Electronic voltage transformer

Abstract

The present invention discloses an electronic voltage transformer. Its DC voltage dividing branch and AC voltage dividing branch are connected in parallel between the voltage input terminal and the ground. The output terminal of the DC voltage dividing branch is electrically connected to a DC signal selection circuit, the DC signal selection circuit is electrically connected to an integration circuit, the output terminal of the AC voltage dividing branch is electrically connected to an AC signal selection circuit, the AC signal selection circuit is electrically connected to the integration circuit, and the integration circuit is electrically connected to a DC comparison circuit and an AC comparison circuit respectively. By setting the magnitude relationship of the resistance values of the resistors in the DC voltage dividing branch and the AC voltage dividing branch, when a DC voltage is input, the effective value output by the integration circuit and the effective value output by the integration circuit when an AC voltage is input are in the same order of magnitude, so as to simplify the circuit structure of the transformer. At the same time, through the DC comparison circuit and the AC comparison circuit, the DC voltage or the AC voltage can be transmitted to the measuring instrument, improving the applicability of the electronic voltage transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of instrument transformers, and particularly to an electronic voltage transformer. Background Art

[0002] A voltage transformer is one of the basic measuring devices for electric energy metering and relay protection in a power system. Its primary side is connected across the high-voltage grid bus and the ground, and its secondary side is connected to a wattmeter, an electric energy meter, and an electromechanical protection device, providing a bus voltage signal for the electromechanical protection device and electric energy metering. Its measurement accuracy and reliability are closely related to the safe, reliable, and economic operation of the power system.

[0003] When the voltage transformer reduces the DC voltage and AC voltage on the primary side and transmits them to the secondary side, since the voltage values after the DC voltage and AC voltage are reduced differ by at least one order of magnitude, the circuit structure is relatively complex when processing voltages at different orders of magnitude subsequently. Summary of the Invention

[0004] The present invention provides an electronic voltage transformer to reduce the circuit complexity of the transformer.

[0005] The present invention provides an electronic voltage transformer, including: a DC voltage division branch, an AC voltage division branch, a DC signal selection circuit, an AC signal selection circuit, an integration circuit, a DC comparison circuit, and an AC comparison circuit. The DC comparison circuit includes a first voltage setting terminal and a second voltage setting terminal, and the AC comparison circuit includes a third voltage setting terminal and a fourth voltage setting terminal. The DC voltage division branch and the AC voltage division branch are connected in parallel between a voltage input terminal and the ground. The output terminal of the DC voltage division branch is electrically connected to the input terminal of the DC signal selection circuit. The output terminal of the DC signal selection circuit is electrically connected to the input terminal of the integration circuit. The output terminal of the AC voltage division branch is electrically connected to the input terminal of the AC signal selection circuit. The output terminal of the AC signal selection circuit is electrically connected to the input terminal of the integration circuit. The output terminal of the integration circuit is electrically connected to the input terminals of the DC comparison circuit and the AC comparison circuit respectively. The output terminal of the DC comparison circuit is electrically connected to a measuring instrument, and the output terminal of the AC comparison circuit is electrically connected to the measuring instrument; the resistance values of the DC voltage division branch and the AC voltage division branch are different so that when the voltages applied to the DC voltage division branch and the AC voltage division branch are the same, the voltage values output by the output terminals of the DC voltage division branch and the AC voltage division branch are different;

[0006] The DC voltage division branch is configured to reduce the voltage input at the voltage input terminal and then transmit it to the DC signal selection circuit, and the AC voltage division branch is configured to reduce the voltage input at the voltage input terminal and then transmit it to the AC signal selection circuit; the DC signal selection circuit is configured to filter out the AC signals in the circuit, and the AC signal selection circuit is configured to filter out the DC signals in the circuit; the DC comparison circuit is configured to output the effective value signal to the measuring instrument when it is determined that the effective value signal generated by the integration circuit is greater than the voltage at the first voltage setting terminal and less than the voltage at the second voltage setting terminal; the AC comparison circuit is configured to output the effective value signal to the measuring instrument when it is determined that the effective value signal generated by the integration circuit is greater than the voltage at the third voltage setting terminal and less than the voltage at the fourth voltage setting terminal; the voltage at the first voltage setting terminal is less than the voltage at the second voltage setting terminal, and the voltage at the third voltage setting terminal is less than the voltage at the fourth voltage setting terminal.

[0007] Optionally, the voltage at the first voltage setting terminal is less than the voltage output at the output terminal of the DC voltage division branch when a DC voltage is input at the voltage input terminal, and the voltage at the second voltage setting terminal is less than the magnitude of the effective value signal output at the output terminal of the integration circuit when an AC voltage is input at the voltage input terminal; the voltage at the third voltage setting terminal is greater than the voltage at the second voltage setting terminal, and the voltage at the fourth voltage setting terminal is greater than the magnitude of the effective value signal output at the output terminal of the integration circuit when an AC voltage is input at the voltage input terminal.

[0008] Optionally, the electronic voltage transformer further includes a control module, a DC indication module and an AC indication module electrically connected to the control module. The first input terminal of the control module is electrically connected to the output terminal of the DC comparison circuit, and the second input terminal of the control module is electrically connected to the output terminal of the AC comparison circuit. The control module is configured to control the DC indication module to conduct when the effective value signal is output at the output terminal of the DC comparison circuit and no voltage signal is output at the output terminal of the AC comparison circuit, and is further configured to control the AC indication module to conduct when the effective value signal is output at the output terminal of the AC comparison circuit and no voltage signal is output at the output terminal of the DC comparison circuit.

[0009] Optionally, the DC comparison circuit includes a first amplifier, a second amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor; the first input terminal of the first amplifier serves as the input terminal of the DC comparison circuit, one end of the first resistor is connected to a first fixed potential, the other end of the first resistor is electrically connected to the second input terminal of the first amplifier, the other end of the first resistor is also connected to one end of the second resistor, the other end of the second resistor is grounded, the other end of the second resistor is also connected to the output terminal of the first amplifier, and the second input terminal of the first amplifier serves as the first voltage setting terminal; the second input terminal of the second amplifier is electrically connected to the first input terminal of the first amplifier, one end of the third resistor is connected to a second fixed potential, the other end of the third resistor is electrically connected to the first input terminal of the second amplifier, the other end of the third resistor is also connected to one end of the fourth resistor, the other end of the fourth resistor is grounded, the second input terminal of the second amplifier is also connected to the output terminal of the second amplifier, the first input terminal of the second amplifier serves as the second voltage setting terminal, the output terminal of the first amplifier is connected to the output terminal of the second amplifier, and the output terminal of the first amplifier serves as the output terminal of the DC comparison circuit; the potential signals of the first fixed potential and the second fixed potential are opposite;

