A self-calibration circuit and method for voltage divider ratio of resistive voltage divider

Abstract

The present invention discloses a circuit and method for self-calibrating the voltage divider ratio of a resistive voltage divider. The circuit comprises a voltage divider ratio arm that provides a voltage divider output voltage. The voltage divider ratio arm comprises a plurality of voltage divider resistors of the same resistance value and specification arranged in series, and a voltage divider reference arm formed by voltage divider resistors of the same resistance value, specification, and quantity as the voltage divider ratio arm, arranged in the same order. The voltage divider ratio arm comprises a first single-pole double-throw switch connected between the first voltage divider resistor on the positive side of the power supply and the positive terminal of the power supply, a second single-pole double-throw switch connected to the upper end of the voltage divider output resistor of the voltage divider output voltage, and a third single-pole double-throw switch connected between the lower end of the voltage divider output resistor and the negative terminal of the reference voltage. The circuit employs a voltage ratio self-calibration technique based on a reference potential, and through differential measurement, reduces the accuracy requirements of the reference source and voltmeter during the self-calibration process, thereby achieving high-accuracy voltage ratio self-calibration.

Description

Technical Field

[0001] The present invention relates to precise measurement of voltage, and in particular to a circuit and method for self-calibrating the voltage division ratio of a resistive voltage divider. Background Art

[0002] Resistive voltage dividers are small and portable, making them widely used in DC value transfer and high-precision voltage amplifier calibration. They are also becoming increasingly attractive for actual voltage measurements.

[0003] The high-voltage and low-voltage arms of a resistive voltage divider are both resistors. Under low-frequency conditions, the voltage ratio accuracy of the voltage divider mainly depends on the accuracy and temperature drift of the voltage divider resistors. This is especially true when the voltage divider has a low-ratio voltage output. Therefore, how to accurately calibrate the voltage divider ratio coefficient becomes a major challenge.

[0004] Traditional calibration methods, using higher-precision equipment for direct calibration, yield better results. However, higher-precision equipment is often more expensive and difficult to move, requiring resistive voltage dividers to be regularly sent to various metrology institutes for calibration. This process is complex and significantly increases costs. Therefore, a simple and easy-to-use self-calibration device has been developed to enable on-the-go calibration of the system. This device can correct for scale factor drift caused by long-term component use and ambient temperature fluctuations, thereby extending the equipment's regular inspection period and reducing calibration costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a resistive voltage divider voltage divider ratio self-calibration circuit and method, which can quickly complete the high-precision proportional self-calibration of the voltage divider resistor without high-precision equipment, and is suitable for the high-precision proportional self-calibration of the voltage divider resistor of the voltage divider low divided output voltage.

[0006] In order to achieve the above object, the scheme of the present invention is:

[0007] A resistive voltage divider voltage ratio self-calibration circuit includes providing a voltage divider output voltage V out The voltage divider proportional arm includes multiple voltage divider resistors R1, R2, R3, R4...R with the same resistance value and arranged in series. n , where: Use the same voltage divider resistors R1', R2', R3', R4'...R as the voltage divider proportional arm resistance specifications and quantity n 'Arrange in the same order to form a voltage divider reference arm, and connect a reference voltage V in parallel to both ends of the voltage divider ratio arm and the voltage divider reference arm. in The positive and negative electrodes of the voltage divider reference arm are arranged in sequence with the voltage divider resistors R1', R2', R3', R4'...R n ' is a series connection from the negative low potential to the positive high potential of the reference voltage;

[0008] The first voltage divider resistor R on the positive side of the power supply is n Connect the first single-pole double-throw switch between the positive pole of the power supply and the common end of the first single-pole double-throw switch to the first voltage divider resistor R n , the voltage divider proportional arm is at the voltage divider output voltage V out The voltage divider output resistor R x The upper end is connected to the second single-pole double-throw switch, and the common end of the second single-pole double-throw switch is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor is disconnected at the upper end, and the voltage divider output resistor R x The lower end is connected to the reference voltage V in A third single-pole double-throw switch is connected between the negative poles, and the common end of the third single-pole double-throw switch is connected to the voltage divider output resistor R x lower end;

