AC voltage sampling circuit and AC power supply

Abstract

The utility model provides an AC voltage sampling circuit and an AC power supply, including: multiple dial switches, a voltage dividing module, an isolation amplifier, a conversion unit and a voltage detection unit; each dial switch is connected to a unique corresponding different AC voltage output terminal; each AC voltage output terminal outputs a range of AC voltage; a target dial switch among the multiple dial switches receives a closed signal, connects the isolation amplifier and the target AC voltage output terminal corresponding to the target dial switch; the voltage dividing module divides the target AC voltage output by a preset multiple to obtain an AC voltage to be detected; the isolation amplifier isolates and amplifies the AC voltage to be detected, and outputs an isolated and amplified AC voltage signal; the conversion unit converts the isolated and amplified AC voltage signal into a DC signal; and the voltage detection unit detects the voltage value of the DC signal. The circuit improves system stability and is generally applicable to multi-voltage scenarios.

Description

Technical Field

[0001] The utility model relates to the technical field of AC voltage sampling, in particular to an AC voltage sampling circuit and an AC power supply. Background Art

[0002] Usually, AC voltage sampling circuit is used to detect and measure voltage. Through the above AC voltage sampling circuit, the AC voltage signal of the power system can be converted into a DC signal, and then measured and analyzed to ensure the normal operation of the power system. The AC voltage sampling circuit usually includes a sampling resistor, a sampling capacitor, a rectifier circuit, a filter circuit, and an amplifier circuit.

[0003] However, general industrial control includes both strong and weak current parts. In order to ensure system stability, it is often necessary to isolate strong and weak currents. Existing sampling circuits often do not isolate strong and weak currents and are relatively complex. They can only collect voltages within a fixed range. Once the collected input voltage exceeds the collection range, the circuit needs to modify the front-stage sampling resistor, so it cannot be used in multi-voltage scenarios. Utility Model Content

[0004] The purpose of the utility model is to provide an AC voltage sampling circuit and an AC power supply to alleviate the technical problems of poor system stability and limited application scenarios in the prior art, improve system stability and be applicable to multi-voltage scenarios.

[0005] In the first aspect, an embodiment of the utility model provides an AC voltage sampling circuit, comprising: a plurality of dip switches, a voltage divider module, an isolation amplifier, an AC / DC conversion unit and a voltage detection unit connected in sequence; each of the above-mentioned dip switches is connected to a uniquely corresponding different AC voltage output terminal; each of the above-mentioned AC voltage output terminals outputs an AC voltage within a preset voltage range; a target dip switch among the above-mentioned multiple dip switches is used to receive a closing signal to connect the above-mentioned isolation amplifier and the target AC voltage output terminal corresponding to the above-mentioned target dip switch; the above-mentioned voltage divider module is used to divide the target AC voltage outputted by the above-mentioned target AC voltage output terminal by a preset multiple to obtain an AC voltage to be detected; the above-mentioned isolation amplifier is used to isolate and amplify the above-mentioned AC voltage to be detected, and output an isolated and amplified AC voltage signal; the above-mentioned AC / DC conversion unit is used to convert the above-mentioned isolated and amplified AC voltage signal into a DC signal; the above-mentioned voltage detection unit is used to detect the voltage value of the above-mentioned DC signal to determine the voltage value of the target AC voltage.

[0006] In a preferred embodiment of the present invention, the AC / DC conversion unit includes: a first differential amplifier module and a second differential amplifier module; the first differential amplifier module is used to perform positive differential amplification on the AC voltage signal after the isolation amplification, and output a positive phase signal corresponding to the AC voltage signal after the isolation amplification; the second differential amplifier module is used to perform negative differential amplification on the AC voltage signal after the isolation amplification, and output a negative phase signal corresponding to the AC voltage signal after the isolation amplification.