[0010] The AC comparison circuit includes a third amplifier, a fourth amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; the first input terminal of the third amplifier serves as the input terminal of the AC comparison circuit, one end of the fifth resistor is connected to the first fixed potential, the other end of the fifth resistor is electrically connected to the second input terminal of the third amplifier, the other end of the fifth resistor is also connected to one end of the sixth resistor, the other end of the sixth resistor is grounded, the other end of the sixth resistor is also connected to the output terminal of the third amplifier, and the second input terminal of the third amplifier serves as the third voltage setting terminal; the second input terminal of the fourth amplifier is electrically connected to the first input terminal of the third amplifier, one end of the seventh resistor is connected to the second fixed potential, the other end of the seventh resistor is electrically connected to the first input terminal of the fourth amplifier, the other end of the seventh resistor is also connected to one end of the eighth resistor, the other end of the eighth resistor is grounded, the second input terminal of the fourth amplifier is also connected to the output terminal of the fourth amplifier, the first input terminal of the fourth amplifier serves as the fourth voltage setting terminal, the output terminal of the third amplifier is connected to the output terminal of the fourth amplifier, and the output terminal of the third amplifier serves as the output terminal of the AC comparison circuit.

[0011] Optionally, the DC voltage division branch includes a ninth resistor and a tenth resistor. The first end of the ninth resistor is electrically connected to the voltage input terminal. The second end of the ninth resistor is electrically connected to the first end of the tenth resistor. The second end of the ninth resistor serves as the output end of the DC voltage division branch, and the second end of the tenth resistor is grounded.

[0012] The AC voltage division branch includes an eleventh resistor and a twelfth resistor. The first end of the eleventh resistor is electrically connected to the voltage input terminal. The second end of the eleventh resistor is electrically connected to the first end of the twelfth resistor. The second end of the eleventh resistor serves as the output end of the AC voltage division branch, and the second end of the twelfth resistor is grounded.

[0013] Optionally, the ratio of the resistance value of the ninth resistor to that of the tenth resistor is a first ratio, and the ratio of the resistance value of the eleventh resistor to that of the twelfth resistor is a second ratio. The ratio of the second ratio to the first ratio is 5 - 25.

[0014] Optionally, the integration circuit includes a fifth amplifier, a first capacitor, a thirteenth resistor, and a fourteenth resistor. The first input terminal of the fifth amplifier serves as the input terminal of the integration circuit. The second input terminal of the fifth amplifier is grounded. One end of the first capacitor is electrically connected to the first input terminal of the fifth comparator, and the other end of the first capacitor is electrically connected to the output terminal of the fifth comparator. One end of the thirteenth resistor is electrically connected to the first input terminal of the fifth comparator, and the other end of the thirteenth resistor is electrically connected to the output terminal of the fifth comparator. The output terminal of the fifth comparator is electrically connected to one end of the fourteenth resistor, and the other end of the fourteenth resistor serves as the output end of the integration circuit.

[0015] Optionally, the electronic voltage transformer further includes a first voltage follower and a second voltage follower. The first input terminal of the first voltage follower is electrically connected to the output terminal of the first voltage follower. The second input terminal of the first voltage follower is electrically connected to the output terminal of the DC signal selection circuit. The output terminal of the first voltage follower is electrically connected to the input terminal of the integration circuit.

[0016] The first input terminal of the second voltage follower is electrically connected to the output terminal of the second voltage follower. The second input terminal of the second voltage follower is electrically connected to the output terminal of the AC signal selection circuit. The output terminal of the second voltage follower is electrically connected to the input terminal of the integration circuit.

[0017] Optionally, the electronic voltage transformer further includes a first filter circuit and a second filter circuit. The first filter circuit includes a fifteenth resistor, a sixteenth resistor, a second capacitor, and a third capacitor. The second filter circuit includes a seventeenth resistor, an eighteenth resistor, a fourth capacitor, and a fifth capacitor.

[0018] One end of the fifteenth resistor is electrically connected to the output end of the DC signal selection circuit. The other end of the fifteenth resistor is electrically connected to one end of the second capacitor. The other end of the second capacitor is grounded. The other end of the fifteenth resistor is also electrically connected to one end of the sixteenth resistor. The other end of the sixteenth resistor is electrically connected to one end of the third capacitor. The other end of the third capacitor is grounded. The other end of the sixteenth resistor is electrically connected to the input end of the integration circuit.

[0019] One end of the seventeenth resistor is electrically connected to the output end of the AC signal selection circuit. The other end of the seventeenth resistor is electrically connected to one end of the fourth capacitor. The other end of the fourth capacitor is grounded. The other end of the seventeenth resistor is also electrically connected to one end of the eighteenth resistor. The other end of the eighteenth resistor is electrically connected to one end of the fifth capacitor. The other end of the fifth capacitor is grounded. The other end of the eighteenth resistor is electrically connected to the input end of the integration circuit.

[0020] Optionally, the electronic voltage transformer further includes an output module. The first input end of the output module is electrically connected to the output end of the DC comparison circuit. The second input end of the output module is electrically connected to the output end of the AC comparison circuit. The output end of the output module is electrically connected to the measuring instrument. The output module is configured to convert the effective value signal output by the DC comparison circuit or the AC comparison circuit into a matching signal and output it to the measuring instrument. The matching signal is a current signal.

[0021] An embodiment of the present invention provides an electronic voltage transformer, which includes a DC voltage division branch, an AC voltage division branch, a DC signal selection circuit, an AC signal selection circuit, an integration circuit, a DC comparison circuit, and an AC comparison circuit. The DC voltage division branch and the AC voltage division branch are connected in parallel between a voltage input terminal and the ground. The output terminal of the DC voltage division branch is electrically connected to the input terminal of the DC signal selection circuit. The output terminal of the DC signal selection circuit is electrically connected to the input terminal of the integration circuit. The output terminal of the AC voltage division branch is electrically connected to the input terminal of the AC signal selection circuit. The output terminal of the AC signal selection circuit is electrically connected to the input terminal of the integration circuit. The output terminal of the integration circuit is electrically connected to the input terminals of the DC comparison circuit and the AC comparison circuit respectively. The output terminal of the DC comparison circuit is electrically connected to a measuring instrument. The output terminal of the AC comparison circuit is electrically connected to the measuring instrument. The resistance values of the DC voltage division branch and the AC voltage division branch are different, so that when the voltages applied to the DC voltage division branch and the AC voltage division branch are the same, the voltage values output by the output terminals of the DC voltage division branch and the AC voltage division branch are different. By setting the magnitude relationship of the resistance values of the resistors included in the DC voltage division branch and the AC voltage division branch, when the voltages applied to the DC voltage division branch and the AC voltage division branch are the same, the voltage values output by the output terminals of the DC voltage division branch and the AC voltage division branch are different, so that when a DC voltage is input to the voltage input terminal, the effective value output by the output terminal of the integration circuit and the effective value output by the output terminal of the integration circuit when an AC voltage is input to the voltage input terminal are in the same order of magnitude, so as to simplify the structures of circuits such as the DC comparison circuit and the AC comparison circuit, which is beneficial to the simplification of the circuit design of the electronic voltage transformer. At the same time, the DC comparison circuit and the AC comparison circuit can be used to transmit a DC voltage or an AC voltage to the measuring instrument, improving the applicability of the electronic voltage transformer.

