A differential voltage measurement method for unbalanced high-resistance isolation network

Abstract

The present invention discloses a differential voltage measurement method applied to an unbalanced high-resistance isolation network, comprising the steps of: 1) pre-calibrating the unbalanced high-resistance isolation network, obtaining a fixed function relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and converting the relationship into a differential voltage calculation formula; 2) obtaining an input voltage at an input end of the unbalanced high-resistance isolation network and an output voltage at an output end; 3) substituting the input voltage and the output voltage into a differential voltage calculation formula to obtain a differential voltage of the unbalanced high-resistance isolation network. The present invention has the advantages of simple measurement process and high measurement accuracy.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of voltage measurement circuits, and in particular to a differential voltage measurement method applied to an unbalanced high-resistance isolation network. Background Art

[0002] In the field of rail transit or many other industrial fields, it is necessary to monitor the current parameters of certain key electrical circuits to determine whether the electrical equipment in the circuit is working properly, whether the internal resistance of the electrical equipment has increased abnormally, etc. In engineering practice, these electrical circuits often have unfavorable factors such as high voltage levels, large voltage and current fluctuation ranges, and high-frequency ripple signal interference. At the same time, monitoring these key electrical circuits also needs to meet extremely low leakage current requirements, which means that the monitoring circuit itself must have good high-resistance isolation characteristics. These factors combined make it difficult to accurately obtain the differential voltage on the line. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in view of the technical problems existing in the prior art, the present invention provides a differential voltage measurement method for an unbalanced high-resistance isolation network with a simple measurement process and accurate measurement.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0005] A differential voltage measurement method applied to an unbalanced high-resistance isolation network comprises the following steps:

[0006] 1) The unbalanced high-resistance isolation network is calibrated in advance to obtain a fixed functional relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and the fixed functional relationship is converted into a differential voltage calculation formula;

[0007] 2) obtaining an input voltage at an input end and an output voltage at an output end of an unbalanced high-impedance isolation network;

[0008] 3) Substituting the input voltage and the output voltage into the differential voltage calculation formula, the differential voltage of the unbalanced high-resistance isolation network is obtained.

[0009] Preferably, the specific process of obtaining the fixed function relationship in step 1) is:

[0010] Mathematical modeling of the unbalanced high-resistance isolation network yields:

[0011]

[0012] Where v1 and v2 are the voltages at both ends of the circuit to be tested, v ε is the output voltage of the unbalanced high-impedance isolation network;

[0013] Using the common-mode reference voltage v cm Calibrate the unbalanced high-impedance isolation network. At this time, v1 and v2 are the same, both of which are the common-mode reference voltage v input externally. cm , the measured differential voltage v εcm , according to formula (4):

[0014]

[0015] Formula (5) is a fixed function relationship between the pressure division coefficient α and the pressure division coefficient β.

[0016] Preferably, in step 1), the specific process of converting the fixed function relationship into the differential voltage calculation formula is:

[0017] After obtaining the fixed function relationship between the pressure division coefficient α and the pressure division coefficient β, the following transformation is performed:

[0018]

[0019] That is, the actual differential voltage across the circuit to be tested

[0020] Substituting equation (6) into equation (4), eliminating coefficient β, we get the differential voltage calculation formula:

[0021]

[0022] Preferably, the unbalanced high-resistance isolation network includes high-resistance elements Z1 and Z2, and medium-resistance elements Y1 and Y2, one end of Z1 is connected to the front end of the electrical circuit to be measured, and the other end of Z1 is connected to one end of Y1; one end of Z2 is connected to the rear end of the electrical circuit to be measured, and the other end of Z2 is connected to one end of Y2, and the other end of Y1 is connected to the other end of Y2 and is grounded to form a reference zero potential point; the output end of the unbalanced high-resistance isolation network is formed between one end of Y1 and one end of Y2.

[0023] Preferably, the output end of the unbalanced high-impedance isolation network is connected to an analog-to-digital conversion unit, such as an analog-to-digital converter.

[0024] The present invention also discloses a differential voltage measurement system applied to an unbalanced high-resistance isolation network, comprising:

[0025] The first program module is used to pre-calibrate the unbalanced high-resistance isolation network, obtain a fixed function relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and convert it into a differential voltage calculation formula;

[0026] The second program module is used to obtain the input voltage of the input end and the output voltage of the output end of the unbalanced high-impedance isolation network;

[0027] The third program module is used to substitute the input voltage and the output voltage into the differential voltage calculation formula to obtain the differential voltage of the unbalanced high-resistance isolation network.

