CN217425573U - Network voltage detection circuit, welding machine circuit and welding machine - Google Patents

Abstract

The utility model belongs to the technical field of voltage detection, especially, relate to a net pressure detection circuitry, welding machine circuit and welding machine, wherein, net pressure detection circuitry includes n way detection subcircuits that set up one by one with the n alternating current electricity that the input side net pressed and the analog-to-digital sampling circuit who detects subcircuit connection with n way, it includes first converting circuit to detect the subcircuit, second converting circuit and current type voltage transformer, through first converting circuit, second converting circuit and current type voltage transformer have realized the wide range and have measured, and simultaneously, because the voltage signal who will input converts current signal into current signal and transmits the sampling, and current signal is stronger than voltage signal interference killing feature, consequently anti net pressure distortion ability is stronger, the detection precision of net pressure has further been submitted.

Description

Network voltage detection circuit, welding machine circuit and welding machine

Technical Field

The utility model belongs to the technical field of voltage detection, especially, relate to a net pressure detection circuitry, welding machine circuit and welding machine.

Background

At present, in a single-phase or three-phase low-voltage (0-1000VAC) power supply system, the following commonly used network voltage detection circuit schemes are provided:

1. a group of measuring windings are added on a transformer of the flyback power supply, and the homonymous ends of the measuring windings are consistent with the main winding, so that the network voltage change trend can be detected on the measuring windings when the flyback power supply works, and the size of input network voltage is indirectly measured;

2. the change of the conduction degree of the optocoupler is utilized to convert the network voltage change trend into the change of the conduction pulse width of the optocoupler, so that the size of the input network voltage is indirectly measured;

3. by using the voltage reduction principle of the power frequency transformer, the network voltage is attenuated according to the transformation ratio of the power frequency transformer and then is sampled and measured, so that the size of the input network voltage is measured.

In combination with the foregoing, the conventional network voltage detection circuit has the following problems in practical applications:

in the first scheme, the scheme that a group of measuring windings are added on a transformer of the flyback power supply has the advantages of low cost, simple design and larger defect that when the flyback power supply supplies power and carries a load in a wide network voltage range, the voltage value sampled by the measuring windings is greatly influenced by the duty ratio due to the larger adjustment range of the duty ratio, the nonlinear change of the measured value in the wide network voltage range is very serious, the measuring error is large, the circuit debugging difficulty is large, and the debugging period is long;

in the second scheme, the network voltage change trend is converted into the change of the conduction pulse width of the optical coupler by utilizing the change of the conduction degree of the optical coupler, so that the scheme of indirectly measuring the input network voltage mainly has two problems, one problem is that the measurement range is limited, a low-voltage section measurement dead angle exists, the other problem is that the common optical coupler has a nonlinear problem, and the final presented result is that the measurement error is large;

in the third scheme, the grid voltage is sampled and measured after being attenuated according to the transformation ratio of the power frequency transformer by utilizing the voltage reduction principle of the power frequency transformer, the measurement linearity and accuracy are good, but the introduction of the power frequency transformer causes higher design cost and larger circuit volume, and the accuracy of the measurement mode of the attenuated voltage is greatly reduced for the working occasions with larger distortion of the grid voltage.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a detection circuitry is pressed to net aims at solving traditional net and presses detection circuitry and lead to detecting the poor problem of precision because of there being detection dead angle and distortion.

The embodiment of the utility model provides a first aspect provides a network voltage detection circuit, include n way detection subcircuits that set up one by one with the n alternating current electricity of input side network voltage and with n way the analog-digital sampling circuit that detects subcircuit and be connected, each way the detection subcircuit is used for measuring one of them looks alternating current, n ≧ 1;

each path of the detection subcircuit comprises:

the first conversion circuit is used for converting a voltage signal of alternating current into a current signal;

the current type voltage transformer is connected with the first conversion circuit and used for scaling and outputting the current signal according to a preset proportion;

and the second conversion circuit is used for converting the current signal which is output in a scaling mode into a voltage sampling signal, outputting the voltage sampling signal to the analog-digital sampling circuit for sampling and determining the voltage of the alternating current.

