JP2016080537A - Voltage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a voltage of an object to be detected without contacting, even when an insulator exists between the object to be detected and a detection electrode.SOLUTION: A voltage detection device comprises: a detection electrode 11 disposed in contact with an insulator 51 covering an object 52 to be detected; a vibrator 13 for causing the insulator 51 to vibrate; a current-voltage conversion circuit 14 having an arithmetic amplifier 14a which, in a state where a first input terminal is set to a reference voltage, a second input terminal is connected to the detection electrode 11, and a feedback resistor 14b is connected between the second input terminal and an output terminal, with the insulator 51 made to vibrate, converts a detection current I flowing from the object 52 to be detected to the reference voltage via the detection electrode 11, modulated in amplitude in accordance with a potential difference Vdi between a voltage V1 to be detected and the reference voltage, and synchronized to the vibration of the vibrator 51, to a detection voltage signal V2; and a detection circuit 16 for detecting a detection output V3 indicating the potential difference Vdi from the detection voltage signal V2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-contact type voltage detection device that detects a voltage to be detected covered with an insulating material through the insulating material.

  As a non-contact type voltage detection device, a voltage detection device (non-contact type static voltage follower) disclosed in Patent Document 1 below is known. This voltage detection device includes a probe for voltage detection. The probe is operatively connected to a detection electrode arranged towards a measurement surface (surface to be detected) having an electrostatic quantity to be measured and to modulate capacitive coupling between the detection electrode and the measurement surface. Modulator or drive means, and means for defining a path of radiation directed to the measurement surface to illuminate an area of the measurement surface that coincides with the detection electrode.

  The detection electrode is accommodated in the housing. The housing is provided with a first opening or window, and the detection electrode is exposed to the measurement surface through the first opening or window. The detection electrode is connected to a summing input terminal (inverting input terminal) of an amplifier (an operational amplifier for current / voltage conversion) accommodated in the housing by a line, and the non-inverting input terminal of the amplifier is connected to a reference unit by the line. Connected to the housing. Further, for example, a piezoelectric transducer can be used as the modulator or the driving means, and the modulator or the driving means mechanically moves (vibrates) the operation-connected detection electrode, so that the measurement surface, the detection electrode, The capacitance (coupling capacitance) formed between the two is modulated.

  In the voltage detection device including the probe, when the capacitance is modulated, the capacitance and current / voltage conversion flow through a resistor connected between the addition input terminal (inverting input terminal) and the output terminal of the amplifier. Based on the current, the voltage on the measurement surface can be detected in a non-contact manner.

Japanese Examined Patent Publication No. 7-92487 (6th page, Fig. 7)

  However, the above voltage detection device has the following problems to be solved. That is, in this voltage detection apparatus, it is necessary to arrange the probe on the measurement surface so that the detection electrode is exposed to the measurement surface through the first opening (or window) provided in the housing. This is because when the first opening is covered with an insulator, charges appear theoretically on the surface of the insulator due to the voltage of the measurement surface, but the charges appearing on the surface of the insulator easily escape. Disappear. Therefore, this voltage detection device has a problem to be solved that the voltage on the measurement surface cannot be detected when an insulator is interposed between the measurement surface and the detection electrode.

  The present invention has been made to solve such a problem, and even when an insulator is present between the detection target and the detection electrode, voltage detection that can detect the voltage of the detection target in a non-contact manner. The main purpose is to provide a device.

  In order to achieve the above object, a voltage detection device according to claim 1 is a voltage detection device for detecting a detection target voltage generated in a detection target covered with an insulator, and the voltage detection device is directly or otherwise applied to the insulator. A detection electrode disposed in indirect contact with an insulator interposed; a vibrating body that vibrates the insulator; and the detection from the detection target in a state where the insulator is vibrated A current voltage that flows to a reference voltage via an electrode and converts a detection current synchronized with vibration of the vibrating body whose amplitude is modulated according to a potential difference between the detection target voltage and the reference voltage into a detection voltage signal A conversion circuit; and a detection circuit that detects a detection output indicating the potential difference from the detection voltage signal.

  The voltage detection apparatus according to claim 2 is the voltage detection apparatus according to claim 1, wherein the detection circuit detects the detection output by synchronously detecting the detection voltage signal with a synchronization signal synchronized with the detection voltage signal. .

