Non-contact three-phase power frequency AC voltage measuring device and measuring method

Abstract

The present invention belongs to the field of non-contact measurement technology, and particularly relates to a non-contact three-phase power-frequency AC voltage measurement device and a measurement method, which include a main controller, a signal conversion and processing circuit, a driving circuit, a power amplifier and step-up circuit, a differential amplification circuit and an attenuation circuit; the signal conversion and processing circuit is used to convert the collected micro-current into a power-frequency line voltage signal, and input the power-frequency line voltage signal into the main controller, and the main controller calculates the currently collected voltage value and frequency value, and forms a reference signal; the driving circuit is used to drive the power amplifier and step-up circuit to step up according to the reference signal; the power amplifier and step-up circuit is used to step up and form an internal reconstructed voltage signal; the differential amplification circuit is used to judge whether a differential current is generated according to the internal reconstructed voltage signal and the external induced line voltage. The measurement device of the present application can effectively reduce the interference of adjacent other lines, thereby improving the acquisition signal and measurement accuracy.

Description

Technical Field

[0001] This application relates to the field of non-contact measurement technologies, and particularly relates to a non-contact three-phase power-frequency AC voltage measurement device and a measurement method. Background Art

[0002] In the related art, a three-phase power-frequency voltage measurement circuit generally includes a detection component and a differential charge amplifier. The detection component is used to sense the change in the electric field in the space near the cable to be measured, and then couple out the signal Uq on the cable. This signal Uq is transmitted to the differential charge amplifier, and after differential amplification, the relative change in the electric fields of the two cables is obtained Δ U, and the voltage is calculated based on this relative change Δ U. During the actual application process, the applicant found the following problems: In reality, the three-phase cables are all bundled together in multiple strands. Then, during measurement, it is easy to be affected by the electric fields of other cables, ultimately resulting in inaccurate measurement results.

[0003] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure. Therefore, it may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] In view of at least one of the above technical problems, this application provides a non-contact three-phase power-frequency AC voltage measurement device and a measurement method, which solve the problem that in reality, the three-phase cables are all bundled together in multiple strands, and during measurement, it is easy to be affected by the electric fields of other cables, ultimately resulting in inaccurate measurement results.

[0005] An embodiment of the first aspect of this application provides a non-contact three-phase power-frequency AC voltage measurement device, including a main controller, a signal conversion and processing circuit, a driving circuit, a power amplifier and boost circuit, a differential amplification circuit, and an attenuation circuit;

[0006] The signal conversion and processing circuit is used to convert the collected micro-current into a power-frequency line voltage signal, and input this power-frequency line voltage signal into the main controller. The main controller calculates the currently collected voltage value and frequency value, and forms a reference signal;

[0007] The driving circuit is used to drive the power amplifier and boost circuit to boost the voltage according to the reference signal;

[0008] The power amplifier and boost circuit is used to boost the voltage and form an internal reconstructed voltage signal;

[0009] The differential amplification circuit is used to determine whether a differential current is generated according to the internal reconstructed voltage signal and the external induced line voltage;

[0010] When the internal reconstructed voltage signal is equal to the external induced line voltage, the attenuation circuit outputs a DC voltage signal; the main controller calculates the AC voltage to be measured based on this DC voltage signal.

[0011] The present application has the following technical effects: The measuring device of the present application cooperates with each other through the main controller, signal conversion and processing circuit, drive circuit, power amplifier boost circuit, differential amplifier circuit and attenuation circuit, which can effectively reduce the interference of adjacent other lines, thereby improving the acquisition signal and measurement accuracy.

[0012] In one implementation, when the internal reconstructed voltage signal is not equal to the external induced line voltage and the differential current is greater than zero, the main controller performs a subtraction integration process on the drive circuit and forms a new internal reconstructed voltage signal; this new internal reconstructed voltage signal is then rejudged with the external induced line voltage to determine whether a differential current is generated.

[0013] In one implementation, when the internal reconstructed voltage signal is not equal to the external induced line voltage and the differential current is less than zero, the main controller performs an addition integration process on the drive circuit and forms a new internal reconstructed voltage signal; this new internal reconstructed voltage signal is then rejudged with the external induced line voltage to determine whether a differential current is generated.