[0007] In a preferred embodiment of the utility model, the first differential amplifier module includes: a first resistor, a second resistor, a first potentiometer, a second potentiometer and a first operational amplifier; the first resistor is respectively connected to the output positive signal pin of the isolation amplifier and the negative input pin of the first operational amplifier; the second resistor is respectively connected to the output negative signal pin of the isolation amplifier and the positive input pin of the first operational amplifier; one end of the first potentiometer is connected to the negative input pin of the first operational amplifier, and the other end of the first potentiometer is connected to the output pin of the first operational amplifier; one end of the second potentiometer is connected to the positive input pin of the first operational amplifier, and the second potentiometer is connected to the positive input pin of the first operational amplifier. The other end of the resistor is grounded; the second differential amplifier module includes: a third resistor, a fourth resistor, a third potentiometer, a fourth potentiometer and a second operational amplifier; the third resistor is respectively connected to the output positive signal pin of the isolation amplifier and the negative input pin of the second operational amplifier; the fourth resistor is respectively connected to the output negative signal pin of the isolation amplifier and the positive input pin of the second operational amplifier; one end of the third potentiometer is connected to the negative input pin of the second operational amplifier, and the other end of the third potentiometer is connected to the output pin of the second operational amplifier; one end of the fourth potentiometer is connected to the positive input pin of the second operational amplifier, and the other end of the fourth potentiometer is grounded.

[0008] In a preferred embodiment of the present invention, the AC / DC conversion unit further includes a first capacitor connected to the output ends of the first differential amplifier module and the second differential amplifier module; the other end of the first capacitor is grounded.

[0009] In a preferred embodiment of the present invention, the input end of the isolation amplifier is powered by a first power supply of an external device; the output end of the isolation amplifier is powered by a second power supply of an external device; and the AC / DC conversion unit is powered by the second power supply.

[0010] In a preferred embodiment of the utility model, one end of the second capacitor is connected between the first power supply and the input end of the isolation amplifier; one end of the third capacitor is connected between the second power supply and the output end of the isolation amplifier; the other end of the second capacitor and the other end of the third capacitor are both grounded.

[0011] In a preferred embodiment of the present invention, one end of a fourth capacitor is connected between the positive power supply pin of the first operational amplifier and the second power supply; the other end of the fourth capacitor is grounded.

[0012] In a preferred embodiment of the present invention, the voltage detection unit includes an ADC sampling chip.

[0013] In a preferred embodiment of the present invention, the voltage dividing module comprises: a plurality of resistors of preset resistance values ​​connected in series.

[0014] In a second aspect, an embodiment of the utility model provides an AC power supply, including: the above-mentioned AC voltage sampling circuit, and also including: an AC power supply body connected to the above-mentioned AC voltage sampling circuit.

[0015] The embodiments of the present invention have the following beneficial technical effects:

[0016] The utility model embodiment provides an AC voltage sampling circuit and an AC power supply, including: a plurality of dip switches, a voltage divider module, an isolation amplifier, an AC / DC conversion unit and a voltage detection unit connected in sequence; each of the above-mentioned dip switches is connected to a unique corresponding different AC voltage output terminal; each of the above-mentioned AC voltage output terminals outputs an AC voltage in a preset voltage range; the target dip switch among the above-mentioned multiple dip switches is used to receive a closed signal to connect the above-mentioned isolation amplifier and the target AC voltage output terminal corresponding to the above-mentioned target dip switch; the above-mentioned voltage divider module is used to divide the target AC voltage outputted by the above-mentioned target AC voltage output terminal by a preset multiple to obtain the AC voltage to be detected; the above-mentioned isolation amplifier is used to isolate and amplify the above-mentioned AC voltage to be detected, and output the isolated and amplified AC voltage signal; the above-mentioned AC / DC conversion unit is used to convert the above-mentioned isolated and amplified AC voltage signal into a DC signal; the above-mentioned voltage detection unit is used to detect the voltage value of the above-mentioned DC signal to determine the voltage value of the target AC voltage. The circuit isolates the strong electric part and the weak electric part through the isolation amplifier, and is based on the voltage divider module and connected to the unique corresponding different AC voltage output terminals through the dip switch, so the circuit is also applicable to multi-voltage scenarios.

