JP2010175276A - Magnetic proportion system current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic proportion system current sensor capable of fulfilling the function of outputting a malfunction detection signal on the occasion of a fault, even if two or more magnetic detection elements are not provided for one current to be measured, and capable of reducing cost as compared with the case where two or more magnetic detection elements are provided. <P>SOLUTION: A ringlike magnetic core 15 having a gap G is arranged in such a way as to surround a bus-bar 12, a Hall element 25 is located in the gap G, and a coil 35 is arranged so that the gap G may be present inside. The ringlike magnetic core 15 and the coil 35 constitute a current transformer. A malfunction detection circuit 50 outputs a malfunction detection signal E(det) whose level differs, depending on whether or not the difference between a current detection result (sensor output V<SB>O</SB>) based on the principle of a magnetic proportion system by the use of the Hall element 25, and a current detection result (current transformer output V<SB>CU</SB>) by the current transformer constituted of the ringlike magnetic core 15 and the coil 35, is within a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a current sensor for measuring, for example, a battery current and a motor driving current of a hybrid car or an electric vehicle, and more particularly to a magnetic proportional current sensor having a function of outputting an abnormality detection signal.

2. Description of the Related Art Conventionally, a magnetic proportional sensor is known as a current sensor that detects a current (current to be measured) flowing through a bus bar in a non-contact state using a magnetic detection element such as a Hall element. As illustrated in FIG. 9, the magnetic proportional current sensor includes a ring-shaped magnetic core 820 having a gap G (such as a silicon steel plate or a permalloy core with high permeability and low residual magnetism), and a hole disposed in the gap G. And an element 816 (an example of a magnetic detection element). The magnetic core 820 is arranged so that the bus bar 810 through which the measured current I _in flows. Therefore, a magnetic field is generated in the gap G by the current I _{in to} be measured, and this is applied to the magnetosensitive surface of the Hall element 816. Since the intensity of the magnetic field is proportional to the measured current I _in, the measured current I _in is determined from the output voltage of the Hall element 816.

  By the way, when a failure occurs in a current sensor used in a hybrid car or an EV (electric vehicle), for example, in the case of an “inverter current monitoring current sensor”, motor control becomes unstable or an IGBT (Insulated Gate) which is a switching element. Bipolar Transistor) can be destroyed in the worst case. From such a problem, it can be said that it is important to appropriately detect a failure of the current sensor. Hereinafter, known literature relating to current sensor failure detection will be described.

  The following Patent Document 1 discloses a current detector that improves the fail-safety of the system by outputting an “abnormal signal” at the time of failure and enabling failure determination from a host system. This current detector has two or more magnetosensitive elements arranged in the gap of the magnetic core, and has an independent signal processing circuit for each magnetosensitive element, and the deviation of the output from these signal processing circuits is set It is configured to determine that the current detector has failed when the range is exceeded.

  The following Patent Document 2 has an object to provide an inverter device that can drive while maintaining driving comfort as much as possible even if a sensor failure occurs during vehicle travel. The current detection unit used in the inverter device is, for example, Two current sensors (241A, 241B, 242A, 242B) are included in each of the V phase and the W phase in order to detect each current of the V phase and the W phase twice. Then, the outputs of the current sensors 241A and 241B are compared with each other, and the outputs of the current sensors 242A and 242B are also compared to monitor whether a failure has occurred in the sensors.

  Although the following Patent Document 3 is not related to failure detection, the manufacturing process can be simplified and the cost can be reduced by dividing the circular core into a U-shaped core and a rod-shaped core.

JP 2000-275279 A JP 2007-185043 A Japanese Utility Model Publication No. 5-64779

  Both of the techniques of Patent Documents 1 and 2 have a problem in that it is necessary to provide two or more magnetic detection elements such as Hall elements for one current to be measured, which tends to increase costs. The technique disclosed in Patent Document 3 cannot solve such a problem.

  The present invention has been made in recognition of such a situation, and the object thereof is to realize a function of outputting an abnormality detection signal at the time of failure without providing two or more magnetic detection elements for one current to be measured. An object of the present invention is to provide a magnetic proportional current sensor capable of reducing the cost as compared with the case where two or more magnetic detection elements are provided for one current to be measured.

