WO2014147996A1 - Current sensor - Google Patents
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- WO2014147996A1 WO2014147996A1 PCT/JP2014/001364 JP2014001364W WO2014147996A1 WO 2014147996 A1 WO2014147996 A1 WO 2014147996A1 JP 2014001364 W JP2014001364 W JP 2014001364W WO 2014147996 A1 WO2014147996 A1 WO 2014147996A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/205—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using magneto-resistance devices, e.g. field plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
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- the present disclosure relates to a current sensor including a self-diagnosis circuit.
- Patent Document 1 Conventionally, a current detector having a failure diagnosis function has been proposed in Patent Document 1, for example. Specifically, in Patent Document 1, two magnetosensitive elements are arranged in one gap of a magnetic core, and a signal processing circuit having the same configuration is provided for each magnetosensitive element. There has been proposed a configuration of a current detector that determines a failure by comparing outputs. That is, the current detector is provided with two circuits each including a magnetosensitive element and a signal processing circuit.
- the current sensor includes a magnetic field generation unit that generates a second magnetic field in a direction perpendicular to the first magnetic field generated when the detected current flows through the detected current path.
- the current sensor has a plurality of magnetoresistive elements, and based on a change in resistance values of the plurality of magnetoresistive elements when the plurality of magnetoresistive elements are affected by an external magnetic field, A sensor element is provided that outputs a sine wave signal including a sine value corresponding to an angle ⁇ formed by a combined magnetic field composed of a magnetic field and a second magnetic field, and a cosine wave signal including a cosine value.
- the current sensor inputs a sine wave signal and a cosine wave signal from the sensor element, and outputs a sensor signal corresponding to the magnitude of the detected current by performing a predetermined calculation on the sine wave signal and the cosine wave signal.
- An output arithmetic circuit is provided.
- the current sensor is provided with a self-diagnosis circuit that inputs a sine wave signal and a cosine wave signal from the sensor element and performs failure determination of the sensor element based on the sine wave signal and the cosine wave signal.
- the self-diagnosis circuit that performs the failure diagnosis based on the two signals of the sine wave signal and the cosine wave signal output from the sensor element is provided, a sensor element and an output arithmetic circuit for failure diagnosis are separately provided. There is no need. Accordingly, self-diagnosis can be performed in a current sensor having one sensor element and one output arithmetic circuit.
- FIG. 1 is a schematic diagram when the current sensor according to the first embodiment of the present disclosure is attached to a bus bar.
- FIG. 2 is a cross-sectional view of the current sensor shown in FIG.
- FIG. 3 is a circuit diagram of the current sensor shown in FIG.
- FIG. 4 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when the self-diagnosis result is normal
- FIG. 5 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when an offset variation occurs in Vs.
- FIG. 6 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when an offset variation occurs in Vc.
- FIG. 7 is a diagram illustrating an output voltage output from the self-diagnosis circuit via the diagnosis terminal.
- FIG. 8 is a diagram illustrating a normal Lissajous waveform drawn by the self-diagnosis circuit according to the second embodiment of the present disclosure.
- FIG. 9 is a diagram showing a Lissajous waveform drawn by the self-diagnosis circuit when an offset variation occurs in Vs in the second embodiment.
- FIG. 10 is a diagram illustrating a Lissajous waveform drawn by the self-diagnostic circuit when an offset variation occurs in Vc in the second embodiment.
- FIG. 11 is a circuit diagram of a current sensor according to the fourth embodiment of the present disclosure.
- FIG. 12 is a diagram illustrating an output voltage output via an output terminal in the fourth embodiment.
- the current sensor according to the present embodiment detects, for example, a detected current flowing in a bus bar connected to an in-vehicle battery or the like.
- the current sensor 10 includes a substrate 20, a bias magnet 30, a sensor element 40, a circuit chip 50, leads 60, and a mold resin 70.
- the current magnetic field Bi is generated when the detected current I flows through the bus bar 80 that is the detection target.
- the bias magnet 30 generates a bias magnetic field Bb in a direction perpendicular to the current magnetic field Bi.
- the bias magnet 30 is installed on one surface 21 of the substrate 20. The bias magnet 30 applies this bias magnetic field Bb to the sensor element 40.
- the sensor element 40 is a plate-like chip component having a plurality of magnetoresistive elements whose resistance values change when affected by an external magnetic field. As shown in FIG. 2, the sensor element 40 is disposed on the bias magnet 30. For this reason, for example, the variation in the angle of the bias magnetic field Bb affecting each magnetoresistive element is suppressed as compared with the case where the sensor element 40 is disposed near the corner of the rectangular bias magnet 30 or the like.
- the circuit chip 50 includes a signal processing circuit for performing a preset operation on the signal input from the sensor element 40.
- the circuit chip 50 is installed on the one surface 21 of the substrate 20.
- the lead 60 electrically connects the outside and the current sensor 10.
- the plurality of leads 60 are arranged in a direction perpendicular to the longitudinal direction of the leads 60.
- Each lead 60 is electrically connected to the circuit chip 50 via a wire (not shown).
- Mold resin 70 seals part of substrate 20, bias magnet 30, sensor element 40, circuit chip 50, and lead 60. Specifically, the mold resin 70 seals each component 20, 30, 40, 50, 60 so that the portion of the lead 60 opposite to the substrate 20, that is, the outer lead portion is exposed. Yes. Thereby, the current sensor 10 is formed as a mold IC.
- Examples of the material of the mold resin 70 include an epoxy resin.
- the current sensor 10 is assembled to the bus bar 80 as shown in FIG. Specifically, the current sensor 10 is assembled to the bus bar 80 so that the direction of the current flowing through the bus bar 80, that is, the longitudinal direction of the bus bar 80 and the bias magnetic field Bb are parallel to each other. In other words, the current sensor 10 is assembled to the bus bar 80 so that the current magnetic field Bi generated by the detected current I flowing in the bus bar 80 and the bias magnetic field Bb are perpendicular to each other.
- the sensor element 40 is applied with a synthetic magnetic field Bs composed of a bias magnetic field Bb and a current magnetic field Bi.
- the sensor element 40 includes a first detection unit 40a and a second detection unit 40b.
- the first detection unit 40a the four magnetoresistive elements 41 to 44 form a bridge circuit.
- the second detector 40b the four magnetoresistive elements 45 to 48 form a bridge circuit.
- the magnetoresistive elements 41 to 48 are configured as TMR elements in which a pin magnetic layer, a tunnel layer, a free magnetic layer, and an upper electrode are sequentially formed on the lower electrode.
- the pinned magnetic layer is a ferromagnetic metal layer whose magnetization direction is fixed.
- the tunnel layer is an insulating layer for allowing a current to flow from the free magnetic layer to the pinned magnetic layer by the tunnel effect.
- the free magnetic layer is a ferromagnetic metal layer whose magnetization direction changes under the influence of an external magnetic field.
- the magnetization directions of the pinned magnetic layers are parallel to each other. Further, the magnetization directions of the pin magnetic layers of the magnetoresistive elements 45 to 48 constituting the second detection unit 40b are relative to the magnetization directions of the pin magnetic layers of the magnetoresistive elements 41 to 44 constituting the first detection unit 40a. And vertical.
- the magnetization directions of the magnetoresistive elements 41 to 44 of the first detection unit 40a are perpendicular to the bias magnetic field Bb, and the magnetization directions of the magnetoresistive elements 45 to 48 of the second detection unit 40b are bias magnetic fields. It is installed on the bias magnet 30 so as to be parallel to Bb. For this reason, as shown in FIG. 1, when the angle formed by the bias magnetic field Bb and the combined magnetic field Bs is ⁇ , the voltage signals Vs + and Vs ⁇ output from the first detection unit 40a include sine values, that is, sin ⁇ . This is a signal (SIN output). On the other hand, the voltage signals Vc + and Vc ⁇ output from the second detection unit 40b are signals (COS output) including a cosine value, that is, cos ⁇ .
- the sensor element 40 has the bias magnetic field Bb and the combined magnetic field Bs based on the change in resistance value of the plurality of magnetoresistive elements 41 to 48 when the plurality of magnetoresistive elements 41 to 48 are affected by the external magnetic field.
- a voltage signal corresponding to the angle ⁇ formed by is output.
- the circuit chip 50 includes a power supply circuit 51, a first amplifier circuit 52 (AMP), a second amplifier circuit 53 (AMP), an output arithmetic circuit 54, and a self-diagnosis circuit 55. Furthermore, the circuit chip 50 includes a power supply terminal 56 (V), an output terminal 57 (Vout), a diagnosis terminal 58 (Diag), and a ground terminal 59 (GND).
- the power supply circuit 51 is a constant voltage circuit that generates a constant voltage based on a power supply voltage V applied from an external power supply via a power supply terminal 56. Specifically, the power supply circuit 51 uses the constant voltage Vcc generated from the power supply voltage V as the midpoint of the magnetoresistive elements 41 and 44 of the first detection unit 40a of the sensor element 40 and the magnetoresistive element of the second detection unit 40b. Apply to the midpoint of 45,48. The power supply circuit 51 generates and applies voltages for operating the amplifier circuits 52 and 53, the output arithmetic circuit 54, and the self-diagnosis circuit 55, respectively.
- the first amplification circuit 52 amplifies the voltage signals Vs + and Vs ⁇ input from the first detection unit 40a of the sensor element 40, and outputs a sine wave signal Vs including a sine value, that is, sin ⁇ .