[0017] Other features and advantages of the utility model will be described in the subsequent description, or some features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the above-mentioned technology of the utility model.

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of an AC voltage sampling circuit provided by an embodiment of the utility model;

[0021] Figure 2 A waveform diagram of an in-phase signal corresponding to an isolated and amplified AC voltage signal provided in an embodiment of the utility model;

[0022] Figure 3 A waveform diagram of an inverted signal corresponding to an isolated and amplified AC voltage signal provided in an embodiment of the utility model;

[0023] Figure 4 A schematic diagram of the structure of another AC voltage sampling circuit provided by an embodiment of the utility model;

[0024] Figure 5 A schematic diagram of the structure of an AC power supply provided in an embodiment of the utility model.

[0025] Icon: 11-multiple dip switches; 12-voltage divider module; 13-isolation amplifier; 14-AC / DC conversion unit; 15-voltage detection unit; 21-first resistor; 22-second resistor; 23-first potentiometer; 24-second potentiometer; 25-first operational amplifier; 31-third resistor; 32-fourth resistor; 33-third potentiometer; 34-fourth potentiometer; 35-second operational amplifier; 40-first capacitor; 51-first power supply; 52-second power supply; 53-second capacitor; 54-third capacitor; 55-fourth capacitor; 61-first voltage divider resistor; 62-second voltage divider resistor; 63-third voltage divider resistor; 64-fourth voltage divider resistor; 65-fifth voltage divider resistor; 66-sixth voltage divider resistor; 67-seventh voltage divider resistor; 68-eighth voltage divider resistor; 69-ninth voltage divider resistor; 70-bypass capacitor; 500-AC voltage sampling circuit; 600-AC power supply body. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Existing sampling circuits often do not isolate strong and weak electricity and are relatively complex. They can only collect voltages within a fixed range. Once the collected input voltage exceeds the collection range, the circuit needs to modify the front-stage sampling resistor, so it cannot be used in multi-voltage scenarios.

[0028] Based on this, the embodiment of the utility model provides an AC voltage sampling circuit and an AC power supply. The circuit isolates the strong current part and the weak current part through an isolation amplifier, and is based on a voltage divider module and connects the uniquely corresponding different AC voltage output terminals through a dip switch, so the circuit is also applicable to multi-voltage scenarios. To facilitate understanding of this embodiment, first, an AC voltage sampling circuit disclosed in the utility model embodiment is introduced.

[0029] Example 1

[0030] In this embodiment, Figure 1 A schematic diagram of the structure of an AC voltage sampling circuit provided in an embodiment of the utility model.

[0031] Depend on Figure 1 As can be seen, the AC voltage sampling circuit includes: a plurality of dip switches 11, a voltage divider module 12, an isolation amplifier 13, an AC / DC conversion unit 14 and a voltage detection unit 15 connected in sequence; each of the above-mentioned dip switches is connected to a uniquely corresponding different AC voltage output terminal; each of the above-mentioned AC voltage output terminals outputs an AC voltage within a preset voltage range; the target dip switch among the above-mentioned multiple dip switches 11 is used to receive a closing signal to connect the above-mentioned isolation amplifier 13 with the target AC voltage output terminal corresponding to the above-mentioned target dip switch; the above-mentioned voltage divider module 12 is used to divide the target AC voltage outputted from the above-mentioned target AC voltage output terminal by a preset multiple to obtain the AC voltage to be detected; the above-mentioned isolation amplifier 13 is used to isolate and amplify the above-mentioned AC voltage to be detected, and output the isolated and amplified AC voltage signal; the above-mentioned AC / DC conversion unit 14 is used to convert the above-mentioned isolated and amplified AC voltage signal into a DC signal; the above-mentioned voltage detection unit 15 is used to detect the voltage value of the above-mentioned DC signal to determine the voltage value of the target AC voltage.

[0032] In a specific implementation, the closing signal can be performed by an operator manually operating the target dip switch to perform a closing operation, or can be performed based on a closing signal transmitted by a controller.

