Voltage division proportion self-calibration circuit and method for resistive voltage divider

Abstract

The invention discloses a resistive voltage divider voltage division proportion self-calibration circuit and method, and the circuit comprises a voltage division proportion arm which provides a voltage division output voltage, and the voltage division proportion arm is provided with a plurality of voltage division resistors which have the same resistance value specification and are sequentially arranged and connected in series. Divider resistors with the same resistance specification and number as the divider proportional arm are arranged in the same sequence to form a divider reference arm; according to the voltage division proportion arm, a first single-pole double-throw switch is connected between a first voltage division resistor on the positive electrode side of a power supply and the positive electrode of the power supply, a second single-pole double-throw switch is connected to the upper end of a voltage division output resistor of voltage division output voltage, and a third single-pole double-throw switch is connected between the lower end of the voltage division output resistor and the negative electrode of reference voltage. According to the invention, a voltage proportion self-calibration technology based on reference potential is adopted, and through differential measurement, the accuracy requirements of a reference source and a voltmeter in the self-calibration process are reduced, so that high-accuracy voltage proportion self-calibration is realized.

Description

Technical Field

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

[0002] The resistive voltage divider has the characteristics of small volume and portability. It is widely used in the direct current value transfer and the calibration work of high-precision voltage amplifiers, and is also increasingly attractive for actual voltage measurement.

[0003] Both the high-voltage arm and the low-voltage arm of the resistive voltage divider are resistors. Under low-frequency conditions, the voltage ratio accuracy of the voltage divider mainly depends on the accuracy and temperature drift of the voltage-dividing resistors, especially when the voltage divider outputs a low-ratio voltage. Therefore, how to obtain an accurate voltage divider ratio coefficient through calibration has become a major problem.

[0004] The traditional calibration method, that is, direct calibration through higher-precision equipment, although the calibration result is good, the higher-precision equipment is often more expensive and difficult to move. As a result, the resistive voltage divider needs to be sent to metrology institutes at all levels for calibration regularly, and the calibration process is complex and the cost increases significantly. Therefore, it has become an urgent problem to develop a set of simple and feasible self-calibration equipment to realize on-demand calibration of the system, calibrate the ratio coefficient drift caused by factors such as long-term use of components and environmental temperature changes, so as to extend the regular inspection period of the equipment and reduce the calibration cost. Summary of the Invention

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

[0006] To achieve the above purpose, the solution of the present invention is:

[0007] A voltage division ratio self-calibration circuit for a resistive voltage divider includes a voltage division ratio arm for providing a voltage division output voltage V out , the voltage division ratio arm includes a plurality of voltage-dividing resistors R1, R2, R3, R4...R arranged in series in the same resistance value specification and in sequence n , where: a voltage division reference arm is composed of voltage-dividing resistors R1', R2', R3', R4'...R n ' with the same resistance value specification and the same number as the voltage division ratio arm and arranged in the same sequence. The two ends of the voltage division ratio arm and the two ends of the voltage division reference arm are connected in parallel to the positive and negative poles of a reference voltage V in . The voltage-dividing resistors R1', R2', R3', R4'...R n ' arranged in sequence of the voltage division reference arm are connected in series from the low potential of the negative pole of the reference voltage to the high potential of the positive pole;

[0008] The first voltage dividing resistor R on the positive side of the power supply of the voltage dividing ratio arm n is connected to the positive pole of the power supply through a first single-pole double-throw switch, and the common terminal of the first single-pole double-throw switch is connected to the first voltage dividing resistor R n , and the voltage dividing output resistor R of the voltage dividing ratio arm is at the voltage dividing output voltage V out The upper end of is connected to a second single-pole double-throw switch, and the common terminal of the second single-pole double-throw switch is connected to the lower end of the voltage dividing resistor that is disconnected from the upper end of the voltage dividing output resistor R x At the upper end, a third single-pole double-throw switch is connected between the lower end of the voltage dividing output resistor R x and the negative pole of the reference voltage V x , and the common terminal of the third single-pole double-throw switch is connected to the lower end of the voltage dividing output resistor R in ; x The upper end;

