WO2014147996A1

WO2014147996A1 - Current sensor

Info

Publication number: WO2014147996A1
Application number: PCT/JP2014/001364
Authority: WO
Inventors: 江介野村
Original assignee: 株式会社デンソー
Priority date: 2013-03-19
Filing date: 2014-03-11
Publication date: 2014-09-25
Also published as: JP2014181981A

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

Current sensor

Cross-reference of related applications

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.

The present disclosure relates to a current sensor including a self-diagnosis circuit.

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.

Japanese published patent publication 2000-275279

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.

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.

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.

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.

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.

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.

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.

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.

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.

(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.

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.

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. 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).

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.

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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. .

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.

(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.

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.

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.

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.

(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.

(Fourth embodiment)
In the present embodiment, parts different from the first to third embodiments will be described. As shown in FIG. 11, in the circuit 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.

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.

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.

(Other embodiments)
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. 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.

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.

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.

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.

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.

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.

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

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.
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).
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.
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.
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.
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.