- the first amplifier circuit 52 is, for example, a differential amplifier circuit. In this case, one input terminal of the first amplifier circuit 52 is connected to the midpoint of the magnetoresistive elements 43 and 44 of the first detection unit 40a, and the voltage signal Vs + is input to the input terminal. The other input terminal of the first amplifier circuit 52 is connected to the midpoint of the magnetoresistive elements 41 and 42, and the voltage signal Vs ⁇ is input to the input terminal. Therefore, the first amplifier circuit 52 differentially amplifies the input voltage signals Vs + and Vs ⁇ and outputs a sine wave signal Vs to the output arithmetic circuit 54.
- the second amplification circuit 53 amplifies the voltage signals Vc + and Vc ⁇ input from the second detection unit 40b of the sensor element 40 and outputs a cosine wave signal Vc including a cosine value, that is, cos ⁇ .
- the second amplifier circuit 53 is a differential amplifier circuit like the first amplifier circuit 52. In this case, one input terminal of the second amplifier circuit 53 is connected to the midpoint of the magnetoresistive elements 47 and 48 of the second detection unit 40b, and the voltage signal Vc + is input to the input terminal. The other input terminal of the second amplifier circuit 53 is connected to the midpoint of the magnetoresistive elements 45 and 46, and the voltage signal Vc ⁇ is input to the input terminal. Accordingly, the second amplifier circuit 53 differentially amplifies the input voltage signals Vc + and Vc ⁇ and outputs a cosine wave signal Vc to the output arithmetic circuit 54.
- A is a parameter common to the sine wave signal Vs and the cosine wave signal Vc.
- the output calculation circuit 54 receives the sine wave signal Vs and the cosine wave signal Vc from the sensor element 40, and performs a predetermined calculation on the sine wave signal Vs and the cosine wave signal Vc to obtain the magnitude of the detected current I. Outputs the corresponding sensor signal. Specifically, the output arithmetic circuit 54 uses the sine wave signal Vs and the cosine wave signal Vc input from the amplifier circuits 52 and 53, and the tangent value (tan ⁇ ) at the angle ⁇ between the bias magnetic field Bb and the combined magnetic field Bs. And outputs a signal corresponding to the tangent value to the outside through the output terminal 57 as a sensor signal. That is, the output calculation circuit 54 performs a calculation of dividing the sine wave signal Vs by the cosine wave signal Vc to obtain a tangent value (tan ⁇ ), and outputs a signal corresponding to the calculation result as a sensor signal.
- tan ⁇ (current magnetic field Bi) / (bias magnetic field Bb).
- the bias magnetic field Bb is constituted by the bias magnet 30 and is constant. Therefore, the sensor signal is proportional to the current magnetic field Bi generated by the detected current I flowing through the bus bar 80. That is, the sensor signal changes linearly with respect to the detected current I flowing through the bus bar 80.
- the output calculation circuit 54 outputs a signal corresponding to tan ⁇ as a sensor signal.
- output a signal corresponding to a tangent value as a sensor signal means that a value obtained by adding a predetermined offset to the calculated tangent value is output as a sensor signal, or the calculated tangent value is directly used as a sensor signal. Or output. In this embodiment, the calculated tangent value is output as it is.
- the self-diagnosis circuit 55 inputs the sine wave signal Vs and the cosine wave signal Vc from the sensor element 40, and determines the failure of the sensor element 40 or each of the amplification circuits 52 and 53 based on the sine wave signal Vs and the cosine wave signal Vc. Do. Since the sine wave signal Vs and the cosine wave signal Vc are signals obtained via the sensor element 40 and the amplifier circuits 52 and 53, the self-diagnosis circuit 55 is one of the sensor element 40 and the amplifier circuits 52 and 53. It is diagnosed that there is a possibility of failure.
- the self-diagnosis circuit 55 calculates the sum of Vs 2 and Vc 2, and compares the calculation result with a preset failure determination value to determine a failure of the sensor element 40.
- the failure determination value is a boundary value, that is, a threshold value between a normal value range and an abnormal value range of Vs 2 + Vc 2 , and is stored in a storage unit provided in the self-diagnosis circuit 55 at the time of product shipment.
- the sine wave signal Vs or the cosine wave signal Vc includes a failure component.
- the sum of Vs 2 and Vc 2 includes a component of Voffs and a component of sin ⁇ . Therefore, as shown in FIG. 5, the sum of Vs 2 and Vc 2 is not constant with respect to the current value.
- Voffs corresponds to a failure component included in the sine wave signal Vs.
- Vc A ⁇ cos ⁇ + Voffc. Therefore, the sum of Vs 2 and Vc 2 includes a component of Voffc and a component of cos ⁇ . Therefore, as shown in FIG. 6, the sum of Vs 2 and Vc 2 is not constant with respect to the current value. Voffc corresponds to a failure component included in the cosine wave signal Vc.
- the self-diagnosis circuit 55 compares the sum of Vs 2 and Vc 2 with the failure determination value, determines that the calculation result is abnormal, and abnormalities are detected in either the sensor element 40 or each of the amplifier circuits 52 and 53. It is determined that it has occurred.
- the self-diagnosis circuit 55 outputs a failure diagnosis result to the outside via the diagnosis terminal 58 after performing the failure determination as described above. Specifically, as shown in FIG. 7, when the self-diagnosis result is normal, the self-diagnosis circuit 55 outputs the output voltage during normal operation as the output voltage when the self-diagnosis result is normal. That is, when the self-diagnosis result is normal, the self-diagnosis circuit 55 does not change the voltage applied to the diagnosis terminal 58.
- the self-diagnosis circuit 55 when the self-diagnosis result is abnormal, the self-diagnosis circuit 55 outputs a higher output voltage than that during normal operation. That is, when the self-diagnosis result is abnormal, the self-diagnosis circuit 55 changes the voltage applied to the diagnosis terminal 58. In this way, the self-diagnosis circuit 55 transmits an abnormality to the outside.
- the present embodiment includes the self-diagnosis circuit 55 that performs failure diagnosis based on the two signals of the sine wave signal Vs and the cosine wave signal Vc. Further, since the self-diagnosis circuit 55 performs failure diagnosis using the angle components of the sine wave signal Vs and the cosine wave signal Vc, separate configurations of the sensor element 40 and the output arithmetic circuit 54 for failure diagnosis are unnecessary. can do. Therefore, the self-diagnosis can be enabled by one sensor element 40 and one output arithmetic circuit 54 provided in the current sensor 10.
- the detected current I flowing through the bus bar 80 is not always a constant value.
- the current sensor 10 detects an average value or a peak value of the current value for such a measurement object “current”. Therefore, in order to confirm whether or not the current value detected by the current sensor 10 is a really correct value, conventionally, it has been necessary to provide a current detection unit having exactly the same configuration and compare both values.
- the current sensor 10 according to the present embodiment performs failure determination using the sine wave signal Vs and the cosine wave signal Vc including the failure component. Therefore, it is not necessary to compare the output of the sensor element 40 with the output of another sensor element having the same configuration, and the self-diagnosis function of the current sensor 10 can be realized only by providing the self-diagnosis circuit 55. .
- the current magnetic field Bi corresponds to the “first magnetic field” of the present disclosure.
- the bias magnetic field Bb corresponds to the “second magnetic field” of the present disclosure.
- the bias magnet 30 corresponds to a “magnetic field generation unit” of the present disclosure.
- the bus bar 80 corresponds to the “detected current path” of the present disclosure.
- the self-diagnosis circuit 55 performs failure determination based on the Lissajous waveform drawn by the sine wave signal Vs and the cosine wave signal Vc.
- the self-diagnosis circuit 55 draws a Lissajous waveform by the sine wave signal Vs and the cosine wave signal Vc input from the amplifier circuits 52 and 53.
- the Lissajous waveform is a plane figure drawn on orthogonal coordinates by synthesizing two simple vibrations of the sine wave signal Vs and the cosine wave signal Vc.
- FIG. 8 shows a normal Lissajous waveform at the time of product shipment, for example.
- the Lissajous waveform moves in the sin ⁇ -axis direction from the normal time as shown in FIG.
- the Lissajous waveform moves in the cos ⁇ axis direction from the normal time as shown in FIG.
- the self-diagnosis circuit 55 compares the Lissajous waveform drawn by the sine wave signal Vs and the cosine wave signal Vc with a failure determination value based on a preset Lissajous waveform at the time of product shipment, thereby obtaining a sensor element. 40 failure determinations are made. That is, the self-diagnosis circuit 55 determines whether or not a predetermined amount has deviated from the circular waveform at the time of product shipment. As described above, the failure can be easily visually determined by drawing the Lissajous waveform.
- the self-diagnosis circuit 55 compares sin ⁇ with (1-cos 2 ⁇ ) 1/2 or compares (1-sin 2 ⁇ ) 1/2 with cos ⁇ .
- the failure determination of the sensor element 40 is performed.
- the sine and cosine can be expressed by sin ⁇ or cos ⁇ . Therefore, the self-diagnosis circuit 55 can also perform failure determination using the sine wave signal Vs and the cosine wave signal Vc without using the failure determination value.
- the self-diagnosis circuit 55 is connected to the output terminal 57A (Vout / Diag). As a result, the self-diagnosis circuit 55 outputs the self-diagnosis result to the outside via the output terminal 57A.
- the output terminal 57A corresponds to a terminal that outputs both the sensor signal and the self-diagnosis result.
- the output arithmetic circuit 54 outputs the voltage of the normal state output voltage within a certain range. However, when the self-diagnosis circuit 55 determines that the sensor element 40 has failed, the self-diagnosis circuit 55 changes the output of the output arithmetic circuit 54.
- the self-diagnosis circuit 55 applies a voltage value exceeding the normal state output voltage within a certain range to the output terminal 57A.
- the self-diagnosis circuit 55 outputs a voltage higher than the maximum value of the normal state output voltage within a certain range when the self-diagnosis result is abnormal. In this way, the self-diagnosis result can be output to the outside via the output terminal 57A.