[0009] One of the first single-pole double-throw switch's throw points and one of the third single-pole double-throw switch's throw points are connected to the positive high potential of the power supply, and the other throw point of the first single-pole double-throw switch and one of the second single-pole double-throw switch's throw points are connected to the voltage divider output resistor R x At the upper end, the other throw point of the second single-pole double-throw switch and one throw point of the third single-pole double-throw switch are connected to the reference voltage V in Negative electrode low potential;

[0010] The voltage divider output resistor R x is the output from the voltage divider V out Terminal to reference voltage V in The negative low potential terminal resistor R1 or the combined voltage-dividing resistor including the terminal resistor R1, and the number of the voltage-dividing resistors in the voltage-dividing proportional arm is a common multiple of the number of the combined voltage-dividing resistors.

[0011] The solution is to control the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch to divide the voltage divider proportional arm into two series connections:

[0012] The first series connection: connect the high potential first resistor R n Connected to the positive pole of the power supply, the voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected, the voltage divider output resistor R x The lower end is connected to the reference voltage V in The negative electrode has a low potential, which makes the output resistor R X The voltage divider resistor R x ,…,R n From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential;

[0013] The second series connection: connect the high potential first resistor R n With the voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected is connected to the reference voltage V in The negative low potential, voltage divider output resistor R x The lower end is connected to the reference voltage V in The positive electrode of the high potential makes the order of the voltage divider resistors in the voltage divider ratio arm be..., R n 、R x From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential;

[0014] The first voltage divider proportional arm and the voltage divider reference arm connected in series with the voltage divider resistors correspond to each other to form a first differential measurement network;

[0015] The second series-connected voltage divider proportional arm and the voltage divider reference arm are connected in series with voltage divider resistors corresponding to each other to form a second differential measurement network.

[0016] The solution is further as follows: the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch are relay switches, and a controller is connected to the relay switches.

[0017] The solution is further that: the voltage divider resistors of the voltage divider proportional arm and the voltage divider reference arm are precision foil resistors with an accuracy below 5E-5 and a temperature drift below 5ppm / °C.

[0018] A resistive voltage divider voltage ratio self-calibration method is based on the voltage ratio self-calibration device, and the method includes:

[0019] Step 1: According to the voltage division output voltage V out At the position of the voltage divider proportional arm, determine the voltage divider output resistance R x The number of voltage divider resistors is included, and the voltage divider measurement points of the voltage divider resistors of the voltage divider ratio arm and the voltage divider reference arm are divided according to the number of voltage divider resistors included;

[0020] Step 2: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm and the voltage divider reference arm of the first differential measurement network respectively. n , n is the number of voltage division measurement points;

[0021] Step 3: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm and the voltage divider reference arm of the second differential measurement network respectively. n ', n is the number of voltage divider measurement points;

[0022] Step 4: Calculate the voltage divider output resistance R according to the resistance mismatch error formulax The voltage divider proportional coefficient δ is used to calibrate the voltage divider proportional resistance;

[0023] The resistance mismatch error formula is

[0024] in:

[0025] ΣΔ is the differential voltage Δ of the first differential measurement network n sum;

[0026] ΣΔ' is the differential voltage Δ of the second differential measurement network n 'sum.

[0027] The solution further comprises: obtaining the respective differential voltages Δ of the first differential measurement network n , and obtaining the respective differential voltages Δ of the second differential measurement network n ' is obtained by direct measurement using a digital voltmeter.

[0028] The solution further comprises: the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch are relay switches, a controller is connected to the relay switches to control the conversion between the first differential measurement network and the second differential measurement network; the controller is also connected to a gating circuit, and the controller controls the digital voltmeter to measure and obtain the differential voltage Δ n and the differential voltage Δ n '.

[0029] The solution is further that: the input resistance of the digital voltmeter is greater than 1E10Ω.