[0022] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 is a schematic structural diagram of an electronic voltage transformer provided by an embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of another electronic voltage transformer provided by an embodiment of the present invention;

[0026] Figure 3 It is a schematic structural diagram of another electronic voltage transformer provided by an embodiment of the present invention. Detailed implementation manners

[0027] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or system comprising a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or systems.

[0029] Figure 1 It is a schematic structural diagram of an electronic voltage transformer provided by an embodiment of the present invention. Refer to Figure 1, the electronic voltage transformer includes a DC voltage dividing branch 10, an AC voltage dividing branch 11, a DC signal selection circuit 12, an AC signal selection circuit 13, an integration circuit 14, a DC comparison circuit 15 and an AC comparison circuit 16. The DC comparison circuit 15 includes a first voltage setting terminal A1 and a second voltage setting terminal A2. The AC comparison circuit 16 includes a third voltage setting terminal A3 and a fourth voltage setting terminal A4. The DC voltage dividing branch 10 and the AC voltage dividing branch 11 are connected in parallel between a voltage input terminal INT1 and a ground GND. The output terminal B1 of the DC voltage dividing branch 10 is electrically connected to the input terminal of the DC signal selection circuit 12. The output terminal of the DC signal selection circuit 12 is electrically connected to the input terminal A5 of the integration circuit 14. The output terminal B2 of the AC voltage dividing branch 11 is electrically connected to the input terminal of the AC signal selection circuit 13. The output terminal of the AC signal selection circuit 13 is electrically connected to the input terminal A5 of the integration circuit 14. The output terminal B3 of the integration circuit 14 is respectively electrically connected to the input terminal A6 of the DC comparison circuit 15 and the input terminal A7 of the AC comparison circuit 16. The output terminal B4 of the DC comparison circuit 15 is electrically connected to a measuring instrument 17. The output terminal B5 of the AC comparison circuit 16 is electrically connected to the measuring instrument 17; the resistance values of the DC voltage dividing branch 10 and the AC voltage dividing branch 11 are different so that when the voltages applied to the DC voltage dividing branch 10 and the AC voltage dividing branch 11 are the same, the voltage values output from the output terminal B1 of the DC voltage dividing branch 10 and the output terminal B1 of the AC voltage dividing branch 11 are different;

[0030] The DC voltage dividing branch 10 is configured to reduce the voltage input from the voltage input terminal INT1 and then transmit it to the DC signal selection circuit 12. The AC voltage dividing branch 11 is configured to reduce the voltage input from the voltage input terminal INT1 and then transmit it to the AC signal selection circuit 13; the DC signal selection circuit 12 is configured to filter out the AC signal in the circuit, and the AC signal selection circuit 13 is configured to filter out the DC signal in the circuit; the DC comparison circuit 15 is configured to output the effective value signal to the measuring instrument 17 when it is determined that the effective value signal generated by the integration circuit 14 is greater than the voltage of the first voltage setting terminal A1 and less than the voltage of the second voltage setting terminal A2; the AC comparison circuit 16 is configured to output the effective value signal to the measuring instrument 17 when it is determined that the effective value signal generated by the integration circuit 14 is greater than the voltage of the third voltage setting terminal A3 and less than the voltage of the fourth voltage setting terminal A4; the voltage of the first voltage setting terminal A1 is less than the voltage of the second voltage setting terminal A2, and the voltage of the third voltage setting terminal A3 is less than the voltage of the fourth voltage setting terminal A4.

[0031] The voltage input terminal INT1 is used to input the voltage on the bus in the power system. Generally, the bus voltage is relatively large, while the voltage that the measuring instrument 17 can accept is relatively small. Therefore, it is necessary to convert the large voltage on the primary side into a small voltage or small current with the same phase and output it to the measuring instrument 17. When the voltage input terminal INT1 inputs a DC voltage, the DC voltage may be doped with AC signals. The DC signal selection circuit 12 is used to filter out the AC signals. Exemplarily, the DC signal selection circuit 12 at least includes an inductor. By setting the inductance value of the inductor, after the AC signal passes through the inductor, the AC signal is filtered out. When the voltage input terminal INT1 inputs an AC voltage, the AC voltage may be doped with DC signals. The AC signal selection circuit 13 is used to filter out the DC signals. Exemplarily, the AC signal selection circuit 13 at least includes a DC blocking capacitor, and the DC signals are filtered out through the DC blocking capacitor. After passing through the integration circuit 14, the amplitude of the DC voltage remains unchanged, that is, the effective value signal of the DC voltage is equal to the magnitude of its own voltage. After passing through the integration circuit 14, the AC voltage becomes an effective value. The voltage value of the AC voltage remains unchanged at each moment and cannot be input into the subsequent circuit for analysis. Therefore, it is necessary to convert the AC voltage, such as a sinusoidal voltage, into a fixed value, that is, an effective value signal, for analysis.

[0032] Generally, the effective value of the AC voltage on the bus side is 25000V, and the DC voltage is 1500V. By setting the resistance values on the DC voltage dividing branch 10 and the AC voltage dividing branch 11, when the voltage input by the voltage input terminal INT1 is a DC voltage, the voltage output from the output terminal B1 of the DC voltage dividing branch 10 is 1.5V, and the voltage output from the output terminal B2 of the AC voltage dividing branch 11 is 0.15V. When the voltage input by the voltage input terminal INT1 is a DC voltage, no signal is output from the output terminal of the AC signal selection circuit 13, and the 1.5V voltage output by the DC signal selection circuit 12 enters the integration circuit 14. When the voltage of the voltage input terminal INT1 is an AC voltage with an effective value of 25000V, the effective value of the voltage output from the output terminal B1 of the DC voltage dividing branch 10 is 25V (at this time, the resistance ratio of the DC voltage dividing branch and the AC voltage dividing branch has been set when inputting the DC voltage), the effective value of the voltage output from the output terminal B2 of the AC voltage dividing branch 11 is 2.5V, and no voltage is output from the output terminal of the DC signal selection circuit 12. At this time, the voltage input into the integration circuit 14 is the voltage output from the AC signal selection circuit 13.