One embodiment of the present invention is a magnetic proportional current sensor. This magnetic proportional current sensor
A first current detection unit having a magnetic detection element to which a magnetic field generated by a current to be measured is applied;
A second current detector having a coil that generates an induced voltage in crossing with a magnetic field generated by the current to be measured;
Whether the first output voltage of the first current detection unit and the second output voltage of the second current detection unit are input, and the difference between the first and second output voltages is within a predetermined value. And an abnormality detection circuit that outputs abnormality detection signals of different levels.

In an aspect of the magnetic proportional current sensor,
A ring-shaped magnetic core having a gap portion surrounding the path of the current to be measured;
The magnetic detection element may be positioned in the gap portion of the ring-shaped magnetic core.

  In this case, the coil may be arranged such that at least a part of the ring-shaped magnetic core passes through the inside, or the gap portion of the ring-shaped magnetic core exists inside.

  The printed circuit board may further include a printed board inserted into the gap portion of the ring-shaped magnetic core, and the magnetic detection element may be mounted on a portion of the printed board passing through the gap portion.

  Further, it is preferable that at least a part of the printed board has an opening passing through the gap portion, and the magnetic detection element is mounted by being dropped into the opening.

  Furthermore, the coil may be mounted on the printed circuit board so that the gap portion of the ring-shaped magnetic core exists inside, and a plate-like or rod-like core may be provided inside the coil.

  Alternatively, the coil is obtained by winding a bobbin, and is arranged so that the gap portion of the ring-shaped magnetic core exists inside. The magnetic detection element is integrally formed on the bobbin, It is preferable that a winding terminal and a terminal of the magnetic detection element are electrically connected to a pin of the bobbin, and the pin is inserted into a through hole of the printed board.

  The magnetic proportional current sensor according to an aspect may further include a frequency characteristic compensation unit that compensates a frequency characteristic in a low frequency region of the induced voltage generated by the coil.

  In this case, the frequency characteristic compensation means is an amplifier that amplifies the induced voltage and outputs the amplified voltage to the abnormality detection circuit, and this amplifier may have a characteristic that the gain increases as the frequency decreases in the low frequency region.

  Alternatively, the frequency characteristic compensation means has a memory storing a frequency characteristic of the second output voltage in the low frequency region, and refers to the memory with the predetermined value of the abnormality detection circuit in the low frequency region. It is good to adjust.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the magnetic proportional current sensor of the present invention, the first output voltage of the first current detector having the magnetic detection element to which the magnetic field generated by the measured current is applied, and the magnetic field generated by the measured current. And an abnormality detection circuit that outputs an abnormality detection signal of a different level depending on whether or not the difference from the second output voltage of the second current detection unit having a coil that generates an induced voltage crossing with the second output voltage is within a predetermined value. Therefore, the normal state and the abnormal state can be distinguished and output according to the level of the abnormality detection signal. Therefore, it is possible to realize a function of outputting an abnormality detection signal at the time of failure without providing two or more magnetic detection elements for one current to be measured. Here, since the coil is generally cheaper than the magnetic detection element, the cost can be reduced as compared with the case where two or more magnetic detection elements are provided for one current to be measured.

The schematic diagram which shows the principle structure of the magnetic proportional type current sensor which concerns on the 1st Embodiment of this invention. FIG. 2 is a circuit diagram of the magnetic proportional current sensor shown in FIG. 1. (A) is a characteristic diagram showing the relationship between the measured current (instantaneous value) and the sensor output. (B) is an exemplary waveform diagram of the current to be measured. (C) is a characteristic diagram showing the relationship between the measured current (instantaneous value) and the current transformer output. (D) is an exemplary waveform diagram of the sensor output. (E) is an example waveform diagram of a current transformer output. (A) is a principal part expanded sectional view of the magnetic proportional type current sensor which concerns on the 2nd Embodiment of this invention. (B) is a BB 'arrow view of the same figure (A). (A) is a principal part expanded sectional view of the magnetic proportional type current sensor which concerns on the 3rd Embodiment of this invention. (B) is BB 'sectional drawing of the same figure (A). The relationship between the frequency of the current to be measured and the error in the differential amplifier circuit output voltage (sensor output: current detection output by the Hall element) and amplifier output voltage (current transformer output: current detection output by the coil) in FIG. The frequency characteristic figure shown. The block diagram which illustrates a frequency characteristic compensation means regarding the 4th Embodiment of this invention. FIG. 5A is a front sectional view, FIG. 5B is a plan view, and FIG. The schematic perspective view which shows the basic composition of a magnetic proportional type current sensor.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