[0028] The present invention further discloses a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described above are executed.

[0029] The present invention also discloses a computer device, comprising a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is run by the processor, the steps of the method described above are executed.

[0030] The present invention further discloses a terminal, which includes one or more processors and one or more memories, wherein the one or more memories store at least one program code, and the at least one program code is loaded and executed by the one or more processors to implement the operations performed by the method as described above.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] The differential voltage measurement method of the present invention is applied to an unbalanced high-resistance isolation network. By correcting the voltage division coefficients of each part of the voltage division network in the high-resistance isolation network, accurate measurement of the differential voltage in the unbalanced high-resistance isolation network can be achieved. The measurement process of this method is simple and easy to implement.

[0033] The present invention calculates the differential voltage according to the corrected differential voltage calculation formula, which can greatly release the constraint of precise matching of the monitoring circuit hardware. Since only the unilateral voltage division coefficient α is used, the influence caused by the mismatch between the coefficient α and the coefficient β can be effectively offset, thereby greatly improving the calculation accuracy and achieving the purpose of circuit practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a circuit schematic diagram of a high-resistance isolation network in a specific embodiment of the present invention.

[0035] Figure 2 It is an embodiment diagram of the method of the present invention in a specific application.

[0036] Figure 3 The figure is a flow chart of the method of the present invention in a specific embodiment. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] In order to facilitate the specific description of the present invention, a specific structure of an unbalanced high-resistance isolation network is now provided, such as Figure 1As shown, a sampling resistor R (or a sampling resistor network) is connected in series in a certain electrical circuit to be tested. When a current I flows through the sampling resistor R, a certain voltage difference (v1-v2) will be generated across the sampling resistor R, which is the differential voltage across the sampling resistor. Figure 1 The high-resistance isolation network in the circuit includes two impact-resistant high-resistance components (Z1, Z2) and two medium-resistance components (Y1, Y2). The front-end voltage of the sampling resistor R is recorded as v1, and the rear-end voltage is recorded as v2. The front-end voltage v1 is divided by the impact-resistant high-resistance component Z1 and the medium-resistance component Y1 to obtain the voltage v1', while the rear-end voltage v2 is divided by the impact-resistant high-resistance component Z2 and the medium-resistance component Y2 to obtain the voltage v2'. Then, the analog-to-digital converter ADC calculates the voltage difference (v1'-v2', i.e., v ε ) for analog-to-digital conversion.

[0039] The above circuit structure works stably and reliably, and the coefficient error of the left and right bilateral high-resistance isolation voltage divider networks is usually 1% or 0.1%. However, in specific technical fields, due to the high requirements for measurement accuracy, if the solution of direct hardware precise matching is adopted, the error of the bilateral voltage divider network coefficient needs to be controlled to within one in one hundred thousand, which is neither economical nor realistic in engineering practice.

[0040] Assume that the voltage divider coefficient of the voltage divider network at the lower end of voltage V1 is α, the voltage divider coefficient of the voltage divider network at the lower end of voltage V2 is β, and the resistance of high resistance element Z1 is R Z1 , the resistance of high resistance element Z2 is R Z2 , the resistance of the middle resistance element Y1 is R Y1 , the resistance of the middle resistance element Y2 is R Y2 ,but:

[0041] α=(R Y1 +R Z1 ) / R Y1 (1)

[0042] β=(R Y2 +R Z2 ) / R Y2 (2)

[0043] Among them, due to R Z1 and R Z2 Generally, it is megohm level, with a large value. Y1 and R Y2 The value of is generally in the tens of kilo-ohms range. Therefore, in practical applications, it is almost impossible for the voltage divider coefficient α and the voltage divider coefficient β to match completely, that is, it can be expressed as:

[0044] α≠β (3)

[0045] Since the voltage division coefficient cannot be accurately matched, the measured value v obtained after analog-to-digital conversion ε It is impossible to directly reflect the voltage difference across the sampling resistor R according to a certain linear proportional relationship.