[0033] Exemplarily, when the voltage of the first voltage setting terminal A1 is set to be less than the voltage corresponding to the effective value signal output by the integrating circuit 14 when the DC voltage is input to the voltage input terminal INT1, and the voltage of the second voltage setting terminal A2 is greater than the voltage corresponding to the effective value signal output by the integrating circuit 14 when the AC voltage is input to the voltage input terminal INT1. At the same time, the voltage of the third voltage setting terminal A3 is set to be equal to the voltage of the first voltage setting terminal A1, and the voltage of the fourth voltage setting terminal A4 is set to be equal to the voltage of the second voltage setting terminal A2. Exemplarily, the voltage of the first voltage setting terminal A1 is 1.3V, and the voltage of the second voltage setting terminal A2 is 2.7V. Then when the DC voltage is input to the voltage input terminal INT1, the 1.5V voltage output by the output terminal of the integrating circuit 14 is between 1.3V and 2.7V, and can be output to the measuring instrument 17 through the DC comparison circuit 15 and the AC comparison circuit 16. When the AC voltage is input to the voltage input terminal INT1, the 2.5V voltage output by the output terminal of the integrating circuit 14 is between 1.3V and 2.7V, and can be output to the measuring instrument 17 through the DC comparison circuit 15 and the AC comparison circuit 16. Thus, it is realized that the voltage signal can be transmitted to the measuring instrument whether the DC voltage or the AC voltage is input to the voltage input terminal INT1.

[0034] In the electronic voltage transformer of this embodiment, by setting the magnitude relationship of the resistance values of the resistors included in the DC voltage division branch and the AC voltage division branch, when the voltages applied to the DC voltage division branch and the AC voltage division branch are the same, the voltage values output by the output terminals of the DC voltage division branch and the AC voltage division branch are different, so that when the DC voltage is input to the voltage input terminal, the magnitude of the effective value output by the output terminal of the integrating circuit is of the same order of magnitude as the magnitude of the effective value output by the output terminal of the integrating circuit when the AC voltage is input to the voltage input terminal, so as to simplify the structures of circuits such as the DC comparison circuit and the AC comparison circuit, which is beneficial to the simplification of the circuit design of the electronic voltage transformer. At the same time, through the DC comparison circuit and the AC comparison circuit, the DC voltage or the AC voltage can be transmitted to the measuring instrument, improving the applicability of the electronic voltage transformer.

[0035] Continue to refer to Figure 1 , optionally, the voltage of the first voltage setting terminal A1 is less than the voltage output by the output terminal B1 of the DC voltage division branch 10 when the DC voltage is input to the voltage input terminal INT1, and the voltage of the second voltage setting terminal A2 is less than the magnitude of the effective value signal output by the output terminal B3 of the integrating circuit 14 when the AC voltage is input to the voltage input terminal INT1; the voltage of the third voltage setting terminal A3 is greater than the voltage of the second voltage setting terminal A3, and the voltage of the fourth voltage setting terminal A4 is greater than the magnitude of the effective value signal output by the output terminal B3 of the integrating circuit 14 when the AC voltage is input to the voltage input terminal INT1.

[0036] Exemplarily, the voltage of the first voltage setting terminal A1 is equal to 1.3V, the voltage of the second voltage setting terminal A2 is equal to 1.7V, the voltage of the third voltage setting terminal A3 is 2V, and the voltage of the fourth voltage setting terminal A4 is 2.7V. When the voltage input at the voltage input terminal INT1 is a DC voltage, the 1.5V voltage output by the integration circuit 14 is output through the DC comparison circuit 15, and no signal is output by the AC comparison circuit 16. When the voltage input at the voltage input terminal INT1 is an AC voltage, the 2.5V voltage output by the integration circuit 14 is output through the AC comparison circuit 16, and no signal is output by the DC comparison circuit 15.

[0037] Continuing to refer to Figure 1 , optionally, the electronic voltage transformer further includes a control module 18, a DC indication module 19 and an AC indication module 20 electrically connected to the control module. The first input terminal A9 of the control module 18 is electrically connected to the output terminal B4 of the DC comparison circuit 15, and the second input terminal A10 of the control module 18 is electrically connected to the output terminal B5 of the AC comparison circuit 16. The control module 18 is configured to control the DC indication module 19 to conduct when a valid value signal is output at the output terminal B4 of the DC comparison circuit 15 and no voltage signal is output at the output terminal B5 of the AC comparison circuit 16, and is further configured to control the AC indication module 20 to conduct when a valid value signal is output at the output terminal B5 of the AC comparison circuit 16 and no voltage signal is output at the output terminal B4 of the DC comparison circuit 15.

[0038] The DC indication module 19 can be an indicator light, and the AC indication module 20 can be an indicator light. The control module 18 determines the type of the voltage input at the voltage input terminal INT1 according to whether there is a voltage signal output by the DC comparison circuit 15 and the AC comparison circuit 16, and controls the corresponding indication module to light up, so as to facilitate the user to directly obtain the type of the voltage input at the voltage input terminal INT1.

[0039] Continuing to refer to Figure 1, optionally, the DC comparison circuit 15 includes a first amplifier Q1, a second amplifier Q2, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4; the first input terminal D1 of the first amplifier Q1 serves as the input terminal A6 of the DC comparison circuit 15, one end of the first resistor R1 is connected to a first fixed potential V1, the other end of the first resistor R1 is electrically connected to the second input terminal D2 of the first amplifier Q1, the other end of the first resistor R1 is also electrically connected to one end of the second resistor R2, the other end of the second resistor R2 is grounded to GND, the other end of the second resistor R2 is also electrically connected to the output terminal E1 of the first amplifier Q1, and the second input terminal D2 of the first amplifier Q1 serves as the first voltage setting terminal A1; the second input terminal D4 of the second amplifier Q2 is electrically connected to the first input terminal D1 of the first amplifier Q1, one end of the third resistor R3 is connected to a second fixed potential V2, the other end of the third resistor R3 is electrically connected to the first input terminal D3 of the second amplifier Q2, the other end of the third resistor R3 is also electrically connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is grounded to GND, the second input terminal D4 of the second amplifier Q2 is also electrically connected to the output terminal E2 of the second amplifier Q2, the first input terminal D3 of the second amplifier Q2 serves as the second voltage setting terminal A2, the output terminal E1 of the first amplifier Q1 is electrically connected to the output terminal E2 of the second amplifier Q2, and the output terminal E1 of the first amplifier Q1 serves as the output terminal B4 of the DC comparison circuit 15; the potential signals of the first fixed potential V1 and the second fixed potential V2 are opposite;