(First embodiment)
FIG. 1 is a schematic diagram showing the basic configuration of a magnetic proportional current sensor 100 according to the first embodiment of the present invention.

The magnetic proportional current sensor 100 includes a bus bar 12 as a path of a current to be measured I _in (alternating current), a ring-shaped magnetic core 15 forming a ring-shaped magnetic path, a hall element 25 as a magnetic detection element, and an amplifier circuit. Differential amplifier circuit 27, coil 35, amplifier 37, and abnormality detection circuit 50. The Hall element 25 and the differential amplifier circuit 27 form a first current detection unit, and the coil 35 and the amplifier 37 form a second current detection unit.

  For example, a rectangular ring-shaped magnetic core 15 having a gap portion G (made of a silicon steel plate, a permalloy core, amorphous, or the like having high permeability and low residual magnetism) is disposed so as to surround the bus bar 12, and the Hall element 25 is disposed in the gap portion G. Is located (arranged), and the coil 35 is arranged so that the gap portion G exists inside. The ring-shaped magnetic core 15 and the coil 35 form a current transformer. The coil 35 may be an air core, or may have a plate-like or rod-like core provided inside. When the coil 35 has an air core, at least a part of the ring-shaped magnetic core 15 may penetrate the inside of the coil 35.

The output voltage of the Hall element 25 is amplified by the differential amplifier circuit 27 to become a sensor output V _O (first output voltage) and output to the abnormality detection circuit 50. The coil 35 intersects with the magnetic field generated by the current to be measured (alternating current) to generate an induced voltage V _L at both ends of the load resistance R _L , and this induced voltage V _L is amplified by an amplifier 37 as necessary to detect an abnormality. 50 (second output voltage). The abnormality detection circuit 50 includes a sensor output V _O (first output voltage) input from the differential amplifier circuit 27 and an induced voltage (second output voltage: current transformer output V _CU ) input from the amplifier 37. And an abnormality detection signal E (det) having a different level (high or low) depending on whether or not the difference between the two is within a predetermined value. The abnormality detection circuit 50 is configured in, for example, an ECU (Electric Control Unit).

That is, the magnetic proportional current sensor 100 according to the present embodiment includes a current detection result (sensor output V _O ) based on the principle of the magnetic proportional expression using the Hall element 25, the current formed by the ring-shaped magnetic core 15 and the coil 35. Compares the current detection result by the transformer (current transformer output V _CU ) and outputs an abnormality detection signal E (det) at a different level depending on whether or not the difference between both current detection results is within a predetermined value. is there. The abnormality detection signal E (det) is, for example, a high level when the difference between the two is within a predetermined value, and a low level when the difference between the two is not within the predetermined value. Then, the host system may determine that an abnormality has occurred when the abnormality detection signal E (det) becomes a low level. Hereinafter, the circuit configuration of the present embodiment will be described in more detail with reference to FIG.

FIG. 2 is a circuit diagram of the magnetic proportional current sensor 100 shown in FIG. In the circuit shown in this figure, the Hall element 25 is equivalently represented by a bridge connection of four resistors, and is output by passing a constant Hall element drive current between the terminals b and d by a constant current circuit 29, for example. A voltage V _H proportional to the applied magnetic field (in other words, proportional to the measured current I _in ) is obtained between the terminals c and e. The output terminals c and e of the Hall element 25 are respectively connected to the input terminals of the differential amplifier circuit 27, and the output terminals of the differential amplifier circuit 27 are connected to the input terminals of the abnormality detection circuit 50. One terminal f of the coil 35 is connected to a reference voltage terminal (voltage V _ref ), the other terminal a is connected to the input terminal of the amplifier 37, and a load resistor R _L is connected between the terminals a and f of the coil 35. The The output terminal of the amplifier 37 is connected to the input terminal of the abnormality detection circuit 50. In this embodiment, the power supply voltage is illustratively V _CC = 5V, and the reference voltage of the differential amplifier circuit 27 and the coil 35 is V _ref = 2.5V.