Optionally, the first conversion circuit comprises a first resistor;

the first end of the first resistor is used for inputting alternating current, and the second end of the first resistor is connected with the first end of the primary winding of the current-type voltage transformer;

the second end of the primary winding of the current-type voltage transformer is connected with a zero line, or is connected with the second end of the primary winding of the current-type voltage transformer in the other detection sub-circuit in common;

the second conversion circuit comprises a second resistor;

and two ends of the second resistor are connected in parallel with two ends of a secondary winding of the current type voltage transformer.

Optionally, the detection sub-circuit further comprises:

and the differential amplifying circuit is used for carrying out differential amplification on the voltage sampling signal and is connected between the second conversion circuit and the analog-digital sampling circuit.

Optionally, the detection sub-circuit further comprises:

and the filter circuit is used for filtering the voltage sampling signal output by the differential amplification circuit and is connected between the differential amplification circuit and the analog-digital sampling circuit.

Optionally, the differential amplifying circuit includes a third resistor, a fourth resistor, a fifth resistor, a first capacitor, and a first operational amplifier;

the first end of the third resistor and the first end of the fourth resistor are correspondingly connected with the signal output end of the second conversion circuit, the second end of the third resistor, the first end of the fifth resistor, the first end of the first capacitor and the inverting input end of the first operational amplifier are interconnected, the second end of the fourth resistor is connected with the non-inverting input end of the first operational amplifier, and the output end of the first operational amplifier, the second end of the fifth resistor and the second end of the first capacitor are interconnected.

Optionally, the differential amplifier circuit further includes a second capacitor and a sixth resistor;

the first end of the second capacitor, the first end of the sixth resistor, the second end of the fourth resistor and the positive-phase input end of the first operational amplifier are connected, the second end of the second capacitor is grounded, and the second end of the sixth resistor is connected with a voltage end and used for inputting a potential boosting voltage.

Optionally, the detection sub-circuit further comprises:

and the small signal rectifying circuit is used for rectifying and converting the voltage sampling signal output by the filtering circuit, and is connected between the filtering circuit and the analog-digital sampling circuit.

Optionally, the detection sub-circuit further comprises:

and the attenuation and impedance matching circuit is used for performing signal attenuation and impedance matching on the direct current sampling signal output by the small signal rectification circuit, and is connected between the small signal rectification circuit and the analog-digital sampling circuit.

The utility model provides a second aspect provides a welding machine circuit, include as above net pressure detection circuitry.

The third aspect of the embodiment of the utility model provides a welding machine, including the welding machine body with as above the welding machine circuit, the welding machine circuit with the welding machine body corresponds the connection.

The network voltage detection circuit of the embodiment of the utility model realizes the respective voltage detection of each phase of alternating current by adopting the detection sub-circuit of n phase of alternating current corresponding to the network voltage of the input side and the analog-digital sampling circuit, meanwhile, the voltage-to-current conversion is realized through the first conversion circuit, the current signal is scaled and output through the current type voltage transformer, and finally the current signal is converted and output through the second conversion circuit, so that the analog-to-digital sampling circuit realizes the final voltage size determination of the alternating current, the first conversion circuit, the second conversion circuit and the current type voltage transformer realize the measurement without dead angle and in a wide range, and simultaneously, because the input voltage signal is converted into the current signal for transmission and sampling, and the current signal has stronger anti-interference capability than the voltage signal, the network voltage distortion resistance is stronger, and the detection accuracy of the network voltage is further provided.

