Current sensor

Abstract

A first magnetic detection element (21), a second magnetic detection element (22), and a third magnetic detection element (23) for detecting a magnetic field produced by a current flowing in a bus bar are provided at positions at different distances from the bus bar with respect to a first direction. Each magnetic field detection element detects, in addition to the magnetic field produced from the bus bar, magnetic fields produced by a plurality of external magnetic field sources other than the bus bar. A current detection circuit (10) performs signal processing of: correcting, in accordance with magnetic field detection signals outputted by the first magnetic detection element (21), the second magnetic detection element (22), and the third magnetic detection element (23), the magnetic field detection signals so as to cancel the magnetic fields produced by the external magnetic field sources other than the bus bar; and outputting the corrected detection signal as a detection signal for the current flowing in the bus bar.

Description

Current Sensor

[0001] The present invention relates to a current sensor.

[0002] A prior art document disclosing the configuration of a current measuring device is Japanese Patent Laid-Open Publication No. 2005-195427 (Patent Document 1). The current measuring device disclosed in Patent Document 1 includes multiple magnetic sensors and a signal processing means. The signal processing means calculates the value of the current flowing through the conductor under measurement based on output signals that reflect differences in the current sensitivities of the magnetic sensors.

[0003] Japanese Patent Application Laid-Open No. 2005-195427

[0004] In the current measuring device described in Patent Document 1, an external magnetic field can be canceled only when a uniform external magnetic field acts on the multiple magnetic sensors. However, in the current measuring device described in Patent Document 1, when a non-uniform external magnetic field acts on the magnetic sensors, such as when external magnetic fields generated by multiple external magnetic field sources act on the magnetic sensors, there is a risk that the detection accuracy of the current flowing through the conductor to be measured will decrease.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a current sensor that can improve the detection accuracy of the current flowing through the bus bar to be detected, even when external magnetic fields generated by multiple external magnetic field sources act on the magnetic field detection element.

[0006] According to an aspect of the present disclosure, there is provided a current sensor including at least three magnetic field detection elements that detect a magnetic field generated by a current flowing through a bus bar, and a current detection circuit that outputs a detection signal of the current flowing through the bus bar in response to the magnetic field detection signals output from the at least three magnetic field detection elements. The at least three magnetic field detection elements are disposed at different distances in one direction from the bus bar, and each of the magnetic field detection elements detects a magnetic field generated from the bus bar as well as magnetic fields generated from a plurality of external magnetic field sources other than the bus bar. The current detection circuit performs signal processing in response to the magnetic field detection signals output from the at least three magnetic field detection elements to correct the magnetic field detection signals to cancel the magnetic fields generated from the plurality of external magnetic field sources, and outputs the corrected detection signal as a detection signal of the current flowing through the bus bar.

[0007] According to the present invention, even when external magnetic fields generated from a plurality of external magnetic field sources act on the magnetic field detection element, it is possible to improve the detection accuracy of the current flowing through the bus bar to be detected.

[0008] 1 is a perspective view showing a configuration of a plurality of current sensors according to a first embodiment; FIG. 2 is a side view of the plurality of current sensors of FIG. 1 as viewed from the direction of arrow II; FIG. 3 is a perspective view showing the inside of a magnetic sensor unit; FIG. 4 is a layout diagram of the first magnetic detection element, the second magnetic detection element, the third magnetic detection element, and the bus bar as viewed from the direction of arrow IV in FIG. 3; FIG. 5 is a layout diagram of the first magnetic detection element, the second magnetic detection element, the third magnetic detection element, and the second bus bar as viewed from the direction of arrow V in FIG. 3; FIG. 6 is a diagram showing the relationship between the first magnetic detection element, the second magnetic detection element, and the third magnetic detection element and the first bus bar, the second bus bar, and the third bus bar; FIG. 7 is a circuit diagram showing the configuration of a current detection circuit; FIG. 8 is a layout diagram of the first magnetic detection element, the second magnetic detection element, the third magnetic detection element, and the second bus bar according to a second embodiment; FIG. 9 is a layout diagram of the first magnetic detection element, the second magnetic detection element, the third magnetic detection element, and the second bus bar according to the second embodiment; and FIG. 10 is a circuit diagram showing the configuration of an external magnetic field detection circuit that detects an external magnetic field according to a third embodiment. FIG. 10 is a diagram showing the relationship between the first magnetic detection element, the second magnetic detection element, and the third magnetic detection element and the bus bar and external magnetic fields from other than the bus bar when a plurality of external magnetic fields that affect the second current sensor according to embodiment 4 include an external magnetic field from the bus bar and an external magnetic field from other than the bus bar. FIG. 11 is a diagram showing the external output state of detection signals of the first magnetic detection element, the second magnetic detection element, and the third magnetic detection element in a test mode according to embodiment 5. FIG. 12 is a circuit diagram showing an example of a gain adjustment circuit that can adjust the gains of the first amplifier to the seventh amplifier according to embodiment 5.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. While multiple embodiments will be described below, it is anticipated from the beginning that the configurations described in each embodiment will be appropriately combined. Note that identical or corresponding parts in the drawings will be designated by the same reference numerals, and their description will not be repeated.