FIG. 3A is a characteristic diagram showing the relationship between the measured current I _in (instantaneous value) and the sensor output V _O. The sensor output V _O has a linear characteristic of 0.5 V to 4.5 V in the range of −300 A to +300 A of the measured current I _in .

FIG (B) is an exemplary waveform diagram of the current to be measured I _in. In this figure, the cases where the measured current I _in (peak to peak) is a sine wave of 600 A (case 1), 300 A (case 2), and 0 A (case 3) are illustrated.

FIG. 6C is a characteristic diagram showing the relationship between the measured current I _in (instantaneous value) and the current transformer output V _CU . Similar to the sensor output V _O , the current transformer output V _CU has a linear characteristic of 0.5 V to 4.5 V in the range of −300 A to +300 A of the measured current I _in .

FIG. 4D is an exemplary waveform diagram of the sensor output V _O. FIG. 5E is an exemplary waveform diagram of the current transformer output _VCU . Cases 1 to 3 shown in these drawings correspond to cases 1 to 3 in FIG. That is, when the measured current I _in (peak to peak) is 600 A, 300 A, and 0 A, the sensor output V _O (peak to peak) and the rent transformer output V _CU (peak to peak) are 4 V, 2 V, and 0 V, respectively. .

In the circuit shown in FIG. 2, the output voltage V _H (voltage between the output terminals c and e) of the Hall element 25 is amplified by the differential amplifier circuit 27. The differential amplifier circuit 27 is configured by resistors R ₁ to R ₄ and an operational amplifier 128, for example. The output voltage (sensor output V _O ) of the differential amplifier circuit 27 is output from the sensor output terminal 110 and is one input of the abnormality detection circuit 50. An induced voltage V _L (voltage between terminals a and f) generated by the coil 35 crossing the magnetic field generated by the current I _in (AC) to be measured is amplified by the amplifier 37. The output voltage of the amplifier 37 (current transformer output V _CU ) is the other input of the abnormality detection circuit 50. That is, one input of the abnormality detection circuit 50 is a current detection output (sensor output V _O ) by the Hall element 25, and the other input is a current detection output (current transformer) formed by a current transformer formed by the ring-shaped magnetic core 15 and the coil 35. Output V _CU ).

The abnormality detection circuit 50 constituted by an amplifier, a comparator, etc. compares two input current detection outputs (sensor output V _O and current transformer output V _CU ), for example, the difference between both voltages is within a predetermined value. If it is, the abnormality detection signal E (det) at the high level is output to the host system. When the inputted abnormality detection signal E (det) is at a low level, the host system may urge the operator (driver, etc.) to go to the repair shop by turning on a warning lamp or displaying the display, for example. . Note that the cause of the abnormal state (the abnormality detection signal E (det) is at a low level, for example) includes destruction of the Hall element 25 and short-circuiting or disconnection of the coil 35.

According to the present embodiment, the output voltage (first output voltage: first output voltage) of the differential amplifier circuit 27 that amplifies the output voltage V _H of the Hall element 25 to which the magnetic field generated by the measured current I _in (AC) is applied. The output voltage of the amplifier 37 (second output voltage: current transformer output V _CU) that amplifies the induced voltage V _L generated by the coil 35 that intersects the magnetic field generated by the sensor output V _O ) and the measured current I _in (AC). ) Has an abnormality detection circuit 50 that outputs an abnormality detection signal E (det) at a different level depending on whether or not the difference is within a predetermined value. Different levels can be output according to the level (high or low). Accordingly, it is possible to realize a function of outputting an abnormality detection signal at the time of failure without providing two or more Hall elements for one current to be measured. Here, since the coil is generally cheaper than the Hall element, the cost can be reduced as compared with the case where two or more Hall elements are provided.