- the diagnosis terminal 58 can be omitted, and the configuration of the circuit chip 50 can be simplified.
- the configuration of the current sensor 10 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present disclosure.
- the positional relationship between the bias magnet 30 and the sensor element 40 as long as the relationship between the magnetization direction of the pin magnetic layer of each of the magnetoresistive elements 41 to 48 and the direction of the bias magnetic field Bb can be maintained as described above, An arrangement relationship may be used.
- each of the magnetoresistive elements 41 to 48 of the sensor element 40 is a TMR element, but may be a GMR element.
- the amplifier circuits 52 and 53 are provided in the circuit chip 50, but may be provided in the sensor element 40. Even in this case, the output calculation circuit 54 performs a predetermined calculation on the sine wave signal Vs and the cosine wave signal Vc.
- the self-diagnosis circuit 55 outputs a voltage higher than the maximum value of the normal state output voltage within a certain range when the self-diagnosis result is abnormal. A voltage lower than the minimum value may be output.
- the current sensor 10 measures the detected current I flowing in the bus bar 80 connected to the vehicle-mounted battery or the like. This is an example of application of the current sensor 10. Therefore, the measurement target is not limited to the vehicle bus bar 80, and the current sensor 10 may be applied to wiring used for other purposes.
- the current sensor includes a magnetic field generation unit that generates a second magnetic field in a direction perpendicular to the first magnetic field generated when the detected current flows through the detected current path.
- the current sensor has a plurality of magnetoresistive elements, and based on a change in resistance values of the plurality of magnetoresistive elements when the plurality of magnetoresistive elements are affected by an external magnetic field, A sensor element is provided that outputs a sine wave signal including a sine value corresponding to an angle ⁇ formed by a combined magnetic field composed of a magnetic field and a second magnetic field, and a cosine wave signal including a cosine value.
- the current sensor inputs a sine wave signal and a cosine wave signal from the sensor element, and outputs a sensor signal corresponding to the magnitude of the detected current by performing a predetermined calculation on the sine wave signal and the cosine wave signal.
- An output arithmetic circuit is provided.
- the current sensor is provided with a self-diagnosis circuit that inputs a sine wave signal and a cosine wave signal from the sensor element and performs failure determination of the sensor element based on the sine wave signal and the cosine wave signal.
- the self-diagnosis circuit that performs the failure diagnosis based on the two signals of the sine wave signal and the cosine wave signal output from the sensor element is provided, a sensor element and an output arithmetic circuit for failure diagnosis are separately provided. There is no need. Therefore, a self-diagnosis can be performed in a current sensor including one sensor element and one output arithmetic circuit.
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Abstract
Disclosed is a current sensor provided with a magnetic-field generation unit (30), a sensor element (40) that has a plurality of magnetoresistive elements (41 through 48), an output-computation circuit (54), and a self-diagnostic circuit (55). The magnetic-field generation unit (30) generates a second magnetic field in a direction perpendicular to a first magnetic field. The sensor element (40) outputs a sine-wave signal and a cosine-wave signal that represent the sine and the cosine, respectively, of the angle (θ) between the second magnetic field and a composite magnetic field comprising the first and second magnetic fields. The output-computation circuit (54) outputs a sensor signal corresponding to the magnitude of a detected current. The self-diagnostic circuit (55) uses the aforementioned sine-wave and cosine-wave signals to determine whether the sensor element (40) is malfunctioning.
Description
本出願は、2013年3月19日に出願された日本国特許出願2013-56098号に基づくものであり、ここにその記載内容を参照により援用する。
This application is based on Japanese Patent Application No. 2013-56098 filed on Mar. 19, 2013, the contents of which are incorporated herein by reference.
本開示は、自己診断回路を備えた電流センサに関する。
The present disclosure relates to a current sensor including a self-diagnosis circuit.
従来より、故障診断機能を備えた電流検出器が、例えば特許文献1で提案されている。具体的に、特許文献1では、磁性体コアの一つのギャップに二つの感磁素子が配置され、各感磁素子に対して同じ構成の信号処理回路が備えられており、各信号処理回路の出力を比較することにより故障を判定する電流検出器の構成が提案されている。すなわち、電流検出器には、感磁素子と信号処理回路とで構成された回路が2つ設けられている。
Conventionally, a current detector having a failure diagnosis function has been proposed in Patent Document 1, for example. Specifically, in Patent Document 1, two magnetosensitive elements are arranged in one gap of a magnetic core, and a signal processing circuit having the same configuration is provided for each magnetosensitive element. There has been proposed a configuration of a current detector that determines a failure by comparing outputs. That is, the current detector is provided with two circuits each including a magnetosensitive element and a signal processing circuit.
しかしながら、上記従来の技術では、電流検出器の故障を診断するために電流を検出するための回路と全く同じ構成の故障診断用の回路が別個に設けられている。このため、電流検出器の全体構成が煩雑になり、故障診断を行うためのコストが高くなるという問題がある。
However, in the above conventional technique, a fault diagnosis circuit having the same configuration as that of the current detection circuit is separately provided for diagnosing a fault in the current detector. For this reason, there exists a problem that the whole structure of a current detector becomes complicated and the cost for performing a failure diagnosis becomes high.
本開示は上記点に鑑み、磁気を検出するセンサ素子を用いて電流を検出する電流センサにおいて、センサ素子を2個用いなくても自己診断を可能な電流センサを提供することを目的とする。
In view of the above points, it is an object of the present disclosure to provide a current sensor that can perform self-diagnosis without using two sensor elements in a current sensor that detects current using a sensor element that detects magnetism.
本開示に係る電流センサは、被検出電流経路に被検出電流が流れることによって生じる第1磁界に対して垂直方向に第2磁界を発生させる磁界発生部を備えている。
The current sensor according to the present disclosure includes a magnetic field generation unit that generates a second magnetic field in a direction perpendicular to the first magnetic field generated when the detected current flows through the detected current path.
電流センサは、複数の磁気抵抗素子を有し、複数の磁気抵抗素子が外部の磁場の影響を受けたときの複数の磁気抵抗素子の抵抗値の変化に基づいて、第2磁界と、第1磁界及び第2磁界で構成される合成磁界と、の成す角度θに応じた正弦値を含む正弦波信号及び余弦値を含む余弦波信号を出力するセンサ素子を備えている。
The current sensor has a plurality of magnetoresistive elements, and based on a change in resistance values of the plurality of magnetoresistive elements when the plurality of magnetoresistive elements are affected by an external magnetic field, A sensor element is provided that outputs a sine wave signal including a sine value corresponding to an angle θ formed by a combined magnetic field composed of a magnetic field and a second magnetic field, and a cosine wave signal including a cosine value.
また、電流センサは、センサ素子から正弦波信号及び余弦波信号を入力し、正弦波信号及び余弦波信号に対して所定の演算を行うことにより被検出電流の大きさに対応したセンサ信号を出力する出力演算回路を備えている。
The current sensor inputs a sine wave signal and a cosine wave signal from the sensor element, and outputs a sensor signal corresponding to the magnitude of the detected current by performing a predetermined calculation on the sine wave signal and the cosine wave signal. An output arithmetic circuit is provided.
さらに、電流センサは、センサ素子から正弦波信号及び余弦波信号を入力すると共に、正弦波信号及び余弦波信号に基づいてセンサ素子の故障判定を行う自己診断回路を備えている。
Furthermore, the current sensor is provided with a self-diagnosis circuit that inputs a sine wave signal and a cosine wave signal from the sensor element and performs failure determination of the sensor element based on the sine wave signal and the cosine wave signal.
このように、センサ素子が出力する正弦波信号及び余弦波信号の2つの信号に基づいて故障診断を行う自己診断回路を備えているので、故障診断のためのセンサ素子及び出力演算回路を別途設ける必要がない。したがって、1つのセンサ素子及び1つの出力演算回路を備えた電流センサにおいて自己診断が可能となる。
As described above, since the self-diagnosis circuit that performs the failure diagnosis based on the two signals of the sine wave signal and the cosine wave signal output from the sensor element is provided, a sensor element and an output arithmetic circuit for failure diagnosis are separately provided. There is no need. Accordingly, self-diagnosis can be performed in a current sensor having one sensor element and one output arithmetic circuit.
本開示についての上記および他の目的、特徴や利点は、添付の図面を参照した下記の詳細な説明から、より明確になる。添付図面において
図1は、本開示の第1実施形態における電流センサをバスバーに取り付けたときの模式図であり、
図2は、図1に示す電流センサの断面図であり、
図3は、図1に示す電流センサの回路図であり、
図4は、自己診断結果が正常の場合の電流値とVs2+Vc2との関係を示した図であり、
図5は、Vsにオフセット変動が生じた場合の電流値とVs2+Vc2との関係を示した図であり、
図6は、Vcにオフセット変動が生じた場合の電流値とVs2+Vc2との関係を示した図であり、
図7は、自己診断回路からダイアグ端子を介して出力される出力電圧を示した図であり、
図8は、本開示の第2実施形態に係る自己診断回路が描いた正常なリサージュ波形を示した図であり、
図9は、第2実施形態において、Vsにオフセット変動が生じた場合に自己診断回路が描いたリサージュ波形を示した図であり、
図10は、第2実施形態において、Vcにオフセット変動が生じた場合に自己診断回路が描いたリサージュ波形を示した図であり、
図11は、本開示の第4実施形態に係る電流センサの回路図であり、
図12は、第4実施形態において、出力端子を介して出力される出力電圧を示した図である。
The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the attached drawings
FIG. 1 is a schematic diagram when the current sensor according to the first embodiment of the present disclosure is attached to a bus bar. FIG. 2 is a cross-sectional view of the current sensor shown in FIG. FIG. 3 is a circuit diagram of the current sensor shown in FIG. FIG. 4 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when the self-diagnosis result is normal, FIG. 5 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when an offset variation occurs in Vs. FIG. 6 is a diagram showing the relationship between the current value and Vs 2 + Vc 2 when an offset variation occurs in Vc. FIG. 7 is a diagram illustrating an output voltage output from the self-diagnosis circuit via the diagnosis terminal. FIG. 8 is a diagram illustrating a normal Lissajous waveform drawn by the self-diagnosis circuit according to the second embodiment of the present disclosure. FIG. 9 is a diagram showing a Lissajous waveform drawn by the self-diagnosis circuit when an offset variation occurs in Vs in the second embodiment. FIG. 10 is a diagram illustrating a Lissajous waveform drawn by the self-diagnostic circuit when an offset variation occurs in Vc in the second embodiment. FIG. 11 is a circuit diagram of a current sensor according to the fourth embodiment of the present disclosure. FIG. 12 is a diagram illustrating an output voltage output via an output terminal in the fourth embodiment.