[0009] One throw point of the first single-pole double-throw switch and one throw point of the third single-pole double-throw switch are jointly 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 throw point of the second single-pole double-throw switch are jointly connected to the upper end of the voltage dividing output resistor R x , and 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 jointly connected to the negative low potential of the reference voltage V in Negative low potential;

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

[0011] The solution further is: controlling 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 dividing ratio arm into two series connections:

[0012] The first series connection: connecting the high-potential first resistor R of the voltage dividing ratio arm n to the positive pole of the power supply, connecting the upper end of the voltage dividing output resistor R x to the lower end of the voltage dividing resistor that is disconnected from the upper end of the voltage dividing output resistor R x , connecting the lower end of the voltage dividing output resistor R x to the negative low potential of the reference voltage V in , so that the voltage dividing resistor containing the voltage dividing output resistor R X R x 、…、R n is connected in series from the negative low potential of the reference voltage V in to the positive high potential in sequence;

[0013] The second series connection: Connect the high-potential first resistor R of the voltage-dividing ratio arm n to the upper end of the voltage-dividing output resistor R x and connect the lower end of the voltage-dividing resistor with its upper end disconnected to the negative low potential of the reference voltage V x , and connect the lower end of the voltage-dividing output resistor R in to the positive high potential of the reference voltage V x , so that the sequence of the voltage-dividing resistors of the voltage-dividing ratio arm is …, R in ,R n ,R x Connect in series in sequence from the negative low potential to the positive high potential of the reference voltage V in to form a series connection;

[0014] The voltage-dividing resistors of the voltage-dividing ratio arm and the voltage-dividing reference arm in the first series connection correspond to each other to form the first differential measurement network;

[0015] The voltage-dividing resistors of the voltage-dividing ratio arm and the voltage-dividing reference arm in the second series connection correspond to each other to form the second differential measurement network.

[0016] A further aspect of the solution is 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.

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

[0018] A method for self-calibrating the voltage-dividing ratio of a resistive voltage divider is a self-calibrating method based on the voltage ratio self-calibrating device, and the method includes:

[0019] The first step: Determine the number of voltage-dividing resistors contained in the voltage-dividing output resistor R according to the position of the voltage-dividing output voltage V out in the voltage-dividing ratio arm, and divide the voltage-dividing measurement points of the voltage-dividing resistors of the voltage-dividing ratio arm and the voltage-dividing reference arm according to the number of voltage-dividing resistors contained; x The second step: Obtain the respective differential voltages Δ

[0020] between the corresponding voltage-dividing measurement points of the voltage-dividing ratio arm and the voltage-dividing reference arm of the first differential measurement network respectively, where n is the number of voltage-dividing measurement points; n , n is the number of voltage-dividing measurement points;

[0021] The third step: Obtain the respective differential voltages Δ n ' between the corresponding voltage-dividing measurement points of the voltage-dividing ratio arm and the voltage-dividing reference arm of the second differential measurement network respectively, where n is the number of voltage-dividing measurement points;

[0022] The fourth step: Calculate the voltage-dividing output resistor R according to the resistance mismatch error formulax The voltage division ratio coefficient δ is used to calibrate the voltage division ratio resistors.

[0023] The formula for the resistor mismatch error is

[0024] Where:

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

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

[0027] The further solution is: obtaining the differential voltages Δ of each differential voltage in the first differential measurement network n , and obtaining the differential voltages Δ' of each differential voltage in the second differential measurement network n ' is directly measured and obtained by a digital voltmeter.

[0028] The further solution is: 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 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 ' through the gating circuit.

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

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

[0031] The present invention adopts a voltage ratio self-calibration technology based on the reference potential method. Through differential measurement, the accuracy requirements for the reference source and the voltmeter in the self-calibration process are reduced, thereby realizing high-accuracy voltage ratio self-calibration. Through this technology, the system can be calibrated as needed, calibrating the drift of the ratio coefficient caused by factors such as long-term use of components and environmental temperature changes, thereby extending the period for regular inspection of the equipment and significantly reducing the calibration cost. The present invention realizes fast and high-accuracy ratio self-calibration through three relays, greatly reducing the module volume and significantly reducing the error introduced by the relays.