  The voltage detection device according to claim 3 is the voltage detection device according to claim 1 or 2, wherein the current-voltage conversion circuit has a first input terminal defined by the reference voltage and a second input terminal detected by the detection. An operational amplifier is connected to the electrode and a feedback circuit is connected between the second input terminal and the output terminal, and the detection current flowing through the feedback circuit is converted into the detection voltage signal.

  A voltage detection device according to a fourth aspect is the voltage detection device according to any one of the first to third aspects, wherein the voltage detection device is formed of an insulating material, and the detection electrode, the vibrator, the current-voltage conversion circuit, and the detection A circuit is provided with a case disposed therein, and the detection electrode is provided on an inner surface of the wall as the other insulator in which an outer surface of the plurality of walls constituting the case is brought into contact with the insulator. The vibrating body is fixed to an inner surface of any one of the plurality of wall portions and vibrates the case.

  The voltage detection device according to claim 5 is the voltage detection device according to any one of claims 1 to 4, further comprising a shield member that covers the detection electrode, the vibrator, the current-voltage conversion circuit, and the detection circuit. Yes.

  According to the voltage detection device of claim 1, a detection current is generated between the detection target and the detection electrode by vibrating the insulator with the detection electrode in direct or indirect contact with the vibrating body, Since the inspection target voltage is detected based on the detected current, the inspection target voltage is detected in a non-contact manner (detection of the detection electrode) even when an insulator exists between the detection target and the detection electrode. (Without direct contact with the object).

  According to the voltage detection apparatus of the second aspect, the detection circuit can detect the detection output in a state where the influence of the disturbance is small by outputting the detection output by synchronously detecting the detection voltage signal with the synchronization signal.

  According to the voltage detection device of the third aspect, since the current-voltage conversion circuit includes the operational amplifier and the feedback resistor, the detection current can be detected with high sensitivity and converted into the detection voltage signal.

  According to the voltage detection device of claim 4, the voltage detection device is housed (arranged) in a case made of an insulating material so that the detection electrode and the vibrating body are not exposed. Since it is possible to save the trouble of individually contacting the vibrating body with the insulator, the operation of detecting the inspection target voltage can be performed more efficiently.

  According to the voltage detection device of the fifth aspect, since the influence of disturbances (external magnetic field, external electric field, etc.) on the circuit constituting the voltage detection apparatus 1 can be reduced, detection can be performed in a state where the influence of the disturbance is even less. Output can be detected and output.

1 is a configuration diagram of a voltage detection device 1. FIG. 10 is an explanatory diagram for explaining another arrangement of the detection electrode 11 and the vibrating body 13. FIG. 11 is an explanatory diagram for explaining still another arrangement of the detection electrode 11 and the vibrating body 13. FIG. 4 is an explanatory diagram for explaining a configuration of a voltage detection device 1 including a case 21. FIG.

  Hereinafter, embodiments of a voltage detection device will be described with reference to the accompanying drawings.

  First, the configuration of the voltage detection device will be described with reference to the drawings.

  A voltage detection device 1 as a voltage detection device shown in FIG. 1 is a non-contact type voltage detection device. As an example, a detection electrode 11, an oscillation circuit 12, a vibrating body 13, a current-voltage conversion circuit 14, and a buffer amplifier 15 are used. The detection circuit 16, the phase adjustment circuit 17, and the output circuit 18 are provided so that the voltage (detection target voltage) V <b> 1 generated in the detection target 52 covered with the insulator 51 can be detected without contact.

  In this case, as shown in FIG. 1, the detection target 52 may be partially covered with an insulator 51 as shown in FIG. 1, or the entire surface may be insulated as shown in FIGS. It may be covered with the body 51 (for example, the detection target 52 may be a core wire of a covered electric wire whose entire outer peripheral surface is covered with an insulating coating). The insulator 51 may have a single layer structure made of one type of insulating material, or may have a multilayer structure in which a plurality of layers each made of different types of insulating materials are stacked. Good.