[0030] The beneficial effects of the present invention are:

[0031] This invention utilizes a voltage ratio self-calibration technique based on the reference potential method. Through differential measurement, the accuracy requirements of the reference source and voltmeter during the self-calibration process are reduced, thereby achieving high-accuracy voltage ratio self-calibration. This technique enables on-the-fly calibration of the system, correcting for proportional coefficient drift caused by factors such as long-term component use and ambient temperature fluctuations. This reduces the need for regular equipment inspections and significantly reduces calibration costs. The invention utilizes three relays to achieve rapid, high-accuracy ratio self-calibration, significantly reducing module size and relay-induced errors.

[0032] The invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the first differential measurement network composed of the first series connection of the present invention;

[0034] Figure 2is a schematic diagram of a second differential measurement network composed of a second series connection according to the present invention;

[0035] Figure 3 It is a schematic diagram of the measurement control circuit of the present invention;

[0036] Figure 4 It is a schematic diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Example 1:

[0038] A resistive voltage divider voltage ratio self-calibration circuit is suitable for high-precision proportional self-calibration of the voltage divider resistor of the voltage divider low voltage output voltage, such as Figures 1 to 4 As shown, it includes providing a divided output voltage V out The voltage divider proportional arm 1 includes a plurality of voltage divider resistors R1, R2, R3, R4...R with the same resistance value and arranged in series. n , where the voltage divider resistors R1', R2', R3', R4'...R are the same as those of the voltage divider proportional arm 1 in terms of resistance specification and quantity. n 'Arrange in the same order to form a voltage divider reference arm 2, and connect a reference voltage V in parallel to both ends of the voltage divider ratio arm 1 and the voltage divider reference arm 2. in The positive and negative electrodes of the voltage divider reference arm 2 are arranged in sequence with the voltage divider resistors R1', R2', R3', R4'...R n 'The same as the voltage divider proportional arm 1, both are arranged in series from the negative low potential to the positive high potential of the reference voltage;

[0039] Wherein: the first voltage divider resistor R of the voltage divider proportional arm 1 on the positive side of the power supply n A first single-pole double-throw switch 101 is connected between the positive terminal of the power supply and the common terminal of the first single-pole double-throw switch 101, and the first voltage divider resistor R of the high-end potential is connected. n , the voltage divider proportional arm 1 is at the voltage divider output voltage V out The voltage divider output resistor R x The upper end is connected to the second single-pole double-throw switch 102, and the common end of the second single-pole double-throw switch 102 is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor is disconnected at the upper end, and the voltage divider output resistor R x The lower end is connected to the reference voltage V in A third single-pole double-throw switch 103 is connected between the negative electrodes, and the common end of the third single-pole double-throw switch is connected to the voltage divider output resistor R x lower end;

[0040] One of the first single-pole double-throw switch 101 and one of the third single-pole double-throw switch 103 are connected to the positive high potential of the power supply, and the other of the first single-pole double-throw switch 101 and one of the second single-pole double-throw switch 102 are connected to the voltage divider output resistor R x The other throw point of the second single-pole double-throw switch 102 and one throw point of the third single-pole double-throw switch 103 are connected to the reference voltage V in Negative electrode low potential;

[0041] The voltage divider output resistor R x is the output from the voltage divider V out Terminal to reference voltage V in The negative low potential terminal resistor R1 or a combined voltage divider resistor including the terminal resistor R1 (eg Figure 1 R1 and R2 in the figure), and in order for the resistor mismatch error formula to be established later, the number of voltage divider resistors in the voltage divider ratio arm must be a common multiple of the number of combined voltage divider resistors, that is, an integer multiple, and an integer multiple greater than 2, which determines that the voltage divider output voltage must be less than 1 / 2V in .

[0042] Among them: controlling the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch divides the voltage divider proportional arm into two series connections:

[0043] The first type of series connection, such as Figure 1 As shown: the first resistor R n Connected to the positive pole of the power supply, the voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected, the voltage divider output resistor R x The lower end is connected to the reference voltage V in The negative electrode has a low potential, which makes the output resistor R X The voltage divider resistor R x ,…,R n From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential;

[0044] The second series connection: Figure 2 As shown, the first resistor R n With the voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected is connected to the reference voltage V in The negative low potential, voltage divider output resistor R x The lower end is connected to the reference voltage V in The positive electrode of the high potential makes the order of the voltage divider resistors in the voltage divider ratio arm be..., Rn 、R x From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential;

[0045] The first type of voltage divider resistors connected in series with the voltage divider proportional arm 1 and the voltage divider reference arm 2 correspond to each other and form the following Figure 1 a first differential measurement network shown;

[0046] The second type of voltage divider resistors connected in series with the voltage divider proportional arm 1 and the voltage divider reference arm 2 correspond to each other and form the following Figure 2 The second differential measurement network is shown.