[0014] In one implementation, the signal conversion and processing circuit includes a first current-voltage conversion unit, a first band-pass filter unit, and a second band-pass filter unit connected in sequence. The acquisition end of the first current-voltage conversion unit is arranged on the cable under test to collect micro-current, and the second band-pass filter unit is connected to the main controller through a first analog-to-digital converter ADC1;

[0015] The drive circuit includes a first digital-to-analog converter DAC1 and a first AC filter unit connected in sequence. The first digital-to-analog converter is connected to the main controller, and the first AC filter unit is connected to the power amplifier boost circuit.

[0016] In one implementation, the power amplifier boost circuit includes a second AC filter unit, a power amplification unit, and a boost unit connected in sequence;

[0017] The second AC filter unit is connected to the drive circuit;

[0018] The boost unit is connected to the differential amplifier circuit and the attenuation circuit respectively.

[0019] In one implementation, the power amplification unit includes diode D100, diode D101, triode Q9014, triode Q8050, and triode Q8550. The negative electrode of diode D100 is connected to the positive electrode of diode D101. A first node N1 is provided between diode D100 and diode D101. The base of triode Q9014 is connected to the first node N1. The base of this triode Q9014 is connected to the second AC filtering unit. The collector of this triode Q9014 is connected to the negative electrode of diode D101. The base and collector of triode Q8050 are connected to the positive electrode of diode D100. The emitter of triode Q8050 is connected to the first node N1. The emitter of triode Q8550 is connected to the emitter of triode Q8050. The base of triode Q8550 is connected to the collector of triode Q9014. The first node N1 is connected to the boost unit.

[0020] In one implementation, the boost unit includes transformer T1. The first end of transformer T1 is connected to the power amplification unit. The second end of transformer T1 is connected to the differential amplification circuit and the attenuation circuit. The second end of this transformer T1 is used to form an internal reconstructed voltage signal.

[0021] In one implementation, the differential amplification circuit includes a differential current acquisition unit and a second current-voltage conversion unit connected in sequence;

[0022] The first acquisition end of the differential current acquisition unit is provided on the cable to be measured. The second acquisition end of this differential current acquisition unit is connected to the power amplifier boost circuit;

[0023] The second current-voltage conversion unit is connected to the main controller through the second analog-to-digital converter ADC2.

[0024] In one implementation, the attenuation circuit includes an attenuation unit and a signal conversion unit connected in sequence;

[0025] The attenuation unit includes operational amplifier U12A and resistor R200. The non-inverting input terminal of operational amplifier U12A is connected to the power amplifier boost circuit through resistor R200. The output terminal of this operational amplifier U12A is respectively connected to the inverting input terminal of operational amplifier U12A and the signal conversion unit;

[0026] The signal conversion unit is used to convert the internal reconstructed voltage signal into a DC voltage signal and output it to the main controller through the third analog-to-digital converter ADC3.

[0027] An embodiment of the second aspect of this application provides a measurement method, including:

[0028] Using a three-phase power frequency AC voltage measuring device to sequentially obtain the AC voltages of phase A, phase B, and phase C;

[0029] The AC voltages of phase A, phase B, and phase C are displayed on a three-phase power frequency AC voltage measuring device.

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0032] Figure 1 It is the first schematic diagram of the measuring device in the embodiment of the present invention;

[0033] Figure 2 It is the second schematic diagram of the measuring device in the embodiment of the present invention;

[0034] Figure 3 It is the schematic diagram for judging differential current in the embodiment of the present invention;

[0035] Figure 4 It is the circuit diagram of the first current-voltage conversion unit in the embodiment of the present invention;

[0036] Figure 5 It is the circuit diagram of the first band-pass filter unit and the second band-pass filter unit in the embodiment of the present invention;

[0037] Figure 6 It is the circuit diagram of the drive circuit in the embodiment of the present invention;

[0038] Figure 7 It is the circuit diagram of the power amplifier boost circuit in the embodiment of the present invention;

[0039] Figure 8 It is the circuit diagram of the differential amplifier circuit in the embodiment of the present invention;

[0040] Figure 9 It is the circuit diagram of the attenuation circuit in the embodiment of the present invention;

[0041] Figure 10 It is the schematic diagram of the measuring method in the embodiment of the present invention; Detailed Embodiments