以下、本開示の実施形態について図に基づいて説明する。なお、以下の各実施形態相互において、互いに同一もしくは均等である部分には、図中、同一符号を付してある。
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.
(第1実施形態)
以下、本開示の第1実施形態について図を参照して説明する。本実施形態に係る電流センサは、例えば、車載バッテリ等に接続されるバスバーに流れる被検出電流を検出するものである。 (First embodiment)
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. The current sensor according to the present embodiment detects, for example, a detected current flowing in a bus bar connected to an in-vehicle battery or the like.
以下、本開示の第1実施形態について図を参照して説明する。本実施形態に係る電流センサは、例えば、車載バッテリ等に接続されるバスバーに流れる被検出電流を検出するものである。 (First embodiment)
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. The current sensor according to the present embodiment detects, for example, a detected current flowing in a bus bar connected to an in-vehicle battery or the like.
図1及び図2に示されるように、電流センサ10は、基板20、バイアス磁石30、センサ素子40、回路チップ50、リード60、及びモールド樹脂70を備えている。
1 and 2, the current sensor 10 includes a substrate 20, a bias magnet 30, a sensor element 40, a circuit chip 50, leads 60, and a mold resin 70.
電流磁界Biは、検出対象であるバスバー80に被検出電流Iが流れることによって生じる。バイアス磁石30は、電流磁界Biに対して垂直方向にバイアス磁界Bbを発生させる。バイアス磁石30は、基板20の一面21に設置されている。バイアス磁石30は、このバイアス磁界Bbをセンサ素子40に印加する。
The current magnetic field Bi is generated when the detected current I flows through the bus bar 80 that is the detection target. The bias magnet 30 generates a bias magnetic field Bb in a direction perpendicular to the current magnetic field Bi. The bias magnet 30 is installed on one surface 21 of the substrate 20. The bias magnet 30 applies this bias magnetic field Bb to the sensor element 40.
センサ素子40は、外部の磁場の影響を受けたときに抵抗値が変化する複数の磁気抵抗素子を有する板状のチップ部品である。図2に示されるように、センサ素子40はバイアス磁石30の上に配置されている。このため、例えば、センサ素子40が矩形状のバイアス磁石30の角部近傍等に配置される場合と比較して、各磁気抵抗素子に影響するバイアス磁界Bbの角度のばらつきが抑制される。
The sensor element 40 is a plate-like chip component having a plurality of magnetoresistive elements whose resistance values change when affected by an external magnetic field. As shown in FIG. 2, the sensor element 40 is disposed on the bias magnet 30. For this reason, for example, the variation in the angle of the bias magnetic field Bb affecting each magnetoresistive element is suppressed as compared with the case where the sensor element 40 is disposed near the corner of the rectangular bias magnet 30 or the like.
回路チップ50は、センサ素子40から入力した信号に対して予め設定された演算を行うための信号処理回路を備えている。回路チップ50は、基板20の一面21に設置されている。
The circuit chip 50 includes a signal processing circuit for performing a preset operation on the signal input from the sensor element 40. The circuit chip 50 is installed on the one surface 21 of the substrate 20.
リード60は、外部と電流センサ10とを電気的に接続する。本実施形態では、複数のリード60が当該リード60の長手方向に垂直な方向に並べられている。そして、各リード60が図示しないワイヤを介して回路チップ50と電気的に接続されている。
The lead 60 electrically connects the outside and the current sensor 10. In the present embodiment, the plurality of leads 60 are arranged in a direction perpendicular to the longitudinal direction of the leads 60. Each lead 60 is electrically connected to the circuit chip 50 via a wire (not shown).
モールド樹脂70は、基板20、バイアス磁石30、センサ素子40、回路チップ50、及びリード60の一部を封止する。具体的には、モールド樹脂70は、リード60のうち基板20側とは反対側の部分すなわちアウターリードの部分が露出するように、各部品20、30、40、50、60を封止している。これにより、電流センサ10はモールドIC化されている。モールド樹脂70の材料は、例えばエポキシ樹脂等がある。
Mold resin 70 seals part of substrate 20, bias magnet 30, sensor element 40, circuit chip 50, and lead 60. Specifically, the mold resin 70 seals each component 20, 30, 40, 50, 60 so that the portion of the lead 60 opposite to the substrate 20, that is, the outer lead portion is exposed. Yes. Thereby, the current sensor 10 is formed as a mold IC. Examples of the material of the mold resin 70 include an epoxy resin.
上記の電流センサ10は、図1に示されるように、バスバー80に組み付けられる。具体的には、電流センサ10は、バスバー80に流れる電流方向すなわちバスバー80の長手方向とバイアス磁界Bbとが平行になるように、バスバー80に組み付けられる。言い換えると、電流センサ10は、バスバー80に流れる被検出電流Iによって生成される電流磁界Biとバイアス磁界Bbとが垂直となるように、バスバー80に組み付けられる。そして、センサ素子40には、バイアス磁界Bb及び電流磁界Biで構成される合成磁界Bsが印加されるようになっている。
The current sensor 10 is assembled to the bus bar 80 as shown in FIG. Specifically, the current sensor 10 is assembled to the bus bar 80 so that the direction of the current flowing through the bus bar 80, that is, the longitudinal direction of the bus bar 80 and the bias magnetic field Bb are parallel to each other. In other words, the current sensor 10 is assembled to the bus bar 80 so that the current magnetic field Bi generated by the detected current I flowing in the bus bar 80 and the bias magnetic field Bb are perpendicular to each other. The sensor element 40 is applied with a synthetic magnetic field Bs composed of a bias magnetic field Bb and a current magnetic field Bi.
次に、電流センサ10におけるセンサ素子40と回路チップ50の回路構成について説明する。図3に示されるように、センサ素子40は、第1検出部40aと、第2検出部40bと、を有している。第1検出部40aは、4つの磁気抵抗素子41~44がブリッジ回路を形成する。また、第2検出部40bは、4つの磁気抵抗素子45~48がブリッジ回路を形成する。
Next, the circuit configuration of the sensor element 40 and the circuit chip 50 in the current sensor 10 will be described. As shown in FIG. 3, the sensor element 40 includes a first detection unit 40a and a second detection unit 40b. In the first detection unit 40a, the four magnetoresistive elements 41 to 44 form a bridge circuit. In the second detector 40b, the four magnetoresistive elements 45 to 48 form a bridge circuit.
磁気抵抗素子41~48は、図示しないが、下部電極の上にピン磁性層、トンネル層、フリー磁性層、及び上部電極が順に形成されたTMR素子として構成されている。ピン磁性層は磁化の向きが固定された強磁性金属層である。トンネル層はトンネル効果によりフリー磁性層からピン磁性層に電流を流すための絶縁層である。フリー磁性層は、外部の磁場の影響を受けて磁化の向きが変化する強磁性金属層である。
Although not shown, the magnetoresistive elements 41 to 48 are configured as TMR elements in which a pin magnetic layer, a tunnel layer, a free magnetic layer, and an upper electrode are sequentially formed on the lower electrode. The pinned magnetic layer is a ferromagnetic metal layer whose magnetization direction is fixed. The tunnel layer is an insulating layer for allowing a current to flow from the free magnetic layer to the pinned magnetic layer by the tunnel effect. The free magnetic layer is a ferromagnetic metal layer whose magnetization direction changes under the influence of an external magnetic field.
ここで、第1検出部40aを構成する各磁気抵抗素子41~44はそれぞれピン磁性層の磁化方向が互いに平行とされている。また、第2検出部40bを構成する各磁気抵抗素子45~48のピン磁性層の磁化方向は、第1検出部40aを構成する各磁気抵抗素子41~44のピン磁性層の磁化方向に対して垂直である。
Here, in each of the magnetoresistive elements 41 to 44 constituting the first detection unit 40a, the magnetization directions of the pinned magnetic layers are parallel to each other. Further, the magnetization directions of the pin magnetic layers of the magnetoresistive elements 45 to 48 constituting the second detection unit 40b are relative to the magnetization directions of the pin magnetic layers of the magnetoresistive elements 41 to 44 constituting the first detection unit 40a. And vertical.