[0033] Furthermore, the AC / DC conversion unit includes: a first differential amplifier module and a second differential amplifier module; the first differential amplifier module is used to perform positive differential amplification on the AC voltage signal after the isolation amplification, and output a positive phase signal corresponding to the AC voltage signal after the isolation amplification; the second differential amplifier module is used to perform negative differential amplification on the AC voltage signal after the isolation amplification, and output a negative phase signal corresponding to the AC voltage signal after the isolation amplification.

[0034] For ease of understanding, Figure 2 A waveform diagram of an in-phase signal corresponding to an isolated and amplified AC voltage signal provided in an embodiment of the utility model; Figure 3 The present invention provides a waveform diagram of an inverted signal corresponding to an isolated and amplified AC voltage signal according to an embodiment of the present invention.

[0035] For ease of understanding, Figure 4 A schematic diagram of the structure of another AC voltage sampling circuit provided in an embodiment of the utility model.

[0036] Depend on Figure 4As can be seen, the first differential amplifier module includes: a first resistor 21, a second resistor 22, a first potentiometer 23, a second potentiometer 24 and a first operational amplifier 25; the first resistor 21 is respectively connected to the output positive signal pin of the isolation amplifier 13 and the negative input pin of the first operational amplifier 25; the second resistor 22 is respectively connected to the output negative signal pin of the isolation amplifier 13 and the positive input pin of the first operational amplifier 25; one end of the first potentiometer 23 is connected to the negative input pin of the first operational amplifier 25, and the other end of the first potentiometer 23 is connected to the output pin of the first operational amplifier 25; one end of the second potentiometer 24 is connected to the positive input pin of the first operational amplifier 25, and the other end of the second potentiometer 24 is connected to the positive input pin of the first operational amplifier 25. The second differential amplifier module includes: a third resistor 31, a fourth resistor 32, a third potentiometer 33, a fourth potentiometer 34 and a second operational amplifier 35; the third resistor 31 is respectively connected to the output positive signal pin of the isolation amplifier 13 and the negative input pin of the second operational amplifier 35; the fourth resistor 32 is respectively connected to the output negative signal pin of the isolation amplifier 13 and the positive input pin of the second operational amplifier 35; one end of the third potentiometer 33 is connected to the negative input pin of the second operational amplifier 35, and the other end of the third potentiometer 33 is connected to the output pin of the second operational amplifier 35; one end of the fourth potentiometer 34 is connected to the positive input pin of the second operational amplifier 35, and the other end of the fourth potentiometer 34 is grounded.

[0037] Furthermore, the AC / DC conversion unit 14 further includes a first capacitor 40 connected to the output ends of the first differential amplifier module and the second differential amplifier module; the other end of the first capacitor 40 is grounded.

[0038] Furthermore, the input end of the isolation amplifier 13 is powered by a first power supply 51 of an external device; the output end of the isolation amplifier 13 is powered by a second power supply 52 of an external device; and the AC / DC conversion unit 14 is powered by the second power supply 52 .

[0039] Furthermore, one end of a second capacitor 53 is connected between the first power supply 51 and the input end of the isolation amplifier 13; one end of a third capacitor 54 is connected between the second power supply 52 and the output end of the isolation amplifier 13; the other end of the second capacitor 53 and the other end of the third capacitor 54 are both grounded.

[0040] Furthermore, one end of a fourth capacitor 55 is connected between the positive power supply pin of the first operational amplifier 25 and the second power supply 52 ; the other end of the fourth capacitor 55 is grounded.

[0041] In actual operation, the voltage detection unit includes an ADC sampling chip.

[0042] Furthermore, the voltage dividing module comprises: a plurality of resistors of preset resistance values ​​connected in series.