[0042] To make the above objects, features, and advantages of the present application more apparent and understandable, the following detailed description of the specific embodiments of the present application will be provided in conjunction with the accompanying drawings. A lot of specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0043] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0044] In the description of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0045] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "mounted", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0046] An embodiment of the first aspect of the present application provides a non-contact three-phase power frequency AC voltage measuring device, as Figures 1 to 10 shown, including a main controller 100, a signal conversion and processing circuit 200, a driving circuit 300, a power amplifier and boost circuit 400, a differential amplifier circuit 500, and an attenuation circuit 600;

[0047] The signal conversion and processing circuit 200 is used to convert the collected micro-current into a power frequency line voltage signal, and input the power frequency line voltage signal into the main controller 100. The main controller 100 calculates the currently collected voltage value and frequency value, and forms a reference signal;

[0048] The driving circuit 300 is used to drive the power amplifier boosting circuit 400 to boost the voltage according to a reference signal;

[0049] The power amplifier boosting circuit 400 is used to boost the voltage and form an internal reconstruction voltage signal;

[0050] The differential amplifier circuit 500 is used to determine whether a differential current is generated according to the internal reconstruction voltage signal and the external induction line voltage;

[0051] When the internal reconstruction voltage signal is equal to the external induction line voltage, the attenuation circuit 600 outputs a DC voltage signal; the main controller 100 calculates the AC voltage to be measured according to this DC voltage signal.

[0052] For the differential amplifier circuit 500, the differential amplifier circuit 500 determines whether a differential circuit is generated according to the internal reconstruction voltage signal and the external induction line voltage signal. The main controller 100 forms a feedback signal according to this differential current, so as to perform corresponding actions on the digital-to-analog converter DAC1. Specifically, the main controller 100 forms a feedback signal according to this differential current, so as to perform corresponding actions on the digital-to-analog converter DAC1, which has three situations.

[0053] First, the induction line voltage signal is equal to the internal reconstruction voltage signal, that is, the differential current is zero; then the main controller 100 does not receive the feedback voltage signal; the output of the digital-to-analog converter DAC1 is maintained. At this time, the internal reconstruction voltage signal generates a DC voltage signal through the attenuation circuit 600, and the main controller 100 calculates the AC voltage to be measured according to this DC voltage signal.

[0054] Second, the induction line voltage signal is not equal to the internal reconstruction voltage signal, and the differential current is greater than zero; the main controller 100 receives the feedback voltage signal; a subtraction integration operation is performed on the digital-to-analog converter DAC1, and the digital-to-analog converter DAC1 outputs again.

[0055] Here, a subtraction integration operation is performed on the acquired voltage signal of the cable to be measured, and the reference signal after the subtraction integration operation is output again. The reference signal after the subtraction integration operation forms a new internal reconstruction voltage signal, and a differential comparison is performed again with the induction line voltage signal in the differential amplifier circuit 500. Until the new internal reconstruction voltage signal is equal to the induction line voltage signal, the first situation is cycled. In this way, it can effectively ensure that the internal reconstruction voltage signal is the same as the induction line voltage signal, so as to collect the internal reconstruction voltage signal for measurement, and can effectively avoid interference from other lines.

[0056] Third, the induction line voltage signal is not equal to the internal reconstruction voltage signal, and the differential current is less than zero; the main controller 100 receives the feedback voltage signal; an addition integration operation is performed on the first digital-to-analog converter DAC1, and the digital-to-analog converter DAC1 outputs again.

[0057] Here, an integration operation is performed on the acquired voltage signal of the cable to be measured, and a reference signal after the integration operation is output again. The reference signal after the integration operation forms a new internally reconstructed voltage signal, and the new internally reconstructed voltage signal is differentially compared with the induced line voltage signal in the differential amplifier circuit 500 again. Until the new internally reconstructed voltage signal is equal to the induced line voltage signal, the first case is looped. In this way, it can effectively ensure that the internally reconstructed voltage signal is the same as the induced line voltage signal, so that the internally reconstructed voltage signal is collected for measurement, and interference from other lines can be effectively avoided.