[0010] [Embodiment 1] Fig. 1 is a perspective view showing the configuration of a plurality of current sensors according to embodiment 1. Fig. 2 is a side view of the plurality of current sensors of Fig. 1 as seen from the direction of arrow II.

[0011] The first current sensor 100a, the second current sensor 100b, and the third current sensor 100c will be described below with reference to Figures 1 and 2. The multiple current sensors according to the first embodiment of the present invention include the first current sensor 100a, the second current sensor 100b, and the third current sensor 100c.

[0012] The first bus bar 110a, the second bus bar 110b, and the third bus bar 110c, which are the objects of current measurement, are arranged at intervals in a first direction (X-axis direction). For example, the first bus bar 110a, the second bus bar 110b, and the third bus bar 110c are three-phase, three-wire bus bars. A U-phase AC current flows through the first bus bar 110a. A V-phase AC current flows through the second bus bar 110b. A W-phase AC current flows through the third bus bar 110c.

[0013] The first current sensor 100a, the second current sensor 100b, and the third current sensor 100c are arranged at intervals in a first direction (X-axis direction). The first current sensor 100a is provided corresponding to the first bus bar 110a to detect the current in the first bus bar 110a. The second current sensor 100b is provided corresponding to the second bus bar 110b to detect the current in the second bus bar 110b. The third current sensor 100c is provided corresponding to the third bus bar 110c to detect the current in the third bus bar 110c.

[0014] The first current sensor 100a is arranged at a distance from the first bus bar 110a in a second direction (Z-axis direction) perpendicular to the first direction (X-axis direction). The second current sensor 100b is arranged at a distance from the second bus bar 110b in the second direction (Z-axis direction) perpendicular to the first direction (X-axis direction). The third current sensor 100c is arranged at a distance from the third bus bar 110c in the second direction (Z-axis direction) perpendicular to the first direction (X-axis direction).

[0015] Each of the first current sensor 100a, the second current sensor 100b, and the third current sensor 100c includes a magnetic sensor unit 160. The substrate 170 is provided at a position away from the first bus bar 110a, the second bus bar 110b, and the third bus bar 110c, and extends in a first direction (X-axis direction). The three magnetic sensor units 160 are mounted on the substrate 170.

[0016] On the substrate 170, the magnetic sensor unit 160 of the first current sensor 100a is provided at a position facing the first bus bar 110a via the substrate 170. On the substrate 170, the magnetic sensor unit 160 of the second current sensor 100b is provided at a position facing the second bus bar 110b via the substrate 170. On the substrate 170, the magnetic sensor unit 160 of the third current sensor 100c is provided at a position facing the third bus bar 110c via the substrate 170.

[0017] The three magnetic sensor units 160 do not necessarily have to be mounted on one substrate 170. At least one of the three magnetic sensor units 160 may be disposed at a different position in the second direction (Z-axis direction) from the other magnetic sensor units 160.

[0018] Next, the internal configuration of the magnetic sensor unit 160 will be described. Fig. 3 is a perspective view showing the inside of the magnetic sensor unit 160. Fig. 3 shows the magnetic sensor unit 160 in the second current sensor 100b as an example. The configuration of the magnetic sensor unit 160 in the first current sensor 100a is similar to the configuration of the magnetic sensor unit 160 in the second current sensor 100b and the configuration of the magnetic sensor unit 160 in the third current sensor 100c.

[0019] 3, in the magnetic sensor unit 160, a first magnetic detection element 21, a second magnetic detection element 22, a third magnetic detection element 23, a processing circuit 130, etc. are provided inside a housing 140. The housing 140 is made of a thermoplastic resin such as engineering plastic, or a thermosetting resin such as an epoxy resin or a urethane resin.