[0043] For ease of understanding, Figure 4 As can be seen, the voltage-dividing module 12 includes: a first voltage-dividing resistor 61 and a second voltage-dividing resistor 62 connected in series, wherein the first voltage-dividing resistor 61 and the second voltage-dividing resistor 62 are connected to the first dip switch among the multiple dip switches 11; a third voltage-dividing resistor 63, a fourth voltage-dividing resistor 64 and a fifth voltage-dividing resistor 65 connected in series, wherein the fourth voltage-dividing resistor 64 and the fifth voltage-dividing resistor 65 are connected to the second dip switch among the multiple dip switches 11; a sixth voltage-dividing resistor 66, a seventh voltage-dividing resistor 67, an eighth voltage-dividing resistor 68 and a ninth voltage-dividing resistor 69 connected in series, wherein the eighth voltage-dividing resistor 68 and the ninth voltage-dividing resistor 69 are connected to the third dip switch among the multiple dip switches 11; the second voltage-dividing resistor 62, the fifth voltage-dividing resistor 65 and the ninth voltage-dividing resistor 69 are grounded, so that each of the dip switches is connected to a uniquely corresponding different AC voltage output terminal to collect AC voltages within a plurality of preset voltage ranges.

[0044] Furthermore, in this embodiment, the grounds of the input end and the output end of the isolation amplifier 13 are also isolated from each other.

[0045] Furthermore, a bypass capacitor 70 is connected in parallel between the positive signal output pin and the negative signal output pin of the isolation amplifier 13 ; one end of the bypass capacitor 70 is grounded.

[0046] Here, the bypass capacitor 70 can filter out high-frequency signals in the AC signal, so that the filtered low-voltage AC signal is input to the output positive signal pin of the isolation amplifier 13 .

[0047] The utility model embodiment provides an AC voltage sampling circuit, including: a plurality of dip switches, a voltage divider module, an isolation amplifier, an AC / DC conversion unit and a voltage detection unit connected in sequence; each of the above-mentioned dip switches is connected to a uniquely corresponding different AC voltage output terminal; each of the above-mentioned AC voltage output terminals outputs an AC voltage of a preset voltage range; the target dip switch among the above-mentioned multiple dip switches is used to receive a closed signal to connect the above-mentioned isolation amplifier and the target AC voltage output terminal corresponding to the above-mentioned target dip switch; the above-mentioned voltage divider module is used to divide the target AC voltage outputted by the above-mentioned target AC voltage output terminal by a preset multiple to obtain the AC voltage to be detected; the above-mentioned isolation amplifier is used to isolate and amplify the above-mentioned AC voltage to be detected, and output the isolated and amplified AC voltage signal; the above-mentioned AC / DC conversion unit is used to convert the above-mentioned isolated and amplified AC voltage signal into a DC signal; the above-mentioned voltage detection unit is used to detect the voltage value of the above-mentioned DC signal to determine the voltage value of the target AC voltage. The circuit isolates the strong electric part and the weak electric part through the isolation amplifier, and is based on the voltage divider module and connects the uniquely corresponding different AC voltage output terminals through the dip switch, so the circuit is also applicable to multi-voltage scenarios.

[0048] Example 2

[0049] Based on the above embodiments, Figure 5 A schematic diagram of the structure of an AC power supply provided in an embodiment of the utility model.

[0050] Depend on Figure 5 As can be seen, the AC power supply includes: the AC voltage sampling circuit 500 mentioned above, and also includes: an AC power supply body 600 connected to the AC voltage sampling circuit 500 .

[0051] The AC power supply provided in this embodiment has the same technical features as the AC voltage sampling circuit provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the AC power supply described above can refer to the corresponding process of the AC voltage sampling circuit in the above terminal device embodiment, and will not be repeated here.

[0052] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0053] In the description of the present utility model, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances. Finally, it should be explained that the above embodiments are only used to illustrate the technical solution of the present utility model, not to limit it; although the present utility model is described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present utility model.