[0058] The measuring device of the present application cooperates with each other through the main controller 100, the signal conversion and processing circuit 200, the drive circuit 300, the power amplifier boost circuit 400, the differential amplifier circuit 500 and the attenuation circuit 600, which can effectively reduce the interference from adjacent other lines, thereby improving the acquisition signal and measurement accuracy.

[0059] In some embodiments, as Figure 3 shown, when the internally reconstructed voltage signal is not equal to the externally induced line voltage and the differential current is greater than zero, the main controller 100 performs a subtraction integration process on the drive circuit 300 and forms a new internally reconstructed voltage signal; the new internally reconstructed voltage signal is then rejudged with the externally induced line voltage to determine whether a differential current is generated.

[0060] In order to make the internally reconstructed voltage signal equal to the externally induced line voltage, so as to realize the acquisition of the internally reconstructed voltage signal and reduce the interference of the external line on the cable to be measured. When the internally reconstructed voltage signal is not equal to the externally induced line voltage and the generated differential current is greater than zero, the main controller 100 will perform a subtraction integration process on the drive circuit 300, that is, perform a subtraction integration process on the reference voltage acquired last time, and then form a new internally reconstructed voltage signal through the drive circuit 300 and the power amplifier boost circuit 400. The differential amplifier circuit 500 compares the new internally reconstructed voltage signal with the externally induced line voltage again and determines whether a new differential current is generated. If no differential current is generated, it indicates that the new internally reconstructed voltage signal is equal to the externally induced line voltage, and the output of the drive circuit 300 is maintained. At this time, the power amplifier boost circuit 400 outputs the new internally reconstructed voltage signal to the attenuation circuit 600.

[0061] In some embodiments, as Figure 3 shown, when the internally reconstructed voltage signal is not equal to the externally induced line voltage and the differential current is less than zero, the main controller 100 performs an addition integration process on the drive circuit 300 and forms a new internally reconstructed voltage signal; the new internally reconstructed voltage signal is then rejudged with the externally induced line voltage to determine whether a differential current is generated.

[0062] In this embodiment, when the internal reconstruction voltage signal is not equal to the external induction line voltage and the differential current is less than zero, the main controller 100 performs an integration addition process on the drive circuit 300 and forms a new internal reconstruction voltage signal. Similar to the principle when the differential current is greater than zero, it will not be elaborated here.

[0063] In some embodiments, as Figures 1 to 10 shown, the signal conversion processing circuit 200 includes a first current-voltage conversion unit 210, a first band-pass filtering unit 220, and a second band-pass filtering unit 230 connected in sequence. The acquisition end of the first current-voltage conversion unit 210 is disposed on the cable to be measured for acquiring a micro current. The second band-pass filtering unit 230 is connected to the main controller 100 through a first analog-to-digital converter ADC1 (not shown);

[0064] The drive circuit 300 includes a first digital-to-analog converter DAC1 and a first AC filtering unit 310 connected in sequence. The first digital-to-analog converter is connected to the main controller 100, and the first AC filtering unit 310 is connected to the power amplifier boost circuit 400.

[0065] Please refer to Figure 4 , for the signal conversion processing circuit 200, the acquisition end V1 is disposed on the cable to be measured. The first current-voltage conversion unit 210 includes, but is not limited to, an operational amplifier U4. The inverting input end of the operational amplifier U4 is the acquisition end V1, and the output end of the operational amplifier U4 is connected to the first band-pass filtering unit 220 through a port V200.

[0066] Please refer to Figure 5 , the first band-pass filtering unit 220 and the second band-pass filtering unit 230 are common low-pass filters and will not be elaborated here. The signals acquired are filtered by the first band-pass filtering unit 220 and the second band-pass filtering unit 230 to reduce interference. Among them, the first band-pass filtering unit 220 is connected to the first current-voltage conversion unit 210 through the V200 end. The second band-pass filtering unit 230 is connected to the main controller 100 through the V300 end.

[0067] Please refer to Figure 6 , the first digital-to-analog converter DAC1 is a common digital-to-analog converter and will not be elaborated here. The first AC filtering unit 310 includes, but is not limited to, an operational amplifier U100. The inverting input end of the operational amplifier U100 is connected to the first digital-to-analog converter DAC1, and the output end of the operational amplifier U100 is connected to the power amplifier boost circuit 400. The model of the operational amplifier U100 is ADA4637-1. Among them, the output end of the operational amplifier U100 is connected to the power amplifier boost circuit 400 through the DAC1_OUT end.