(Second embodiment)
In the present embodiment, a specific example (part 1) of the mounting structure of the hall element 25 and the coil 35 in the magnetic proportional current sensor 100 of the first embodiment shown in FIG. 1 will be described.

  FIG. 4A is an enlarged cross-sectional view of a main part of a magnetic proportional current sensor 200 according to the second embodiment of the present invention. FIG. 5B is a BB ′ arrow view of FIG. In FIG. 5B, the bobbin 131 and the plate-like core 135 are indicated by imaginary lines.

  In addition to the configuration of the magnetic proportional current sensor 100 of the first embodiment, the magnetic proportional current sensor 200 of the present embodiment is held in a case (not shown), for example, in the gap portion G of the ring-shaped magnetic core 15. A printed circuit board 17 is further provided. Then, the hall element 25 (surface mount type) is mounted on the surface of the printed circuit board 17 through the gap portion G by, for example, a mounter, and the coil 35 is formed by applying a winding 139 to the bobbin 131 (resin molded body), for example. Is mounted on the printed circuit board 17 by, for example, a mounter so that the gap portion G exists inside. A plate-shaped (or rod-shaped) core 135 is provided inside the coil 35. It is preferable that the printed circuit board 17 has at least a part of the portion passing through the gap portion G to be the opening 19, and the Hall element 25 is dropped into the opening 19 and mounted on the surface.

  According to the present embodiment, in addition to the effects of the first embodiment, since the hall element 25 and the coil 35 are mounted on the same printed circuit board 17, the hall element 25 and the coil 35 for the ring-shaped magnetic core 15 are mounted. Is easy to arrange. Further, when the opening 19 is provided in the printed circuit board 17 and the Hall element 25 is dropped into the opening 19 for surface mounting, the amount of the Hall element 25 protruding on the printed circuit board 17 can be reduced, and the Hall element 25 and the coil 35 can be reduced. Can be inserted and disposed in the gap G having a shorter length. For this reason, sensitivity and noise tolerance are improved by shortening the length of the gap part G, and highly accurate current detection becomes possible.

(Third embodiment)
In the present embodiment, a specific example (part 2) of the mounting structure of the hall element 25 and the coil 35 in the magnetic proportional current sensor 100 of the first embodiment shown in FIG. 1 will be described.

  FIG. 5A is an enlarged cross-sectional view of a main part of a magnetic proportional current sensor 300 according to the third embodiment of the present invention. FIG. 4B is a cross-sectional view taken along the line BB ′ of FIG. In FIG. 5B, the bobbin 131 is indicated by a virtual line.

  In addition to the configuration of the magnetic proportional current sensor 100 of the first embodiment, the magnetic proportional current sensor 300 of the present embodiment is, for example, held in a case (not shown) of the gap portion G of the ring-shaped magnetic core 15. A printed circuit board 17 is further provided at a predetermined position outside. The coil 35 is formed by winding the bobbin 131 with a winding 139, and the hall element 25 (for example, in a bare chip state) is integrally molded with the bobbin 131 and positioned inside the coil 35.

  Both ends of the winding 139 of the coil 35 are electrically connected to pins a and f (corresponding to the terminals a and f in FIG. 2) of the bobbin 131, respectively, and the four terminals of the hall element 25 are the pins b to b of the bobbin 131. e (corresponding to terminals b to e in FIG. 2) is electrically connected. The electrical connection is made by, for example, winding and soldering. The pins a to f of the bobbin 131 are inserted through the through holes of the printed circuit board 17, and the gap portion G of the ring-shaped magnetic core 15 exists inside the coil 35 in this state. The hall element 25 is located in the gap part G.

  In the present embodiment, the Hall element 25 is formed integrally with the bobbin 131 of the coil 35, and the pins a to f are inserted into the bobbin 131, simplifying them as one component, and providing the winding 139. Therefore, in addition to the effects of the first embodiment, workability when mounting the coil 35 and the Hall element 25 on the printed circuit board 17 is improved. Further, since the Hall element 25 is within the length range of the coil 35 in the winding axis direction, the Hall element 25 and the coil 35 can be inserted and disposed in the gap portion G having a shorter length. For this reason, sensitivity and noise tolerance are improved by shortening the length of the gap part G, and highly accurate current detection becomes possible.

