtain the position offset factor Pf using the following formula: This step ultimately yields a unique, dimensionless index that varies between -1 and +1 and can precisely characterize the radial position of the conductor.

[0087] In one embodiment, the method further includes the following steps:

[0088] If the absolute value of the position offset factor is greater than the effective installation threshold, the installation status of the open-type AC voltage probe is determined to be invalid.

[0089] Discard the main amplitude signal and position offset factor calculated in the current acquisition period, and generate an alarm signal through the main control unit;

[0090] The alarm signal is output to the outside through the communication unit.

[0091] In this implementation, if the wire offset is too large, the electric field distribution of the sensor will be distorted, exceeding the correction capability of the preset model. Forced compensation in this case will produce misleading results. Therefore, a boundary condition needs to be set, namely, an effective installation threshold Pt for comparison. If |Pf| is determined to be greater than Pt, it means that the physical position of the wire has exceeded the tolerance limit of the sensor design, and the installation state of the open-type AC voltage probe is determined to be invalid. Once the installation state is determined to be invalid, the main control unit will immediately execute a series of chain response actions to prevent the further propagation of erroneous data and provide immediate feedback to the user. In one specific implementation, the firmware program within the main control unit will trigger an interrupt or jump instruction, skipping all subsequent compensation calculations and normal data output processes. Simultaneously, the main amplitude signal Vs and the position offset factor Pf, calculated in the current acquisition cycle, will be cleared from memory or registers, or marked as invalid, to prevent them from being incorrectly used in other calculations. Following this, the main control unit will generate an internal alarm signal. After the alarm signal is generated internally, this alarm information must be effectively transmitted to the external user or the host system to prompt human intervention.

[0092] In one implementation, the process of taking the main amplitude signal and the position offset factor as inputs, and obtaining the compensated voltage measurement value by querying a preset two-dimensional correction model in the main control unit includes the following steps:

[0093] Using the main amplitude signal and position offset factor as target coordinates, four adjacent reference grid points are located in the two-dimensional correction model preset in the main control unit.

[0094] Read the pre-stored reference voltage values ​​from the four reference grid points;

[0095] Based on the relative positional relationship between the target coordinates and the four reference grid points, a bilinear interpolation algorithm is used to perform weighted calculations on the four reference voltage values ​​to obtain the compensated voltage measurement value.

[0096] In this embodiment, once the installation status is deemed valid, a pre-established mathematical model describing the error distribution of the sensor under different operating conditions can be used to accurately correct the measured data. One specific implementation involves using the main amplitude signal Vs and the position offset factor Pf as a target coordinate (Vs, Pf). The main control unit queries a pre-set two-dimensional correction model stored in its non-volatile flash memory within this coordinate system. This model is formally a two-dimensional lookup table (2D-LUT). During the query, a search algorithm locates the smallest rectangular grid containing the target coordinates within the table. The four vertices of this grid are the adjacent reference grid points, denoted as (V1, P1), (V2, P1), (V1, P2), and (V2, P2).

[0097] After locating four adjacent reference grid points, the main control unit reads the pre-stored reference voltage values ​​corresponding to these four grid points from the two-dimensional calibration model. These reference voltage values ​​are the true values ​​obtained during the calibration phase before the sensor leaves the factory, by applying a standard voltage and measuring at each grid point under operating conditions. They represent the most accurate measurement results at these discrete points. In one specific implementation, the main control unit directly reads the reference voltage values ​​corresponding to the four grid points (V1,P1), (V2,P1), (V1,P2), and (V2,P2) through memory address indexing, denoted as Q11, Q21, Q12, and Q22 respectively. Assuming that the voltage value changes linearly within the small curved surface formed by the four reference grid points, the weight of the four reference voltage values ​​can be determined by their distance. Finally, a weighted calculation can be performed based on the relative positional relationship between the target coordinates and the four reference grid points to obtain the final compensated voltage measurement value. Specifically, a bilinear interpolation algorithm can be used. First, the relative positions of the target coordinates (Vs, Pf) along the two axes are calculated, and then two linear interpolations are performed. The final compensated voltage measurement value Vc can be calculated using the following formula based on the core idea:

[0098]

[0099] Here, t and u are normalized distances along two axes calculated from the target coordinates (Vs, Pf) and the coordinates of four reference grid points, with values ​​between 0 and 1. Through smooth mathematical interpolation, the discrete reference true value is transformed into a continuous and accurate compensation value that serves specific working conditions, thereby eliminating the nonlinear error introduced by position offset at the algorithm level and achieving high-precision dynamic compensation.