[0032] The following describes the invention in detail with reference to the drawings and embodiments. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of the first differential measurement network composed of the first type of series in the present invention;

[0034] Figure 2It is a schematic diagram of the second differential measurement network composed of the second type of series connection in 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 implementation manners

[0037] Embodiment 1:

[0038] A voltage division ratio self-calibration circuit for a resistive voltage divider is applicable to the high-precision ratio self-calibration of the voltage division resistors for the low-voltage division output voltage of the voltage divider. As Figures 1 to 4 shown, it includes a voltage division ratio arm 1 that provides a voltage division output voltage V out . The voltage division ratio arm includes a plurality of voltage division resistors R1, R2, R3, R4...R n arranged in series in the same resistance value specification and in sequence. Among them, voltage division resistors R1', R2', R3', R4'...R n ' with the same resistance value specification and quantity as the voltage division ratio arm 1 are arranged in the same sequence to form a voltage division reference arm 2. The two ends of the voltage division ratio arm 1 and the two ends of the voltage division reference arm 2 are connected in parallel with the positive and negative poles of a reference voltage V in . The voltage division resistors R1', R2', R3', R4'...R n ' arranged in sequence in the voltage division reference arm 2 are connected in series in the same order as the voltage division ratio arm 1 from the low potential of the negative pole of the reference voltage to the high potential of the positive pole;

[0039] Among them: A first single-pole double-throw switch 101 is connected between the first voltage division resistor R n at the first position on the positive pole side of the power supply and the positive pole of the power supply. The common terminal of the first single-pole double-throw switch 101 is connected to the first voltage division resistor R n with a high-end potential. A second single-pole double-throw switch 102 is connected to the upper end of the voltage division output resistor R out of the voltage division ratio arm 1. The common terminal of the second single-pole double-throw switch 102 is connected to the lower end of the voltage division resistor that is disconnected from the upper end of the voltage division output resistor R x . A third single-pole double-throw switch 103 is connected between the lower end of the voltage division output resistor R x and the negative pole of the reference voltage V x . The common terminal of the third single-pole double-throw switch is connected to the lower end of the voltage division output resistor R in ; x

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

[0041] The voltage-dividing output resistor R x is the terminal resistor R1 from the voltage-dividing output V out terminal to the negative low potential of the reference voltage V in or a combined voltage-dividing resistor including the terminal resistor R1 (such as Figure 1 R1 and R2 in), and, in order for the subsequent resistor mismatch error formula to hold, the number of voltage-dividing ratio arm voltage-dividing resistors must be a common multiple of the number of combined voltage-dividing resistors, that is, an integer multiple, and an integer multiple greater than 2, which also determines that the voltage-dividing output voltage is 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-dividing ratio arm into two series connections:

[0043] The first series connection, as Figure 1 shown: Connect the high-potential first resistor R of the voltage-dividing ratio arm 1 n to the positive pole of the power supply, connect the upper end of the voltage-dividing output resistor R x to the lower end of the voltage-dividing resistor whose upper end is disconnected from the upper end of the voltage-dividing output resistor R x , connect the lower end of the voltage-dividing output resistor R x to the negative low potential of the reference voltage V in , so that the voltage-dividing resistors containing the voltage-dividing output resistor R X R x 、…、R n are sequentially connected from the negative low potential to the positive high potential of the reference voltage V in to form a series connection;

[0044] The second series connection: As Figure 2 shown, connect the high-potential first resistor R of the voltage-dividing ratio arm 1 n to the upper end of the voltage-dividing output resistor R x , connect the lower end of the voltage-dividing resistor whose upper end is disconnected from the upper end of the voltage-dividing output resistor R x to the negative low potential of the reference voltage V in , connect the lower end of the voltage-dividing output resistor R x to the positive high potential of the reference voltage V in so that the order of the voltage-dividing ratio arm voltage-dividing resistors is …、Rn , R x is connected in series in the order from the negative low potential to the positive high potential of the reference voltage V in ;