  The detection electrode 11 is in direct contact with the surface of the insulator 51 that covers the detection object 52, or another insulator (insulator other than a gas such as air) disposed in contact (contact) with the surface. It is comprised in the shape which can be made to contact indirectly in the state which interposed. In this case, the detection electrode 11 is preferably brought into contact with the surface of the insulator 51 in a state of being closer to the close contact. For this reason, for example, when the surface of the insulator 51 is planar, correspondingly, the contact surface with the surface of the insulator 51 is formed in a planar shape, and the surface of the insulator 51 is cylindrical. In the case of a shape, the contact surface with the surface of the insulator 51 is correspondingly formed into a concave shape.

  The oscillation circuit 12 generates and outputs a drive signal S1 having a constant frequency (predetermined frequency) of, for example, about several tens of kHz to several MHz. In this case, the oscillation circuit 12 can employ a configuration that continuously outputs the drive signal S1 during operation, or can employ a configuration that outputs intermittently at regular intervals. It is also possible to adopt a configuration that outputs only for a certain period of time only at the time of measurement. In addition, the oscillation circuit 12 outputs, for example, one of a rectangular wave signal, a triangular wave signal, and a sine wave signal as the driving signal S1. Note that the oscillation circuit 12 is replaced with a configuration in which the drive signal S1 is generated and output at a constant frequency as described above, for example, the frequency changes with time within a predetermined lower limit frequency and upper limit frequency range. It is also possible to adopt a configuration in which the drive signal S1 is generated and output as a sweep signal, or a configuration in which the drive signal S1 is generated and output as a random signal (noise signal) whose frequency changes randomly with time.

  The vibrating body 13 is driven by the drive signal S1 from the oscillation circuit 12, and, as an example, vibrates at the same vibration frequency (predetermined frequency in this example) as the frequency of the drive signal S1 (this example). Then, mechanical vibration is transmitted to the insulator). The vibrating body 13 can be configured by, for example, an ultrasonic vibrator, a piezoelectric vibrator, a ceramic vibrator, an electromagnetic induction vibrator, a magnetostrictive vibrator, or a vibrator using a rotor.

  As an example, the current-voltage conversion circuit 14 includes an operational amplifier 14a and a feedback resistor 14b as a feedback circuit. In the operational amplifier 14a, a non-inverting input terminal (first input terminal) is connected to a reference potential (ground) to be regulated to a reference voltage (zero volts), and an inverting input terminal (second input terminal) is connected to the detection electrode 11. A feedback resistor 14b is connected between the inverting input terminal and the output terminal. In this example, the feedback circuit is configured by one feedback resistor 14b as an example. However, the feedback circuit is configured by a series circuit or a parallel circuit of a plurality of resistors, or a series-parallel circuit combining a series circuit and a parallel circuit. It can also be configured.

  As will be described later, the current-voltage conversion circuit 14 is used when the capacitance value of the capacitance of the insulator 51 located between the detection object 52 and the detection electrode 11 is changed by vibration from the vibrating body 13. In addition, the potential difference Vdi between the voltage V1 of the detection object 52 and the voltage of the detection electrode 11 (the reference voltage is the reference voltage because each input terminal of the operational amplifier 14a is in a virtual short state). ), The detection current I flowing from the detection object 52 to the reference potential via the detection electrode 11 with a current value (amplitude) corresponding to the magnitude of the potential difference Vdi is converted into a detection voltage signal V2 and output. . That is, in the current-voltage conversion circuit 14, the detection current synchronized with the vibration of the vibrating body 13 whose amplitude is modulated according to the potential difference between the voltage V 1 of the detection target 52 and the voltage (reference voltage) of the detection electrode 11. I is converted into a detection voltage signal V2.

  In this case, the detection current I is generated due to the change in the capacitance value of the capacitance of the insulator 51 at the vibration frequency of the vibrating body 13, and therefore is an AC signal having the same frequency as the vibration frequency. The amplitude is generated as an AC signal modulated to a level corresponding to the potential difference Vdi (voltage V1 in this example). Therefore, the detection voltage signal V2 is also an AC signal having the same frequency as the vibration frequency, and the current-voltage conversion circuit 14 is an AC signal whose amplitude is modulated to a level corresponding to the potential difference Vdi (voltage V1 in this example). Is output from.