Drawings

Fig. 1 is a schematic block diagram of a network voltage detection circuit according to an embodiment of the present invention;

fig. 2 is a first circuit schematic diagram of a network voltage detection circuit according to a second embodiment of the present invention;

fig. 3 is a second schematic circuit diagram of a network voltage detection circuit according to a second embodiment of the present invention;

fig. 4 is a third circuit schematic diagram of a network voltage detection circuit according to the second embodiment of the present invention;

fig. 5 is a schematic diagram of a fourth circuit of the network voltage detection circuit according to the second embodiment of the present invention;

fig. 6 is a schematic block diagram of a network voltage detection circuit provided in the third embodiment of the present invention;

fig. 7 is a schematic circuit diagram of a network voltage detection circuit according to a fourth embodiment of the present invention;

fig. 8 is a schematic circuit diagram of a network voltage detection circuit according to a fifth embodiment of the present invention;

fig. 9 is a schematic block diagram of a network voltage detection circuit according to a sixth embodiment of the present invention;

fig. 10 is a schematic circuit diagram of a network voltage detection circuit according to a sixth embodiment of the present invention.

Detailed Description

In order to make the technical problem, technical solution and advantageous effects to be solved by the present invention more clearly understood, the following description is given in conjunction with the accompanying drawings and embodiments to illustrate the present invention in further detail. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

Example one

A first aspect of the embodiment of the present invention provides a network voltage detection circuit, including n detection sub-circuits 10 arranged one by one with n ac voltages of an input side network voltage and an analog-to-digital sampling circuit 20 connected to the n detection sub-circuits 10, where each detection sub-circuit 10 is configured to measure one of the n ac voltages, n ≧ 1;

each path detection sub-circuit 10 includes:

a first conversion circuit 11 for converting a voltage signal of the alternating current into a current signal;

the current-type voltage transformer 12 is connected with the first conversion circuit 11, and the current-type voltage transformer 12 is used for scaling and outputting a current signal according to a preset proportion;

and the second conversion circuit 13 is connected with the current-type voltage transformer 12, and the second conversion circuit 13 is used for converting the scaled and output current signal into a voltage sampling signal, and outputting the voltage sampling signal to the analog-to-digital sampling circuit 20 for sampling and determining the voltage magnitude of the alternating current.

In this embodiment, the network voltage detection circuit is used for detecting the voltage of the alternating current, wherein the first conversion circuit 11 is used for realizing the conversion from the voltage signal to the current signal, the current signal outputted by the conversion is outputted through the current type voltage transformer 12 via mutual inductance and is transmitted to the second conversion circuit 13, the second conversion circuit 13 performs dc-to-voltage conversion and sampling on the transmitted current signal, so as to indirectly complete the sampling function of the network voltage on the input side, the voltage sampling signal outputted by the conversion and the network voltage measurement are in a preset ratio, the voltage sampling signal is inputted to the analog-to-digital sampling circuit 20 for sampling, the analog-to-digital sampling circuit 20 completes the processing of the signal, and finally determines the voltage of the network voltage on the input side.

The voltage signal to be measured by the input side network voltage is converted into a current signal, and the current signal is transmitted to the second conversion circuit 13 through the current type voltage transformer 12 and is reduced into a voltage signal to be sampled and measured, so that the measurement of the input side network voltage is indirectly completed.

Meanwhile, the current type voltage transformer 12 is adopted, the measurable voltage range is 0V-1 KV, and the wide voltage range and voltage dead-angle-free measurement are realized.

And the network voltage measuring circuit is convenient for function expansion and is suitable for measurement of single-phase, two-phase and three-phase network voltage or phase-lack detection.

The first converting circuit 11 and the second converting circuit 13 may select corresponding converting circuits according to functional requirements, for example, resistance circuits with different types of structures, and the specific structure is not limited, and meanwhile, the type and the turn ratio of the current-type voltage transformer 12 are correspondingly set according to sampling requirements.

The analog-to-digital sampling circuit 20 may employ a corresponding ADC module, or other types of processing circuits, and the specific structure and type are not limited.

The network voltage detection circuit of the embodiment of the present invention realizes the voltage detection of each phase of alternating current by using the detection sub-circuit 10 and the analog-to-digital sampling circuit 20 of n-phase alternating current corresponding to the network voltage of the input side, and simultaneously, realizes the voltage-to-current conversion by the first conversion circuit 11, and realizes the scaling output of current signal by the current type voltage transformer 12, and finally realizes the conversion output of current signal to voltage signal by the second conversion circuit 13, so that the analog-to-digital sampling circuit 20 realizes the voltage size determination of the final alternating current, and realizes the dead-angle-free wide-range measurement by the first conversion circuit 11, the second conversion circuit 13, and the current type voltage transformer 12, and simultaneously, because the input voltage signal is converted into the current signal for transmission sampling, and the current signal has stronger anti-interference capability than the voltage signal, and therefore has stronger anti-network voltage distortion capability, and further submitting the detection accuracy of the network pressure.