[0020] 3 , inside the housing 140, the input terminal 150 and the output terminal 151 are electrically connected to the processing circuit 130. The input terminal 150 and the output terminal 151 are drawn out from the inside to the outside of the housing 140 and are electrically connected to an electric circuit (not shown) provided on the substrate 170. The input terminal 150 is drawn out in one direction of a third direction (Y-axis direction) that is perpendicular to each of the first direction (X-axis direction) and the second direction (Z-axis direction), and the output terminal 151 is drawn out in the other direction of the third direction (Y-axis direction).

[0021] The input terminal 150 and the output terminal 151 are configured with a lead frame made of a conductive metal such as copper. When the magnetic sensor unit 160 is configured as a pre-molded package, the base of the housing 140 is molded integrally with the lead frame.

[0022] The input terminal 150 and the output terminal 151 may be formed on a single printed circuit board. The core material of the printed circuit board is made of glass epoxy or a thermosetting resin such as epoxy resin, phenol resin, melamine resin, or urethane resin.

[0023] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged to face a bus bar to be measured, such as the second bus bar 110b, at different distances (heights) in the second direction (Z-axis direction). The distances (heights) from the bus bar to be measured satisfy the relationship: first magnetic detection element 21 < second magnetic detection element 22 < third magnetic detection element 23.

[0024] Such an arrangement is realized by providing a stepped member 20 on the bottom surface of the housing 140, arranging the first magnetic detection element 21 on the bottom surface of the housing 140, arranging the second magnetic detection element 22 on the first step surface of the stepped member 20, and arranging the third magnetic detection element 23 on the second step surface of the stepped member 20. As a result, within the housing 140 of the magnetic sensor unit 160, the first magnetic detection element 21 is provided at the lowest position and the third magnetic detection element 23 is provided at the highest position, with the height relationship being first magnetic detection element 21 < second magnetic detection element 22 < third magnetic detection element 23.

[0025] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are fixed in the areas where they are arranged by a die attach film, an insulating adhesive, a conductive adhesive, or the like.

[0026] The processing circuit 130 is electrically connected to the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23. The processing circuit 130 is configured with an IC chip such as an ASIC (Application Specific Integrated Circuit). The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 and the processing circuit 130 may be configured on a single IC chip. The processing circuit 130 is fixed to a structure 25 provided on the base of the housing 140 by a die attach film, an insulating adhesive, a conductive adhesive, or the like.

[0027] The processing circuit 130 is electrically connected to the input terminal 150 and is supplied with a driving power source. The processing circuit 130 processes the detection signals from the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23. The processing circuit 130 is electrically connected to the output terminal 151, and the detection signals are processed by the processing circuit 130 to produce output signals, which are then output from the output terminal 151.

[0028] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are electrically connected to the processing circuit 130 by wire bonding. The input terminal 150 and the output terminal 151 are electrically connected to the processing circuit 130 by wire bonding. The processing circuit 130 may be electrically connected to a lead frame or a printed circuit board by flip-chip mounting.

[0029] The first magnetic detection element 21, the second magnetic detection element 22, the third magnetic detection element 23, and the processing circuit 130 are coated with a coating material such as silicone resin or epoxy resin. When the magnetic sensor unit 160 is configured as a transfer mold package, the first magnetic detection element 21, the second magnetic detection element 22, the third magnetic detection element 23, and the processing circuit 130 are sealed with mold resin.

[0030] 4 and 5, the positional relationship between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 in the magnetic sensor unit 160, and the positional relationship between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 and a bus bar that is the target of current detection, such as the second bus bar 110b, will be described. The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 in the second current sensor 100b are shown as an example in FIGS.

[0031] Fig. 4 is a layout diagram of the first magnetic detection element 21, the second magnetic detection element 22, the third magnetic detection element 23, and the second bus bar 110b as viewed from the direction of arrow IV in Fig. 3. Fig. 5 is a layout diagram of the first magnetic detection element 21, the second magnetic detection element 22, the third magnetic detection element 23, and the second bus bar 110b as viewed from the direction of arrow V in Fig. 3.

[0032] 4, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged side by side in the third direction (Y-axis direction) above the second bus bar 110b. The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 overlap with the center of the second bus bar 110b in the first direction (X-axis direction).

[0033] As shown in Figure 4, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged in the second direction (Z-axis direction) so that the distance (height) from the second bus bar 110b satisfies the relationship: first magnetic detection element 21 < second magnetic detection element 22 < third magnetic detection element 23.

[0034] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are provided at regular intervals in the second direction (Z-axis direction). Note that the intervals between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 do not have to be regular intervals.