センサ素子40は、第1検出部40aの各磁気抵抗素子41~44の磁化方向がバイアス磁界Bbと垂直となると共に、第2検出部40bの各磁気抵抗素子45~48の磁化方向がバイアス磁界Bbと平行となるようにバイアス磁石30の上に設置される。このため、図1に示されるように、バイアス磁界Bbと合成磁界Bsとの成す角度をθとすると、第1検出部40aから出力される電圧信号Vs+、Vs-は、正弦値すなわちsinθを含む信号(SIN出力)である。一方、第2検出部40bから出力される電圧信号Vc+、Vc-は余弦値すなわちcosθを含む信号(COS出力)である。
In the sensor element 40, the magnetization directions of the magnetoresistive elements 41 to 44 of the first detection unit 40a are perpendicular to the bias magnetic field Bb, and the magnetization directions of the magnetoresistive elements 45 to 48 of the second detection unit 40b are bias magnetic fields. It is installed on the bias magnet 30 so as to be parallel to Bb. For this reason, as shown in FIG. 1, when the angle formed by the bias magnetic field Bb and the combined magnetic field Bs is θ, the voltage signals Vs + and Vs− output from the first detection unit 40a include sine values, that is, sin θ. This is a signal (SIN output). On the other hand, the voltage signals Vc + and Vc− output from the second detection unit 40b are signals (COS output) including a cosine value, that is, cos θ.
したがって、センサ素子40は、複数の磁気抵抗素子41~48が外部の磁場の影響を受けたときの複数の磁気抵抗素子41~48の抵抗値の変化に基づいて、バイアス磁界Bbと合成磁界Bsとの成す角度θに応じた電圧信号を出力する。
Therefore, the sensor element 40 has the bias magnetic field Bb and the combined magnetic field Bs based on the change in resistance value of the plurality of magnetoresistive elements 41 to 48 when the plurality of magnetoresistive elements 41 to 48 are affected by the external magnetic field. A voltage signal corresponding to the angle θ formed by is output.
回路チップ50は、電源回路51、第1増幅回路52(AMP)、第2増幅回路53(AMP)、出力演算回路54、及び自己診断回路55を有している。さらに、回路チップ50は、電源端子56(V)、出力端子57(Vout)、ダイアグ端子58(Diag)、及びグランド端子59(GND)を備える。
The circuit chip 50 includes a power supply circuit 51, a first amplifier circuit 52 (AMP), a second amplifier circuit 53 (AMP), an output arithmetic circuit 54, and a self-diagnosis circuit 55. Furthermore, the circuit chip 50 includes a power supply terminal 56 (V), an output terminal 57 (Vout), a diagnosis terminal 58 (Diag), and a ground terminal 59 (GND).
電源回路51は、電源端子56を介して外部の電源から印加される電源電圧Vに基づいて一定の電圧を生成する定電圧回路である。具体的には、電源回路51は、電源電圧Vから生成した定電圧Vccをセンサ素子40の第1検出部40aの磁気抵抗素子41、44の中点、及び第2検出部40bの磁気抵抗素子45、48の中点に印加する。また、電源回路51は、各増幅回路52、53、出力演算回路54、及び自己診断回路55を動作させるための電圧を生成してそれぞれに印加する。
The power supply circuit 51 is a constant voltage circuit that generates a constant voltage based on a power supply voltage V applied from an external power supply via a power supply terminal 56. Specifically, the power supply circuit 51 uses the constant voltage Vcc generated from the power supply voltage V as the midpoint of the magnetoresistive elements 41 and 44 of the first detection unit 40a of the sensor element 40 and the magnetoresistive element of the second detection unit 40b. Apply to the midpoint of 45,48. The power supply circuit 51 generates and applies voltages for operating the amplifier circuits 52 and 53, the output arithmetic circuit 54, and the self-diagnosis circuit 55, respectively.
第1増幅回路52は、センサ素子40の第1検出部40aから入力した電圧信号Vs+、Vs-を増幅して正弦値すなわちsinθを含む正弦波信号Vsを出力する。第1増幅回路52は、例えば差動増幅回路である。この場合、第1増幅回路52の一方の入力端子が第1検出部40aの磁気抵抗素子43、44の中点に接続され、当該入力端子に電圧信号Vs+が入力される。また、第1増幅回路52の他方の入力端子が磁気抵抗素子41、42の中点に接続され、当該入力端子に電圧信号Vs-が入力される。したがって、第1増幅回路52は、入力された電圧信号Vs+、Vs-を差動増幅して出力演算回路54に正弦波信号Vsを出力する。
The first amplification circuit 52 amplifies the voltage signals Vs + and Vs− input from the first detection unit 40a of the sensor element 40, and outputs a sine wave signal Vs including a sine value, that is, sin θ. The first amplifier circuit 52 is, for example, a differential amplifier circuit. In this case, one input terminal of the first amplifier circuit 52 is connected to the midpoint of the magnetoresistive elements 43 and 44 of the first detection unit 40a, and the voltage signal Vs + is input to the input terminal. The other input terminal of the first amplifier circuit 52 is connected to the midpoint of the magnetoresistive elements 41 and 42, and the voltage signal Vs− is input to the input terminal. Therefore, the first amplifier circuit 52 differentially amplifies the input voltage signals Vs + and Vs− and outputs a sine wave signal Vs to the output arithmetic circuit 54.
第2増幅回路53は、センサ素子40の第2検出部40bから入力した電圧信号Vc+、Vc-を増幅して余弦値すなわちcosθを含む余弦波信号Vcを出力する。第2増幅回路53は、第1増幅回路52と同様に差動増幅回路である。この場合、第2増幅回路53の一方の入力端子が第2検出部40bの磁気抵抗素子47、48の中点に接続され、当該入力端子に電圧信号Vc+が入力される。また、第2増幅回路53の他方の入力端子が磁気抵抗素子45、46の中点に接続され、当該入力端子に電圧信号Vc-が入力される。したがって、第2増幅回路53は、入力された電圧信号Vc+、Vc-を差動増幅して出力演算回路54に余弦波信号Vcを出力する。
The second amplification circuit 53 amplifies the voltage signals Vc + and Vc− input from the second detection unit 40b of the sensor element 40 and outputs a cosine wave signal Vc including a cosine value, that is, cos θ. The second amplifier circuit 53 is a differential amplifier circuit like the first amplifier circuit 52. In this case, one input terminal of the second amplifier circuit 53 is connected to the midpoint of the magnetoresistive elements 47 and 48 of the second detection unit 40b, and the voltage signal Vc + is input to the input terminal. The other input terminal of the second amplifier circuit 53 is connected to the midpoint of the magnetoresistive elements 45 and 46, and the voltage signal Vc− is input to the input terminal. Accordingly, the second amplifier circuit 53 differentially amplifies the input voltage signals Vc + and Vc− and outputs a cosine wave signal Vc to the output arithmetic circuit 54.
上記の正弦波信号Vsは、例えばVs=A・sinθとして表される。また、余弦波信号Vcは、例えばVc=A・cosθとして表される。ここで、各増幅回路52、53は同じ構成であるので、増幅率は同じ値となる。また、各検出部40a、40bは、ピン磁性層の磁化方向以外は同じ構成とされている磁気抵抗素子41~48にて構成されているので、温度特性も同じ値となる。したがって、Aは正弦波信号Vs及び余弦波信号Vcで共通のパラメータである。
The sine wave signal Vs is expressed as Vs = A · sin θ, for example. The cosine wave signal Vc is expressed as Vc = A · cos θ, for example. Here, since each amplifier circuit 52 and 53 is the same structure, an amplification factor becomes the same value. Further, since each of the detection units 40a and 40b is configured by the magnetoresistive elements 41 to 48 having the same configuration except for the magnetization direction of the pinned magnetic layer, the temperature characteristics have the same value. Therefore, A is a parameter common to the sine wave signal Vs and the cosine wave signal Vc.
出力演算回路54は、センサ素子40から正弦波信号Vs及び余弦波信号Vcを入力し、正弦波信号Vs及び余弦波信号Vcに対して所定の演算を行うことにより被検出電流Iの大きさに対応したセンサ信号を出力する。具体的には、出力演算回路54は、各増幅回路52、53から入力した正弦波信号Vs及び余弦波信号Vcを用いてバイアス磁界Bbと合成磁界Bsとの成す角度θにおける正接値(tanθ)を演算し、この正接値に対応する信号をセンサ信号として出力端子57を介して外部に出力する。すなわち、出力演算回路54は、正弦波信号Vsを余弦波信号Vcで除算して正接値(tanθ)を取得する演算を行い、この演算結果に対応する信号をセンサ信号として出力する。
The output calculation circuit 54 receives the sine wave signal Vs and the cosine wave signal Vc from the sensor element 40, and performs a predetermined calculation on the sine wave signal Vs and the cosine wave signal Vc to obtain the magnitude of the detected current I. Outputs the corresponding sensor signal. Specifically, the output arithmetic circuit 54 uses the sine wave signal Vs and the cosine wave signal Vc input from the amplifier circuits 52 and 53, and the tangent value (tan θ) at the angle θ between the bias magnetic field Bb and the combined magnetic field Bs. And outputs a signal corresponding to the tangent value to the outside through the output terminal 57 as a sensor signal. That is, the output calculation circuit 54 performs a calculation of dividing the sine wave signal Vs by the cosine wave signal Vc to obtain a tangent value (tan θ), and outputs a signal corresponding to the calculation result as a sensor signal.
図1に示されるように、tanθ=(電流磁界Bi)/(バイアス磁界Bb)となる。バイアス磁界Bbはバイアス磁石30により構成されるもので一定である。よって、センサ信号はバスバー80に流れる被検出電流Iが生成する電流磁界Biに比例する。つまり、センサ信号はバスバー80に流れる被検出電流Iに対してリニアに変化する。出力演算回路54はこのtanθに対応する信号をセンサ信号として出力する。
As shown in FIG. 1, tan θ = (current magnetic field Bi) / (bias magnetic field Bb). The bias magnetic field Bb is constituted by the bias magnet 30 and is constant. Therefore, the sensor signal is proportional to the current magnetic field Bi generated by the detected current I flowing through the bus bar 80. That is, the sensor signal changes linearly with respect to the detected current I flowing through the bus bar 80. The output calculation circuit 54 outputs a signal corresponding to tan θ as a sensor signal.