[0068] In some embodiments, such as Figures 1 to 10 shown, the power amplifier boost circuit 400 includes a second AC filtering unit 410, a power amplification unit 420, and a boost unit 430 connected in sequence;

[0069] The second AC filtering unit 410 is connected to the drive circuit 300;

[0070] The boost unit 430 is respectively connected to the differential amplification circuit 500 and the attenuation circuit 600.

[0071] Please refer to Figure 7 , the second AC filtering unit 410 includes, but is not limited to, an operational amplifier U3A. Among them, the non-inverting input terminal of the operational amplifier U3A is connected to the first AC filtering unit 310, and the output terminal of the operational amplifier U3A is connected to the power amplification unit 420. The second AC filtering unit 410 is connected to the first AC filtering unit 310 through the DAC1_OUT terminal.

[0072] For the power amplifier boost circuit 400, the second AC filtering unit 410 filters the reference signal sent by the main controller 100, and through the power amplification unit 420, enables the boost unit 430 to boost the voltage, thereby forming an internal reconstructed voltage signal.

[0073] For the boost unit, the boost unit is connected to the differential amplification circuit 500 through the V100 terminal. The boost unit is connected to the attenuation circuit through the V400 terminal.

[0074] In some embodiments, such as Figures 1 to 10 shown, the power amplification unit 420 includes a diode D100, a diode D101, a triode Q9014, a triode Q8050, and a triode Q8550. The negative electrode of the diode D100 is connected to the positive electrode of the diode D101. A first node N1 is provided between the diode D100 and the diode D101. The base of the triode Q9014 is connected to the first node N1. The base of the triode Q9014 is connected to the second AC filtering unit 410. The collector of the triode Q9014 is connected to the negative electrode of the diode D101. The base and collector of the triode Q8050 are connected to the positive electrode of the diode D100. The emitter of the triode Q8050 is connected to the first node N1. The emitter of the triode Q8550 is connected to the emitter of the triode Q8050. The base of the triode Q8550 is connected to the collector of the triode Q9014. The first node N1 is connected to the boost unit 430.

[0075] Please refer to Figure 7 , the triodes Q8050 and Q8550 are power amplification complementary transistors. The diode D100 enables the power amplification complementary transistors to be in a static working state, so that the output will not generate crossover distortion.

[0076] In some embodiments, as Figures 1 to 10 shown, the boost unit 430 includes a transformer T1. The first end of the transformer T1 is connected to the power amplification unit 420, and the second end of the transformer T1 is connected to the differential amplification circuit 500 and the attenuation circuit 600. The second end of the transformer T1 is used to form an internal reconstructed voltage signal.

[0077] Among them, the primary / secondary turn ratio of the transformer T1 is 1:385.

[0078] In some embodiments, as Figures 1 to 10 shown, the differential amplification circuit 500 includes a differential current acquisition unit 510 and a second current-voltage conversion unit 520 connected in sequence;

[0079] The first acquisition end of the differential current acquisition unit 510 is disposed on the cable to be measured, and the second acquisition end of the differential current acquisition unit 510 is connected to the power amplifier boost circuit 400;

[0080] The second current-voltage conversion unit 520 is connected to the main controller 100 through a second analog-to-digital converter ADC2 (not shown).

[0081] Please refer to Figure 8 , the differential current acquisition unit 510 includes a resistor R19, a resistor R20, and a resistor R22 connected in series in sequence. The first end of the resistor R19 is the first input end of the differential current acquisition unit 510, the second end of the resistor R19 is the first output end of the differential amplification circuit 500, and the second end of the resistor R19 is connected to the second current-voltage conversion unit 520. The first end of the resistor R22 is the second input end of the differential current acquisition unit 510, the second end of the resistor R22 is the second output end of the differential current acquisition unit 510, and the second end of the resistor R22 is connected to the second current-voltage conversion unit 520. Among them, the resistance value of the resistor R19 is 200 kΩ. The resistance value of the resistor R20 is 1 kΩ. The resistance value of the resistor R22 is 200 kΩ.