[0035] 5 , the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged at regular intervals in the third direction (Y-axis direction). Note that the intervals between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 do not have to be regular. Furthermore, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 may be arranged at the same position in the third direction (Y-axis direction) as long as they are at different positions in the second direction (Z-axis direction). Specifically, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 may be arranged in an aligned manner in the second direction (Z-axis direction).

[0036] 6 is a diagram showing the relationship between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 and the first bus bar 110a, the second bus bar 110b, and the third bus bar 110c. In FIG. 6, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 in the second current sensor 100b are shown as an example.

[0037] The current I1 flowing through the first bus bar 110a, the current I2 flowing through the second bus bar 110b, and the current I3 flowing through the third bus bar 110c flow along the third direction (Y-axis direction). For example, the currents I1, I2, and I3 flow in one direction in the third direction (Y-axis direction) in each bus bar.

[0038] The flow of currents I1, I2, and I3 generates magnetic fields around first bus bar 110a, second bus bar 110b, and third bus bar 110c, as indicated by dashed arrows in the figure. The first magnetic detection element 21, second magnetic detection element 22, and third magnetic detection element 23 each detect the magnetic fields thus generated.

[0039] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are at different distances from the first bus bar 110a, the second bus bar 110b, and the third bus bar 110c, and therefore may output different values ​​of the detection signals when they detect a magnetic field. For example, the closer the distance from the second bus bar 110b, the more susceptible the element is to the magnetic field generated from the second bus bar 110b. Therefore, the output values ​​of the detection signals may differ, with the relationship being first magnetic detection element 21 > second magnetic detection element 22 > third magnetic detection element 23.

[0040] (Configuration of Current Detection Circuit) Next, a description will be given of the current detection circuit 10 included in the processing circuit 130. Fig. 7 is a circuit diagram showing the configuration of the current detection circuit 10. Fig. 7 shows the configuration of the current detection circuit 10 in the second current sensor 100b as an example.

[0041] The current detection circuit 10 is an analog circuit configured by connecting circuit elements such as amplifiers, and receives detection signals from the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23, and outputs a detection voltage V indicating the current detection value in accordance with these detection signals.

[0042] The current detection circuit 10 includes a first amplifier circuit 3, a second amplifier circuit 4, a third amplifier circuit 5, and a fourth amplifier circuit 6. The first amplifier circuit 3 includes a first amplifier 31, a second amplifier 32, and a third amplifier 33. The second amplifier circuit 4 includes a fourth amplifier 41 and a fifth amplifier 42. The third amplifier circuit 5 includes a sixth amplifier 51. The fourth amplifier circuit 6 includes a seventh amplifier 61. The first amplifier 31 to the seventh amplifier 61 are each composed of an operational amplifier that performs differential amplification.

[0043] The first magnetic detection element 21 has a Wheatstone bridge type bridge circuit made up of four TMR (Tunnel Magneto Resistance) elements 24. The second magnetic detection element 22 has a bridge circuit with the same configuration as the first magnetic detection element 21. The third magnetic detection element 23 has a bridge circuit with the same configuration as the first magnetic detection element 21.

[0044] The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 may each include a bridge circuit composed of magnetoresistive elements such as GMR (Giant Magneto Resistance) elements or AMR (Anisotropic Magneto Resistance) elements instead of TMR elements. The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 may each include a half-bridge circuit composed of two magnetoresistive elements. The first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 may each include a Hall element. An IC (integrated circuit) may be incorporated into each of the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23.

[0045] The output signals of the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are passed through the first amplifier circuit 3, the second amplifier circuit 4, the third amplifier circuit 5, and the fourth amplifier circuit 6 in the current detection circuit 10, and are output from the current detection circuit 10 as a detection voltage V.

[0046] The input / output configuration of the first amplifier circuit 3 is as follows: the detection signal of the first magnetic detection element 21 is input to the first amplifier 31. The detection signal of the second magnetic detection element 22 is input to the second amplifier 32. The detection signal of the third magnetic detection element 23 is input to the third amplifier 33. The output signals of the first amplifier 31, the second amplifier 32, and the third amplifier 33 are input to the second amplifier circuit 4.

[0047] The voltage V1 (mV) of the detection signal of the first magnetic detection element 21 input to the first amplifier 31 is expressed by the following equation (1). The voltage V2 (mV) of the detection signal of the second magnetic detection element 22 input to the second amplifier 32 is expressed by the following equation (2). The voltage V3 (mV) of the detection signal of the third magnetic detection element 23 input to the third amplifier 33 is expressed by the following equation (3).