  Note that, as described above, the current-voltage conversion circuit 14 has an operational amplifier 14a and a feedback resistor 14b as described above, and generally detects and detects a detection current I having a very small amplitude (weak) with high sensitivity. Although it can be converted into the voltage signal V2, it is not limited to this. For example, when it is desired to realize the current-voltage conversion circuit 14 with a simpler configuration, instead of the above configuration, although not shown, one end is connected to the detection electrode 11 and the other end is a reference potential. A configuration having a resistor connected to (ground) can also be adopted. In the current-voltage conversion circuit 14 having this configuration, the resistor converts the detection current I flowing from the detection target 52 to the reference potential (reference voltage) via the detection electrode 11 into the detection voltage signal V2. Then, the detection voltage signal V2 converted at one end of the resistor is output to a buffer amplifier 15 described later.

  The buffer amplifier 15 is composed of an amplifier having a high input impedance and a low output impedance, and receives the detection voltage signal V2 output from the current-voltage conversion circuit 14 and outputs it with a low impedance. The detection circuit 16 is configured as a synchronous detection circuit as an example, and detects the amplitude of the detection voltage signal V2 by synchronously detecting the detection voltage signal V2 input from the buffer amplifier 15 with the synchronization signal S2 input from the phase adjustment circuit 17. A component (DC component) is detected (extracted) and output as a detection output (voltage signal) V3. The detection circuit 16 is composed of any one of a multiplier, a changeover switch (multiplexer) composed of analog switches, and a correlator. Note that the detection circuit 16 can also be configured by an envelope detection circuit. When this configuration is adopted, the synchronization signal S2 is not necessary, and therefore the phase adjustment circuit 17 can be omitted.

  The phase adjustment circuit 17 receives the drive signal S1 from the oscillation circuit 12 and outputs it as a synchronization signal S2 with a delay. The phase adjustment circuit 17 is configured to be able to adjust the delay amount of the synchronization signal S2 with respect to the drive signal S1. The delay amount is adjusted in advance so that the phase of the detection voltage signal V2 as an AC signal input to the detection circuit 16 matches the phase of the synchronization signal S2.

  The output circuit 18 includes, for example, a voltmeter that detects and displays the voltage value of the detection output V3, a buffer circuit that inputs the detection output V3 and outputs it at a low impedance, and A / D converts the detection output V3 to convert it An A / D converter that outputs voltage data indicating a voltage value is used.

  Next, the detection operation for the voltage V1 of the detection target 52 by the voltage detection device 1 will be described. The voltage V1 may be a DC voltage or an AC voltage. In this example, as an example, the voltage V1 is a DC voltage.

  First, as shown in FIG. 1, the detection electrode 11 and the vibrating body 13 are brought into contact (contacted) with the surface of the insulator 51 that covers the detection target 52. In this case, as shown in the figure, both the detection electrode 11 and the vibrating body 13 may be brought into contact with the surface on the back side with respect to the contact surface with the detection target 52 in the insulator 51, As shown in FIG. 2, the vibrator 13 may be brought into contact (contact) with the detection electrode 11 brought into contact with the surface of the insulator 51. As shown in FIG. 2, when the configuration in which the vibrating body 13 is brought into contact with the detection electrode 11 is adopted, as shown in FIG. 2, in order to reduce the influence of the electrical signal generated in the vibrating body 13 on the detection electrode 11. Further, a configuration in which a shield sheet (for example, a sheet for shielding an electric field or a magnetic field) 53 is interposed between the detection electrode 11 and the vibrating body 13 is preferable. Further, the adhesion between these members (between the insulator 51 and the detection electrode 11, between the insulator 51 and the vibration body 13, and between the detection electrode 11 (or the shield sheet 53) and the vibration body 13) is improved. In order to improve, another insulator (for example, an insulating sheet or a gel-like insulator) may be interposed between the members.

  As shown in FIG. 3, when the outer periphery of the detection target 52 is covered with the insulator 51 over the entire area, the vibrating body 13 is placed on the back side of the surface of the insulator 51 that is in contact with the detection electrode 11. Can be brought into contact with each other.

  In this state, when the drive signal S1 is output from the oscillation circuit 12, the vibrator 13 is driven by the drive signal S1 and vibrates. In addition, the phase adjustment circuit 17 outputs the synchronization signal S2 by inputting and delaying the drive signal S1.