[0046] In order to solve the above technical problems, an embodiment of the present invention provides a differential voltage measurement method applied to an unbalanced high-resistance isolation network, such as Figure 3 As shown, the steps include:

[0047] 1) The unbalanced high-resistance isolation network is calibrated in advance to obtain a fixed functional relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and the fixed functional relationship is converted into a differential voltage calculation formula;

[0048] 2) obtaining an input voltage at an input end and an output voltage at an output end of an unbalanced high-impedance isolation network;

[0049] 3) Substituting the input voltage and the output voltage into the differential voltage calculation formula, the differential voltage of the unbalanced high-resistance isolation network is obtained.

[0050] The differential voltage measurement method of the present invention is applied to an unbalanced high-resistance isolation network. By correcting the voltage division coefficients of each part of the voltage division network in the high-resistance isolation network, accurate measurement of the differential voltage in the unbalanced high-resistance isolation network can be achieved. The measurement process of this method is simple and easy to implement.

[0051] In a specific embodiment, in step 1), mathematical modeling is performed on the above circuit (high-resistance isolation network), and according to the circuit principle:

[0052]

[0053] v ε It is the differential voltage output by the high-resistance isolation network;

[0054] Using the common-mode reference voltage v cm The circuit is calibrated. At this time, voltage v1 and voltage v2 are the same, both of which are the common-mode reference voltage v input externally. cm , the measured differential voltage is v εcm , according to formula (4):

[0055]

[0056] Formula (5) is the fixed function relationship between the pressure division coefficient α and the pressure division coefficient β. By transforming the formula, we can get:

[0057]

[0058] That is, the actual differential voltage across the sampling resistor R

[0059] Then, by substituting equation (6) into equation (4), the coefficient β can be eliminated, and we get:

[0060]

[0061] Analyzing the right side of equation (8), for a specific circuit, the voltage division coefficient α is a known number, v cm is the common mode voltage used for calibration, v εcm is the differential voltage value measured during calibration, and v2 is the measured value. Therefore, the final differential voltage v can be obtained by equation (8): Δ .

[0062] At the same time, it is noted that the physical meaning of the second term on the right side of equation (8) is the correction term of the unbalanced network. When the high-resistance isolation network is in absolute balance, v εcm is zero, the correction term is also zero, then the differential voltage is given by the first term on the right side of equation (8) (α·v ε ) is completely determined.

[0063] In a specific embodiment, in step 2), the input voltage (v1 and v2) of the input end of the unbalanced high-impedance isolation network and the output voltage v ε Then in step 3), the above parameters are substituted into formula (8) to obtain the differential voltage of the unbalanced high-resistance isolation network. Of course, after obtaining the above differential voltage, the line current of the electrical circuit to be tested can also be calculated.

[0064] The present invention calculates the differential voltage according to the corrected differential voltage calculation formula (Formula (8)), which can greatly release the constraint of precise matching of the monitoring circuit hardware. Since only the unilateral voltage division coefficient α is used, the influence caused by the mismatch between the coefficient α and the coefficient β can be effectively offset, thereby greatly improving the calculation accuracy and achieving the purpose of circuit practicality.

[0065] like Figure 2 As shown, in a rail transit low-voltage electrical appliance online monitoring system, as a part of the ADS1248 typical circuit responsible for ADC and its front-end voltage divider circuit, this circuit structure is used to adopt voltage division and ADC sampling for the electrical parameters of the monitored device.

[0066] The embodiment of the present invention further discloses a differential voltage measurement system applied to an unbalanced high-resistance isolation network, comprising:

[0067] The first program module is used to pre-calibrate the unbalanced high-resistance isolation network, obtain a fixed function relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and convert it into a differential voltage calculation formula;

[0068] The second program module is used to obtain the input voltage of the input end and the output voltage of the output end of the unbalanced high-impedance isolation network;

[0069] The third program module is used to substitute the input voltage and the output voltage into the differential voltage calculation formula to obtain the differential voltage of the unbalanced high-resistance isolation network.

[0070] The differential voltage measurement system of the present invention corresponds to the above differential voltage measurement method and also has the advantages described in the above measurement method.