[0048] V1 = S1 Bn1 I1 + S1 B1 I2 + S1 Bm1 I3 (1) V2 = S2 Bn2 I1 + S2 B2 I2 + S2 Bm2 I2 (2) V3 = S3 Bn3 I1 + S3 B3 I2 + S3 Bm3 I2 (3) For reference, equations (1) to (3) are shown as equation 71 in Figure 7.

[0049] The symbols in equations (1) to (3) have the following meanings: S1 is the sensitivity (mV / mT) of the first magnetic detection element 21. Bn1 is a coefficient (mT / A) for the distance between the first magnetic detection element 21 and the first bus bar 101a. I1 is the current value (A) flowing through the first bus bar 101a. B1 is a coefficient (mT / A) for the distance between the first magnetic detection element 21 and the second bus bar 101b. I2 is the current value (A) flowing through the second bus bar 101b. Bm1 is a coefficient (mT / A) for the distance between the first magnetic detection element 21 and the third bus bar 101c. I3 is the current value (A) flowing through the third bus bar 101c.

[0050] S2 is the sensitivity (mV / mT) of the second magnetic detection element 22. Bn2 is a coefficient (mT / A) for the distance between the second magnetic detection element 22 and the first bus bar 101a. I2 is the value of the current (A) flowing through the second bus bar 101b. B2 is a coefficient (mT / A) for the distance between the second magnetic detection element 22 and the second bus bar 101b. Bm2 is a coefficient (mT / A) for the distance between the second magnetic detection element 22 and the third bus bar 101c.

[0051] S3 is the sensitivity (mV / mT) of the third magnetic detection element 23. Bn3 is a coefficient (mT / A) for the distance between the third magnetic detection element 23 and the first bus bar 101a. I3 is the value of the current (A) flowing through the third bus bar 101c. B3 is a coefficient (mT / A) for the distance between the third magnetic detection element 23 and the second bus bar 101b. Bm3 is a coefficient (mT / A) for the distance between the third magnetic detection element 23 and the third bus bar 101c.

[0052] The input / output configuration of the second amplifier circuit 4 is as follows: the output signal of the second amplifier 32 is input to the non-inverting input terminal (+) of the fourth amplifier 41. The output signal of the third amplifier 33 is input to the inverting input terminal (-) of the fourth amplifier 41 and the inverting input terminal (-) of the fifth amplifier 42. The output signal of the first amplifier 31 is input to the non-inverting input terminal (+) of the fifth amplifier 42. The output signals of the fourth amplifier 41 and the fifth amplifier 42 are input to the third amplifier circuit 5.

[0053] The input / output configuration of the third amplifier circuit 5 is as follows: The output signal of the fourth amplifier 41 passes through the third amplifier circuit 5 and is input to the fourth amplifier circuit 6. The output signal of the fifth amplifier 42 is input to the non-inverting input terminal (+) of the sixth amplifier 51. The inverting input terminal (-) of the sixth amplifier 51 is grounded, although not shown. The output signal of the sixth amplifier 51 is input to the fourth amplifier circuit 6.

[0054] The input / output configuration of the fourth amplifier circuit 6 is as follows: The output signal of the fourth amplifier 41 is input to the inverting input terminal (-) of the seventh amplifier 61. The output signal of the sixth amplifier 51 is input to the non-inverting input terminal (+) of the seventh amplifier 61. The output signal of the sixth amplifier 51 is output from the current detection circuit 10 as a detection voltage V indicating the current detection value.

[0055] 7, the gain settings and calculation details for the first amplifier 31 to the seventh amplifier 61 in the current detection circuit 10 will be described. In the first amplifier 31 to the seventh amplifier 61, the gain is set in order to remove, from the voltage V2 shown in equation (2), the components of the voltage value (S2·Bn2·I1) due to the external magnetic field from the first bus bar 101a and the components of the voltage value (S2·Bm3·I3) due to the external magnetic field from the third bus bar 101c.

[0056] The second amplifier 32 is set to a gain (S3·Bn3 / S2·Bn2) for removing the component of the voltage value (S2·Bn2·I1) due to the external magnetic field from the first bus bar 101a as shown in Fig. 7 from the voltage V2 shown in equation (2). The first amplifier 31 is set to a gain (S3·Bn3 / S1·Bn1) for removing the component of the voltage value (S1·Bn1·I1) due to the external magnetic field from the first bus bar 101a from the voltage V1 shown in equation (1). The third amplifier 33 is set to a gain of (1).