[0082] The second current-voltage conversion unit 520 includes a resistor R6, a resistor R18, a resistor R106, a resistor R7, and an operational amplifier U2. The inverting input terminal of the operational amplifier U2 is connected to the differential current acquisition unit 510 through the resistor R6, and the non-inverting input terminal of the operational amplifier U2 is connected to the differential current acquisition unit 510 through the resistor R18. The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2 through the resistor R106, and the output terminal of the operational amplifier U2 is connected to the main controller 100 through the resistor R7. Among them, the resistance value of the resistor R6 is 100 kΩ. The resistance value of the resistor R18 is 100 kΩ. The resistance value of the resistor 106 is 100 kΩ. The resistance value of the resistor R7 is 1 kΩ. The second current-voltage conversion unit is connected to the main controller 100 through the V101 terminal.

[0083] In some embodiments, as Figures 1 to 10 shown, the attenuation circuit 600 includes an attenuation unit 610 and a signal conversion unit 620 connected in sequence;

[0084] The attenuation unit 610 includes an operational amplifier U12A and a resistor R200. The non-inverting input terminal of the operational amplifier U12A is connected to the power amplifier boost circuit 400 through the resistor R200, and the output terminal of the operational amplifier U12A is connected to the inverting input terminal of the operational amplifier U12A and the signal conversion unit 620 respectively;

[0085] The signal conversion unit 620 is configured to convert the internal reconstructed voltage signal into a DC voltage signal and output it to the main controller 100 through a third analog-to-digital converter ADC3 (not shown).

[0086] Please refer to Figure 9 , the purpose of the attenuation unit 610 is to attenuate the internal reconstructed signal to a voltage range that can be processed by the main controller 100. The attenuation unit 610 is connected to the boost unit through the V400 terminal.

[0087] The signal conversion unit 620 includes a chip U20. The model of the chip U20 is AD8436. The signal conversion unit 620 is connected to the third analog-to-digital converter ADC3 through the V500 terminal.

[0088] The chip U20 can filter and perform RMS conversion on the attenuated voltage signal to obtain a DC voltage signal. The DC voltage signal is in a proportional relationship with the internal reconstructed voltage signal.

[0089] An embodiment of the second aspect of the present application provides a measurement method, as Figures 1 to 10 shown, including:

[0090] S100: Use a three-phase power frequency AC voltage measuring device to sequentially obtain the AC voltages of phase A, phase B, and phase C;

[0091] S200: Display the AC voltages of phase A, phase B, and phase C on the three-phase power frequency AC voltage measuring device.

[0092] Among them, a measurement method provided by an embodiment of the second aspect of this application is implemented based on the measurement device provided by the embodiment of the first aspect of this application. Therefore, its implementation principle, effects, etc. are the same as those of the embodiment of the first aspect of this application, and will not be elaborated here.

[0093] In addition, in step S100, when obtaining the AC voltages of phase A, phase B, and phase C, for example, when measuring the AC voltage of phase A, phase B needs to be used as a reference; when measuring the AC voltage of phase B, phase C needs to be used as a reference; when measuring the AC voltage of phase C, phase A needs to be used as a reference.

[0094] The above are only the preferred embodiments of this application, and do not impose any formal restrictions on this application. Any person skilled in the art can make many possible changes and modifications to the technical solution of this application, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of this application. Therefore, all equivalent changes made according to the shape, structure, and principle of this application without departing from the content of the technical solution of this application shall be covered by the protection scope of this application.

Claims

1. A non-contact three-phase power-frequency AC voltage measuring device, characterized in that, It includes a main controller, a signal conversion and processing circuit, a drive circuit, a power amplifier boost circuit, a differential amplifier circuit and an attenuation circuit; The signal conversion and processing circuit is used to convert the collected micro-current into a power frequency line voltage signal, and input the power frequency line voltage signal into the main controller. The main controller calculates the currently collected voltage value and frequency value, and forms a reference signal; The drive circuit is used to drive the power amplifier boost circuit to boost according to the reference signal; The power amplifier boost circuit is used to boost and form an internal reconstructed voltage signal; The differential amplifier circuit is used to judge whether a differential current is generated according to the internal reconstructed voltage signal and the external induced line voltage; When the internal reconstructed voltage signal is equal to the external induced line voltage, the attenuation circuit outputs a DC voltage signal; The main controller calculates the AC voltage to be measured according to the DC voltage signal; When the internal reconstructed voltage signal is not equal to the external induced line voltage and the differential current is greater than zero, the main controller performs a subtraction integration process on the drive circuit and forms a new internal reconstructed voltage signal; the new internal reconstructed voltage signal is then used to re-judge whether a differential current is generated with the external induced line voltage.