[0100] In one embodiment, the sensor further includes at least one auxiliary physical sensor for monitoring current environmental variables, and the method further includes the step of adaptively correcting a two-dimensional correction model as follows:

[0101] While performing bilinear interpolation, real-time environmental variable parameters are acquired through auxiliary physical sensors.

[0102] Under preset benchmark measurement conditions, identify the compensation residual between the compensation output generated by the two-dimensional calibration model and the theoretical model output;

[0103] The compensation residuals are correlated with real-time environmental variable parameters and provided as input to an online learning model;

[0104] The model is learned online to generate a set of dynamic compensation parameters for correcting the output of the two-dimensional correction model.

[0105] Based on dynamic compensation parameters and real-time environmental variable parameters, a secondary compensation operation is performed on the compensated voltage measurement value obtained by bilinear interpolation to generate a final voltage measurement value after adaptive compensation.

[0106] In this embodiment, to achieve sensor self-adaptation and self-optimization, an environmental sensing process is initiated in parallel while performing conventional dynamic compensation. The principle is that the performance of electronic components is affected by environmental factors such as temperature, causing drift and leading to deviations in the fixed calibration model. Therefore, these variables need to be monitored in real time as a basis for subsequent corrections. One specific implementation involves acquiring the current real-time environmental variable parameter Te through an auxiliary physical sensor integrated within the sensor during the same measurement cycle of the main control unit's bilinear interpolation operation. This parameter can be temperature, humidity, or a combination thereof. This endows the sensor with environmental sensing capabilities, ensuring that each measurement not only includes associated voltage and location information but also a snapshot of the environmental state at that time, providing crucial and synchronous data input for analyzing and compensating for measurement drift caused by environmental changes.

[0107] When the sensor operates under preset reference measurement conditions, such as when the absolute value of the position offset factor Pf is extremely small (close to zero), indicating that the conductor is almost perfectly centered, the main control unit calculates the compensation output Vc generated by the two-dimensional correction model, and simultaneously calculates a simplified theoretical model output Vt that is only related to the main amplitude signal Vs. Subsequently, the compensation residual Er is calculated using the following formula: By conducting internal comparisons under ideal physical installation conditions, the compensation residuals of the current solidified model caused by environmental drift and other factors were successfully quantified. This provides a clear and explicit optimization objective for online learning algorithms, namely, to make the residuals approach zero by adjusting the parameters.

[0108] After obtaining the compensation residual Er and the corresponding environmental variable parameter Te, the data pair (Te, Er) is fed as input to a lightweight online learning model, such as a recursive least squares (RLS) algorithm. This algorithm updates and optimizes one or more internal weight coefficients of the model in real time based on each new input sample. These coefficients together constitute a dynamic model that describes the environmental impact. After processing the latest data samples, the RLS algorithm outputs a set of updated dynamic compensation parameters, such as the slope parameter Ks and the intercept parameter Ki. These two parameters together define a linear correction function that describes how much adjustment is needed to the original compensation value under different environmental variables Te.

[0109] Finally, based on the generated dynamic compensation parameters, the voltage value obtained from the conventional compensation process is finely adjusted a second time. This integrates the static model calibrated at the factory with the dynamic model obtained through online learning, achieving complementary advantages. One specific implementation involves substituting the compensated voltage measurement value Vc obtained through bilinear interpolation, the dynamic compensation parameters Ks and Ki output by the online learning model, and the current real-time environmental variable parameter Te into the following secondary compensation formula to obtain the final adaptively compensated voltage measurement value Vf: By superimposing a dynamic correction value related to the real-time environment onto the original compensation value, the final output voltage value not only corrects for the error introduced by position offset but also compensates for the drift error caused by environmental changes. This allows the sensor to maintain extremely high measurement accuracy throughout its entire lifespan.

[0110] In one embodiment, the method further includes the following steps:

[0111] The open-type AC voltage probe receives a self-calibration trigger command when no test lead is present.

[0112] In response to the self-calibration trigger command, the system acquires the no-load signal generated by the first electrode segment and the second electrode segment, and converts it into the first baseline digital signal and the second baseline digital signal, respectively.