[0057] 7, the fourth amplifier 41 subtracts the voltage value V3 of the output signal of the third amplifier 33 from the voltage value (S3·Bn3 / S2·Bn2s)·V2 of the output signal of the second amplifier 32, and outputs a voltage value [(S3·Bn3 / S2·Bn2)·V2-V3] indicating the subtraction result. This makes it possible to remove the component of the voltage value (S2·Bn2·I1) due to the external magnetic field from the first bus bar 101a from the voltage V2 indicated in equation (2).

[0058] 7, the fifth amplifier 42 subtracts the voltage value V3 of the output signal of the third amplifier 33 from the voltage value (S3·Bn3 / S1·Bn1)·V1 of the output signal of the first amplifier 31, and outputs a voltage value [(S3·Bn3 / S1·Bn1)·V1-V3] indicating the subtraction result. This makes it possible to remove the component of the voltage value (S1·Bn1·I1) due to the external magnetic field from the first bus bar 101a from the voltage V1 indicated in equation (1).

[0059] In the sixth amplifier 51, a gain [(Bn3 / Bn2) Bm2 - Bm3] / [(Bn3 / Bn1) Bm1 - Bm3)] is set to remove the component of the voltage value (S2 Bm2 I3) due to the external magnetic field from the third bus bar 101c as shown in Figure 7 from the voltage V2 shown in equation (2).

[0060] In the seventh amplifier 61, the voltage value [(S3·Bn3 / S2·Bn2)·V2−V3] of the output signal of the fourth amplifier 41 as shown in Fig. 7 is subtracted from the voltage value [(Bn3 / Bn2)·Bm2−Bm3] / [(Bn3 / Bn1)·Bm1−Bm3)]×[(S3·Bn3 / S1·Bn1)·V1−V3] of the output signal of the sixth amplifier 51 as shown in Fig. 7. This makes it possible to remove the component of the voltage value (S2·Bm2·I3) due to the external magnetic field from the third bus bar 101c from the voltage V2 shown in equation (2).

[0061] The voltage value V indicating the subtraction result in the seventh amplifier 61 can be rearranged to V=[[(Bn3 / Bn2) Bm2 - Bm3] / [(Bn3 / Bn1) Bm1 - Bm3]] x [(S3 Bn3 B1 / Bn1) - S3 B3] - [(S3 Bn3 B2 / Bn2) - S3 B3]] x I2, as shown as detection voltage formula 72 in Fig. 7. The voltage value V calculated in this way by the seventh amplifier 61 is output from the current detection circuit 10 as the detection voltage V indicating the current detection value by the current detection circuit 10.

[0062] As described above, the current detection circuit 10 removes from voltage V the voltage component due to the external magnetic field from the first bus bar 101a and the voltage component due to the external magnetic field from the third bus bar 101c, in accordance with voltage V indicating the current detected by the first magnetic detection element 21, voltage V indicating the current detected by the second magnetic detection element 22, and voltage V indicating the current detected by the third magnetic detection element 23. This allows the current detection circuit 10 to correct voltage V of the detection signal indicating the current value I of the second bus bar 101b detected by the second magnetic detection element 22 to cancel the external magnetic fields from the first bus bar 101a and the third bus bar 101c. As a result, the current detection circuit 10 can output a detection voltage V indicating the current value of the second bus bar 101b, with the external magnetic fields from the first bus bar 101a and the third bus bar 101c canceled out.

[0063] In this way, the detected voltage V obtained by canceling out the multiple external magnetic fields from the voltage V2 is output from the current detection circuit 10 as a voltage value indicating the current value I2 of the second bus bar 101b detected by the current detection circuit 10. As a result, in the first embodiment, even when external magnetic fields generated from multiple external magnetic field sources, such as the first bus bar 101a and the third bus bar 101c, act on the first to third magnetic detection elements 21 to 23 in a current sensor such as the second current sensor 100b, the detection accuracy of the current flowing through the bus bar to be detected can be improved.

[0064] Specifically, in the first embodiment, even if there are multiple busbars adjacent to a busbar to be detected by the current sensor, it is possible to obtain a detected current value in which the effect of the external magnetic fields generated by the multiple adjacent busbars is canceled, thereby preventing the current sensor from being affected by the external magnetic fields generated by the multiple adjacent busbars. This improves the detection accuracy of the current flowing through the busbar to be detected, even if there are multiple busbars adjacent to the busbar to be detected by the current sensor.