なお、「正接値に対応する信号をセンサ信号として出力する」とは、演算した正接値に対して所定のオフセットを付加した値をセンサ信号として出力したり、演算した正接値をそのままセンサ信号として出力したりすることである。本実施形態では演算した正接値をそのまま出力する。
Note that “output a signal corresponding to a tangent value as a sensor signal” means that a value obtained by adding a predetermined offset to the calculated tangent value is output as a sensor signal, or the calculated tangent value is directly used as a sensor signal. Or output. In this embodiment, the calculated tangent value is output as it is.
自己診断回路55は、センサ素子40から正弦波信号Vs及び余弦波信号Vcを入力すると共に、正弦波信号Vs及び余弦波信号Vcに基づいてセンサ素子40もしくは各増幅回路52、53の故障判定を行う。正弦波信号Vsや余弦波信号Vcはセンサ素子40及び各増幅回路52、53を経由して得られた信号であるので、自己診断回路55はセンサ素子40及び各増幅回路52、53のいずれかに故障の可能性があることを診断することとなる。
The self-diagnosis circuit 55 inputs the sine wave signal Vs and the cosine wave signal Vc from the sensor element 40, and determines the failure of the sensor element 40 or each of the amplification circuits 52 and 53 based on the sine wave signal Vs and the cosine wave signal Vc. Do. Since the sine wave signal Vs and the cosine wave signal Vc are signals obtained via the sensor element 40 and the amplifier circuits 52 and 53, the self-diagnosis circuit 55 is one of the sensor element 40 and the amplifier circuits 52 and 53. It is diagnosed that there is a possibility of failure.
具体的に、自己診断回路55は、Vs2とVc2との和を演算し、この演算結果と予め設定された故障判定値とを比較することにより、センサ素子40の故障判定を行う。故障判定値は、Vs2+Vc2の正常値の範囲と異常値の範囲との境界値すなわち閾値であり、製品出荷時に自己診断回路55に設けられた記憶部に記憶される。
Specifically, the self-diagnosis circuit 55 calculates the sum of Vs 2 and Vc 2, and compares the calculation result with a preset failure determination value to determine a failure of the sensor element 40. The failure determination value is a boundary value, that is, a threshold value between a normal value range and an abnormal value range of Vs 2 + Vc 2 , and is stored in a storage unit provided in the self-diagnosis circuit 55 at the time of product shipment.
そして、センサ素子40が正常に動作している場合、上述のように、正弦波信号VsはVs=A・sinθで表され、余弦波信号VcはVc=A・cosθで表される。したがって、Vs2とVc2との和は、Vs2+Vc2=A2(sin2θ+cos2θ)=A2となる。すなわち、Vs2とVc2との和は、図4に示されるように、被検出電流Iの電流値に関らず一定の値となる。このような場合、自己診断回路55はA2と故障判定値とを比較し、演算結果であるA2が正常範囲に含まれていると判定すると共にセンサ素子40や各増幅回路52、53は正常であると判定する。
When the sensor element 40 is operating normally, as described above, the sine wave signal Vs is represented by Vs = A · sin θ, and the cosine wave signal Vc is represented by Vc = A · cos θ. Therefore, the sum of Vs 2 and Vc 2 is Vs 2 + Vc 2 = A 2 (sin 2 θ + cos 2 θ) = A 2 . That is, the sum of Vs 2 and Vc 2 is a constant value regardless of the current value of the detected current I, as shown in FIG. In such a case, the self-diagnosis circuit 55 compares the failure determination value and A 2, the sensor element 40 and the amplifier circuits 52 and 53 as well as determined that the operation result A 2 is included in the normal range Determined to be normal.
一方、センサ素子40の劣化等により、異常が発生した場合、正弦波信号Vsや余弦波信号Vcに故障の成分が含まれる。例えば、正弦波信号Vsにオフセット変動が生じた場合、正弦波信号VsはVs=A・sinθ+Voffsで表される。このため、Vs2とVc2との和にはVoffsの成分やsinθの成分が含まれる。したがって、図5に示されるように、Vs2とVc2との和は電流値に対して一定にならない。Voffsが正弦波信号Vsに含まれる故障の成分に相当する。
On the other hand, when an abnormality occurs due to deterioration of the sensor element 40 or the like, the sine wave signal Vs or the cosine wave signal Vc includes a failure component. For example, when an offset variation occurs in the sine wave signal Vs, the sine wave signal Vs is expressed by Vs = A · sin θ + Voffs. For this reason, the sum of Vs 2 and Vc 2 includes a component of Voffs and a component of sin θ. Therefore, as shown in FIG. 5, the sum of Vs 2 and Vc 2 is not constant with respect to the current value. Voffs corresponds to a failure component included in the sine wave signal Vs.
また、余弦波信号Vcにオフセット変動が生じた場合、余弦波信号VcはVc=A・cosθ+Voffcで表される。このため、Vs2とVc2との和にはVoffcの成分やcosθの成分が含まれる。したがって、図6に示されるように、Vs2とVc2との和は電流値に対して一定にならない。Voffcは余弦波信号Vcに含まれる故障の成分に相当する。
When an offset variation occurs in the cosine wave signal Vc, the cosine wave signal Vc is expressed by Vc = A · cos θ + Voffc. Therefore, the sum of Vs 2 and Vc 2 includes a component of Voffc and a component of cos θ. Therefore, as shown in FIG. 6, the sum of Vs 2 and Vc 2 is not constant with respect to the current value. Voffc corresponds to a failure component included in the cosine wave signal Vc.
このように、Vs2とVc2との和が電流値に対して一定にならない場合、Vs2とVc2との和は、正常範囲を超える。したがって、自己診断回路55はVs2とVc2との和と故障判定値とを比較し、演算結果が異常であると判定すると共にセンサ素子40や各増幅回路52、53のいずれかに異常が発生していると判定する。
Thus, when the sum of Vs 2 and Vc 2 is not constant with respect to the current value, the sum of Vs 2 and Vc 2 exceeds the normal range. Accordingly, the self-diagnosis circuit 55 compares the sum of Vs 2 and Vc 2 with the failure determination value, determines that the calculation result is abnormal, and abnormalities are detected in either the sensor element 40 or each of the amplifier circuits 52 and 53. It is determined that it has occurred.
自己診断回路55は、上記のように故障判定を行った後、ダイアグ端子58を介して故障診断結果を外部に出力する。具体的には、図7に示されるように、自己診断結果が正常の場合、自己診断回路55は通常動作時の出力電圧を自己診断結果が正常である時の出力電圧として出力する。すなわち、自己診断結果が正常である時、自己診断回路55はダイアグ端子58に印加する電圧を変化させない。
The self-diagnosis circuit 55 outputs a failure diagnosis result to the outside via the diagnosis terminal 58 after performing the failure determination as described above. Specifically, as shown in FIG. 7, when the self-diagnosis result is normal, the self-diagnosis circuit 55 outputs the output voltage during normal operation as the output voltage when the self-diagnosis result is normal. That is, when the self-diagnosis result is normal, the self-diagnosis circuit 55 does not change the voltage applied to the diagnosis terminal 58.
一方、自己診断結果が異常の場合、自己診断回路55は通常動作時よりも高い出力電圧を出力する。すなわち、自己診断結果が異常である時、自己診断回路55はダイアグ端子58に印加する電圧を変化させる。このようにして、自己診断回路55は外部に異常を伝える。
On the other hand, when the self-diagnosis result is abnormal, the self-diagnosis circuit 55 outputs a higher output voltage than that during normal operation. That is, when the self-diagnosis result is abnormal, the self-diagnosis circuit 55 changes the voltage applied to the diagnosis terminal 58. In this way, the self-diagnosis circuit 55 transmits an abnormality to the outside.
以上説明したように、本実施形態では、正弦波信号Vs及び余弦波信号Vcの2つの信号に基づいて故障診断を行う自己診断回路55を備えている。また、自己診断回路55は、正弦波信号Vs及び余弦波信号Vcの角度成分を利用して故障診断を行うので、故障診断のためのセンサ素子40及び出力演算回路54の別途の構成を不要とすることができる。したがって、電流センサ10に備えられた1つのセンサ素子40及び1つの出力演算回路54によって自己診断を可能とすることができる。
As described above, the present embodiment includes the self-diagnosis circuit 55 that performs failure diagnosis based on the two signals of the sine wave signal Vs and the cosine wave signal Vc. Further, since the self-diagnosis circuit 55 performs failure diagnosis using the angle components of the sine wave signal Vs and the cosine wave signal Vc, separate configurations of the sensor element 40 and the output arithmetic circuit 54 for failure diagnosis are unnecessary. can do. Therefore, the self-diagnosis can be enabled by one sensor element 40 and one output arithmetic circuit 54 provided in the current sensor 10.
ここで、バスバー80に流れる被検出電流Iは常に一定の値ではない。このような「電流」という測定対象に対して電流センサ10は電流値の平均値やピーク値を検出することになる。したがって、電流センサ10が検出した電流値が本当に正しい値であるかを確かめるためには、従来は全く同じ構成の電流検出部を設けて両者の値を比較しなければならなかった。しかしながら、本実施形態に係る電流センサ10は、故障の成分が含まれた正弦波信号Vs及び余弦波信号Vcを用いて故障判定を行っている。したがって、センサ素子40の出力と、全く同じ構成の他のセンサ素子の出力と、の比較を行う必要がなく、自己診断回路55を設けるだけで電流センサ10の自己診断機能を実現することができる。
Here, the detected current I flowing through the bus bar 80 is not always a constant value. The current sensor 10 detects an average value or a peak value of the current value for such a measurement object “current”. Therefore, in order to confirm whether or not the current value detected by the current sensor 10 is a really correct value, conventionally, it has been necessary to provide a current detection unit having exactly the same configuration and compare both values. However, the current sensor 10 according to the present embodiment performs failure determination using the sine wave signal Vs and the cosine wave signal Vc including the failure component. Therefore, it is not necessary to compare the output of the sensor element 40 with the output of another sensor element having the same configuration, and the self-diagnosis function of the current sensor 10 can be realized only by providing the self-diagnosis circuit 55. .