[0040] The AC comparison circuit 16 includes a third amplifier Q3, a fourth amplifier Q4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8; the first input terminal D5 of the third amplifier Q3 serves as the input terminal A7 of the AC comparison circuit 16, one end of the fifth resistor R5 is connected to a first fixed potential V1, the other end of the fifth resistor R5 is electrically connected to the second input terminal D6 of the third amplifier Q3, the other end of the fifth resistor R5 is also electrically connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is grounded to GND, the other end of the sixth resistor R6 is also electrically connected to the output terminal E3 of the third amplifier Q3, and the second input terminal D6 of the third amplifier Q3 serves as the third voltage setting terminal A3; the second input terminal D8 of the fourth amplifier Q4 is electrically connected to the first input terminal D5 of the third amplifier Q3, one end of the seventh resistor R7 is connected to a second fixed potential V2, the other end of the seventh resistor R7 is electrically connected to the first input terminal D7 of the fourth amplifier Q4, the other end of the seventh resistor R7 is also electrically connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is grounded to GND, the second input terminal D8 of the fourth amplifier Q4 is also electrically connected to the output terminal E4 of the fourth amplifier Q4, the first input terminal D7 of the fourth amplifier Q4 serves as the fourth voltage setting terminal A4, the output terminal E3 of the third amplifier Q3 is electrically connected to the output terminal E4 of the fourth amplifier Q4, and the output terminal E3 of the third amplifier Q3 serves as the output terminal B5 of the AC comparison circuit 16.

[0041] Exemplarily, the models of the first amplifier Q1 and the second amplifier Q2 can be LM393. The non-inverting input terminal of the first amplifier Q1 serves as the second input terminal D2 of the first amplifier Q1, and the inverting input terminal of the first amplifier Q1 serves as the first input terminal D1 of the first amplifier Q1. The non-inverting input terminal of the second amplifier Q2 serves as the second input terminal D4 of the second amplifier Q2, and the inverting input terminal of the second amplifier Q2 serves as the first input terminal D3 of the second amplifier Q2. The first input terminal D1 of the first amplifier Q1 is electrically connected to the output terminal B3 of the integrating circuit 14 through the nineteenth resistor R19. The second input terminal D2 of the first amplifier Q1 is also electrically connected to the output terminal E1 of the first amplifier Q1 through the twentieth resistor R20. The second input terminal D4 of the second amplifier Q2 is electrically connected to the output terminal B3 of the integrating circuit 14 through the twenty-first resistor R21. The second input terminal D4 of the second amplifier Q2 is also electrically connected to the output terminal E2 of the second amplifier Q2 through the twenty-second resistor R22. The first resistor R1 and the second resistor R2 form a voltage dividing circuit, and the voltage of the first voltage setting terminal A1 is set by setting the resistance values of the first resistor R1, the second resistor R2, and the first fixed potential V1. The third resistor R3 and the fourth resistor R4 form a voltage dividing circuit, and the voltage of the second voltage setting terminal A2 is set by setting the resistance values of the third resistor R3, the fourth resistor R4, and the second fixed potential V2. Exemplarily, the first fixed potential V1 is a positive voltage, and the second fixed potential V2 is a negative voltage. The first amplifier Q1 and the second amplifier Q2 form a comparator, and only the voltage between the first voltage setting terminal A1 and the second voltage setting terminal A2 is allowed to pass through.

[0042] The models of the third amplifier Q3 and the fourth amplifier Q4 can be LM393. The non-inverting input terminal of the third amplifier Q3 serves as the second input terminal D6 of the third amplifier Q3, and the inverting input terminal of the third amplifier Q3 serves as the first input terminal D5 of the third amplifier Q3. The non-inverting input terminal of the fourth amplifier Q4 serves as the second input terminal D8 of the fourth amplifier Q4, and the inverting input terminal of the fourth amplifier Q4 serves as the first input terminal D7 of the fourth amplifier Q4. The first input terminal D5 of the third amplifier Q3 is electrically connected to the output terminal B3 of the integrating circuit 14 through the twenty-third resistor R23. The second input terminal D6 of the third amplifier Q3 is also electrically connected to the output terminal E3 of the third amplifier Q3 through the twenty-fourth resistor R24. The second input terminal D8 of the fourth amplifier Q4 is electrically connected to the output terminal B3 of the integrating circuit 14 through the twenty-fifth resistor R25. The second input terminal D8 of the fourth amplifier Q4 is also electrically connected to the output terminal E4 of the fourth amplifier Q4 through the twenty-sixth resistor R26. The fifth resistor R5 and the sixth resistor R6 form a voltage dividing circuit, and the voltage magnitude of the third voltage setting terminal A3 is set by setting the resistance values of the fifth resistor R5, the sixth resistor R6, and the first fixed potential V1. The seventh resistor R7 and the eighth resistor R8 form a voltage dividing circuit, and the voltage magnitude of the fourth voltage setting terminal A4 is set by setting the resistance values of the seventh resistor R7, the eighth resistor R8, and the second fixed potential V2. The third amplifier Q3 and the fourth amplifier Q4 form a comparator, and only the voltage between the third voltage setting terminal A3 and the fourth voltage setting terminal A4 is allowed to pass through.

[0043] Figure 2 Another structural schematic diagram of the electronic voltage transformer provided by the embodiment of the present invention is shown in reference Figure 2 , Optionally, the DC voltage dividing branch 10 includes a ninth resistor R9 and a tenth resistor R10. The first end of the ninth resistor R9 is electrically connected to the voltage input terminal INT1, the second end of the ninth resistor R9 is electrically connected to the first end of the tenth resistor R10, the second end of the ninth resistor R9 serves as the output terminal B1 of the DC voltage dividing branch 10, and the second end of the tenth resistor R10 is grounded to GND;

[0044] The AC voltage dividing branch 11 includes an eleventh resistor R11 and a twelfth resistor R12. The first end of the eleventh resistor R11 is electrically connected to the voltage input terminal INT1, the second end of the eleventh resistor R11 is electrically connected to the first end of the twelfth resistor R12, the second end of the eleventh resistor R11 serves as the output terminal B2 of the AC voltage dividing branch 11, and the second end of the twelfth resistor R12 is grounded to GND.

[0045] The voltage input from the voltage input terminal INT1 is converted into a small voltage through the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12. The structure is simple and the volume is small, which is beneficial to the miniaturization of the device.