[0065] Furthermore, in embodiment 1, even if there are multiple bus bars arranged adjacent to the bus bar to be detected by the current sensor, the current sensor can be prevented from being affected by the external magnetic field generated by the multiple adjacent bus bars, thereby improving the freedom of arrangement when arranging the bus bars.

[0066] Furthermore, in the first embodiment, even if there are multiple bus bars adjacent to the bus bar to be detected by the current sensor, the current sensor can be prevented from being affected by the external magnetic field generated by the multiple adjacent bus bars, thereby eliminating the need to provide a shield to block the external magnetic field in the current sensor, thereby reducing the manufacturing cost of the current sensor.

[0067] Furthermore, in embodiment 1, the current detection circuit 10 is configured with an analog circuit including the first amplifier 31 to the seventh amplifier 61, so when performing processing related to current detection including correction to cancel multiple external magnetic fields, the processing speed can be increased compared to when the processing is performed digitally.

[0068] In the first embodiment, an example of detecting the current in the second bus bar 101b has been described as an example of the current detection circuit 10. The current detection circuit of the first current sensor 100a that detects the current in the first bus bar 101a and the current detection circuit of the third current sensor 100c that detects the current in the third bus bar 101c can be configured as circuits that perform processing related to current detection, including correction to cancel multiple external magnetic fields, based on the same technical concept as the current detection circuit 10 that detects the current in the second bus bar 101b.

[0069] Furthermore, in the first embodiment, an example of a configuration in which processing related to current detection including correction for canceling a plurality of external magnetic fields is performed using the circuit elements of the first amplifier 31 to the seventh amplifier 61 has been shown as an example of the current detection circuit 10. However, the current detection circuit is not limited to this, and may employ a circuit element configuration other than that shown in FIG. 7 as long as it is capable of performing processing related to current detection including correction for canceling a plurality of external magnetic fields.

[0070] Second Embodiment Next, a second embodiment will be described. In the second embodiment, another example of the arrangement of the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 will be described.

[0071] 8 and 9 are layout diagrams of the first magnetic detection element 21, the second magnetic detection element 22, the third magnetic detection element 23, and the second bus bar 110b according to embodiment 2. Fig. 8 is a layout diagram viewed from the same direction as Fig. 4. Fig. 9 is a layout diagram viewed from the same direction as Fig. 5.

[0072] As shown in Figures 8 and 9, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged so that the distance (height) from the second bus bar 110b in the second direction (Z-axis direction) is the first magnetic detection element 21 < the second magnetic detection element 22 < the third magnetic detection element 23, as in the examples of Figures 4 and 5, but they are not aligned in the third direction (Y-axis direction) as in the examples of Figures 4 and 5.

[0073] As shown in FIGS. 8 and 9, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 only need to differ in at least their distance (height) from the second bus bar 110b.

[0074] 8 and 9 , if the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are arranged such that at least their distances (heights) from the second bus bar 110b are different, the current detection circuit 10 can correct the voltage V2 of the detection signal indicating the current detected by the second magnetic detection element 22 to cancel the external magnetic field from the first bus bar 101a and the external magnetic field from the third bus bar 101c, as in the case of embodiment 1. Therefore, the configuration of embodiment 2 can achieve the same effects as those achieved by the configuration of embodiment 1.

[0075] Furthermore, the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 only need to be arranged at different distances (heights) from the second bus bar 110b, which improves the degree of freedom in arranging the multiple magnetic detection elements. In this way, the degree of freedom in arranging the multiple magnetic detection elements is improved, which provides robustness against installation errors between the magnetic detection elements and against installation errors of the magnetic detection elements relative to the bus bar, thereby improving the ease of manufacturing in the manufacturing process.

[0076] [Third Embodiment] Next, a third embodiment will be described. In the third embodiment, an external magnetic field detection circuit 11 that detects an external magnetic field will be described. Fig. 10 is a circuit diagram showing the configuration of the external magnetic field detection circuit 11 that detects an external magnetic field according to the third embodiment. Fig. 10 shows the configuration of the external magnetic field detection circuit 11 in the second current sensor 100b as an example. The external magnetic field detection circuit 11 is included in the processing circuit 130 together with the current detection circuit 10 described above.

[0077] The external magnetic field detection circuit 11 includes a first amplifier 31 to a seventh amplifier 61 connected in the same manner as the current detection circuit 10. In the first amplifier 31 to the seventh amplifier 61, the gain is set so as to remove the components of the voltage value (S2·Bn2·I1) due to the external magnetic field from the first bus bar 101a and the components of the voltage value (S2·B2·I2) due to the magnetic field from the second bus bar 101b from the voltage V2 shown in equation (2), and to obtain the component of the voltage value (S2·Bm3·I3) due to the external magnetic field from the third bus bar 101c as the value of the external magnetic field.