Claims

1. An AC voltage sampling circuit, characterized in that: include: A plurality of dip switches, voltage divider modules, isolation amplifiers, AC / DC conversion units and voltage detection units connected in sequence; each of the dip switches is connected to a uniquely corresponding different AC voltage output terminal; each of the AC voltage output terminals outputs an AC voltage within a preset voltage range; A target dip switch among the plurality of dip switches is used to receive a closing signal to connect the isolation amplifier to a target AC voltage output terminal corresponding to the target dip switch; The voltage division module is used to divide the target AC voltage output by a preset multiple to obtain the AC voltage to be detected; The isolation amplifier is used to isolate and amplify the AC voltage to be detected, and output the isolated and amplified AC voltage signal; The AC / DC conversion unit is used to convert the isolated and amplified AC voltage signal into a DC signal; The voltage detection unit is used to detect the voltage value of the DC signal to determine the voltage value of the target AC voltage.

2. The AC voltage sampling circuit according to claim 1, characterized in that: The AC / DC conversion unit includes: a first differential amplifier module and a second differential amplifier module; The first differential amplifier module is used to perform forward differential amplification on the isolated and amplified AC voltage signal, and output an in-phase signal corresponding to the isolated and amplified AC voltage signal; The second differential amplifier module is used to perform negative differential amplification on the isolated and amplified AC voltage signal, and output an inverted signal corresponding to the isolated and amplified AC voltage signal.

3. The AC voltage sampling circuit according to claim 2, characterized in that: The first differential amplifier module includes: a first resistor, a second resistor, a first potentiometer, a second potentiometer and a first operational amplifier; the first resistor is respectively connected to the output positive signal pin of the isolation amplifier and the negative input pin of the first operational amplifier; the second resistor is respectively connected to the output negative signal pin of the isolation amplifier and the positive input pin of the first operational amplifier; one end of the first potentiometer is connected to the negative input pin of the first operational amplifier, and the other end of the first potentiometer is connected to the output pin of the first operational amplifier; one end of the second potentiometer is connected to the positive input pin of the first operational amplifier, and the other end of the second potentiometer is grounded; The second differential amplifier module includes: a third resistor, a fourth resistor, a third potentiometer, a fourth potentiometer and a second operational amplifier; the third resistor is respectively connected to the output positive signal pin of the isolation amplifier and the negative input pin of the second operational amplifier; the fourth resistor is respectively connected to the output negative signal pin of the isolation amplifier and the positive input pin of the second operational amplifier; one end of the third potentiometer is connected to the negative input pin of the second operational amplifier, and the other end of the third potentiometer is connected to the output pin of the second operational amplifier; one end of the fourth potentiometer is connected to the positive input pin of the second operational amplifier, and the other end of the fourth potentiometer is grounded.

4. The AC voltage sampling circuit according to claim 3, characterized in that: The AC / DC conversion unit further includes a first capacitor connected to output ends of the first differential amplifier module and the second differential amplifier module; the other end of the first capacitor is grounded.

5. The AC voltage sampling circuit according to claim 4, characterized in that: The input end of the isolation amplifier is powered by a first power supply of an external device; the output end of the isolation amplifier is powered by a second power supply of an external device; and the AC / DC conversion unit is powered by the second power supply.

6. The AC voltage sampling circuit according to claim 5, characterized in that: One end of a second capacitor is connected between the first power supply and the input end of the isolation amplifier; one end of a third capacitor is connected between the second power supply and the output end of the isolation amplifier; the other end of the second capacitor and the other end of the third capacitor are both grounded.

7. The AC voltage sampling circuit according to claim 6, characterized in that: One end of a fourth capacitor is connected between the positive power supply pin of the first operational amplifier and the second power supply; the other end of the fourth capacitor is grounded.

8. The AC voltage sampling circuit according to claim 1, characterized in that: The voltage detection unit includes an ADC sampling chip.

9. The AC voltage sampling circuit according to claim 1, characterized in that: The voltage dividing module includes: a plurality of resistors of preset resistance values ​​connected in series.

10. An AC power supply, characterized in that: include: The AC voltage sampling circuit according to any one of claims 1 to 9 further comprises: an AC power source body connected to the AC voltage sampling circuit.

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