[0045] The first series voltage dividing ratio arm 1 and the voltage dividing reference arm 2 are connected in series with the voltage dividing resistors corresponding to each other to form the first differential measurement network as shown in Figure 1 ;

[0046] The second series voltage dividing ratio arm 1 and the voltage dividing reference arm 2 are connected in series with the voltage dividing resistors corresponding to each other to form the second differential measurement network as shown in Figure 2 ;

[0047] In order to achieve automatic control: as shown in Figure 3 , 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] Wherein: the voltage dividing resistors of the voltage dividing ratio arm and the voltage dividing reference arm are precision foil resistors, with an accuracy below 5E-5 and a temperature drift below 5ppm / °C.

[0049] Embodiment 2:

[0050] A voltage dividing ratio self-calibration method for a resistive voltage divider is a self-calibration method based on the voltage ratio resistor self-calibration device described in Embodiment 1. The content of Embodiment 1 is applicable to this embodiment. Since the voltage dividing resistor mismatch error represents the error of the voltage divider ratio coefficient caused by the error of the voltage dividing resistors constituting the voltage divider, the accurate voltage divider ratio coefficient can be obtained by self-calibrating and correcting this error; therefore, the method includes:

[0051] The first step: According to the voltage dividing output voltage V out at the position of the voltage dividing ratio arm 1, determine the number of voltage dividing resistors in the voltage dividing output resistor R x , and divide the voltage dividing measurement points of the voltage dividing resistors of the voltage dividing ratio arm 1 and the voltage dividing reference arm 2 according to the number of voltage dividing resistors.

[0052] The second step: respectively obtain each differential voltage Δ n between the corresponding voltage dividing measurement points of the voltage dividing ratio arm and the voltage dividing reference arm of the first differential measurement network, where n is the number of voltage dividing measurement points;

[0053] The third step: respectively obtain each differential voltage Δ n ' between the corresponding voltage dividing measurement points of the voltage dividing ratio arm 1 and the voltage dividing reference arm 2 of the second differential measurement network, where n is the number of voltage dividing measurement points;

[0054] The fourth step: calculate the voltage dividing output resistor R according to the resistor mismatch error formula xThe voltage division ratio coefficient δ is used to calibrate the voltage division ratio resistors.

[0055] The formula for the resistor mismatch error is

[0056] Where:

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

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

[0059] Obtaining the differential voltages Δ of each differential voltage in the first differential measurement network n , and obtaining the differential voltages Δ' of each differential voltage in the second differential measurement network n ' can be obtained by first measuring the voltage division voltages at each voltage division measurement point and then through calculation, but this method incorporates the error of the digital voltmeter 4, affecting the calibration accuracy: In this embodiment, for obtaining the differential voltages Δ of each differential voltage in the first differential measurement network n , and obtaining the differential voltages Δ' of each differential voltage in the second differential measurement network n ', it is obtained by directly measuring with a digital voltmeter, improving the calibration accuracy.

[0060] To achieve automatic measurement control: As Figure 3 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 each differential voltage in the first differential measurement network n and the differential voltages Δ' of each differential voltage in the second differential measurement network n '.

[0061] The following uses a specific 10:1 embodiment to further illustrate the above description:

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

[0063] 1. During the actual use process, due to the influence of resistor mismatch error, if you want to obtain the correct resistor ratio output, it needs to be calibrated. The calibration process of this structure is summarized as follows:

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

[0065]

[0066] 2. When switches 101, 102, and 103 are in the left state 2, each pair of sampling points is measured again. Note that at this time, the relative position of the sampling points changes, and the voltage division output voltage V out becomes V y . The measurement results are as follows:

[0067]

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

[0069]

[0070] Subtract the above two equations to get:

[0071]

[0072] Simplify to get:

[0073]

[0074] From the above equation, it can be seen that the input-output relationship of the actual overall module can be obtained through calibration, where δ is the resistor mismatch error to be calibrated. As the correction of the voltage division output voltage: Since the actual output and input relationship of the voltage divider V out / V in is known, the actual voltage division output can be corrected by obtaining the voltage division ratio coefficient δ of the voltage division output resistor R x . Taking the conversion of 10V voltage to the required 1V voltage as an example, first obtain the resistor mismatch error δ of the voltage divider through self-calibration (such as the actually measured and calculated δ is 3.49×10 -5 , that is, the actual ratio is 0.10000349). At this time, according to the formula the actual output voltage obtained by the standard 10V voltage passing through this voltage divider is 1.0000349V.

