Detection device and detection method

Abstract

To detect the open / closed state of a clamp part in a clamp type current sensor that has higher reliability.SOLUTION: The detection device comprises: a signal supply circuit 10 that supplies a prescribed given detection signal to a current sensor 2; and a determination circuit 11 that compares the value of an electric signal outputted from a magnetic senor 21 that corresponds to a magnetic flux density B in a magnetic core 20 when the detection signal is supplied, with a preliminarily set electric signal determination reference value, and determines the presence of abutting defects at edges ac1, bc2 of divided cores 20a, 20b, 20c. The magnetic flux density in the magnetic core 20 includes a magnetic flux density B2 in the magnetic core 20 that has occurred as the result of the detection signal having been supplied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a detection device and a detection method, and more particularly to a technique for detecting the open / closed state of a clamp portion in a clamp-type current sensor. [Background technology]

[0002] Clamp-type current sensors are known as magnetic field detection current sensors. Fig. 9(a) is a schematic diagram showing the internal structure of a conventional clamp-type current sensor 900. A magnetic core 901 is disposed inside the clamp portion of the conventional clamp-type current sensor 900. The current sensor 900 also includes a loop-shaped magnetic core 901 having a gap G1, and a magnetic sensor 902 disposed within the gap G1. In the example of Fig. 9, a conductor 800 extends in a direction perpendicular to the plane of the paper, and a current I1 to be measured flows from the back to the front of the paper.

[0003] Clamp-type current sensor 900 clamps conductor 800, through which current I1 to be measured flows, in its clamping section, and collects the generated magnetic flux with magnetic core 901 to convert it into a current value. In order for clamp-type current sensor 900 to accurately measure current I1 to be measured flowing through conductor 800, ends ac1 and bc2 of the divided cores of magnetic core 901 must be butted against each other and in contact with each other when opening and closing the clamping section of current sensor 900 to clamp conductor 800, as shown in Figure 9(a). In this specification, this state is referred to as the clamping section of current sensor 900 being closed.

[0004] 9(b) is a schematic diagram showing the internal structure of clamp-type current sensor 900 when the clamp is not closed properly. Current sensor 900 shown in FIG. 9(b) is in a state where ends ac1 and bc2 of the divided cores of magnetic core 901 inside are separated from each other due to foreign matter such as fine dust getting into the opening and closing ends of the clamp during installation, or due to forgetting to close the clamp.

[0005] A new gap G2 is formed between ends ac1 and bc2 of the divided cores of magnetic core 901, and the gap length of magnetic core 901 is now wider than the predetermined gap G1 length (gap G1'). In this way, in clamp-type current sensor 900, when ends ac1 and bc2 of the divided cores of magnetic core 901 are separated from each other, the current flowing through conductor 800 cannot be measured correctly, resulting in a measurement error.

[0006] Therefore, in order to prevent measurement errors in clamp-type current sensors, there has been a demand for technology to detect whether the ends of the split cores are butted together so that they are in contact with each other, i.e., the open / closed state of the clamp part of the current sensor.

[0007] Therefore, Patent Document 1 discloses a technology for determining whether or not foreign matter such as dust has become trapped in the clamp of a clamp-type current sensor based on the measurement principle of a magnetic balance system.The technology disclosed in Patent Document 1 uses a switch circuit to periodically switch the roles of the power supply terminal and the sensor signal input terminal of the Hall element, and determines whether or not foreign matter has become trapped in the clamp based on the magnitude of the resulting change in the current sensor output.

[0008] In Patent Document 1, based on the fact that the magnetic flux density does not actually become 0 due to variations in the sensitivity of Hall elements, etc., two types of variations in the sensitivity of the Hall elements are prepared to determine the presence or absence of foreign matter in the clamping section.

[0009] However, in the technology disclosed in Patent Document 1, which changes latent noise by switching the sensitivity of the Hall element, if the two sensitivity values ​​of the Hall elements are the same or if the latent noise is small, no difference in sensor output occurs due to the sensor signal input. Furthermore, in light of the measurement principle of the magnetic balance method, there is a risk that changes in the sensitivity of sensors such as Hall elements will be canceled out and become invisible.

[0010] Furthermore, in Patent Document 1, the degree of freedom in selecting the signal amplitude and frequency is low, which may make it difficult to use the device as a detection device. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2018-017687 Summary of the Invention [Problem to be solved by the invention]

[0012] According to conventional techniques, it has been difficult to detect the open / closed state of the clamp portion of a clamp-type current sensor with high reliability.

[0013] The present invention has been made to solve the above-mentioned problems, and has an object to detect the open / closed state of a clamp portion in a clamp-type current sensor with higher reliability. [Means for solving the problem]

[0014] In order to solve the above-mentioned problems, the detection device of the present invention is a detection device connected to a current sensor comprising a magnetic core in which the ends of split cores are butted together to form a loop-shaped magnetic path and are arranged to surround the conductor through which the current to be measured flows, and a magnetic sensor that detects the magnetic flux density generated by the current to be measured and outputs a corresponding electrical signal, and is characterized in that it comprises a signal supply circuit that supplies a predetermined constant detection signal to the current sensor, and a judgment circuit that compares the value of the electrical signal output from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core when the detection signal is supplied, with a predetermined reference value for the electrical signal to determine whether or not there is a poor butting at the ends of the split core, and the magnetic flux density in the magnetic core includes a first magnetic flux density in the magnetic core generated as a result of the detection signal being supplied.

[0015] In addition, in the detection device of the present invention, the current sensor may further include a detection coil wound around the magnetic core, the signal supply circuit may pass a predetermined constant detection current through the detection coil, and the judgment circuit may determine that there is a mismatch when the output voltage from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core including the first magnetic flux density generated in the detection coil, is lower than a predetermined judgment voltage.

[0016] In the detection device according to the present invention, the frequency of the detection current that the signal supply circuit supplies to the detection coil may be different from the frequency of the current to be measured.

[0017] In addition, in the detection device of the present invention, the judgment voltage may be the output voltage from the magnetic sensor when the signal supply circuit passes the detection current through the detection coil in the current sensor in a state where there is no butting failure at the end of the split core.

[0018] In addition, in the detection device according to the present invention, the current sensor may further include a feedback coil wound around the magnetic core, an amplifier circuit that amplifies and outputs an output voltage from the magnetic sensor, and a current conversion circuit that converts the amplified voltage output from the amplifier circuit into a current to generate a feedback current and passes the feedback current to the feedback coil, wherein the feedback current is passed through the feedback coil in a direction that generates a magnetic flux density that cancels out the magnetic flux density generated by the current to be measured, the signal supply circuit inputs a predetermined constant detection voltage to the amplifier circuit, and the determination circuit determines that there is a mismatch when the output current from the current sensor, which corresponds to the magnetic flux density in the magnetic core when the detection voltage is input to the amplifier circuit, is greater than a predetermined determination current, the magnetic flux density in the magnetic core includes the first magnetic flux density generated in the feedback coil as a result of the detection voltage being input to the amplifier circuit, and the output current may be a current obtained by converting, by the current conversion circuit, an output voltage corresponding to the magnetic flux density in the magnetic core detected by the magnetic sensor.