なお、電流磁界Biが本開示の「第1磁界」に対応する。バイアス磁界Bbが本開示の「第2磁界」に対応する。また、バイアス磁石30が本開示の「磁界発生部」に対応する。バスバー80が本開示の「被検出電流経路」に対応する。
The current magnetic field Bi corresponds to the “first magnetic field” of the present disclosure. The bias magnetic field Bb corresponds to the “second magnetic field” of the present disclosure. The bias magnet 30 corresponds to a “magnetic field generation unit” of the present disclosure. The bus bar 80 corresponds to the “detected current path” of the present disclosure.
(第2実施形態)
本実施形態では、第1実施形態と異なる部分について説明する。本実施形態では、自己診断回路55は、正弦波信号Vs及び余弦波信号Vcによって描かれるリサージュ波形に基づいて故障判定を行う。 (Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. In the present embodiment, the self-diagnosis circuit 55 performs failure determination based on the Lissajous waveform drawn by the sine wave signal Vs and the cosine wave signal Vc.
本実施形態では、第1実施形態と異なる部分について説明する。本実施形態では、自己診断回路55は、正弦波信号Vs及び余弦波信号Vcによって描かれるリサージュ波形に基づいて故障判定を行う。 (Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. In the present embodiment, the self-
すなわち、自己診断回路55は各増幅回路52、53から入力した正弦波信号Vs及び余弦波信号Vcによってリサージュ波形を描く。リサージュ波形は、図8に示されるように、正弦波信号Vs及び余弦波信号Vcの二つの単振動を合成して直交座標上に描かれる平面図形である。図8は、例えば製品出荷時の正常なリサージュ波形である。
That is, the self-diagnosis circuit 55 draws a Lissajous waveform by the sine wave signal Vs and the cosine wave signal Vc input from the amplifier circuits 52 and 53. As shown in FIG. 8, the Lissajous waveform is a plane figure drawn on orthogonal coordinates by synthesizing two simple vibrations of the sine wave signal Vs and the cosine wave signal Vc. FIG. 8 shows a normal Lissajous waveform at the time of product shipment, for example.
そして、正弦波信号Vsにオフセット変動が生じた場合、図9に示されるように、リサージュ波形は正常時からsinθ軸方向に移動する。余弦波信号Vcにオフセット変動が生じた場合、図10に示されるように、リサージュ波形は正常時からcosθ軸方向に移動する。
When the offset fluctuation occurs in the sine wave signal Vs, the Lissajous waveform moves in the sin θ-axis direction from the normal time as shown in FIG. When an offset variation occurs in the cosine wave signal Vc, the Lissajous waveform moves in the cos θ axis direction from the normal time as shown in FIG.
したがって、自己診断回路55は、正弦波信号Vs及び余弦波信号Vcによって描かれたリサージュ波形と、予め設定された製品出荷時のリサージュ波形に基づく故障判定値と、を比較することにより、センサ素子40の故障判定を行う。すなわち、自己診断回路55は、製品出荷時の円波形から所定量だけ外れたか否かを判定する。以上のように、リサージュ波形を描くことにより、故障を視覚的に容易に判定することができる。
Accordingly, the self-diagnosis circuit 55 compares the Lissajous waveform drawn by the sine wave signal Vs and the cosine wave signal Vc with a failure determination value based on a preset Lissajous waveform at the time of product shipment, thereby obtaining a sensor element. 40 failure determinations are made. That is, the self-diagnosis circuit 55 determines whether or not a predetermined amount has deviated from the circular waveform at the time of product shipment. As described above, the failure can be easily visually determined by drawing the Lissajous waveform.
(第3実施形態)
本実施形態では、第1、第2実施形態と異なる部分について説明する。本実施形態では、自己診断回路55は、sinθと(1-cos2θ)1/2とを比較するか、または、(1-sin2θ)1/2とcosθとを比較することにより、センサ素子40の故障判定を行う。このように、正弦及び余弦をsinθもしくはcosθで表すことができる。したがって、自己診断回路55は、故障判定値を用いずに、正弦波信号Vs及び余弦波信号Vcを用いて故障判定を行うこともできる。 (Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. In the present embodiment, the self-diagnosis circuit 55 compares sin θ with (1-cos 2 θ) 1/2 or compares (1-sin 2 θ) 1/2 with cos θ. The failure determination of the sensor element 40 is performed. Thus, the sine and cosine can be expressed by sin θ or cos θ. Therefore, the self-diagnosis circuit 55 can also perform failure determination using the sine wave signal Vs and the cosine wave signal Vc without using the failure determination value.
本実施形態では、第1、第2実施形態と異なる部分について説明する。本実施形態では、自己診断回路55は、sinθと(1-cos2θ)1/2とを比較するか、または、(1-sin2θ)1/2とcosθとを比較することにより、センサ素子40の故障判定を行う。このように、正弦及び余弦をsinθもしくはcosθで表すことができる。したがって、自己診断回路55は、故障判定値を用いずに、正弦波信号Vs及び余弦波信号Vcを用いて故障判定を行うこともできる。 (Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. In the present embodiment, the self-
(第4実施形態)
本実施形態では、第1~第3実施形態と異なる部分について説明する。図11に示されるように、本実施形態に係る回路チップ50では、自己診断回路55が出力端子57A(Vout/Diag)に接続されている。これにより、自己診断回路55は、出力端子57Aを介して外部に自己診断結果を出力する。言い換えると、出力端子57Aはセンサ信号と自己診断結果の両方を出力する端子に相当する。 (Fourth embodiment)
In the present embodiment, parts different from the first to third embodiments will be described. As shown in FIG. 11, in thecircuit chip 50 according to the present embodiment, the self-diagnosis circuit 55 is connected to the output terminal 57A (Vout / Diag). As a result, the self-diagnosis circuit 55 outputs the self-diagnosis result to the outside via the output terminal 57A. In other words, the output terminal 57A corresponds to a terminal that outputs both the sensor signal and the self-diagnosis result.
本実施形態では、第1~第3実施形態と異なる部分について説明する。図11に示されるように、本実施形態に係る回路チップ50では、自己診断回路55が出力端子57A(Vout/Diag)に接続されている。これにより、自己診断回路55は、出力端子57Aを介して外部に自己診断結果を出力する。言い換えると、出力端子57Aはセンサ信号と自己診断結果の両方を出力する端子に相当する。 (Fourth embodiment)
In the present embodiment, parts different from the first to third embodiments will be described. As shown in FIG. 11, in the
通常、出力演算回路54は、図12に示されるように、一定範囲内の通常状態出力電圧の電圧を出力する。しかしながら、自己診断回路55は、センサ素子40が故障していると判定した場合、出力演算回路54の出力を変化させる。
Normally, as shown in FIG. 12, the output arithmetic circuit 54 outputs the voltage of the normal state output voltage within a certain range. However, when the self-diagnosis circuit 55 determines that the sensor element 40 has failed, the self-diagnosis circuit 55 changes the output of the output arithmetic circuit 54.
具体的には、自己診断回路55は、一定範囲の通常状態出力電圧を超えた電圧値を出力端子57Aに印加する。本実施形態では、自己診断回路55は、自己診断結果が異常である時、一定範囲の通常状態出力電圧の最大値よりも高い電圧を出力する。このようにして、出力端子57Aを介して自己診断結果を外部に出力することもできる。また、ダイアグ端子58を不要とすることができ、回路チップ50の構成を簡略化することができる。
Specifically, the self-diagnosis circuit 55 applies a voltage value exceeding the normal state output voltage within a certain range to the output terminal 57A. In the present embodiment, the self-diagnosis circuit 55 outputs a voltage higher than the maximum value of the normal state output voltage within a certain range when the self-diagnosis result is abnormal. In this way, the self-diagnosis result can be output to the outside via the output terminal 57A. Further, the diagnosis terminal 58 can be omitted, and the configuration of the circuit chip 50 can be simplified.
(他の実施形態)
上記各実施形態で示された電流センサ10の構成は一例であり、上記で示した構成に限定されることなく、本開示を実現できる他の構成としてもよい。例えば、バイアス磁石30とセンサ素子40との配置関係については、上述のように各磁気抵抗素子41~48のピン磁性層の磁化方向とバイアス磁界Bbの方向との関係が維持できれば、どのような配置関係でも良い。 (Other embodiments)
The configuration of thecurrent sensor 10 shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present disclosure. For example, regarding the positional relationship between the bias magnet 30 and the sensor element 40, as long as the relationship between the magnetization direction of the pin magnetic layer of each of the magnetoresistive elements 41 to 48 and the direction of the bias magnetic field Bb can be maintained as described above, An arrangement relationship may be used.
上記各実施形態で示された電流センサ10の構成は一例であり、上記で示した構成に限定されることなく、本開示を実現できる他の構成としてもよい。例えば、バイアス磁石30とセンサ素子40との配置関係については、上述のように各磁気抵抗素子41~48のピン磁性層の磁化方向とバイアス磁界Bbの方向との関係が維持できれば、どのような配置関係でも良い。 (Other embodiments)
The configuration of the
上記各実施形態では、センサ素子40の各磁気抵抗素子41~48はTMR素子であるが、GMR素子であっても良い。
In each of the above embodiments, each of the magnetoresistive elements 41 to 48 of the sensor element 40 is a TMR element, but may be a GMR element.