[0046] Continue to refer to Figure 2 Optionally, the resistance ratio of the ninth resistor R9 to the tenth resistor R10 is a first ratio, the resistance ratio of the eleventh resistor R11 to the twelfth resistor R12 is a second ratio, and the ratio of the second ratio to the first ratio is 5-25.

[0047] For the voltage input at the voltage input terminal INT1, if it is an AC voltage, it is generally 25 KV, and if it is a DC voltage, it is generally 1500 V, that is, the AC voltage value and the DC voltage value differ by about 10 times. Exemplarily, if the voltage to be input is a DC voltage, after the 1500 V DC voltage is input to the first voltage division branch 10 and the second voltage division branch 11, the voltage output from the output terminal B1 of the first voltage division branch 10 is 1.5 V, then the first ratio is 999. If the voltage input at the voltage input terminal INT1 is an AC voltage, after the 25 KV AC voltage is input to the first voltage division branch 10 and the second voltage division branch 11, in order for the voltage output from the output terminal B2 of the second voltage division branch 11 to be in the same order of magnitude as the voltage output from the output terminal B1 of the first voltage division branch 10 when it is DC, the voltage output from the output terminal B2 of the second voltage division branch 11 should be about 1-5 V. If it is 1 V, the second ratio is 24999, and if it is 5 V, the second ratio is 4999, that is, the ratio of the second ratio to the first ratio is about 5-25.

[0048] Continue to refer to Figure 2 Optionally, the integrating circuit 14 includes a fifth amplifier Q5, a first capacitor C1, a thirteenth resistor R13, and a fourteenth resistor R14. The first input terminal D9 of the fifth amplifier Q5 serves as the input terminal A5 of the integrating circuit 14. The second input terminal D10 of the fifth amplifier Q5 is grounded to GND. One end of the first capacitor C1 is electrically connected to the first input terminal D9 of the fifth comparator Q5, and the other end of the first capacitor C1 is electrically connected to the output terminal E5 of the fifth comparator Q5. One end of the thirteenth resistor R13 is electrically connected to the first input terminal D9 of the fifth comparator Q5, and the other end of the thirteenth resistor R13 is electrically connected to the output terminal E5 of the fifth comparator Q5. The output terminal E5 of the fifth comparator Q5 is electrically connected to one end of the fourteenth resistor R14, and the other end of the fourteenth resistor R14 serves as the output terminal B3 of the integrating circuit 14.

[0049] An integrating circuit is formed by connecting a first capacitor C1, a thirteenth resistor R13, a fourteenth resistor R14, and a fifth amplifier Q5. When an AC voltage is input to the voltage input terminal INT1, the AC voltage output by the AC signal selection circuit 13 is integrated to generate an effective value signal. The model of the fifth amplifier Q5 can be LM324, the capacitance value of the first capacitor C1 can be set to 10NF, the resistance value of the thirteenth resistor R13 can be 20KΩ, and the resistance value of the fourteenth resistor R14 can be 100Ω. The fifth amplifier Q5 is also connected to a first fixed potential V1 and a second fixed potential V2 to supply power to itself.

[0050] Figure 3 The following is a schematic structural diagram of another electronic voltage transformer provided by an embodiment of the present invention. Refer to Figure 3 , optionally, the electronic voltage transformer includes a first voltage follower Q6 and a second voltage follower Q7. The first input terminal D11 of the first voltage follower Q6 is electrically connected to the output terminal E6 of the first voltage follower Q6. The second input terminal D12 of the first voltage follower Q6 is electrically connected to the output terminal of the DC signal selection circuit 12. The output terminal E6 of the first voltage follower Q6 is electrically connected to the input terminal A5 of the integrating circuit 14;

[0051] The first input terminal D13 of the second voltage follower Q7 is electrically connected to the output terminal E7 of the second voltage follower Q7. The second input terminal D14 of the second voltage follower Q7 is electrically connected to the output terminal of the AC signal selection circuit 13. The output terminal E7 of the second voltage follower Q7 is electrically connected to the input terminal A5 of the integrating circuit 14.

[0052] The model of the first voltage follower Q6 can be LM324, the signal of the second voltage follower Q7 can be LM324. The output terminal E6 of the first voltage follower Q6 is electrically connected to the input terminal A5 of the integrating circuit 14 through a resistor, and the output terminal E7 of the second voltage follower Q7 is also electrically connected to the input terminal A5 of the integrating circuit 14 through a resistor. The main characteristics of the first voltage follower Q6 and the second voltage follower Q7 are: high input resistance, low output resistance, and the voltage gain is approximately 1. When the input impedance is very high, it is equivalent to opening the previous-stage circuit (the circuit connected to the second input terminal D12 of the first voltage follower Q6 or the circuit connected to the second input terminal D14 of the second voltage follower Q7). When the output impedance is very low, it is equivalent to a constant voltage source for the subsequent-stage circuit (the circuit connected to the output terminal E6 of the first voltage follower Q6 or the circuit connected to the output terminal E7 of the second voltage follower Q7), that is, the output voltage is not affected by the impedance of the subsequent-stage circuit. A circuit that is equivalent to an open circuit for the previous-stage circuit and the output voltage is not affected by the subsequent-stage impedance has an isolation effect, that is, the previous-stage and subsequent-stage circuits do not affect each other.

[0053] Continue to refer to Figure 3, optionally, the electronic voltage transformer further includes a first filter circuit and a second filter circuit. The first filter circuit includes a fifteenth resistor R15, a sixteenth resistor R16, a second capacitor C2, and a third capacitor C3. The second filter circuit includes a seventeenth resistor R17, an eighteenth resistor R18, a fourth capacitor C4, and a fifth capacitor C5;

[0054] One end of the fifteenth resistor R15 is electrically connected to the output end of the DC signal selection circuit 12. The other end of the fifteenth resistor R15 is electrically connected to one end of the second capacitor C2. The other end of the second capacitor C2 is grounded to GND. The other end of the fifteenth resistor R15 is also electrically connected to one end of the sixteenth resistor R16. The other end of the sixteenth resistor R16 is electrically connected to one end of the third capacitor C3. The other end of the third capacitor C3 is grounded to GND. The other end of the sixteenth resistor R16 is electrically connected to the input end A5 of the integration circuit 14;

[0055] One end of the seventeenth resistor R17 is electrically connected to the output end of the AC signal selection circuit 13. The other end of the seventeenth resistor R17 is electrically connected to one end of the fourth capacitor C4. The other end of the fourth capacitor C4 is grounded to GND. The other end of the seventeenth resistor R17 is also electrically connected to one end of the eighteenth resistor R18. The other end of the eighteenth resistor R18 is electrically connected to one end of the fifth capacitor C5. The other end of the fifth capacitor C5 is grounded to GND. The other end of the eighteenth resistor R18 is electrically connected to the input end A5 of the integration circuit 14.