[0019] Furthermore, in the detection device according to the present invention, the signal supply circuit adds the detection voltage to a reference voltage of the amplifier circuit and inputs the result to the amplifier circuit, the amplifier circuit amplifies a voltage difference between the detection voltage and the reference voltage and an output voltage of the magnetic sensor to output an amplified voltage, and the current conversion circuit converts the amplified voltage into a current to generate a first feedback current, which generates the first magnetic flux density in the feedback coil in a direction that cancels out the magnetic flux density generated by the current to be measured, and the output current may be the first feedback current.

[0020] In addition, in the detection device of the present invention, the judgment current may be an output current obtained by converting the output voltage from the magnetic sensor into a current when the signal supply circuit inputs the detection voltage to the amplifier circuit in the current sensor in a state where there is no butting failure at the end of the split core.

[0021] In the detection device according to the present invention, the frequency of the detection voltage input from the signal supply circuit to the amplifier circuit may be different from the frequency of the current to be measured.

[0022] In the detection device according to the present invention, the magnetic sensor may include a Hall element.

[0023] In order to solve the above-mentioned problems, the detection method of the present invention is a detection method performed by a detection device comprising a signal supply circuit and a judgment circuit connected to a current sensor comprising a magnetic core in which the ends of split cores are butted together to form a loop-shaped magnetic path and are arranged to surround a conductor through which a measured current flows, and a magnetic sensor that detects the magnetic flux density generated by the measured current and outputs a corresponding electrical signal, the detection method comprising: a first step in which the signal supply circuit supplies a predetermined constant detection signal to the current sensor; and a second step in which the judgment circuit compares the value of the electrical signal output from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core when the detection signal is supplied, with a predetermined reference value for the electrical signal, to determine whether or not there is a butting failure at the ends of the split cores, and the magnetic flux density in the magnetic core includes a first magnetic flux density in the magnetic core generated as a result of the detection signal being supplied.

[0024] Furthermore, in the detection method according to the present invention, the current sensor may further include a detection coil wound around the magnetic core, and in the first step, the signal supply circuit may pass a predetermined constant detection current through the detection coil, and in the second step, the judgment circuit may determine that there is a mismatch if the output voltage from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core including the first magnetic flux density generated in the detection coil, is lower than a predetermined judgment voltage.

[0025] In addition, in the detection method according to the present invention, the current sensor may further include a feedback coil wound around the magnetic core, an amplifier circuit that amplifies and outputs an output voltage from the magnetic sensor, and a current conversion circuit that converts the amplified voltage output from the amplifier circuit into a current to generate a feedback current and passes the feedback current to the feedback coil, wherein the feedback current is passed through the feedback coil in a direction that generates a magnetic flux density that cancels out the magnetic flux density generated by the current to be measured, and in the first step, the signal supply circuit inputs a predetermined constant detection voltage to the amplifier circuit, and in the second step, the determination circuit determines that there is a mismatch if the output current from the current sensor, which corresponds to the magnetic flux density in the magnetic core when the detection voltage is input to the amplifier circuit, is greater than a predetermined determination current, the magnetic flux density in the magnetic core includes the first magnetic flux density generated in the feedback coil as a result of the detection voltage being input to the amplifier circuit, and the output current may be a current obtained by converting, by the current conversion circuit, an output voltage corresponding to the magnetic flux density in the magnetic core detected by the magnetic sensor. [Effects of the Invention]

[0026] According to the present invention, the value of the electrical signal output from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core and includes a first magnetic flux density generated by supplying a predetermined constant detection signal to the current sensor, is compared with a predetermined reference value for the electrical signal, thereby enabling detection of the open / closed state of the clamp of the clamp-type current sensor with higher reliability. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a detection device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a detection device according to this embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the configuration of the detection device according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart illustrating the operation of the detection device according to the first embodiment. [Figure 5] FIG. 5 is a block diagram showing the configuration of a detection device according to the second embodiment. [Figure 6] FIG. 6 is a block diagram showing the configuration of a signal supply circuit included in the detection device according to the second embodiment. [Figure 7] FIG. 7 is a schematic diagram of the circuit of the detection device according to the second embodiment. [Figure 8] FIG. 8 is a flowchart illustrating the operation of the detection device according to the second embodiment. [Figure 9] FIG. 9 is a schematic diagram showing the internal structure of a conventional clamp-type current sensor. [Figure 10] FIG. 10 is a schematic diagram showing the internal structure of a conventional magnetic balance type clamp-type current sensor. DETAILED DESCRIPTION OF THE INVENTION

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to FIGS. [Summary of the Invention] First, an overview of the detection device 1 according to the embodiment of the present invention will be described. The detection device 1 according to the embodiment of the present invention detects a state in which the clamp part of the clamp-type current sensor 2 is open due to, for example, forgetting to close the clamp part or having foreign matter such as fine dust caught in the clamp part.

[0029] Fig. 1 is a schematic diagram of the internal structure of a clamp-type current sensor 2 connected to a detection device 1 according to an embodiment of the present invention. Fig. 1(a) is a schematic diagram of a magnetic core 20 when the clamp of the current sensor 2 is closed. The current sensor 2 includes a loop-shaped magnetic core 20, a magnetic sensor 21 disposed in a gap G1 formed in the magnetic core 20, and a coil (detection coil) 22 wound around the magnetic core 20, and a detection current I2 is supplied to the coil 22 by a current source 10a.

[0030] In the magnetic core 20, the ends ac1 and bc2 of the multiple split cores 20a, 20b, and 20c are butted together so that they come into contact with each other, forming a loop-shaped magnetic path with a gap G1. In the magnetic core 20 shown in Fig. 1(a), the split surface formed at the end a of the split core 20a and the split surface formed at the end c1 of the split core 20c (hereinafter referred to as "end ac1") are butted together so that they come into contact with each other.

[0031] Similarly, the dividing surface formed at end b of split core 20b and the dividing surface formed at end c2 of split core 20c (hereinafter referred to as "end bc2") are butted together so as to be in contact with each other. Note that ends ac1 and bc2 may be collectively referred to as "ends ac1, bc2."

[0032] Furthermore, the state in which the ends ac1 and bc2 of the split cores 20a, 20b, and 20c are butted together so as to contact each other may be a correct butted state in which the current sensor 2 can measure the current value without measurement error. For example, as long as the magnetic core 20 can form a loop-shaped magnetic path and surround the conductor 300, the ends ac1 and bc2 do not need to be joined.

[0033] 1(b) is a schematic diagram of the magnetic core 20 when the clamping portion of the current sensor 2 is open. In the current sensor 2 shown in FIG. 1(b), if the opening and closing ends of the clamping portion are left unclosed or if foreign matter such as dust is caught in the clamping portion, the ends ac1 and bc2 of the split cores 20a, 20b, and 20c of the magnetic core 20 move away from each other, forming a new gap G2.