[0071] The embodiment of the present invention further discloses a computer-readable storage medium, on which a computer program is stored, and the computer program executes the steps of the above method when it is executed by a processor. The embodiment of the present invention also discloses a computer device, including a memory and a processor, on which a computer program is stored, and the computer program executes the steps of the above method when it is executed by the processor. The present invention also discloses a terminal, which includes one or more processors and one or more memories, and the one or more memories store at least one program code, and the at least one program code is loaded and executed by the one or more processors to implement the operations performed by the above method.

[0072] The present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned method embodiment can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable media include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. The memory is used to store computer programs and / or modules, and the processor implements various functions by running or executing computer programs and / or modules stored in the memory, and calling data stored in the memory. The memory may include high-speed random access memory and may also include non-volatile memory, such as a hard disk, an internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0073] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A differential voltage measurement method applied to an unbalanced high-resistance isolation network, characterized in that: Includes steps: 1) The unbalanced high-resistance isolation network is calibrated in advance to obtain a fixed functional relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and the fixed functional relationship is converted into a differential voltage calculation formula; 2) obtaining an input voltage at an input end and an output voltage at an output end of an unbalanced high-impedance isolation network; 3) Substituting the input voltage and the output voltage into the differential voltage calculation formula, the differential voltage of the unbalanced high-resistance isolation network is obtained: The specific process of obtaining the fixed function relationship in step 1) is: Mathematical modeling of the unbalanced high-resistance isolation network yields: Where v1 and v2 are the voltages at both ends of the circuit to be tested, v ε is the output voltage of the unbalanced high-impedance isolation network; Using the common-mode reference voltage v cm Calibrate the unbalanced high-impedance isolation network. At this time, v1 and v2 are the same, both of which are the common-mode reference voltage v input externally. cm , the measured differential voltage v εcm , according to formula (4): Formula (5) is the fixed function relationship between the pressure division coefficient α and the pressure division coefficient β; In step 1), the specific process of converting the fixed function relationship into the differential voltage calculation formula is: After obtaining the fixed function relationship between the pressure division coefficient α and the pressure division coefficient β, the following transformation is performed: That is, the actual differential voltage across the circuit to be tested Substituting equation (6) into equation (4), eliminating coefficient β, we get the differential voltage calculation formula:

2. The differential voltage measurement method applied to an unbalanced high-resistance isolation network according to claim 1, characterized in that: The unbalanced high-resistance isolation network includes high-resistance elements Z1 and Z2, and medium-resistance elements Y1 and Y2. One end of Z1 is connected to the front end of the electrical circuit to be tested, and the other end of Z1 is connected to one end of Y1; one end of Z2 is connected to the rear end of the electrical circuit to be tested. The other end of Z2 is connected to one end of Y2, and the other end of Y1 is connected to the other end of Y2 and grounded to form a reference zero potential point; the output end of an unbalanced high-resistance isolation network is formed between one end of Y1 and one end of Y2.

3. The differential voltage measurement method applied to an unbalanced high-resistance isolation network according to claim 2, characterized in that: The output end of the unbalanced high-impedance isolation network is connected to an analog-to-digital conversion unit.

4. The differential voltage measurement method applied to an unbalanced high-resistance isolation network according to claim 3, characterized in that: The analog-to-digital conversion unit is an analog-to-digital converter.

5. A differential voltage measurement system applied to an unbalanced high-resistance isolation network, used to perform the steps of the method as claimed in any one of claims 1 to 4, characterized in that: include: The first program module is used to pre-calibrate the unbalanced high-resistance isolation network, obtain a fixed function relationship between a voltage division coefficient α at one end of the unbalanced high-resistance isolation network and a voltage division coefficient β at the other end, and convert it into a differential voltage calculation formula; The second program module is used to obtain the input voltage of the input end and the output voltage of the output end of the unbalanced high-impedance isolation network; The third program module is used to substitute the input voltage and the output voltage into the differential voltage calculation formula to obtain the differential voltage of the unbalanced high-resistance isolation network.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program executes the steps of the method according to any one of claims 1 to 4 when executed by a processor.

7. A computer device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: The computer program executes the steps of the method according to any one of claims 1 to 4 when executed by a processor.

8. A terminal, characterized in that: The terminal includes one or more processors and one or more memories, wherein the one or more memories store at least one program code, and the at least one program code is loaded and executed by the one or more processors to implement the operations performed by the method as claimed in any one of claims 1 to 4.

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