(Fourth embodiment)
In the present embodiment, frequency characteristic compensation means for compensating the frequency characteristic in the low frequency region of the induced voltage V _L generated by the coil 35 constituting the current transformer in the first embodiment shown in FIG. 2 will be described.

6 shows the frequency of the current I _{in to} be measured, the output voltage of the differential amplifier circuit 27 in FIG. 2 (sensor output V _O : current detection output by the Hall element 25), and the output voltage of the amplifier 37 (current transformer output V _CU. : Is a frequency characteristic diagram showing the relationship with the error of the current detection output) by the coil 35. As shown in this figure, the current detection output (sensor output V _O ) by the Hall element 25 has a characteristic with almost no error regardless of the frequency, while the current detection output (current transformer) by the coil 35 forming the current transformer. The output V _CU ) has almost no error at a frequency of 100 Hz or more, but the error increases as the frequency decreases at a frequency of 100 Hz or less. The frequency at which the error starts to increase varies depending on the coil configuration, and the above 100 Hz is merely an example.

In the present embodiment, a frequency characteristic compensation means for compensating the frequency characteristic of the current transformer output V _CU in a low frequency region of 100 Hz or less is provided to prevent the abnormality detection circuit 50 from erroneously detecting a failure in the low frequency region. . Hereinafter, two frequency characteristic compensation means will be exemplified.

The first frequency characteristic compensation means uses an amplifier 37 that amplifies the induced voltage _VL generated by the coil 35 forming the current transformer and has a characteristic that the gain increases as the frequency decreases in the low frequency region. Realized. That is, the frequency characteristic is compensated by canceling the decrease in the induced voltage V _L of the coil 35 in the low frequency region by increasing the gain of the amplifier 37.

As shown in the block diagram of FIG. 7, the second frequency characteristic compensation means is a frequency characteristic (EX. Error in the low frequency region) of the current transformer output V _CU (induced voltage generated by the coil 35 forming the current transformer). : Deviation from the ideal value) is stored in the memory 57 in advance, and the predetermined value (the value at which the level of the abnormality detection signal E (det) switches) in the low frequency region is referred to the memory 57. (For example, increase the frequency as the frequency decreases). That is, the frequency characteristic is compensated by adjusting (increasing) the predetermined value of the abnormality detection circuit 50 in accordance with a decrease in the induced voltage V _L of the coil 35 in the low frequency region. Note that the memory 57 may also store the frequency characteristics of the output voltage of the differential amplifier circuit 27 (sensor output V _O : current detection output by the Hall element 25) in the low frequency region as necessary.

  The present invention has been described above by taking the embodiment as an example. However, it will be understood by those skilled in the art that various modifications can be made to each component of the embodiment within the scope of the claims. Hereinafter, modifications will be described.

In the embodiment, the case where the magnetic proportional current sensor has a configuration including the ring-shaped magnetic core 15 has been described. However, in a modified example, a coreless type magnetic proportional current sensor that does not include the ring-shaped magnetic core 15 may be used. Alternatively, as shown in FIG. 8, instead of the ring-shaped magnetic core 15, linear magnetic yokes 28 may be provided on the front surface and / or the back surface of the Hall element 25. In this case, the coil 35 may be one in which the magnetic yoke 28 is positioned inside the bobbin 26 to which the winding 32 is applied. As shown in FIG. 8, the coil 35 may be provided on both the front surface and the back surface of the Hall element 25 and connected in series, or may be provided only on either the front surface or the back surface of the Hall element 25. In the modification shown in FIG. 8, two coils 35 forming a current transformer are arranged in series on the main surface of a bus bar 12 having a flat plate shape (for example, a copper plate) that forms a path of the current I _{in to} be measured and connected in series. This is a bus bar-integrated configuration in which the Hall element 25 is disposed between 35.