[0034] More specifically, in the magnetic core 20, the dividing surface formed at the end a of the split core 20a and the dividing surface formed at the end c1 of the split core 20c are separated from each other. Similarly, the dividing surface formed at the end b of the split core 20b and the dividing surface formed at the end c2 of the split core 20c are separated from each other.

[0035] 1(b) is in a state where the gap length (gap G1') is widened, and in this state, a measurement error occurs in the current value measured by the current sensor 2. In this specification, the state of the magnetic core 20 as shown in FIG. 1(b) is referred to as a state where a butting failure has occurred at the ends ac1 and bc2 of the split cores 20a, 20b, and 20c.

[0036] For simplicity of explanation, let us assume that the magnetic permeability of the magnetic material is sufficiently higher than that of air. For example, if the gap length of the magnetic core 20 is increased from a gap G1 of 1.0 mm to a total of 2.0 mm, the ease of transmission of the magnetic flux in the magnetic circuit will be halved. For example, when the current source 10a shown in FIG. 1(a) applies a detection current I2, which is an excitation current of 1 mA, to the coil 22, the output voltage V of the magnetic sensor 21 will be out 1(b), when the clamp of the current sensor 2 is open, if the same detection current I2 of 1 mA is passed from the current source 10a to the coil 22, the magnetic sensor 21 will output only half the voltage, 0.5 mV.

[0037] The detection device 1 according to the embodiment of the present invention focuses on the fact that when the gap length of the magnetic core 20 is wider than a predetermined gap length, the magnetic resistance of the magnetic circuit increases and the generated magnetic flux density decreases, and analyzes the output of the current sensor 2 when a predetermined constant detection signal is supplied to the magnetic circuit. This allows the detection device 1 to detect when the clamp part of the current sensor 2 has been left loose or when a foreign object is present in the clamp part.

[0038] Furthermore, the detection device 1 according to the embodiment of the present invention utilizes the above-described principle to detect the open / closed state of the clamp of the current sensor based on the measurement principles of the magnetic proportional system and the magnetic balance system.

[0039] Here, the measurement principle of the magnetic proportional current sensor 2 will be explained using an example of the internal structure of the current sensor 2 shown in Fig. 1(a). As shown in Fig. 1(a), in the magnetic proportional current sensor 2, a current I1 to be measured flows through a conductor 300, generating a magnetic field around the conductor 300 whose magnitude is proportional to the current I1 to be measured. A magnetic field is generated in a gap G1 of a magnetic core 20 that is disposed so as to surround the conductor 300, and a magnetic flux density B1 proportional to the current I1 to be measured is detected by a magnetic sensor 21.

[0040] In the detection device 1 according to the embodiment of the present invention, in order to detect the open / closed state of the clamp part of the clamp-type current sensor 2 based on the magnetic proportional system, a coil (detection coil) 22 is provided around the magnetic core 20, and a predetermined constant excitation current is passed through the coil 22 as a detection current I2, and an output voltage V from the magnetic sensor 21 is generated. out When the clamp of the current sensor 2 is closed and a detection current I2 of 1 mA is applied to the coil 22, the output voltage V from the magnetic sensor 21 is out The change in output voltage V is 1.0 mV. out Determine the voltage V out_r On the other hand, when the clamp portion of current sensor 2 is in the open state and a detection current I2 of 1 mA is passed through coil 22, the magnetic resistance increases and the generated magnetic flux density decreases, so the change in output of magnetic sensor 21 is 0.5 mV.

[0041] In this way, the detection device 1 according to the embodiment of the present invention detects the output voltage V of the current sensor 2 generated by passing a predetermined constant detection current I2 through the coil 22. out The voltage change and the judgment voltage V out_r By comparing the change in the current sensor 2 with the change in the current sensor 2, the open / closed state of the clamp of the magnetic proportional current sensor 2 is detected.

[0042] Next, an outline of the configuration of a detection device 1A according to an embodiment of the present invention for detecting the open / closed state of a clamp-type current sensor 2A based on a magnetic balance system will be described. FIG. 10 is a schematic diagram showing an example of the internal structure of a conventional magnetic balance-type current sensor 910. Similar to the magnetic proportional current sensor 2, the conventional clamp-type current sensor 910 based on a magnetic balance system includes, for example, a magnetic core 901 having a predetermined gap G1 and having split cores 20a, 20b, and 20c butted together so that their ends ac1 and bc2 contact each other to form a loop-shaped magnetic path, and a magnetic sensor 902 disposed within the gap G1. The current sensor 910 further includes a feedback coil 903 wound around the magnetic core 901, and is configured to perform feedback control to cancel the output of the magnetic sensor 902.

[0043] When the magnetic flux density B1 generated by the current to be measured I1 and the magnetic flux density B2 generated by the feedback current I2 cancel each other out and the magnetic flux density of the magnetic core 20 becomes 0, the feedback current I2 flowing through the feedback coil 903 with N2 turns becomes 1 / N2 of the current to be measured I1. The current sensor 910 detects this feedback current I2 to determine the current to be measured I1.

[0044] In an ideal magnetic balance type current sensor 910 with no internal offset voltage, the output of the magnetic sensor 902 when there is no magnetic flux density, that is, when the current sensor 910 is not measuring, is set to V0. The voltage V0 and the output voltage V of the magnetic sensor 902 are out is input to the amplifier circuit 904, the output voltage V out When the value of changes, the closed circuit of the current sensor 910 operates, and a feedback current I2 flows through the feedback coil 903. When the feedback current I2 flows through the feedback coil 903, a magnetic flux density B2 opposite to the magnetic flux density B1 generated by the conductor 800 of the primary current line is applied to the magnetic sensor 902, and the output voltage V of the magnetic sensor 902 out Then, the voltage V0 in the non-measurement state is balanced again, and the magnetic flux density B in the magnetic core 901 becomes zero.

[0045] Conductor 800, which is the primary current line, is represented by coil L1 with N1 turns, the magnetic flux density generated by the current to be measured I1 [A] is represented by B1 [T], and the output of magnetic sensor 902 due to magnetic flux density B1 is represented by output voltage V1 [V]. Furthermore, the feedback current of current sensor 910 is represented by I2, and feedback coil 903 is represented by coil L2 with N2 turns. Furthermore, the magnetic flux density generated by feedback current I2 [A] is represented by B2 [T], and the output of magnetic sensor 902 due to the generation of magnetic flux density B2 is represented by output voltage V2 [V].

[0046] Since coil L2 is oriented in such a way that the magnetic flux densities B1 cancel each other out, the output voltages of magnetic sensor 902 generated by the magnetic flux densities B1 and B2 are balanced by the balancing circuit as expressed by the following equation (1). V1-V2=0 (1) The magnetic flux densities B1 and B2 in the magnetic core 901 are expressed by the following equation (2). B1-B2=0 (2) The circuit is operated so that the feedback current I2 that satisfies the above equations (1) and (2) satisfies the following equation (3). N1I1-N2I2=0 (3) If the above equation (3) is compiled into an equation for the feedback current I2, the following equation (4) is obtained. I2=(N1 / N2)·I1···(4) The current sensor 910 measures the measurement target current I1 flowing through the conductor 800 by detecting the current I2 of the above equation (4) as the output current.