[0056] In this embodiment, an electronic voltage transformer is exemplarily shown to further include a first voltage follower Q6 and a second voltage follower Q7. The other end of the sixteenth resistor R16 is electrically connected to the input terminal A5 of the integrating circuit 14 through the first voltage follower Q6, and the other end of the sixteenth resistor R16 is electrically connected to the second input terminal D12 of the first voltage follower Q6. The other end of the eighteenth resistor R18 is electrically connected to the input terminal A5 of the integrating circuit 14 through the second voltage follower Q7, and the other end of the eighteenth resistor R18 is electrically connected to the second input terminal D14 of the second voltage follower Q7. The fifteenth resistor R15 and the second capacitor C2 form a first-order filter circuit, and the sixteenth resistor R16 and the third capacitor C3 form a first-order filter circuit. Exemplarily, the resistance value of the fifteenth resistor R15 can be 1 KΩ, the capacitance value of the second capacitor C2 can be 100 pF, the resistance value of the sixteenth resistor R16 can be 3.3 KΩ, and the capacitance value of the third capacitor C3 can be 100 pF. Through the two filter circuits, the interference signals in the signals output from the output terminal of the DC signal selection circuit 12 can be filtered to improve the accuracy of signal transmission. The seventeenth resistor R17 and the fourth capacitor C4 form a first-order filter circuit, and the eighteenth resistor R18 and the fifth capacitor C5 form a first-order filter circuit. Exemplarily, the resistance value of the seventeenth resistor R17 can be 1 KΩ, the capacitance value of the fourth capacitor C4 can be 100 pF, the resistance value of the eighteenth resistor R18 can be 3.3 KΩ, and the capacitance value of the fifth capacitor C5 can be 100 pF. Through the two filter circuits, the interference signals in the signals output from the output terminal of the AC signal selection circuit 13 can be filtered to improve the accuracy of signal transmission.

[0057] Continuing to refer to Figure 3 , optionally, the electronic voltage transformer further includes an output module 21. The first input terminal of the output module 21 is electrically connected to the output terminal B4 of the DC comparison circuit 15, the second input terminal of the output module 21 is electrically connected to the output terminal B5 of the AC comparison circuit 16, and the output terminal of the output module 21 is electrically connected to the measuring instrument 17. The output module 21 is configured to convert the effective value signal output from the DC comparison circuit 15 or the AC comparison circuit 16 into a matching signal and output it to the measuring instrument 17, and the matching signal 17 is a current signal.

[0058] The signals output from the DC comparison circuit 15 or the AC comparison circuit 16 are voltage signals. When the measuring instrument 17 can only receive current signals, such as current signals of 4 mA - 20 mA, the output module 21 is required to convert the voltage signal into a corresponding current signal and output it to the measuring instrument.

[0059] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is imposed herein.

[0060] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electronic voltage transformer, characterized in that, Including: A DC voltage dividing branch, an AC voltage dividing branch, a DC signal selection circuit, an AC signal selection circuit, an integrating circuit, a DC comparison circuit, and an AC comparison circuit. The DC comparison circuit includes a first voltage setting terminal and a second voltage setting terminal. The AC comparison circuit includes a third voltage setting terminal and a fourth voltage setting terminal. The DC voltage dividing branch and the AC voltage dividing branch are connected in parallel between a voltage input terminal and ground. The output terminal of the DC voltage dividing branch is electrically connected to the input terminal of the DC signal selection circuit. The output terminal of the DC signal selection circuit is electrically connected to the input terminal of the integrating circuit. The output terminal of the AC voltage dividing branch is electrically connected to the input terminal of the AC signal selection circuit. The output terminal of the AC signal selection circuit is electrically connected to the input terminal of the integrating circuit. The output terminal of the integrating circuit is electrically connected to the input terminals of the DC comparison circuit and the AC comparison circuit respectively. The output terminal of the DC comparison circuit is electrically connected to a measuring instrument. The output terminal of the AC comparison circuit is electrically connected to the measuring instrument; the resistance values of the DC voltage dividing branch and the AC voltage dividing branch are different so that when the voltages applied to the DC voltage dividing branch and the AC voltage dividing branch are the same, the voltage values output by the output terminals of the DC voltage dividing branch and the AC voltage dividing branch are different. The DC voltage dividing branch is configured to reduce the voltage input at the voltage input terminal and then transmit it to the DC signal selection circuit. The AC voltage dividing branch is configured to reduce the voltage input at the voltage input terminal and then transmit it to the AC signal selection circuit. The DC signal selection circuit is configured to filter out the AC signals in the circuit. The AC signal selection circuit is configured to filter out the DC signals in the circuit. The AC signal selection circuit includes at least a DC blocking capacitor. The DC comparison circuit is configured to output the effective value signal to the measuring instrument when it is determined that the effective value signal generated by the integrating circuit is greater than the voltage of the first voltage setting terminal and less than the voltage of the second voltage setting terminal. The AC comparison circuit is configured to output the effective value signal to the measuring instrument when it is determined that the effective value signal generated by the integrating circuit is greater than the voltage of the third voltage setting terminal and less than the voltage of the fourth voltage setting terminal. The voltage of the first voltage setting terminal is less than the voltage of the second voltage setting terminal. The voltage of the third voltage setting terminal is less than the voltage of the fourth voltage setting terminal.

2. The electronic voltage transformer according to claim 1, characterized in that, The voltage of the first voltage setting terminal is less than the voltage output by the output terminal of the DC voltage dividing branch when a DC voltage is input at the voltage input terminal. The voltage of the second voltage setting terminal is less than the magnitude of the effective value signal output by the output terminal of the integrating circuit when an AC voltage is input at the voltage input terminal. The voltage of the third voltage setting terminal is greater than the voltage of the second voltage setting terminal. The voltage of the fourth voltage setting terminal is greater than the magnitude of the effective value signal output by the output terminal of the integrating circuit when an AC voltage is input at the voltage input terminal.

3. The electronic voltage transformer according to claim 2, characterized in that, It further includes a control module, a DC indication module and an AC indication module electrically connected to the control module. The first input end of the control module is electrically connected to the output end of the DC comparison circuit, and the second input end of the control module is electrically connected to the output end of the AC comparison circuit. The control module is configured to control the DC indication module to conduct when the effective value signal is output at the output end of the DC comparison circuit and no voltage signal is output at the output end of the AC comparison circuit, and is further configured to control the AC indication module to conduct when the effective value signal is output at the output end of the AC comparison circuit and no voltage signal is output at the output end of the DC comparison circuit.