Example two

The present embodiment is refined and optimized based on the first embodiment, and optionally, as shown in fig. 2 to 5, the first conversion circuit 11 includes a first resistor R1;

a first end of the first resistor R1 is used for inputting alternating current, and a second end of the first resistor R1 is connected with a first end of a primary winding of the current-mode voltage transformer 12;

the second end of the primary winding of the current-mode voltage transformer 12 is connected to the neutral line N, or is connected in common to the second end of the primary winding of the current-mode voltage transformer 12 in the further detection sub-circuit 10;

the second conversion circuit 13 includes a second resistor R2;

the second resistor R2 is connected in parallel across the secondary winding of the current-mode transformer 12.

In this embodiment, the first end of the first resistor R1 is electrically connected to one of the first-phase ac voltages of the input-side network voltage, the first resistor R1 forms a current-limiting resistor, converts the single-phase voltage signal of the input-side network voltage into a current signal, and transmits the current signal to the secondary winding through the current-type voltage transformer 12, and the second resistor R2 forms a sampling resistor, which samples the transmitted current signal and indirectly samples the input-side network voltage, thereby completing the sampling and converting function of the voltage signal of the input-side network voltage, and finally determining the voltage magnitude of the input-side network voltage through the analog-to-digital sampling circuit 20.

According to the magnitude of the phase number N, the second ends of the primary windings of the current-mode voltage transformers 12 are correspondingly connected, wherein, as shown in fig. 2, when N is equal to 1, the second ends of the primary windings of the current-mode voltage transformers 12 are connected with a zero line N, so that voltage sampling of single-phase alternating current is realized.

Or as shown in fig. 3, when N is equal to 2, the first resistors R1 of the two detection sub-circuits 10 are respectively connected to the output ends of the two-phase alternating currents, the second ends of the primary windings of the current type voltage transformers 12 of the two detection sub-circuits 10 are both connected to the zero line N, so as to sample the voltages of the two-phase alternating currents, and the analog-digital sampling circuit 20 determines the final magnitudes of the two-phase voltages.

Or when N is equal to 3, as shown in fig. 4 and 5, the first resistors R1 of the three detection sub-circuits 10 are respectively connected to the output terminals of the three-phase alternating current, and the second terminals of the primary windings of the current-type voltage transformers 12 of the three detection sub-circuits 10 may be all connected to the zero line N or may be commonly connected together.

The connection mode of the current type voltage transformer 12 can be designed correspondingly according to the phase number, the setting of the zero line N and the safety requirement, and the specific connection mode is not limited.

Alternatively, the current mode voltage transformer 12 employs the general n: n-type current mode voltage transformer 12, n: the n-type current type voltage transformer 12 has the advantages of easily available materials, small volume, low price, high measurement precision and the like, and is matched with the first resistor R1 and the second resistor R2, so that the detection sub-circuit 10 has the advantages of low cost, simple design, short debugging period and the like.

Meanwhile, the circuit is strong in universality, the detection sub-circuit 10 can be used independently and is not influenced by other circuits, and the circuit is high in stability and reliability and has better flexibility.

EXAMPLE III

In this embodiment, refinement and optimization are performed based on the first embodiment and the second embodiment, and optionally, as shown in fig. 6, the detection sub-circuit 10 further includes:

and a differential amplification circuit 14 for differentially amplifying the voltage sampling signal, the differential amplification circuit 14 being connected between the second conversion circuit 13 and the analog-to-digital sampling circuit 20.

In this embodiment, both ends of the second resistor R2 output voltage sampling signals with alternating positive and negative, and the differential amplifier circuit 14 performs anti-interference and gain processing on the voltage sampling signals to complete the differential amplification function of the signals.