[0047] As shown in FIG. 2, the detection device 1A according to the embodiment of the present invention is configured such that a predetermined constant detection voltage V is added to a voltage V0 which is a reference voltage. s In the magnetic balance type current sensor 2A, a feedback coil 26 is wound around a loop-shaped magnetic core 20. The current sensor 2A receives an output voltage V from the magnetic sensor 21. out , the voltage V0 in the non-measurement state and the predetermined constant detection voltage V s The sum of these voltages V0+V sis input to the amplifier circuit 24, the output voltage V out When the voltage Vcc changes, the feedback current I2 flows through the feedback coil 26.

[0048] Current sensor 2A detects the voltage V s Since feedback control is performed so that the sum of the outputs of the magnetic sensor 21, including the detected voltage V, is zero, the value of the feedback current I2 also increases accordingly. s Consider the operation of the current sensor 2A when the voltage V is applied. s When this is added, the closed circuit of the current sensor 2A operates to satisfy the following equation (5). (V0+V s )-V out =0 (5)

[0049] The output of the magnetic sensor 21 is detected as a voltage V s To increase the current by one, the feedback coil 26 corresponding to the coil L2 must be supplied with a current I s flows, and the magnetic flux density B s When the output of the magnetic sensor 21 operating in the same manner as the above-described ideal current sensor 910 without offset is considered, the output voltage of the magnetic sensor 21 is balanced as shown in the following equation (6). V1-(V2+V s )=0 (6)

[0050] However, the magnetic flux density is detected by the voltage V s The magnetic flux density B s occurs, the following equation (7) is expressed, and does not become zero inside the magnetic core 20. B1-(B2+B s )≠0 (7)

[0051] Similarly, the feedback current I2 does not cancel out, and is therefore expressed by the following equation (8). N1I1-(N2I2+N2I s )≠0 (8) In the above equation (8), N1 is the number of turns [turns] of the coil L1, which is the primary current line (conductor 300), I1 is the measured current [A] flowing through the coil L1, N2 is the number of turns [turns] of the coil L2 (feedback coil 26), I2 is the current [A] flowing through the coil L2, and I s is the current [A] flowing through coil L2.

[0052] Here, the current I s is defined as the following equation (9) together with the current I2 flowing through the coil L2. I2=(N1 / N2) I1+I s ···(9)

[0053] Next, the entire magnetic core 20 is uniformly divided into two parts with a cross-sectional area S [m 2 ], then, according to the definition of the above equation (9), the magnetic permeability μ [H / m], magnetic flux φ [Wb], and magnetic resistance R m [H -1 ], magnetomotive force F [A], and magnetic path length L [m], the magnetic flux density B [T] is expressed by the following equation (10).

number

[0054] Sensitivity K [V / T] of the magnetic sensor 21 and the generated magnetic flux density B s From the detection voltage V s and current I s The relationship is expressed by the following equation (11).

number

[0055] The above equation (11) is expressed as the current I s Rewriting this as an equation, we obtain the following equation (12).

number

[0056] The magnetic permeability of the magnetic core 20 is μ core , magnetic path length is L core , the magnetic permeability of air is μair , magnetic path length is L air Then, it is expressed by the following equation (13).

number

[0057] From the above equation (13), the magnetic permeability μ of the magnetic core 20 core is the magnetic permeability of air μ air , is sufficiently higher than the following equation (14):

number

[0058] From the above equation (14), the magnetic path length is L air When the detection voltage V s The current I generated by applying s It can be seen that the magnetic path length of the air increases due to a foreign object entering the clamping part of the current sensor 2A. air Since the feedback current I2 changes, the feedback current when the clamp is closed normally (the judgment current I 2_r ) the open / closed state of the clamp portion of the current sensor 2A can be detected.

[0059] For example, the detection voltage V s When 1 mV is added as a result, in the normal state where the clamp of the current sensor 2A is closed, the feedback current I2 is increased by 1 mA, and the balance is reached. The feedback current I2 when the clamp is closed is calculated as the judgment current I 2_r However, when the clamp is open, that is, when the gap G1 is widened, the magnetic resistance increases, and a feedback current I2 of 2 mA, for example, double that when the clamp is closed, is required.

[0060] In this way, the detection device 1A according to the embodiment of the present invention detects a predetermined constant detection voltage V s The output voltage V from the magnetic sensor 21 outThe feedback current I2 generated by inputting the feedback current I2 to the amplifier circuit 24 is measured as the output current, and the change in the output current I2 and the determination current I 2_r By comparing the change in the magnetic balance current sensor 2A with the change in the magnetic balance current sensor 2A, the open / closed state of the clamp portion of the magnetic balance current sensor 2A is detected.

[0061] [First embodiment] Next, the detection device 1 according to the first embodiment of the present invention will be described in detail. FIG. 3 is a block diagram showing the configuration of the detection device 1 and the clamp-type current sensor 2 according to this embodiment.

[0062] [Current sensor configuration] First, the configuration of the magnetic proportional current sensor 2 that is the detection target of the detection device 1 will be described.

[0063] 3, the current sensor 2 includes a magnetic core 20, a magnetic sensor 21, a coil 22, a drive circuit 23 that drives the magnetic sensor 21, and an amplifier circuit 24 that amplifies the output voltage from the magnetic sensor 21. In the magnetic core 20, end a of the split core 20a is butted against end c1 of the split core 20c, and end b of the split core 20b is butted against end c2 of the split core 20c, so as to form a loop-shaped magnetic path with a predetermined gap G1. Hereinafter, in this embodiment, gap G1 is formed between the other opposing ends of the split cores 20a and 20b.

[0064] The magnetic core 20 is made of a magnetic material with high magnetic permeability, such as permalloy, ferrite, etc. The magnetic core 20 is arranged to surround a conductor 300 such as a current line through which the current I1 to be measured flows.

[0065] The magnetic sensor 21 is disposed in the gap G1, detects the magnetic flux density B1 generated by the current I1 to be measured, and outputs a corresponding electrical signal. For example, a Hall element or a fluxgate sensor can be used as the magnetic sensor 21. In this embodiment, a case where a Hall element is used as the magnetic sensor 21 will be described.

[0066] Coil 22 is wound around magnetic core 20, and a detection current I2 supplied from detection device 1 flows through coil 22. Coil 22 is arranged on magnetic core 20 so that magnetic flux density B2 is generated in the same direction as magnetic flux density B1 generated by current I1 to be measured. Furthermore, the number of turns N2 of coil 22 is set so that a predetermined constant magnetic flux density B2 is generated.

[0067] The driving circuit 23 is connected to the magnetic sensor 21 and drives the magnetic sensor 21 with a constant voltage or a constant current.