4. The electronic voltage transformer according to claim 1, characterized in that The DC comparison circuit includes a first amplifier, a second amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; the first input end of the first amplifier serves as the input end of the DC comparison circuit, one end of the first resistor is connected to a first fixed potential, the other end of the first resistor is electrically connected to the second input end of the first amplifier, the other end of the first resistor is also electrically connected to one end of the second resistor, the other end of the second resistor is grounded, the other end of the second resistor is also electrically connected to the output end of the first amplifier, and the second input end of the first amplifier serves as the first voltage setting end; the second input end of the second amplifier is electrically connected to the first input end of the first amplifier, one end of the third resistor is connected to a second fixed potential, the other end of the third resistor is electrically connected to the first input end of the second amplifier, the other end of the third resistor is also electrically connected to one end of the fourth resistor, the other end of the fourth resistor is grounded, the second input end of the second amplifier is also electrically connected to the output end of the second amplifier, the first input end of the second amplifier serves as the second voltage setting end, the output end of the first amplifier is electrically connected to the output end of the second amplifier, and the output end of the first amplifier serves as the output end of the DC comparison circuit; the potential signals of the first fixed potential and the second fixed potential are opposite; The AC comparison circuit includes a third amplifier, a fourth amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor; the first input terminal of the third amplifier serves as the input terminal of the AC comparison circuit, one end of the fifth resistor is connected to the first fixed potential, the other end of the fifth resistor is electrically connected to the second input terminal of the third amplifier, the other end of the fifth resistor is also electrically connected to one end of the sixth resistor, the other end of the sixth resistor is grounded, the other end of the sixth resistor is also electrically connected to the output terminal of the third amplifier, and the second input terminal of the third amplifier serves as the third voltage setting terminal; the second input terminal of the fourth amplifier is electrically connected to the first input terminal of the third amplifier, one end of the seventh resistor is connected to the second fixed potential, the other end of the seventh resistor is electrically connected to the first input terminal of the fourth amplifier, the other end of the seventh resistor is also electrically connected to one end of the eighth resistor, the other end of the eighth resistor is grounded, the second input terminal of the fourth amplifier is also electrically connected to the output terminal of the fourth amplifier, the first input terminal of the fourth amplifier serves as the fourth voltage setting terminal, the output terminal of the third amplifier is electrically connected to the output terminal of the fourth amplifier, and the output terminal of the third amplifier serves as the output terminal of the AC comparison circuit.

5. The electronic voltage transformer according to claim 1, characterized in that, The DC voltage division branch includes a ninth resistor and a tenth resistor. The first end of the ninth resistor is electrically connected to the voltage input terminal, the second end of the ninth resistor is electrically connected to the first end of the tenth resistor, the second end of the ninth resistor serves as the output terminal of the DC voltage division branch, and the second end of the tenth resistor is grounded; The AC voltage division branch includes an eleventh resistor and a twelfth resistor. The first end of the eleventh resistor is electrically connected to the voltage input terminal, the second end of the eleventh resistor is electrically connected to the first end of the twelfth resistor, the second end of the eleventh resistor serves as the output terminal of the AC voltage division branch, and the second end of the twelfth resistor is grounded.

6. The electronic voltage transformer according to claim 5, characterized in that, The resistance ratio of the ninth resistor to the tenth resistor is the first ratio, the resistance ratio of the eleventh resistor to the twelfth resistor is the second ratio, and the ratio of the second ratio to the first ratio is 5 - 25.

7. The electronic voltage transformer according to claim 1, characterized in that, The integration circuit includes a fifth amplifier, a first capacitor, a thirteenth resistor, and a fourteenth resistor. The first input terminal of the fifth amplifier serves as the input terminal of the integration circuit, the second input terminal of the fifth amplifier is grounded, one end of the first capacitor is electrically connected to the first input terminal of the fifth amplifier, the other end of the first capacitor is electrically connected to the output terminal of the fifth amplifier, one end of the thirteenth resistor is electrically connected to the first input terminal of the fifth amplifier, the other end of the thirteenth resistor is electrically connected to the output terminal of the fifth amplifier, the output terminal of the fifth amplifier is electrically connected to one end of the fourteenth resistor, and the other end of the fourteenth resistor serves as the output terminal of the integration circuit.

8. The electronic voltage transformer according to claim 1, characterized in that It further includes a first voltage follower and a second voltage follower. The first input terminal of the first voltage follower is electrically connected to the output terminal of the first voltage follower. The second input terminal of the first voltage follower is electrically connected to the output terminal of the DC signal selection circuit. The output terminal of the first voltage follower is electrically connected to the input terminal of the integration circuit; The first input terminal of the second voltage follower is electrically connected to the output terminal of the second voltage follower. The second input terminal of the second voltage follower is electrically connected to the output terminal of the AC signal selection circuit. The output terminal of the second voltage follower is electrically connected to the input terminal of the integration circuit.

9. The electronic voltage transformer according to claim 1, characterized in that, It further includes a first filter circuit and a second filter circuit. The first filter circuit includes a fifteenth resistor, a sixteenth resistor, a second capacitor and a third capacitor. The second filter circuit includes a seventeenth resistor, an eighteenth resistor, a fourth capacitor and a fifth capacitor; One end of the fifteenth resistor is electrically connected to the output terminal of the DC signal selection circuit. The other end of the fifteenth resistor is electrically connected to one end of the second capacitor. The other end of the second capacitor is grounded. The other end of the fifteenth resistor is also electrically connected to one end of the sixteenth resistor. The other end of the sixteenth resistor is electrically connected to one end of the third capacitor. The other end of the third capacitor is grounded. The other end of the sixteenth resistor is electrically connected to the input terminal of the integration circuit; One end of the seventeenth resistor is electrically connected to the output terminal of the AC signal selection circuit. The other end of the seventeenth resistor is electrically connected to one end of the fourth capacitor. The other end of the fourth capacitor is grounded. The other end of the seventeenth resistor is also electrically connected to one end of the eighteenth resistor. The other end of the eighteenth resistor is electrically connected to one end of the fifth capacitor. The other end of the fifth capacitor is grounded. The other end of the eighteenth resistor is electrically connected to the input terminal of the integration circuit.

10. The electronic voltage transformer according to claim 1, characterized in that, It further includes an output module. The first input terminal of the output module is electrically connected to the output terminal of the DC comparison circuit. The second input terminal of the output module is electrically connected to the output terminal of the AC comparison circuit. The output terminal of the output module is electrically connected to the measuring instrument. The output module is used to convert the effective value signal output by the DC comparison circuit or the AC comparison circuit into a matching signal and output it to the measuring instrument. The matching signal is a current signal.

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