  Since the vibration (mechanical vibration) of the vibration body 13 is transmitted to the insulator 51 in contact with the vibration body 13, the insulator 51 also vibrates at the same frequency as the vibration frequency of the vibration body 13. In this case, the distance or density between the detection object 52 and the detection electrode 11 (density of the insulator 51) changes at the same frequency as the vibration frequency of the vibration body 13, and therefore, between the detection object 52 and the detection electrode 11. The capacitance value of the capacitance of the insulator 51 located also changes at the same frequency as this vibration frequency. In addition, as the capacitance value of the capacitance changes, the detection current I, which is an AC signal having the same frequency as the vibration frequency and whose amplitude is modulated to a level corresponding to the potential difference Vdi (voltage V1), is detected. 52, the current flows through a path including the detection electrode 11 and the feedback resistor 14b of the current-voltage conversion circuit 14.

  The current-voltage conversion circuit 14 converts this detection current I into a detection voltage signal V2 and outputs it, and the buffer amplifier 15 inputs this detection voltage signal V2 output from the current-voltage conversion circuit 14 and outputs it with a low impedance. To do. The detection circuit 16 disturbs the amplitude component (DC component) of the detection voltage signal V2 by synchronously detecting the detection voltage signal V2 output from the buffer amplifier 15 with the synchronization signal S2 output from the phase adjustment circuit 17. And output to the output circuit 18 as a detection output (voltage signal) V3. In this case, the level of the amplitude component (DC component) of the detected voltage signal V2 detected as the detection output V3 changes according to the potential difference Vdi (the voltage V1 in this example).

  The output circuit 18 inputs this detection output (voltage signal) V3 and, for example, when it is constituted by an analog voltmeter, the voltage value of the detection output V3 (voltage value proportional to the potential difference Vdi (voltage V1)). Based on this, by moving the pointer to a numerical value indicating the voltage value of the potential difference Vdi (voltage V1), the voltage value of the potential difference Vdi (voltage V1) is output in a state where it can be visually observed. For example, when the output circuit 18 is configured by a buffer circuit, the detection output V3 is input and output to the outside with a low impedance (for an external measuring instrument or the like based on the detection output V3, the potential difference Vdi (voltage V1) is output so that the voltage value can be detected). For example, when the output circuit 18 is composed of an A / D converter, the detection output V3 is inputted and voltage data indicating the voltage value (voltage data indicating the voltage value of the potential difference Vdi (voltage V1) is also used. Is output to a processing unit (not shown) provided inside or an external processing device.

  As described above, in the voltage detection device 1, the insulator 51 that is in contact with the detection electrode 11 is vibrated by the vibrating body 13 to generate the detection current I. Based on the detection current I, the detection object 52 is detected. The voltage V1 is detected. Therefore, according to this voltage detection device 1, even when the insulator 51 exists between the detection target 52 and the detection electrode 11, the voltage V1 of the detection target 52 is detected without contact (the detection electrode 11 is detected). (Without direct contact with the object 52).

  Further, according to the voltage detection device 1, the detection circuit 16 detects the detection output V3 in a state where the influence of the disturbance is small by synchronously detecting the detection voltage signal V2 with the synchronization signal S2 and outputting the detection output V3. Can be output.

  Further, according to the voltage detection device 1, the current-voltage conversion circuit 14 includes the operational amplifier 14a and the feedback resistor 14b, thereby detecting the detection current I with high sensitivity and converting it to the detection voltage signal V2. Can do.

  In the above example, the configuration in which the detection electrode 11 is brought into direct contact with the insulator 51 covering the detection target 52 is employed. However, as described above, the insulator 51 may have a multilayer structure. Then, as shown in FIG. 4, it is possible to adopt a configuration in which the voltage detection device 1 is housed (arranged) in a case 21 made of an insulating material so that the detection electrode 11 and the vibrating body 13 are not exposed. . In this configuration, as shown in the figure, the detection electrode 11 is arranged on the inner surface of the wall portion 21a as another insulator whose outer surface is brought into contact with the insulator 51 among the plurality of wall portions constituting the case 21. To do. As long as the vibration body 13 can transmit the vibration to the insulator 51 through the case 21, the vibration body 13 may be disposed on any wall portion constituting the case 21. By arranging it on the wall 21a, the vibration can be transmitted to the insulator 51 most efficiently. In FIG. 4, the components other than the detection electrode 11 and the vibrating body 13 are not shown.