[0068] The amplifier circuit 24 amplifies the output voltage V output from the magnetic sensor 21. out The amplifier circuit 24 amplifies the signal and outputs an amplified voltage. A differential amplifier circuit using an operational amplifier can be used as the amplifier circuit 24. The output from the amplifier circuit 24 is input to a determination circuit 11 provided in the detection device 1, which will be described later, via an AD converter or the like (not shown).

[0069] [Detection device configuration] Next, as shown in FIG. 3, the detection device 1 includes a signal supply circuit 10, a determination circuit 11, a control device 12, a memory 13, a communication interface (I / F) 14, an input / output I / O 15, an operation device 16, and a presentation device 17.

[0070] The signal supply circuit 10 supplies a predetermined constant detection current I2 to the coil 22 of the current sensor 2. The signal supply circuit 10 can be configured as a constant current source. The signal supply circuit 10 can also supply a detection current I2 of a known magnitude to the coil 22, with the frequency of the detection current I2 set to a frequency different from the nominal frequency of the current to be measured I1. The value of the detection current I2 can be set depending on the size of the specific foreign object in the clamp portion of the current sensor 2 that the detection device 1 is detecting, etc.

[0071] The determination circuit 11 detects an output voltage V from the magnetic sensor 21, which corresponds to the magnetic flux density B in the magnetic core 20, including the magnetic flux density (first magnetic flux density) B2 generated in the coil 22 when the signal supply circuit 10 passes the detection current I2 through the coil 22.out is the preset judgment voltage V out_r If it is lower than , it is determined that there is a butting failure at the ends ac1, bc2 of the divided cores 20a, 20b, 20c.

[0072] More specifically, the determination circuit 11 calculates the output voltage V from the magnetic sensor 21, which corresponds to the magnetic flux density B=B1+B2, which is the sum of the magnetic flux density B2 generated in the coil 22 and the magnetic flux density B1 generated by the current I1 to be measured. out The change in the preset judgment voltage V out_r If the change is smaller than the change in the end ac1, bc2 of the divided cores 20a, 20b, 20c, it is determined that there is a mismatch.

[0073] The output from the amplifier circuit 24 is also input to the decision circuit 11. The decision circuit 11 determines whether the input output voltage V out and a judgment voltage V, which is the output voltage measured in advance when the ends ac1 and bc2 of the divided cores 20a, 20b, and 20c are correctly butted together. out_r When the ends ac1 and bc2 of the split cores 20a, 20b, and 20c are separated from each other, that is, when the clamps of the current sensor 2 are open, the magnetic flux passing through the magnetic core 20 is less likely to be transmitted than when the clamps are closed. Therefore, both the magnetic flux densities B1 and B2 within the magnetic core 20 decrease.

[0074] In this way, the determination circuit 11 can determine whether there is a misalignment at the ends ac1 and bc2 of the split cores 20a, 20b, and 20c by comparing the amount of decrease in the magnetic flux density B2 generated in the coil 22 due to a predetermined constant detection current I2. The determination result by the determination circuit 11 can be used to detect the open / closed state of the clamping portion of the current sensor 2 and the presence or absence of foreign matter in the clamping portion.

[0075] The control device 12 is configured by a microcomputer having a CPU and memory including RAM and ROM. The control device 12 executes programs stored in the memory using the CPU, thereby realizing various functions of the detection device 1. The control device 12 can also be used as a control device that realizes the measurement function of the current sensor 2. For example, the control device 12 can control a drive circuit 23 that drives the magnetic sensor 21 of the current sensor 2.

[0076] The memory 13 stores the determination voltage V out_r The memory 13 also stores information relating to the detection current I2 supplied by the signal supply circuit 10 to the coil 22. The memory 13 also stores information that is presented by a presentation device 17 (described later) based on the determination result by the determination circuit 11.

[0077] The communication interface (I / F) 14 is an interface circuit for connecting the detection device 1 to various external electronic devices via a network. The communication I / F 14 may be configured to send the determination result of the determination circuit 11 to an external terminal via a network NW (not shown).

[0078] The input / output I / O 15 is configured by an I / O terminal for inputting signals from an external device and outputting signals to an external device. An operation device 16 and a presentation device 17 are connected via the input / output I / O 15.

[0079] The operation device 16 is configured with a touch panel, a keyboard, physical buttons, etc., and receives input from an operator. The operation device 16 is used to set the value of the detection current I2 and the determination voltage V out_r The input of the setting value is accepted.

[0080] The presentation device 17 is configured with a liquid crystal display, a speaker, etc. The presentation device 17 presents the open / closed state of the clamp portion of the current sensor 2 based on the determination result output from the determination circuit 11. For example, if the determination circuit 11 determines that there is a butting failure at the ends ac1 and bc2 of the split cores 20a, 20b, and 20c, the presentation device 17 can issue an alarm indicating that the clamp portion of the current sensor 2 is open. The presentation device 17 can display the alarm text on a display screen or light up an LED warning light. Alternatively, the presentation device 17 can issue an acoustic alarm via a speaker.

[0081] The presentation device 17 may present status information indicating that the clamp portion of the current sensor 2 is in a closed state based not only on the determination result that there is a mismatch at the ends ac1 and bc2 of the split cores 20a, 20b, and 20c, but also on the determination result that there is no mismatch.

[0082] [Detection device operation] Next, the operation of the detection device 1 having the above-described configuration will be described using the flowchart in Fig. 4. First, when the conductor 300 carrying the current to be measured I1 is clamped by the clamping portion by opening and closing the clamping portion, and the current sensor 2 is installed, the detection device 1 executes the following process.

[0083] First, the signal supply circuit 10 supplies a predetermined constant detection current I2 to the coil 22 of the current sensor 2 (step S1). When the detection current I2 flows through the coil 22, a magnetic flux density B2 is generated, which is detected by the magnetic sensor 21 together with the magnetic flux density B1 generated by the current I1 to be measured, and a corresponding output voltage V out will be output.

[0084] Output voltage V from magnetic sensor 21 out is amplified by the amplifier circuit 24 and input to the determination circuit 11, which determines whether or not there is a mismatch at the ends ac1 and bc2 of the divided cores 20a, 20b, and 20c (step S4).

[0085] Specifically, the determination circuit 11 calculates the output voltage V from the magnetic sensor 21, which corresponds to the magnetic flux density B=B1+B2, which is the sum of the magnetic flux density B2 generated in the coil 22 when the signal supply circuit 10 passes the detection current I2 through the coil 22 and the magnetic flux density B1 generated by the current I1 to be measured. out is the preset judgment voltage V out_r If it is lower than (step S3: YES), it is determined that there is a butting failure at the ends ac1, bc2 of the divided cores 20a, 20b, 20c (step S4).

[0086] Thereafter, based on the determination result in step S4, the presentation device 17 issues an alarm indicating that the clamp portion of the current sensor 2 is open (step S5). For example, the presentation device 17 can display the alarm in text on a display screen or output the alarm as audio via a speaker.