Meanwhile, in order to reduce the clutter interference sampling and improve the sampling precision, optionally, the detection sub-circuit 10 further includes:

and the filter circuit 15 is used for filtering the voltage sampling signal output by the differential amplification, and the filter circuit 15 is connected between the differential amplification circuit 14 and the analog-digital sampling circuit 20.

The differential amplifier circuit 14 may adopt a corresponding operational amplifier circuit and a corresponding potential boosting circuit according to requirements, and the specific circuit structure is not limited.

The filter circuit 15 may adopt a corresponding filter capacitor, and may further include a corresponding resistor structure, and the specific structure is not limited.

Example four

In this embodiment, refinement and optimization are performed based on the third embodiment, and optionally, as shown in fig. 7, the differential amplifying circuit 14 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a first operational amplifier U1;

a first end of the third resistor R3 and a first end of the fourth resistor R4 are correspondingly connected to a signal output end of the second conversion circuit 13, a second end of the third resistor R3, a first end of the fifth resistor R5, a first end of the first capacitor C1 and an inverting input end of the first operational amplifier U1 are interconnected, a second end of the fourth resistor R4 is connected to a non-inverting input end of the first operational amplifier U1, and an output end of the first operational amplifier U1, a second end of the fifth resistor R5 and a second end of the first capacitor C1 are interconnected.

In this embodiment, the first operational amplifier U1, the fifth resistor R5, and the first capacitor C1 perform a differential amplification function, the output terminal outputs an alternating-current sampling signal with positive and negative polarities, and the alternating-current sampling signal is output to the filter circuit 15 for filtering, and the third resistor R3 and the fourth resistor R4 form a current-limiting resistor.

The filter circuit 15 comprises a seventh resistor R7, an eighth resistor R8 and a third capacitor C3, wherein a first end of the seventh resistor R7 is connected with an output end of the first operational amplifier U1, a second end of the seventh resistor R7, a first end of the eighth resistor R8 and a first end of the third capacitor C3 are connected in common to form an output end of the filter circuit 15, and second ends of the third capacitor C3 and the eighth resistor R8 are both grounded.

The ac sampling signal is output to the filter circuit 15 for filtering and is input to the analog-to-digital sampling circuit 20 for sampling.

EXAMPLE five

In another embodiment, optionally, the differential amplifying circuit 14 further includes a second capacitor C2 and a sixth resistor R6;

the first end of the second capacitor C2, the first end of the sixth resistor R6, and the second end of the fourth resistor R4 are connected to the non-inverting input terminal of the first operational amplifier U1, the second end of the second capacitor C2 is grounded, and the second end of the sixth resistor R6 is connected to the voltage terminal and is used for inputting the potential boosting voltage VREF.

In this embodiment, the second capacitor C2, the sixth resistor R6, and the corresponding potential boost voltage are added to realize zero potential boost, so that the differential amplifier circuit 14 outputs a voltage sampling signal of positive-phase unidirectional pulse, and outputs the voltage sampling signal to the filter circuit 15 for filtering, so as to change the voltage sampling signal into a unidirectional smooth sampling signal, and the smooth sampling signal enters the analog-to-digital sampling circuit 20, thereby completing the signal sampling processing function.

EXAMPLE six

In this embodiment, optimization is performed based on the fourth embodiment, and optionally, as shown in fig. 9, the detection sub-circuit 10 further includes:

and the small signal rectifying circuit 16 is used for rectifying and converting the voltage sampling signal filtered and output by the filter circuit 15, and the small signal rectifying circuit 16 is connected between the filter circuit 15 and the analog-digital sampling circuit 20.

In this embodiment, since the voltage sampling signals output by the differential amplification circuit 14 and the filter circuit 15 are sampling signals with alternating positive and negative, in order to match the signal requirements of the analog-digital sampling circuit 20, that is, to receive the dc sampling signals, each detection sub-circuit 10 is further provided with a small-signal rectification circuit 16, and the sampling signals with alternating positive and negative are rectified into smooth dc sampling signals with one direction by the small-signal rectification circuit 16 and output to the single-chip ADC or other processing circuits, thereby completing the signal processing.