  As described above, the voltage detection device 1 is housed (arranged) in the case 21 formed of an insulating material so that the detection electrode 11 and the vibrating body 13 are not exposed, whereby the detection electrode 11 and the vibrating body 13 are configured. Therefore, the operation of detecting the voltage V1 can be performed more efficiently.

  Further, as described above, when the configuration in which the voltage detection device 1 is housed in the case 21 made of an insulating material is adopted, as shown in FIG. 4, the case 21 has a shield member (for example, the inner surface of the case 21). It is also possible to adopt a configuration in which the shield member 54 and the shield member 55) on the outer surface of the case 21 are disposed. In this case, a shield member is not interposed between the detection electrode 11 and the detection target 52. In FIG. 4, the shield member 54 and the shield member 55 are disposed using only the wall portion (the upper wall that is in contact with the insulator 51) in the case 21 where the detection electrode 11 and the vibrating body 13 are disposed as an insulating material. It is also possible to adopt a configuration in which the wall portions (side walls and lower wall) are made of a shielding material and the wall portions themselves are used as shielding members. The shield member includes the above-described circuits constituting the voltage detection device 1 (detection electrode 11, oscillation circuit 12, vibration body 13, current-voltage conversion circuit 14, buffer amplifier 15, detection circuit 16, phase adjustment circuit 17, and The output circuit 18) is electrically connected to the reference potential (reference potential to which the non-inverting input terminal of the operational amplifier 14a shown in FIG. 1 is connected).

  According to this configuration, since the voltage detection device 1 is covered by this shield member, each of the above-described circuits (the detection electrode 11, the oscillation circuit 12, the vibration body 13, the current-voltage conversion circuit 14, the buffer) that constitutes the voltage detection device 1. Since it is possible to reduce the influence of disturbance (external magnetic field, external electric field, etc.) on the amplifier 15, the detection circuit 16, the phase adjustment circuit 17 and the output circuit 18), the detection output V3 is detected with less influence of the disturbance. Can be output.

DESCRIPTION OF SYMBOLS 1 Voltage detection apparatus 11 Detection electrode 13 Vibrating body 14 Current-voltage conversion circuit 14a Operational amplifier 14b Feedback resistance 16 Detection circuit 21 Case 51 Insulator 52 Detection object 54,55 Shield member
I Detection current V1 Voltage (Detection target voltage)
V2 detection voltage signal V3 detection output Vdi potential difference

Claims (5)

A voltage detection device for detecting a detection target voltage generated in a detection target covered with an insulator,
A detection electrode disposed in direct contact with the insulator directly or in a state of interposing another insulator;
A vibrator for vibrating the insulator;
In a state where the insulator is vibrated, the amplitude is modulated in accordance with a potential difference between the detection target voltage and the reference voltage while flowing from the detection target to the reference voltage via the detection electrode. A current-voltage conversion circuit that converts a detection current synchronized with the vibration of the vibrating body into a detection voltage signal;
A voltage detection apparatus comprising: a detection circuit that detects a detection output indicating the potential difference from the detection voltage signal.   The voltage detection device according to claim 1, wherein the detection circuit detects the detection output by synchronously detecting the detection voltage signal with a synchronization signal synchronized with the detection voltage signal.   In the current-voltage conversion circuit, a first input terminal is defined by the reference voltage, a second input terminal is connected to the detection electrode, and a feedback circuit is provided between the second input terminal and the output terminal. The voltage detection apparatus according to claim 1, further comprising an operational amplifier connected to convert the detection current flowing through the feedback circuit into the detection voltage signal. A case in which the detection electrode, the vibrating body, the current-voltage conversion circuit, and the detection circuit are formed inside is formed of an insulating material,
The detection electrode is disposed on the inner surface of the wall portion as the other insulator, the outer surface of the plurality of wall portions constituting the case being brought into contact with the insulator,
4. The voltage detection device according to claim 1, wherein the vibrating body is fixed to an inner surface of any one of the plurality of wall portions and vibrates the case. 5.   5. The voltage detection device according to claim 1, further comprising a shield member that covers the detection electrode, the vibrating body, the current-voltage conversion circuit, and the detection circuit.

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