[0087] On the other hand, in step S3, the output voltage V from the magnetic sensor 21 out and the preset judgment voltage V out_r If the output voltages V and V are the same (step S3: NO), the determination circuit 11 determines that there is no mismatch at the ends ac1 and bc2 of the divided cores 20a, 20b, and 20c (step S4). out and the change in the preset judgment voltage V out_r If the change in is the same value, it is determined that there is no mismatch.

[0088] Next, presentation device 17 presents the open / closed state of the clamp portion of current sensor 2 according to the determination result in step S4 (step S6). For example, if it is determined in step S4 that there is no misalignment, presentation device 17 can display text information or use an LED to indicate that the clamp portion of current sensor 2 is properly closed. Furthermore, if it is determined in step S4 that there is a misalignment, presentation device 17 can display the installation status of current sensor 2 separately from issuing an alarm in step S5.

[0089] As described above, according to the detection device 1 of the first embodiment, the output voltage V from the magnetic sensor 21 obtained by passing a predetermined constant detection current I2 through the coil 22 is out and the preset judgment voltage V out_r Since the open / closed state of the clamp portion of the magnetic proportional current sensor 2 is compared with the open / closed state of the clamp portion of the magnetic proportional current sensor 2, the open / closed state of the clamp portion of the magnetic proportional current sensor 2 can be detected with higher reliability.

[0090] Furthermore, the detection device 1 according to the first embodiment uses the detection current I2, which allows for frequency selection and amplitude adjustment, allowing for more flexible design.

[0091] Furthermore, the detection device 1 according to the first embodiment determines whether the magnetic core 20 is misaligned, which prevents the clamp of the current sensor 2 from accidentally opening, eliminating the need to guarantee the characteristics when the clamp is open. As a result, the degree of freedom in the magnetic circuit shape, housing structure, etc. is increased.

[0092] Furthermore, the detection device 1 according to the first embodiment can determine whether the magnetic core 20 is misaligned, thereby achieving the same measurement accuracy and noise resistance of the current sensor 2 as at the time of shipment.

[0093] Furthermore, according to the detection device 1 of the first embodiment, application to an existing product current sensor 2 can be achieved by simply installing a detection coil 22 and a current source and modifying the electronic circuit, so that the open / closed state of the clamp portion in a magnetic proportional current sensor 2 can be detected with a relatively simple configuration.

[0094] [Second embodiment] Next, a detection device 1A according to a second embodiment of the present invention will be described in detail. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.

[0095] The first embodiment has been described as detecting the open / closed state of a clamp in a magnetic proportional current sensor 2. In contrast, the second embodiment detects the open / closed state of a clamp in a magnetic balance current sensor 2A.

[0096] Fig. 5 is a block diagram showing the configurations of detection device 1A and clamp-type current sensor 2A according to this embodiment. As shown in Fig. 5, current sensor 2A differs in configuration from the magnetic proportional current sensor 2 described in the first embodiment in that it further includes feedback coil 26 wound around magnetic core 20 and current conversion circuit 25 that converts the output from amplifier circuit 24 into a current.

[0097] The detection device 1A differs in configuration from the detection device 1 according to the first embodiment in that it includes a signal supply circuit 10A that inputs a detection signal to an amplifier circuit 24, and a determination circuit 11A that receives as input a feedback current I2 flowing through a feedback coil 26. The following description will focus on the configuration that differs from the first embodiment.

[0098] [Current sensor configuration] Current sensor 2A includes magnetic core 20 in which split cores 20a, 20b, and 20c are butted together so that ends ac1 and bc2 thereof contact each other to form a loop-shaped magnetic path with gap G1, magnetic sensor 21 is disposed within gap G1 and detects magnetic flux density B1 generated by the current to be measured and outputs a corresponding electrical signal, and drive circuit 23 drives magnetic sensor 21. Note that magnetic core 20 of current sensor 2A may not have gap G1 as long as it can form a loop-shaped magnetic path.

[0099] Furthermore, the current sensor 2A according to this embodiment includes a feedback coil 26 wound around the magnetic core 20 and an output voltage V out and a current conversion circuit 25 that converts the amplified voltage output from the amplifier circuit 24 into a current to generate a feedback current I2 and passes the feedback current I2 through a feedback coil .

[0100] For example, a Hall element or a fluxgate sensor can be used as the magnetic sensor 21. In this embodiment, a case where a Hall element is used as the magnetic sensor 21 will be described.

[0101] Feedback coil 26 is a coil with N2 turns wound around magnetic core 20. Feedback coil 26 is arranged on magnetic core 20 so as to generate magnetic flux density B2 in the direction opposite to the direction of magnetic flux density B1 generated by current I1 to be measured. Feedback current I2 is passed through feedback coil 26 so as to cancel out magnetic flux density B1 generated by current I1 to be measured flowing through conductor 300.

[0102] One end of the feedback coil 26 is connected to the current conversion circuit 25, and the other end is connected to the determination circuit 11A of the detection device 1A via a shunt resistor and an AD converter (not shown).

[0103] The input terminal of the amplifier circuit 24 receives the output voltage V from the magnetic sensor 21. out and the detection voltage V generated by the signal supply circuit 10A. s is added to the reference voltage V0 of the amplifier circuit 24. s +V0 and +V1 are input, and the output voltage V out and voltage V s The voltage difference with +V0 is amplified. The output voltage of the amplifier circuit 24 is input to the current conversion circuit 25.

[0104] The current conversion circuit 25 converts the amplified voltage output from the amplifier circuit 24 into a current to generate a feedback current I2, which is passed through the feedback coil 26. The feedback current I2 is a current that is amplified by the detection voltage V s The magnetic flux density B generated by the input s The current I corresponding to s is superimposed.

[0105] [Detection device configuration] As shown in FIG. 5, the detection device 1A includes a signal supply circuit 10A, a determination circuit 11A, a control device 12, a memory 13, a communication I / F 14, an input / output I / O 15, an operation device 16, and a presentation device 17.

[0106] The signal supply circuit 10A supplies a predetermined constant detection voltage V s is added to a reference voltage V0 of the amplifier circuit 24 and input to the amplifier circuit 24. As shown in FIG. 6, the signal supply circuit 10A includes a signal source 100A and a combining circuit 101A.

[0107] The signal source 100A generates a detection voltage V having a predetermined amplitude and frequency. s The synthesis circuit 101A generates the detection voltage V s is added to the reference voltage V0 of the amplifier circuit 24, and the combined voltage V0+V s Output.

[0108] Detection voltage V s is determined taking into consideration the size of the foreign object in the clamp portion that the detection device 1A is to detect, the resolution of an AD converter (not shown), etc. For example, when the sensitivity K of the magnetic sensor 21 is 10 mV / 1 mT, the detected voltage V s If we set the value to 100mV, the constant magnetic flux density B s = 10 mT is generated in the magnetic core 20. When the magnetic core 20 is closed, the current I s is 1mA and the magnetic flux density B s = 10 mT, when the magnetic core 20 is open, the magnetic path length increases, so the current I s This ratio depends on the size of the foreign matter and the shape of the magnetic core 20.