[0047] In order to realize automatic control: Figure 3 As shown, the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch are relay switches, and a controller 3 is connected to the relay switches.

[0048] The voltage divider resistors of the voltage divider proportional arm and the voltage divider reference arm are precision foil resistors with an accuracy of less than 5E-5 and a temperature drift of less than 5ppm / °C.

[0049] Example 2:

[0050] A resistive voltage divider voltage divider ratio self-calibration method is based on the voltage proportional resistor self-calibration device described in Example 1. The content of Example 1 is applicable to this embodiment. Since the voltage divider resistor mismatch error represents the voltage divider proportional coefficient error caused by the error in the voltage divider resistors constituting the voltage divider, the error can be corrected by self-calibration to obtain an accurate voltage divider proportional coefficient. Therefore, the method includes:

[0051] Step 1: According to the voltage division output voltage V out At the position of the voltage divider proportional arm 1, determine the voltage divider output resistance R x The number of voltage divider resistors is included, and the voltage divider measurement points of the voltage divider resistors of the voltage divider proportional arm 1 and the voltage divider reference arm 2 are divided according to the number of voltage divider resistors included;

[0052] Step 2: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm and the voltage divider reference arm of the first differential measurement network respectively. n , n is the number of voltage division measurement points;

[0053] Step 3: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm 1 and the voltage divider reference arm 2 of the second differential measurement network respectively. n ', n is the number of voltage divider measurement points;

[0054] Step 4: Calculate the voltage divider output resistance R according to the resistance mismatch error formula xThe voltage divider proportional coefficient δ is used to calibrate the voltage divider proportional resistance;

[0055] The resistance mismatch error formula is

[0056] in:

[0057] ΣΔ is the differential voltage Δ of the first differential measurement network n sum;

[0058] ΣΔ' is the differential voltage Δ of the second differential measurement network n 'sum.

[0059] Obtaining the respective differential voltages Δ of the first differential measurement network n , and obtaining the respective differential voltages Δ of the second differential measurement network n 'The voltage of each voltage dividing point can be measured first and then obtained by calculation, but this method adds the error of the digital voltmeter 4, affecting the calibration accuracy: This embodiment obtains the differential voltages Δ of the first differential measurement network. n , and obtaining the respective differential voltages Δ of the second differential measurement network n 'It is obtained by direct measurement through a digital voltmeter, which improves the calibration accuracy.

[0060] In order to realize automatic measurement control: Figure 3 As shown, the first single-pole double-throw switch 101, the second single-pole double-throw switch 102 and the third single-pole double-throw switch 103 are relay switches, and a controller 3 is connected to the relay switches to control the conversion between the first differential measurement network and the second differential measurement network; the controller 3 is also connected to a gating circuit 5, and the controller 3 controls the digital voltmeter 4 to measure and obtain the differential voltages Δ of the first differential measurement network through the gating circuit 5. n and the second differential measurement network for each differential voltage Δ n '.

[0061] The following is a 10:1 specific example to further illustrate the above statement:

[0062] like Figure 4 As shown, two resistor strings are connected in parallel to form the first differential measurement network on the left and the second differential measurement network on the right. The differential measurement network introduces a reference voltage V in , where: the proportional output voltage V from the voltage divider resistor R1 at the end of the voltage divider proportional arm 1 out The nominal values ​​of all voltage divider resistors are the same, and paired sampling points are set between all voltage divider resistors, such as V x and V y By switching the switches, differential sampling is applied to achieve self-calibration of the entire module.