[0113] The first and second baseline digital signals are stored as baseline bias values, which are used to calibrate the first and second digital signals.

[0114] In this embodiment, a baseline drift self-calibration process can be performed before performing routine measurement tasks to eliminate zero-point errors introduced by DC bias, thermal noise, or slow drift of the sensor's own electronic components. One specific implementation involves sending a self-calibration trigger command to the main control unit via an external button, communication command, or specific power-on sequence, with the open-type AC voltage probe in a completely unloaded, unconnected state. This command initiates a preset calibration procedure. Upon receiving the self-calibration trigger command, the main control unit immediately begins acquiring and processing the no-load signal. The main control unit drives its internal analog-to-digital converter (ADC) to continuously and synchronously acquire the weak no-load signals generated by the first and second electrode segments under no-load conditions within a preset time period (e.g., hundreds of sampling cycles). Subsequently, these acquired signal samples are converted into digital form and averaged to eliminate the influence of random noise, ultimately yielding a stable first baseline digital signal B1 and a second baseline digital signal B2.

[0115] After calculating the baseline digital signals for the two channels, they are stored as baseline bias values ​​and used for real-time calibration in subsequent measurements. During each subsequent routine measurement, the pre-stored static bias is subtracted from the original measured value to obtain a pure value that only reflects changes in the actual external signal. For example, the main control unit writes the calculated first baseline digital signal B1 and the second baseline digital signal B2 to a specific address in its internal non-volatile memory (such as EEPROM or Flash). Upon obtaining the original first digital signal Va and the second digital signal Vb, the following calibration operation involving base subtraction is first performed:

[0116]

[0117] Here, Va' and Vb' are the calibrated digital signals. Subsequently, all subsequent calculations (such as determining the principal amplitude signal and the position offset factor) will be based on these two calibrated signals.

[0118] In one implementation, the two-dimensional correction model is generated through the following steps:

[0119] The actuator moves the conductor under test inside the open-type AC voltage probe to multiple preset radial position points;

[0120] At each radial position point, multiple standard voltage values ​​are applied to the conductor under test through a standard voltage source;

[0121] At each calibration point consisting of a radial position point and a corresponding standard voltage value, a set of calibration main amplitude signals and calibration position offset factors are calculated.

[0122] Establish a mapping relationship between the standard voltage value and the corresponding set of calibration main amplitude signals and calibration position offset factors;

[0123] The mapping relationship is solidified into a two-dimensional correction model and preset in the main control unit.

[0124] In this embodiment, the sensor to be calibrated is fixed, and a high-precision triaxial actuator (robotic arm) driven by a stepper motor clamps a section of the conductor to be tested. The actuator, according to a preset program, controls the conductor to move sequentially and precisely to dozens or even hundreds of preset radial position points along a grid-like path within the internal cross-section of the open-type AC voltage probe. These position points cover the entire effective measurement area from the geometric center to the allowable offset edge. After the conductor is precisely positioned at each radial position point, different measured voltages need to be simulated at these positions. This can be achieved using a high-precision, programmable standard voltage source connected to the conductor via a conductor clamp. While the conductor remains stationary at a specific radial position point, the standard voltage source sequentially applies a series of stable and known standard voltage values ​​covering the entire range of the sensor (e.g., from 50V to 500V, in 10V steps) to the conductor according to program instructions.

[0125] At each combined calibration point, the sensor's main control unit acquires and converts the first and second digital signals, and uses the same algorithm as in actual operation to calculate a corresponding set of calibration main amplitude signals Vsc and calibration position offset factors Pfc. Simultaneously, it records the standard voltage value Ut applied by the standard voltage source at that moment. This process is automatically repeated at all combined calibration points. All acquired data sets (Vsc, Pfc, Ut) are used as a training dataset. Using Vsc and Pfc as two independent variables and Ut as the dependent variable, a mapping relationship describing the relationship between the three is constructed through data fitting or interpolation algorithms. This mapping relationship can be a complex multivariate polynomial or a discrete data lookup table. The effect of this step is to transform a large number of disordered, discrete data points into a predictive, structured mathematical model that inherently contains the sensor's systematic error information under all operating conditions.