[0109] In addition, the detection voltage V s The frequency of the detection voltage V is determined by using a frequency different from the nominal frequency of the current I1 to be measured. s This makes it easy to distinguish between the influence of the detection voltage V and the change in the value of the measured current I1. s The magnetic flux density B generated by sIf the change in magnetic permeability is small on the BH curve, the detection voltage V s The amplitude of the magnetic flux density B can be freely selected. s is limited to a range where the change in magnetic permeability is small, and such a magnetic flux density B s The detection signal V s By setting the above, it is possible to further improve the accuracy of detecting whether the clamp portion is open or closed in the current sensor 2A.

[0110] The reference voltage V0 is the output of the magnetic sensor 21 when there is no magnetic flux density in the magnetic core 20, that is, when the current sensor 2A is not measuring.

[0111] The detection voltage V generated by the 100A signal source s The synthesis circuit 101A that adds the detection voltage V to the reference voltage V0 can be realized by, for example, a configuration that uses a switch. s By using AC voltage for the control microcomputer, the port signal is input to a low-pass filter to generate a voltage V0+V s may be generated.

[0112] Returning to FIG. 5, the determination circuit 11A detects the detected voltage V s is input to the amplifier circuit 24, the output voltage V from the magnetic sensor 21 corresponding to the magnetic flux density B in the magnetic core 20. out The output current converted from is equal to the preset judgment current I 2_r If it is greater than , it is determined that there is a mismatch.

[0113] More specifically, the determination circuit 11A detects the detected voltage V s is added to the reference voltage V0, V0+V s is input to the amplifier circuit 24, the magnetic flux density (first magnetic flux density) B2+B s The magnetic flux density B1 generated by the measured current I1 is added to the magnetic flux density B=B s The output voltage V from the magnetic sensor 21 corresponds to outThe change in the output current I2 converted from the current is equal to the preset judgment current I 2_r If the change is larger than the change in , it is determined that there is a butting failure at the ends ac1, bc2 of the divided cores 20a, 20b, 20c of the magnetic core 20.

[0114] Magnetic flux density B2+B s is generated in the feedback coil 26 in a direction that cancels out the magnetic flux density B1. As shown in FIG. s The amplifier circuit 24 detects the detected voltage V s The voltage difference between the reference voltage V0 and the output voltage V0 of the magnetic sensor 21 is amplified, and the amplified voltage is converted into a current by the current conversion circuit 25 to generate a feedback current (first feedback current) I2. The feedback current I2 is generated by the detection voltage V s The magnetic flux density B generated by supplying s The current I corresponding to s is superimposed.

[0115] The determination current I is used by the determination circuit 11A as a reference value for the determination process. 2_r indicates a state in which there is no misalignment at the ends ac1 and bc2 of the divided cores 20a, 20b, and 20c, that is, a normal state in which the clamp portion of the current sensor 2A is closed, and the signal supply circuit 10A detects the voltage V s is added to the reference voltage V0 and input to the amplifier circuit 24, the output voltage V from the magnetic sensor 21 is out is the output current converted from

[0116] When the clamp of the current sensor 2A is open, the gap length widens, the magnetic resistance increases, and a larger feedback current I2 is required. The determination circuit 11A detects the detected voltage V s The current I generated by the addition of s By comparing the increase in the number of matching errors, it is possible to detect whether or not there is a matching error.

[0117] The memory 13 stores the determination current I2_r The memory 13 also stores the detected voltage V generated by the signal supply circuit 10A. s Store information about.

[0118] [Detection device operation] Next, the operation of the detection device 1A having the above-described configuration will be described using the flowchart in Fig. 8. When the clamping portion of the current sensor 2A is opened or closed, the conductor 300 through which the current to be measured I1 flows is clamped by the clamping portion, and the current sensor 2A is installed, the detection device 1A executes the following process.

[0119] First, the signal supply circuit 10A detects a predetermined constant voltage V s Specifically, the signal source 100A generates a detection voltage V having a predetermined amplitude and frequency. s Next, the signal supply circuit 10A adds the detection voltage Vs to the reference voltage V0 of the amplifier circuit 24 to generate a voltage V0+V s Specifically, the synthesis circuit 101A synthesizes the detection voltage V generated by the signal source 100A (step S11). s is added to the reference voltage V0.

[0120] Next, the signal supply circuit 10A outputs the synthesized voltage V0+V s is input to the amplifier circuit 24 (step S12). In step S12, a voltage V0+V s is input to the other input terminal, and the output voltage V from the magnetic sensor 21 is out is entered.

[0121] Thereafter, the current sensor 2A performs feedback control as shown in Fig. 7. Specifically, the amplifier circuit 24 outputs a voltage V0+V s and the output voltage V out The feedback coil 26 amplifies the voltage difference between the two and outputs the amplified voltage. Furthermore, the current conversion circuit 25 converts the amplified voltage into a current to generate a feedback current I2. Thereafter, the current conversion circuit 25 causes the feedback current I2 to flow through the feedback coil 26.

[0122] Next, the determination circuit 11A acquires the feedback current I2, which is the output current from the current sensor 2A (step S13). Subsequently, the determination circuit 11A determines whether or not there is a mismatch at the ends ac1 and bc2 of the divided cores 20a, 20b, and 20c. Specifically, the determination circuit 11A determines whether or not the change in the feedback current I2 is greater than or equal to a preset determination current I 2_r If the change is larger than the change in (step S14: YES), it is determined that there is a butting failure at the ends ac1, bc2 of the divided cores 20a, 20b, 20c of the magnetic core 20 (step S15).

[0123] Thereafter, based on the determination result in step S15, the presentation device 17 issues an alarm indicating that the clamp portion of the current sensor 2 is open (step S16). For example, the presentation device 17 can display the alarm as text information on a display screen or output an audio alarm via a speaker.

[0124] On the other hand, in step S14, the determination circuit 11A determines whether the output voltage V out and the detection signal V s is added to the reference voltage V0, V0+V s The change in the feedback current I2 obtained by inputting this to the amplifier circuit 24 is a predetermined determination current I 2_r If the change is the same as the change in the end ac1, bc2 of the divided cores 20a, 20b, 20c (step S15), it is determined that there is no butting failure at the ends ac1, bc2 of the divided cores 20a, 20b, 20c.

[0125] Next, presentation device 17 presents the open / closed state of the clamp portion of current sensor 2A according to the determination result in step S15 (step S17). For example, if it is determined in step S15 that there is no misalignment, presentation device 17 can present the installation status by displaying text information indicating that the clamp portion of current sensor 2A is properly closed, illuminating an LED, or the like. Furthermore, if it is determined in step S15 that there is a misalignment, presentation device 17 can display the installation status of current sensor 2A separately from issuing an alarm in step S16.