[0063] 1. In actual use, due to the influence of resistance mismatch error, if you want to get the correct resistance ratio output, you need to calibrate it. The calibration process of this structure is summarized as follows:

[0064] When the overall structure is in state 1 on the left, each pair of sampling points is measured. According to the series resistor voltage divider formula, the results are as follows, where V in is the standard source input, Δ n is the nth sampling point (V x ,V y )The difference in differential measurements.

[0065]

[0066] 2. When switches 101, 102, and 103 are in the left state 2, measure each pair of sampling points again. Note that at this time, the relative positions of the sampling points change. The voltage divider output voltage V out Became V y The measurement results are as follows:

[0067]

[0068] Adding the data obtained from all sampling points in state 1 and state 2, the result is:

[0069]

[0070] Subtracting the above two equations yields:

[0071]

[0072] Simplifying, we get:

[0073]

[0074] From the above formula, the input-output relationship of the actual overall module can be obtained through calibration, where δ is the calibrated resistance mismatch error. As the correction of the voltage divider output voltage: Due to the actual output and input relationship of the voltage divider V out / V in is known, and the voltage divider output resistor R x The voltage divider proportional coefficient δ can be corrected to obtain the actual voltage divider output. Taking the conversion of 10V voltage to the required 1V voltage as an example, the voltage divider resistance mismatch error δ is first obtained through self-calibration (for example, the actual measurement and calculation result is δ of 3.49×10 -5 , that is, the actual ratio is 0.10000349), then according to the formula The actual output voltage obtained by the standard 10V voltage through this voltage divider is 1.0000349V.

[0075] The entire self-calibration process utilizes a resistor rotation method. By repeatedly measuring the voltage difference at different sampling points in different differential measurement networks, the advantages of differential measurement are fully utilized to accurately calculate the actual input-output relationship of the voltage divider. Compared with the calibration method of directly comparing the voltage divider with a standard ratiometer (regular inspection), the calibration speed is faster and the calibration cost is lower.

[0076] The above-mentioned resistive voltage divider voltage ratio self-calibration circuit and method embodiment utilizes a voltage ratio self-calibration technique based on the reference potential method. Through differential measurement, the accuracy requirements of the reference source and voltmeter during the self-calibration process are reduced, thereby achieving high-accuracy voltage ratio self-calibration. This technology enables on-the-fly calibration of the system, calibrating proportional coefficient drift caused by factors such as long-term component use and ambient temperature changes, thereby extending the period during which the equipment needs to be regularly inspected and reducing calibration costs. The present invention uses three relays to achieve rapid and high-accuracy proportional self-calibration, significantly reducing the module size and significantly reducing errors introduced by the relays.

Claims

1. A resistive voltage divider voltage ratio self-calibration circuit, comprising providing a voltage divider output voltage V out The voltage divider proportional arm includes multiple voltage divider resistors R1, R2, R3, R4...R with the same resistance value and arranged in series. n , characterized in that, Use the same voltage divider resistors R1', R2', R3', R4'...R n 'Arrange in the same order to form a voltage divider reference arm, and connect a reference voltage V in parallel to both ends of the voltage divider ratio arm and the voltage divider reference arm. in The positive and negative electrodes of the voltage divider reference arm are arranged in sequence with the voltage divider resistors R1', R2', R3', R4'...R n ' is from the reference voltage V in A series connection from a negative electrode with low potential to a positive electrode with high potential; The voltage divider proportional arm is at the reference voltage V in The first voltage divider resistor R on the positive side n With reference voltage V in The first single-pole double-throw switch is connected between the positive poles, and the common end of the first single-pole double-throw switch is connected to the first voltage divider resistor R n , the voltage divider proportional arm is at the voltage divider output voltage V out The voltage divider output resistor R x The upper end is connected to the second single-pole double-throw switch, and the common end of the second single-pole double-throw switch is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor is disconnected at the upper end, and the voltage divider output resistor R x The lower end is connected to the reference voltage V in A third single-pole double-throw switch is connected between the negative poles, and the common end of the third single-pole double-throw switch is connected to the voltage divider output resistor R x lower end; One throw point of the first single-pole double-throw switch and one throw point of the third single-pole double-throw switch are connected to the reference voltage V in The positive electrode is at high potential, and the other throw point of the first single-pole double-throw switch and one throw point of the second single-pole double-throw switch are connected to the voltage divider output resistor R x At the upper end, the other throw point of the second single-pole double-throw switch and one throw point of the third single-pole double-throw switch are connected to the reference voltage V in Negative electrode low potential; The voltage divider output resistor R x is the output from the voltage divider V out Terminal to reference voltage V in The negative low potential terminal resistor R1 or the combined voltage-dividing resistor including the terminal resistor R1, and the number of the voltage-dividing resistors in the voltage-dividing proportional arm is a common multiple of the number of the combined voltage-dividing resistors.