Optionally, in order to further improve the detection accuracy, the detection sub-circuit 10 further includes:

and the attenuation and impedance matching circuit 17 is used for performing signal attenuation and impedance matching on the direct current sampling signal output by the small signal rectification circuit 16, and the attenuation and impedance matching circuit 17 is connected between the small signal rectification circuit 16 and the analog-digital sampling circuit 20.

The circuit structures of the small-signal rectification circuit 16 and the attenuation and impedance matching circuit 17 can be specifically selected according to the detection precision, optionally, as shown in fig. 10, the small-signal rectification circuit 16 includes a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a second operational amplifier U2, a third operational amplifier U3, a first diode D1, and a second diode D2, and each component realizes a precise full-wave rectification function.

Wherein, the first terminal of the ninth resistor R9 and the first terminal of the eleventh resistor R11 are connected in common to form the signal input terminal of the small-signal rectification circuit 16, the second terminal of the ninth resistor R9, the first terminal of the tenth resistor R10, the cathode of the first diode D1 and the inverting input terminal of the second operational amplifier U2 are connected in common, the non-inverting input terminal of the second operational amplifier U2 is grounded, the output terminal of the second operational amplifier U2, the anode of the first diode D1 and the cathode of the second diode D2 are connected in common, the second terminal of the tenth resistor R10, the anode of the second diode D2 and the first terminal of the twelfth resistor R12 are connected in common, the second terminal of the eleventh resistor R11, the second terminal of the twelfth resistor R12, the first terminal of the thirteenth resistor R13 and the inverting input terminal of the third operational amplifier U3 are connected in common, the second terminal of the thirteenth resistor R13 and the output terminal of the third operational amplifier U3 are connected in common to form the signal output terminal of the small-signal rectification circuit 16, the non-inverting input of the third operational amplifier U3 is connected to ground.

The attenuation and impedance matching circuit 17 comprises a fourth operational amplifier U4, a fourteenth resistor R14, a fifteenth resistor R15 and a fourth capacitor C4, wherein a non-inverting input terminal of the fourth operational amplifier U4 constitutes a signal input terminal of the attenuation and impedance matching circuit 17, an inverting input terminal of the fourth operational amplifier U4, an output terminal of the fourth operational amplifier U4 and a first terminal of the fourteenth resistor R14 are connected, a second terminal of the fourteenth resistor R14, a first terminal of the fifteenth resistor R15 and a first terminal of the fourth capacitor C4 are connected in common to constitute a signal output terminal of the attenuation and impedance matching circuit 17, and a second terminal of the fifteenth resistor R15 and the fourth capacitor C4 are connected to ground.

A set of measured data is obtained according to the corresponding model selection and the actual measurement, taking single-phase network voltage measurement as an example, as shown in table 1.

TABLE 1

As can be seen from table 1, the network voltage detection circuit has the characteristics of wide voltage measurement range, strong distortion resistance, high accuracy, and the like.

EXAMPLE seven

The utility model also provides a welding machine circuit, this welding machine circuit include the net and press detection circuitry, and this net presses detection circuitry's concrete structure to refer to above-mentioned embodiment, because this welding machine circuit has adopted the whole technical scheme of above-mentioned all embodiments, consequently has all beneficial effects that the technical scheme of above-mentioned embodiment brought at least, and the repeated description is no longer given here.

In this embodiment, the network voltage detection circuit is disposed in the welding machine circuit, the welding machine circuit is correspondingly connected with the network voltage at the input side and obtains energy, and the welding machine circuit detects and samples the voltage signal of the network voltage at the input side and feeds back the sampling result to the corresponding control module, so that the control module performs corresponding voltage detection, open-phase detection and other operations.

The welding machine circuit is connected with the welding machine body, and is used for converting and outputting a welding machine power supply corresponding to alternating current and direct current to the welding machine body and driving the welding machine body to execute welding work.

The welder body can include structures such as a welding gun, a switch, and the like.