[0126] Finally, the finalized mapping relationship is organized into a two-dimensional array or lookup table (LUT) to form a two-dimensional calibration model. The two index dimensions of this two-dimensional calibration model are the quantized calibration main amplitude signal and the calibration position offset factor, while the table stores the corresponding standard voltage values. Subsequently, during production, this two-dimensional calibration model file containing complete data is programmed into the non-volatile flash memory of each sensor's main control unit using a programmer.

[0127] In one embodiment, outputting the compensated voltage measurement value to the outside via the communication unit includes the following steps:

[0128] Multiple compensated voltage measurements are acquired within a continuous measurement cycle;

[0129] Store multiple compensated voltage measurements into a data buffer queue;

[0130] A moving average digital filtering algorithm is applied to the data in the data buffer queue to generate the final filtered voltage measurement value.

[0131] The final voltage measurement value is encapsulated into a data frame conforming to a predetermined communication protocol, and the data frame is sent to an external device through the communication unit.

[0132] In this embodiment, the main control unit repeatedly executes the complete measurement and compensation process at a fixed frequency (e.g., 100 times per second). Each process generates a compensated voltage measurement value Vc(i), where i is the sequence number of the measurement cycle. The main control unit continuously generates such a data stream. A fixed-size storage area is allocated in the main control unit's RAM as a data buffer queue. Whenever a new compensated voltage measurement value Vc(i) is generated, it is pushed to the end of the queue; if the queue is full, the oldest data at the head of the queue is discarded. Thus, the queue always stores the results of the most recent N measurement cycles, where N is the length of the queue, i.e., the size of the filtering window. Whenever the data buffer queue is updated, the firmware of the main control unit recalculates the sum of all N data in the queue, divides it by N, and obtains the final filtered voltage measurement value Vout using the following formula: .in, It is the i-th compensated voltage measurement value in the queue. This calculation process continues as the queue slides.

[0133] After generating a stable and smooth final voltage measurement value Vout, the main control unit packages the final voltage measurement value Vout into a complete data frame according to the Modbus RTU protocol commonly used in the industrial field. This data frame has a rigorous structure, typically including the device address for addressing, a function code defining the operation type, bytes indicating the data length, and the core voltage data itself, and finally, a Cyclic Redundancy Check (CRC) code to ensure data integrity. Subsequently, this encapsulated data frame is transmitted to the physical bus through a communication unit, such as an RS-485 transceiver, for external devices to receive.

[0134] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0135] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A digital non-contact AC voltage sensor, characterized in that, include: An open-type AC voltage probe, wherein the open-type AC voltage probe has an openable and closable clamping structure for non-contactly accommodating the conductor to be tested inside it. The open-type AC voltage probe is equipped with a sensing component based on the principle of capacitive voltage division. The sensing component converts the high voltage on the conductor under test into a first voltage analog signal. The open-type AC voltage probe also includes a grounding shielding layer, which covers the outside of the sensing component. A signal acquisition module, wherein the input terminal of the signal acquisition module is connected to the output terminal of the open-type AC voltage probe; The signal acquisition module includes: The signal conditioning circuit is used to receive the first voltage analog signal and perform filtering, DC blocking and amplification processing on the first voltage analog signal to generate a second voltage analog signal; The main control unit integrates an analog-to-digital converter to convert the second voltage analog signal into digital sampled values; The communication unit, connected to the main control unit, is used to output the measurement results processed by the main control unit in the form of digital signals.

2. The digital non-contact AC voltage sensor according to claim 1, characterized in that, The signal conditioning circuit includes a first signal processing channel and a second signal processing channel; When the signal conditioning circuit receives the first voltage analog signal, the first voltage analog signal is simultaneously input to the first signal processing channel and the second signal processing channel. The first signal processing channel is configured with a first amplification factor to process signals within a first preset voltage range; The second signal processing channel is configured with a second amplification factor, which is different from the first amplification factor, and is used to process signals within a second preset voltage range; The main control unit adaptively selects the channel data corresponding to the effective measurement range for processing based on the output signals of the first signal processing channel and the second signal processing channel.

3. The digital non-contact AC voltage sensor according to claim 1 or 2, characterized in that, The sensor also includes a power module, the power module comprising: The first-stage DC-DC conversion circuit is used to convert the external DC power supply into the first internal DC voltage; The second-stage DC-DC conversion circuit is used to convert the first internal DC voltage into an operating voltage for supplying the main control unit and the signal conditioning circuit. A voltage reference circuit is used to generate a reference voltage, which is supplied to the operational amplifier in the signal conditioning circuit as a bias voltage and to the analog-to-digital converter as a reference.