In the embodiment, the case where the induced voltage V _L generated by the coil 35 is amplified by the amplifier 37 and input to the abnormality detection circuit 50 as the current transformer output V _CU has been described. However, in the modification, the induced voltage is not provided and the induced voltage is not provided. V _L may be directly input to the abnormality detection circuit 50 as the current transformer output V _CU . In other words, the amplifier 37 is effective when it is desired to match the gain of the current transformer output V _{CU and} the gain of the sensor output V _O , but may be omitted if such a necessity is not necessary.

  Although the case where the number of measured currents is one has been described in the embodiment, in the modified example, the number of measured currents may be two or more. When the current to be measured is a three-phase alternating current, for example, the current of the V phase and the W phase is monitored by the current sensor having the configuration shown in the embodiment, and the U phase current value is a measured value of the V phase and the W phase It may be calculated from

  In the embodiment, the magnetic proportional current sensor is driven by a single power source. However, in a modification, it may be driven by a dual power source.

12 Busbar 15 Ring-shaped magnetic core 25 Hall element 27 Differential amplifier circuit 29 Constant current circuit 35 Coil 37 Amplifier 50 Abnormality detection circuit 100 Magnetic proportional current sensor 110 Sensor output terminal 131 Bobbin 135 Plate-shaped core 139 Winding

Claims (10)

A first current detection unit having a magnetic detection element to which a magnetic field generated by a current to be measured is applied;
A second current detector having a coil that generates an induced voltage in crossing with a magnetic field generated by the current to be measured;
Whether the first output voltage of the first current detection unit and the second output voltage of the second current detection unit are input, and the difference between the first and second output voltages is within a predetermined value. A magnetic proportional current sensor comprising an abnormality detection circuit that outputs abnormality detection signals at different levels. The magnetic proportional current sensor according to claim 1,
A ring-shaped magnetic core having a gap portion surrounding the path of the current to be measured;
A magnetic proportional current sensor in which the magnetic detection element is located in the gap portion of the ring-shaped magnetic core.   3. The magnetic proportional current sensor according to claim 2, wherein the coil is formed such that at least a part of the ring-shaped magnetic core penetrates the inside, or the gap portion of the ring-shaped magnetic core exists on the inside. Arranged magnetic proportional current sensor.   4. The magnetic proportional current sensor according to claim 2, further comprising a printed circuit board inserted and disposed in the gap part of the ring-shaped magnetic core, wherein the magnetic detection is performed in a portion of the printed circuit board that passes through the gap part. Magnetic proportional current sensor with elements mounted.   5. The magnetic proportional current sensor according to claim 4, wherein at least a part of a portion of the printed circuit board passing through the gap portion is an opening, and the magnetic detection element is mounted by being dropped into the opening. Proportional current sensor.   The magnetic proportional current sensor according to claim 4 or 5, wherein the coil is mounted on the printed circuit board so that the gap portion of the ring-shaped magnetic core exists inside, and a plate shape or a rod shape is formed inside the coil. A magnetic proportional current sensor provided with a core.   3. The magnetic proportional current sensor according to claim 2, wherein the coil is a bobbin wound and disposed so that the gap portion of the ring-shaped magnetic core exists inside the magnetic detection element. Is formed integrally with the bobbin, the winding end of the coil and the terminal of the magnetic detection element are electrically connected to the pins of the bobbin, and the pins are inserted through the through holes of the printed circuit board. Proportional current sensor.   8. The magnetic proportional current sensor according to claim 1, further comprising frequency characteristic compensation means for compensating a frequency characteristic in a low frequency region of the induced voltage generated by the coil.   9. The magnetic proportional current sensor according to claim 8, wherein the frequency characteristic compensation means is an amplifier that amplifies the induced voltage and outputs the amplified induced voltage to the abnormality detection circuit. The amplifier gain increases as the frequency decreases in the low frequency region. Magnetic proportional current sensor that has the characteristic of increasing   9. The magnetic proportional current sensor according to claim 8, wherein the frequency characteristic compensation means includes a memory storing a frequency characteristic of the second output voltage in the low frequency region, and the abnormality detection circuit in the low frequency region. A magnetic proportional current sensor that adjusts the predetermined value with reference to the memory.

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