上記各実施形態では、各増幅回路52、53が回路チップ50に設けられていたが、センサ素子40に設けられていても良い。この場合であっても、出力演算回路54は正弦波信号Vs及び余弦波信号Vcに対して所定の演算を行う。
In each of the above embodiments, the amplifier circuits 52 and 53 are provided in the circuit chip 50, but may be provided in the sensor element 40. Even in this case, the output calculation circuit 54 performs a predetermined calculation on the sine wave signal Vs and the cosine wave signal Vc.
第4実施形態では、自己診断回路55は、自己診断結果が異常である時、一定範囲の通常状態出力電圧の最大値よりも高い電圧を出力していたが、一定範囲の通常状態出力電圧の最小値よりも低い電圧を出力するようにしても良い。
In the fourth embodiment, the self-diagnosis circuit 55 outputs a voltage higher than the maximum value of the normal state output voltage within a certain range when the self-diagnosis result is abnormal. A voltage lower than the minimum value may be output.
さらに、上記各実施形態では、電流センサ10は車載バッテリ等に接続されるバスバー80に流れる被検出電流Iを測定するが、これは電流センサ10の適用の一例である。したがって、測定対象は車両用のバスバー80に限られず、他の用途に用いられる配線に電流センサ10を適用しても良い。
Further, in each of the embodiments described above, the current sensor 10 measures the detected current I flowing in the bus bar 80 connected to the vehicle-mounted battery or the like. This is an example of application of the current sensor 10. Therefore, the measurement target is not limited to the vehicle bus bar 80, and the current sensor 10 may be applied to wiring used for other purposes.
本開示に係る電流センサは、被検出電流経路に被検出電流が流れることによって生じる第1磁界に対して垂直方向に第2磁界を発生させる磁界発生部を備えている。
The current sensor according to the present disclosure includes a magnetic field generation unit that generates a second magnetic field in a direction perpendicular to the first magnetic field generated when the detected current flows through the detected current path.
電流センサは、複数の磁気抵抗素子を有し、複数の磁気抵抗素子が外部の磁場の影響を受けたときの複数の磁気抵抗素子の抵抗値の変化に基づいて、第2磁界と、第1磁界及び第2磁界で構成される合成磁界と、の成す角度θに応じた正弦値を含む正弦波信号及び余弦値を含む余弦波信号を出力するセンサ素子を備えている。
The current sensor has a plurality of magnetoresistive elements, and based on a change in resistance values of the plurality of magnetoresistive elements when the plurality of magnetoresistive elements are affected by an external magnetic field, A sensor element is provided that outputs a sine wave signal including a sine value corresponding to an angle θ formed by a combined magnetic field composed of a magnetic field and a second magnetic field, and a cosine wave signal including a cosine value.
また、電流センサは、センサ素子から正弦波信号及び余弦波信号を入力し、正弦波信号及び余弦波信号に対して所定の演算を行うことにより被検出電流の大きさに対応したセンサ信号を出力する出力演算回路を備えている。
The current sensor inputs a sine wave signal and a cosine wave signal from the sensor element, and outputs a sensor signal corresponding to the magnitude of the detected current by performing a predetermined calculation on the sine wave signal and the cosine wave signal. An output arithmetic circuit is provided.
さらに、電流センサは、センサ素子から正弦波信号及び余弦波信号を入力すると共に、正弦波信号及び余弦波信号に基づいてセンサ素子の故障判定を行う自己診断回路を備えている。
Furthermore, the current sensor is provided with a self-diagnosis circuit that inputs a sine wave signal and a cosine wave signal from the sensor element and performs failure determination of the sensor element based on the sine wave signal and the cosine wave signal.
このように、センサ素子が出力する正弦波信号及び余弦波信号の2つの信号に基づいて故障診断を行う自己診断回路を備えているので、故障診断のためのセンサ素子及び出力演算回路を別途設ける必要がない。したがって、1つのセンサ素子及び1つの出力演算回路を備えた電流センサにおいて自己診断を可能とすることができる。
As described above, since the self-diagnosis circuit that performs the failure diagnosis based on the two signals of the sine wave signal and the cosine wave signal output from the sensor element is provided, a sensor element and an output arithmetic circuit for failure diagnosis are separately provided. There is no need. Therefore, a self-diagnosis can be performed in a current sensor including one sensor element and one output arithmetic circuit.
以上、本開示の実施形態、構成、態様を例示したが、本開示に係わる実施形態、構成、態様は、上述した各実施形態、各構成、各態様に限定されるものではない。例えば、異なる実施形態、構成、態様にそれぞれ開示された技術的部を適宜組み合わせて得られる実施形態、構成、態様についても本開示に係わる実施形態、構成、態様の範囲に含まれる。
The embodiments, configurations, and aspects of the present disclosure have been illustrated above, but the embodiments, configurations, and aspects according to the present disclosure are not limited to the above-described embodiments, configurations, and aspects. For example, embodiments, configurations, and aspects obtained by appropriately combining technical units disclosed in different embodiments, configurations, and aspects are also included in the scope of the embodiments, configurations, and aspects according to the present disclosure.
Claims (6)
- 被検出電流経路(80)に被検出電流が流れることによって生じる第1磁界(Bi)に対して垂直方向に第2磁界(Bb)を発生させる磁界発生部(30)と、
複数の磁気抵抗素子(41~48)を有し、前記複数の磁気抵抗素子(41~48)が外部の磁場の影響を受けたときの前記複数の磁気抵抗素子(41~48)の抵抗値の変化に基づいて、前記第2磁界(Bb)と、前記第1磁界(Bi)及び前記第2磁界(Bb)で構成される合成磁界(Bs)と、の成す角度θに応じた正弦値を含む正弦波信号及び余弦値を含む余弦波信号を出力するセンサ素子(40)と、
前記センサ素子(40)から前記正弦波信号及び前記余弦波信号を入力し、前記正弦波信号及び前記余弦波信号に対して所定の演算を行うことにより前記被検出電流の大きさに対応したセンサ信号を出力する出力演算回路(54)と、
を備え、さらに、
前記センサ素子(40)から前記正弦波信号及び前記余弦波信号を入力すると共に、前記正弦波信号及び前記余弦波信号に基づいて前記センサ素子(40)の故障判定を行う自己診断回路(55)を備えている電流センサ。 A magnetic field generator (30) for generating a second magnetic field (Bb) in a direction perpendicular to the first magnetic field (Bi) generated by the detected current flowing through the detected current path (80);
The plurality of magnetoresistive elements (41 to 48) have a resistance value when the plurality of magnetoresistive elements (41 to 48) are affected by an external magnetic field. Is a sine value corresponding to an angle θ formed by the second magnetic field (Bb) and the combined magnetic field (Bs) composed of the first magnetic field (Bi) and the second magnetic field (Bb). A sensor element (40) for outputting a sine wave signal including a cosine wave signal including a cosine value;
A sensor corresponding to the magnitude of the detected current by inputting the sine wave signal and the cosine wave signal from the sensor element (40) and performing a predetermined calculation on the sine wave signal and the cosine wave signal. An output arithmetic circuit (54) for outputting a signal;
In addition,
A self-diagnosis circuit (55) for inputting the sine wave signal and the cosine wave signal from the sensor element (40) and determining a failure of the sensor element (40) based on the sine wave signal and the cosine wave signal. Equipped with a current sensor. - 前記正弦波信号をVsとし、前記余弦波信号をVcと定義すると、
前記自己診断回路(55)は、Vs2とVc2との和と、故障判定値と、を比較することにより、前記センサ素子(40)の故障判定を行う請求項1に記載の電流センサ。 When the sine wave signal is defined as Vs and the cosine wave signal is defined as Vc,
The self-diagnosis circuit (55), by comparing the sum of Vs 2 and Vc 2, the failure determination value, the current sensor according to claim 1 for failure determination of the sensor element (40). - 前記自己診断回路(55)は、前記正弦波信号及び前記余弦波信号によって描かれるリサージュ波形と、故障判定値と、を比較することにより、前記センサ素子(40)の故障判定を行う請求項1に記載の電流センサ。 The self-diagnosis circuit (55) determines a failure of the sensor element (40) by comparing a Lissajous waveform drawn by the sine wave signal and the cosine wave signal with a failure determination value. The current sensor described in 1.
- 前記正弦波信号はsinθを含んだ信号であると共に、前記余弦波信号はcosθを含んだ信号であり、
前記自己診断回路(55)は、sinθと(1-cos2θ)1/2とを比較することにより、または、(1-sin2θ)1/2とcosθとを比較することにより、前記センサ素子(40)の故障判定を行う請求項1に記載の電流センサ。 The sine wave signal is a signal including sin θ, and the cosine wave signal is a signal including cos θ,
The self-diagnosis circuit (55) compares the sin θ with (1-cos 2 θ) 1/2 or compares the (1-sin 2 θ) 1/2 with cos θ. The current sensor according to claim 1, wherein a failure determination of the sensor element (40) is performed. - 前記自己診断回路(55)の故障診断結果を外部に出力するダイアグ端子(58)を備えている請求項1ないし4のいずれか1つに記載の電流センサ。 The current sensor according to any one of claims 1 to 4, further comprising a diagnosis terminal (58) for outputting a failure diagnosis result of the self-diagnosis circuit (55) to the outside.
- 前記自己診断回路(55)は、前記センサ素子(40)が故障していると判定した場合、前記出力演算回路(54)の出力を変化させる請求項1ないし4のいずれか1つに記載の電流センサ。 The said self-diagnosis circuit (55) changes the output of the said output arithmetic circuit (54), when it determines with the said sensor element (40) having failed, The one of Claims 1 thru | or 4 Current sensor.
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