[0075] The entire self-calibration process uses the resistance rotation method. By measuring the voltage differences at different sampling points of different differential measurement networks multiple times, it makes full use of the advantages of differential measurement to calculate the actual input-output relationship of the accurate voltage divider. Compared with the calibration method of directly comparing the voltage divider with the standard ratio device (periodic inspection), its calibration speed is faster and the calibration cost is lower.

[0076] In the above-described embodiment of the voltage division ratio self-calibration circuit and method for the resistive voltage divider, a voltage ratio self-calibration technique based on the reference potential method is adopted. Through differential measurement, the accuracy requirements for the reference source and the voltmeter in the self-calibration process are reduced, thereby achieving high-accuracy voltage ratio self-calibration. Through this technique, the system can be calibrated as needed, calibrating the drift of the ratio coefficient caused by factors such as long-term use of components and changes in environmental temperature, thereby extending the periodic inspection cycle of the equipment and reducing the calibration cost. The present invention realizes fast and high-accuracy ratio self-calibration through three relays, greatly reducing the module volume and significantly reducing the error 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 dividing proportional arm includes a plurality of voltage dividing resistors R1, R2, R3, R4...R 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 'It is a series connection from the negative low potential of the reference voltage to the positive high potential; 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 connect the common end of the first single-pole double-throw switch to the first voltage-dividing 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 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; One point of the first single-pole double-throw switch and one point of the third single-pole double-throw switch are connected to the positive high potential of the power supply, and another point of the first single-pole double-throw switch and one point of the second single-pole double-throw switch are connected to the voltage divider output resistor R x 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 voltage divider output V out Terminal to reference voltage V in The negative low potential terminal resistor R1 or a combined voltage-dividing resistor including the terminal resistor R1, and the number of the voltage-dividing resistors of the voltage-dividing ratio arm is a common multiple of the number of the combined voltage-dividing resistors.

2. The voltage division ratio self-calibration circuit according to claim 1, characterized in that: 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-dividing proportional arm into two series connections: The first series connection: connect the high potential first resistor R of the voltage divider proportional arm 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; The second series connection: connect the high potential first resistor R of the voltage divider proportional arm n And 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 electrode has a low potential and the 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 to 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; The first voltage-dividing proportional arm and the voltage-dividing reference arm connected in series correspond to each other to form a first differential measurement network; The second voltage-dividing resistors connected in series with the voltage-dividing proportional arm and the voltage-dividing reference arm correspond 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 division ratio self-calibration circuit according to claim 1, characterized in that: The voltage dividing resistors of the voltage dividing ratio arm and the voltage dividing reference arm are precision foil resistors with an accuracy of less than 5E-5 and a temperature drift of less than 5ppm / °C.

5. A method for self-calibrating the voltage ratio of a resistive voltage divider is based on the self-calibration method of the voltage ratio self-calibration circuit of 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-dividing resistors is included, and the voltage-dividing measuring points of the voltage-dividing resistors of the voltage-dividing ratio arm and the voltage-dividing reference arm are divided according to the number of voltage-dividing resistors included; Step 2: Obtain the differential voltages Δ between the voltage divider measurement points corresponding to 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 voltage divider measurement points corresponding to 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 division measurement points; Step 4: Calculate the voltage divider output resistance R according to the resistance mismatch error formula x The voltage division ratio coefficient δ is used to calibrate the voltage division ratio resistance; The resistance mismatch error formula is in: ΣΔ is the differential voltage Δ of the first differential measurement network n sum; ΣΔ ’ The second differential measurement network has a differential voltage Δ 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 obtain the respective differential voltages Δ of the second differential measurement network n ' is obtained by direct measurement through a digital voltmeter.

7. The method according to claim 5 or 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, and 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 '.

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