2. The non-contact three-phase power-frequency AC voltage measuring device according to claim 1, characterized in that, When the internal reconstructed voltage signal is not equal to the external induced line voltage and the differential current is less than zero, the main controller performs an addition integration process on the drive circuit and forms a new internal reconstructed voltage signal; the new internal reconstructed voltage signal is then used to re-judge whether a differential current is generated with the external induced line voltage.

3. The non-contact three-phase power frequency AC voltage measuring device according to claim 1, characterized in that, The signal conversion and processing circuit includes a first current-voltage conversion unit, a first band-pass filter unit and a second band-pass filter unit connected in sequence. The acquisition end of the first current-voltage conversion unit is arranged on the cable to be measured for collecting micro-current, and the second band-pass filter unit is connected to the main controller through a first analog-to-digital converter ADC1; The drive circuit includes a first digital-to-analog converter DAC1 and a first AC filter unit connected in sequence. The first digital-to-analog converter is connected to the main controller, and the first AC filter unit is connected to the power amplifier boost circuit.

4. The non-contact three-phase power frequency AC voltage measuring device according to claim 1, characterized in that, The power amplifier boost circuit includes a second AC filter unit, a power amplification unit and a boost unit connected in sequence; The second AC filter unit is connected to the drive circuit; The boost unit is respectively connected to the differential amplifier circuit and the attenuation circuit.

5. The non-contact three-phase power frequency AC voltage measuring device according to claim 4, characterized in that, The power amplification unit includes diode D100, diode D101, triode Q9014, triode Q8050 and triode Q8550. The negative electrode of diode D100 is connected to the positive electrode of diode D101. A first node N1 is provided between diode D100 and diode D101. The base of triode Q9014 is connected to the first node N1. The base of this triode Q9014 is connected to the second AC filtering unit. The collector of this triode Q9014 is connected to the negative electrode of diode D101. The base and collector of triode Q8050 are connected to the positive electrode of diode D100. The emitter of triode Q8050 is connected to the first node N1. The emitter of triode Q8550 is connected to the emitter of triode Q8050. The base of triode Q8550 is connected to the collector of triode Q9014. The first node N1 is connected to the boost unit.

6. The non-contact three-phase power frequency AC voltage measuring device according to claim 4, wherein The boost unit includes transformer T1. The first end of transformer T1 is connected to the power amplification unit. The second end of transformer T1 is connected to the differential amplification circuit and the attenuation circuit. The second end of this transformer T1 is used to form an internal reconstructed voltage signal.

7. The non-contact three-phase power frequency AC voltage measuring device according to claim 1, wherein, The differential amplification circuit includes a differential current acquisition unit and a second current-voltage conversion unit connected in sequence; The first acquisition end of the differential current acquisition unit is arranged on the cable to be measured. The second acquisition end of this differential current acquisition unit is connected to the power amplifier boost circuit; The second current-voltage conversion unit is connected to the main controller through a second analog-to-digital converter ADC2.

8. The non-contact three-phase power frequency AC voltage measuring device according to claim 1, wherein, The attenuation circuit includes an attenuation unit and a signal conversion unit connected in sequence; The attenuation unit includes operational amplifier U12A and resistor R200. The non-inverting input terminal of operational amplifier U12A is connected to the power amplifier boost circuit through resistor R200. The output terminal of this operational amplifier U12A is respectively connected to the inverting input terminal of operational amplifier U12A and the signal conversion unit; The signal conversion unit is used to convert the internal reconstructed voltage signal into a DC voltage signal and output it to the main controller through a third analog-to-digital converter ADC3.

9. A measurement method implemented by the non-contact three-phase power-frequency AC voltage measurement device according to claim 1, characterized in that, Including: Using the three-phase power frequency AC voltage measuring device to sequentially obtain the AC voltages of phase A, phase B and phase C; Displaying the AC voltages of phase A, phase B and phase C on the three-phase power frequency AC voltage measuring device.

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