[0126] As described above, according to the detection device 1A of the second embodiment, a predetermined constant detection voltage V s is added to the reference voltage V0 and input to the amplifier circuit 24, the output current of the current sensor 2A is obtained by the feedback current I2, and the judgment current I 2_r Therefore, it is possible to detect the open / closed state of the clamp portion of the magnetic balance type clamp-type current sensor 2A with higher reliability.

[0127] Furthermore, according to the detection device 1A of the second embodiment, the constant detection voltage V s allows for free selection of frequency and adjustment of amplitude, enabling flexible design.

[0128] Furthermore, according to the detection device 1A of the second embodiment, the detection voltage V s The magnetic flux density B generated by s Since the change in magnetic permeability on the BH curve can be limited to a range where the change is small regardless of the magnitude of the measured current, it is possible to further improve the detection accuracy of open / close detection.

[0129] Furthermore, according to the detection device 1A of the second embodiment, application to an existing product current sensor 2 can be achieved by simply modifying the electronic circuit, so that the open / closed state of the clamp portion in the magnetic balance type current sensor 2A can be detected with a simple configuration.

[0130] In the first and second embodiments described above, the open / closed state of the clamping portion of the current sensor 2, 2A is detected when the current sensor 2, 2A is installed based on the determination of a butting failure of the magnetic core 20. However, the detection device 1, 1A can detect the open / closed state of the clamping portion of the current sensor 2, 2A not only when the current sensor 2, 2A is installed, but also when the current sensor 2, 2A is in operation. In this case, the detection signal may have a variable amplitude, and the amplitude may be sufficiently small relative to the measured current I1. Furthermore, the detection device 1, 1A can also be used to detect defects in the current sensor 2, 2A during shipping adjustment.

[0131] The above describes embodiments of the detection device and detection method of the present invention, but the present invention is not limited to the described embodiments, and various modifications that a person skilled in the art can make within the scope of the invention described in the claims are possible. [Explanation of symbols]

[0132] 1, 1A...detection device, 2, 2A...current sensor, 10, 10A...signal supply circuit, 11, 11A...determination circuit, 12...control device, 13...memory, 14...communication I / F, 15...input / output I / O, 16...operation device, 17...presentation device, 20...magnetic core, 20a, 20b, 20c...split core, 21...magnetic sensor, 22...coil, 23...drive circuit, 24...amplification circuit, 300...conductor.

Claims

1. a magnetic core in which the ends of the split cores are butted together to form a loop-shaped magnetic path, and the magnetic core is arranged to surround the conductor through which the current to be measured flows; a magnetic sensor that detects the magnetic flux density generated by the current to be measured and outputs a corresponding electric signal; A detection device connected to a current sensor comprising: a signal supply circuit for supplying a predetermined constant detection signal to the current sensor; a determination circuit that determines whether or not there is a mismatch at the end of the divided core by comparing a value of an electric signal output from the magnetic sensor, the value corresponding to the magnetic flux density in the magnetic core when the detection signal is supplied, with a preset reference value for the electric signal; Equipped with the magnetic flux density in the magnetic core includes a first magnetic flux density in the magnetic core generated as a result of the detection signal being supplied; The current sensor a feedback coil wound around the magnetic core; an amplifier circuit that amplifies and outputs an output voltage from the magnetic sensor; a current conversion circuit that converts the amplified voltage output from the amplifier circuit into a current to generate a feedback current and passes the feedback current through the feedback coil; Furthermore, The feedback current is passed through the feedback coil in a direction that generates a magnetic flux density that cancels out the magnetic flux density generated by the current to be measured, the signal supply circuit inputs a predetermined constant detection voltage to the amplifier circuit; the determination circuit determines that the mismatch exists when an output current from the current sensor, which corresponds to a magnetic flux density in the magnetic core when the detected voltage is input to the amplifier circuit, is greater than a preset determination current; the magnetic flux density in the magnetic core includes the first magnetic flux density generated in the feedback coil when the detection voltage is input to the amplifier circuit, The output current is a current obtained by converting an output voltage corresponding to the magnetic flux density in the magnetic core detected by the magnetic sensor, using the current conversion circuit. A detection device characterized by:

2. 2. The detection device according to claim 1, the signal supply circuit adds the detection voltage to a reference voltage of the amplifier circuit and inputs the added voltage to the amplifier circuit; the amplifier circuit amplifies a voltage difference between the detection voltage and the reference voltage and an output voltage of the magnetic sensor to output an amplified voltage, and the current converter circuit converts the amplified voltage into a current to generate a first feedback current, thereby generating the first magnetic flux density in the feedback coil in a direction that cancels out the magnetic flux density generated by the current to be measured; The output current is the first feedback current. A detection device characterized by:

3. 3. The detection device according to claim 1, The determination current is an output current obtained by converting an output voltage from the magnetic sensor into a current when the signal supply circuit inputs the detection voltage to the amplifier circuit in the current sensor in a state where there is no butting failure at the end of the split core. A detection device characterized by:

4. 4. The detection device according to claim 1, The frequency of the detection voltage input from the signal supply circuit to the amplifier circuit is different from the frequency of the current to be measured. A detection device characterized by:

5. 5. The detection device according to claim 1, The magnetic sensor includes a Hall element. A detection device characterized by:

6. a magnetic core in which the ends of the split cores are butted together to form a loop-shaped magnetic path, and the magnetic core is arranged to surround the conductor through which the current to be measured flows; a magnetic sensor that detects the magnetic flux density generated by the current to be measured and outputs a corresponding electric signal; 1. A detection method performed by a detection device comprising a signal supply circuit and a determination circuit connected to a current sensor comprising: a first step in which the signal supply circuit supplies a predetermined constant detection signal to the current sensor; a second step in which the determination circuit compares a value of the electric signal output from the magnetic sensor, which corresponds to the magnetic flux density in the magnetic core when the detection signal is supplied, with a preset reference value for the electric signal, to determine whether or not there is a mismatch at the end of the divided core; Equipped with the magnetic flux density in the magnetic core includes a first magnetic flux density in the magnetic core generated as a result of the detection signal being supplied; The current sensor a feedback coil wound around the magnetic core; an amplifier circuit that amplifies and outputs an output voltage from the magnetic sensor; a current conversion circuit that converts the amplified voltage output from the amplifier circuit into a current to generate a feedback current and passes the feedback current through the feedback coil; Furthermore, The feedback current is passed through the feedback coil in a direction that generates a magnetic flux density that cancels out the magnetic flux density generated by the current to be measured, The first step includes the step of: inputting a predetermined constant detection voltage to the amplifier circuit from the signal supply circuit; In the second step, the determination circuit determines that the mismatch exists when an output current from the current sensor, which corresponds to a magnetic flux density in the magnetic core when the detected voltage is input to the amplifier circuit, is greater than a predetermined determination current; the magnetic flux density in the magnetic core includes the first magnetic flux density generated in the feedback coil when the detection voltage is input to the amplifier circuit, The output current is a current obtained by converting an output voltage corresponding to the magnetic flux density in the magnetic core detected by the magnetic sensor, using the current conversion circuit. A detection method characterized by:

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