4. A digital non-contact AC voltage measurement method, characterized in that, A method is applied to a sensor comprising an open-type AC voltage probe and a signal acquisition module. The open-type AC voltage probe has symmetrically divided first and second electrode segments. The signal acquisition module integrates a main control unit and a communication unit. The method includes the following steps: The test wire is non-contactly housed inside the open-type AC voltage probe. Based on the principle of capacitive voltage division, the probe synchronously senses and collects the first and second electrode segments to generate a first and second voltage analog signals related to the voltage of the test wire. The main control unit converts the first and second analog voltage signals into first and second digital signals, and calculates the main amplitude signal representing the voltage amplitude and the position offset factor representing the radial position of the conductor under test in the probe based on the first and second digital signals. If the absolute value of the position offset factor is less than or equal to the preset effective installation threshold, the installation status of the open-type AC voltage probe is determined to be valid. The main amplitude signal and the position offset factor are used as inputs, and the compensated voltage measurement value is obtained by querying the two-dimensional correction model preset in the main control unit and calculating. The compensated voltage measurement value is output to the outside through the communication unit.

5. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The steps of calculating the main amplitude signal representing the voltage amplitude and the position offset factor representing the radial position of the conductor under test in the probe based on the first digital signal and the second digital signal include the following: The first digital signal and the second digital signal are summed to obtain the main amplitude signal representing the voltage amplitude. The difference between the first digital signal and the second digital signal is obtained by performing a difference operation on the first digital signal and the second digital signal; The position offset factor is obtained by normalizing the differential signal and the main amplitude signal.

6. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The method further includes the following steps: If the absolute value of the position offset factor is greater than the effective installation threshold, the installation status of the open-type AC voltage probe is determined to be invalid. Discard the main amplitude signal and the position offset factor calculated within the current acquisition period, and generate an alarm signal through the main control unit; The alarm signal is output to the outside through the communication unit.

7. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The step of taking the main amplitude signal and the position offset factor as inputs, and obtaining the compensated voltage measurement value by querying the two-dimensional correction model preset in the main control unit and calculating it includes the following steps: Using the main amplitude signal and the position offset factor as target coordinates, four adjacent reference grid points are located in the two-dimensional correction model preset in the main control unit; Read the pre-stored reference voltage values ​​from the four reference grid points; Based on the relative positional relationship between the target coordinates and the four reference grid points, a bilinear interpolation algorithm is used to perform weighted calculations on the four reference voltage values ​​to obtain the compensated voltage measurement value.

8. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The method further includes the following steps: The open-type AC voltage probe receives a self-calibration trigger command when no test lead is present. In response to the self-calibration trigger command, the system acquires the no-load signal generated by the first electrode segment and the second electrode segment, and converts it into a first baseline digital signal and a second baseline digital signal, respectively. The first baseline digital signal and the second baseline digital signal are stored as baseline bias values, which are used to calibrate the first digital signal and the second digital signal.

9. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The two-dimensional correction model is generated through the following steps: The actuator moves the wire under test inside the open-type AC voltage probe to multiple preset radial position points; At each radial position point, multiple standard voltage values ​​are applied to the conductor under test using a standard voltage source; At each calibration point consisting of a radial position point and a corresponding standard voltage value, a set of calibration main amplitude signals and calibration position offset factors are calculated. Establish a mapping relationship between the standard voltage value and the corresponding set of calibration main amplitude signals and calibration position offset factors; The mapping relationship is solidified into a two-dimensional correction model and preset in the main control unit.

10. The digital non-contact AC voltage measurement method according to claim 4, characterized in that, The step of outputting the compensated voltage measurement value to the outside via the communication unit includes the following steps: Multiple compensated voltage measurements are acquired within a continuous measurement cycle; Store multiple compensated voltage measurements into a data buffer queue; A moving average digital filtering algorithm is applied to the data in the data buffer queue to generate the final filtered voltage measurement value. The final voltage measurement value is encapsulated into a data frame conforming to a predetermined communication protocol, and the data frame is sent to an external device through the communication unit.

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