2. The voltage divider ratio self-calibration circuit according to claim 1, characterized in that: Control the first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch to divide the voltage divider proportional arm into two series connections: The first series connection: connect the high potential first resistor R n With reference voltage V in Positive connection, voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected, the voltage divider output resistor R x The lower end is connected to the reference voltage V in The negative electrode has a low potential, which makes the output resistor R X The voltage divider resistor R x ,…,R n From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential; The second series connection: connect the high potential first resistor R n With the voltage divider output resistor R x The upper end is connected to the voltage divider output resistor R x The lower end of the voltage divider resistor with the upper end disconnected is connected to the reference voltage V in The negative low potential, voltage divider output resistor R x The lower end is connected to the reference voltage V in The positive electrode of the high potential makes the order of the voltage divider resistors in the voltage divider ratio arm R x-1 …、R n 、R x From the reference voltage V in A series connection is formed by sequentially connecting the negative electrode with low potential to the positive electrode with high potential; The first voltage divider proportional arm and the voltage divider reference arm connected in series with the voltage divider resistors correspond to each other to form a first differential measurement network; The second series-connected voltage divider proportional arm and the voltage divider reference arm are connected in series with voltage divider resistors corresponding to each other to form a second differential measurement network.

3. The voltage division ratio self-calibration circuit according to claim 1 or 2, characterized in that: The first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch are relay switches, and a controller is connected to the relay switches.

4. The voltage divider ratio self-calibration circuit according to claim 1, wherein: The voltage divider resistors of the voltage divider proportional arm and the voltage divider reference arm are precision foil resistors with an accuracy below 5E-5 and a temperature drift below 5ppm / °C.

5. A method for self-calibrating a voltage divider ratio of a resistive voltage divider, based on the method for self-calibrating a voltage divider ratio of a resistive voltage divider according to claim 2, characterized in that: The method comprises: Step 1: According to the voltage division output voltage V out At the position of the voltage divider proportional arm, determine the voltage divider output resistance R x The number of voltage divider resistors is included, and the voltage divider measurement points of the voltage divider resistors of the voltage divider ratio arm and the voltage divider reference arm are divided according to the number of voltage divider resistors included; Step 2: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm and the voltage divider reference arm of the first differential measurement network respectively. n , n is the number of voltage division measurement points; Step 3: Obtain the differential voltages Δ between the corresponding voltage divider measurement points of the voltage divider ratio arm and the voltage divider reference arm of the second differential measurement network respectively. n ', n is the number of voltage divider measurement points; Step 4: Calculate the voltage divider output resistance R according to the resistance mismatch error formula x The voltage divider proportional coefficient δ is used to calibrate the voltage divider proportional resistance; The resistance mismatch error formula is in: ΣΔ is the differential voltage Δ of the first differential measurement network n sum; ∑Δ is the differential voltage Δ of the second differential measurement network n 'sum.

6. The method according to claim 5, characterized in that Obtaining the respective differential voltages Δ of the first differential measurement network n , and obtaining the respective differential voltages Δ of the second differential measurement network n ' is obtained by direct measurement using a digital voltmeter.

7. The method according to claim 6, characterized in that The first single-pole double-throw switch, the second single-pole double-throw switch and the third single-pole double-throw switch are relay switches. A controller is connected to the relay switches to control the conversion between the first differential measurement network and the second differential measurement network. The controller is also connected to a gating circuit. The controller controls the digital voltmeter to measure and obtain the differential voltage Δ n and the differential voltage Δ n '.

Images