Example eight

The utility model also provides a welding machine, this welding machine include welding machine body and welding machine circuit, and the concrete structure of this welding machine circuit refers to above-mentioned embodiment, because this welding machine has adopted the whole technical scheme of above-mentioned all embodiments, consequently has all beneficial effects that the technical scheme of above-mentioned embodiment brought at least, and the repeated description is no longer given here. Wherein, the welding machine circuit is correspondingly connected with the welding machine body.

The above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims (10)

1. A network voltage detection circuit is characterized by comprising n paths of detection sub-circuits and an analog-digital sampling circuit, wherein the n paths of detection sub-circuits are arranged with n alternating currents of network voltage on an input side one by one, each path of detection sub-circuit is used for measuring one phase of alternating current, and n is not less than 1;

each path of the detection subcircuit comprises:

the first conversion circuit is used for converting a voltage signal of alternating current into a current signal;

the current type voltage transformer is connected with the first conversion circuit and used for scaling and outputting the current signal according to a preset proportion;

and the second conversion circuit is used for converting the current signal which is output in a scaling mode into a voltage sampling signal, outputting the voltage sampling signal to the analog-digital sampling circuit for sampling and determining the voltage of the alternating current.

2. The network voltage detection circuit of claim 1, wherein the first conversion circuit comprises a first resistor;

the first end of the first resistor is used for inputting alternating current, and the second end of the first resistor is connected with the first end of the primary winding of the current-type voltage transformer;

the second end of the primary winding of the current-type voltage transformer is connected with a zero line, or is connected with the second end of the primary winding of the current-type voltage transformer in the other detection sub-circuit in common;

the second conversion circuit comprises a second resistor;

and two ends of the second resistor are connected in parallel with two ends of a secondary winding of the current type voltage transformer.

3. The network voltage detection circuit of claim 1, wherein the detection sub-circuit further comprises:

and the differential amplification circuit is used for carrying out differential amplification on the voltage sampling signal and is connected between the second conversion circuit and the analog-digital sampling circuit.

4. The network voltage detection circuit of claim 3, wherein the detection subcircuit further comprises:

and the filter circuit is used for filtering the voltage sampling signal output by the differential amplification circuit and is connected between the differential amplification circuit and the analog-digital sampling circuit.

5. The network voltage detection circuit of claim 4, wherein the differential amplification circuit comprises a third resistor, a fourth resistor, a fifth resistor, a first capacitor, and a first operational amplifier;

the first end of the third resistor and the first end of the fourth resistor are correspondingly connected with the signal output end of the second conversion circuit, the second end of the third resistor, the first end of the fifth resistor, the first end of the first capacitor and the inverting input end of the first operational amplifier are interconnected, the second end of the fourth resistor is connected with the non-inverting input end of the first operational amplifier, and the output end of the first operational amplifier, the second end of the fifth resistor and the second end of the first capacitor are interconnected.

6. The network voltage detection circuit of claim 5, wherein the differential amplification circuit further comprises a second capacitor and a sixth resistor;

the first end of the second capacitor, the first end of the sixth resistor, the second end of the fourth resistor and the positive-phase input end of the first operational amplifier are connected, the second end of the second capacitor is grounded, and the second end of the sixth resistor is connected with a voltage end and used for inputting a potential boosting voltage.

7. The network voltage detection circuit of claim 5, wherein the detection subcircuit further comprises:

and the small signal rectifying circuit is used for rectifying and converting the voltage sampling signal output by the filtering circuit, and is connected between the filtering circuit and the analog-digital sampling circuit.

8. The network voltage detection circuit of claim 7, wherein the detection subcircuit further comprises:

and the attenuation and impedance matching circuit is used for performing signal attenuation and impedance matching on the direct current sampling signal output by the small signal rectification circuit, and is connected between the small signal rectification circuit and the analog-digital sampling circuit.

9. A welder circuit, characterized in that it comprises a network voltage detection circuit according to any of claims 1 to 8.

10. A welder comprising a welder body and welder circuitry of claim 9, said welder circuitry connected in correspondence with said welder body.

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