[0078] The external magnetic field detection circuit 11 differs from the current detection circuit 10 in the gain set in the sixth amplifier 51 and the calculation content in the seventh amplifier 61 .

[0079] Since the configurations and gains of the first amplifier 31 to the fifth amplifier 42 are similar to those of the first amplifier 31 to the fifth amplifier 42 shown in Figure 7, as described above, in the fourth amplifier 41, it is possible to remove the component of the voltage value (S2 x Bn2 x I1) due to the external magnetic field from the first bus bar 101a from the voltage V2 shown in equation (2).

[0080] In the sixth amplifier 51, a gain [(Bn3 / Bn2) B2 - B3] / [(Bn3 / Bn1) B1 - B3)] is set to remove the component of the voltage value (S2 B2 I2) due to the magnetic field from the second bus bar 101b from the voltage V2 shown in equation (2).

[0081] In the seventh amplifier 61, the voltage value [(S3·Bn3 / S2·Bn2)·V2−V3] of the output signal of the fourth amplifier 41 shown in Fig. 10 is subtracted from the voltage value [(Bn3 / Bn2)·B2−B3] / [(Bn3 / Bn1)·B1−B3)]×[(S3·Bn3 / S1·Bn1)·V1−V3] of the output signal of the sixth amplifier 51 shown in Fig. 10. As a result, the component of the voltage value (S2·B2·I2) due to the magnetic field from the second bus bar 101b is removed from the voltage V2 shown in equation (2).

[0082] The voltage value V indicating the subtraction result in the seventh amplifier 61 can be rearranged to obtain V=[[(Bn3 / Bn2) B2 - B3] / [(Bn3 / Bn1) B1 - B3)] × [(S3 Bn3 Bm1 / Bn1) - S3 Bm3] - [(S3 Bn3 Bm2 / Bn2) - S3 Bm3]] × I3, as shown as detection voltage formula 73 in Fig. 10. The voltage value V calculated in this way by the seventh amplifier 61 is output from the external magnetic field detection circuit 11 as the detection voltage V indicating the value of the external magnetic field from the third bus bar 101c detected by the external magnetic field detection circuit 11.

[0083] As described above, the external magnetic field detection circuit 11 removes from voltage V2 the component of the voltage value due to the external magnetic field from the first bus bar 101a and the component of the voltage value due to the magnetic field from the second bus bar 101b, in accordance with voltage V1 indicating the current detected by the first magnetic detection element 21, voltage V2 indicating the current detected by the second magnetic detection element 22, and voltage V3 indicating the current detected by the third magnetic detection element 23. This allows the external magnetic field detection circuit 11 to make a correction to cancel the external magnetic field from the first bus bar 101a and the magnetic field from the second bus bar 101b in voltage V2 of the detection signal indicating the current detected by the second magnetic detection element 22.

[0084] In this way, the voltage V obtained by canceling out the external magnetic field from the first bus bar 101a and the magnetic field from the second bus bar 101b from the voltage V2 is output from the external magnetic field detection circuit 11 as the detected voltage V due to the external magnetic field from the third bus bar 101c. In this way, in the third embodiment, when external magnetic fields generated by a plurality of external magnetic field sources act on the first to third magnetic field detection elements 21 to 23, the external magnetic fields can be detected.

[0085] In the third embodiment, an example in which an external magnetic field from the third bus bar 101c is detected has been described as an example of the external magnetic field detection circuit 11. An external magnetic field detection circuit that detects an external magnetic field from the first bus bar 101a can be configured using the same technical idea as the external magnetic field detection circuit 11 that detects the external magnetic field from the third bus bar 101c. For example, if an external magnetic field detection circuit is configured in such a way that a voltage V obtained by canceling out the external magnetic field from the third bus bar 101c and the magnetic field from the second bus bar 101b from the voltage V is output as a detected voltage V due to the external magnetic field from the first bus bar 101a, the external magnetic field from the first bus bar 101a can be detected.

[0086] As in embodiment 3, when it becomes possible to detect an external magnetic field using the external magnetic field detection circuit 11, it becomes possible to check the magnitude of the external magnetic field in the system in which the current sensor is installed, and it also becomes possible to detect whether an abnormal state is occurring in the entire system.

[0087] In the third embodiment, an example of a configuration in which a process for detecting an external magnetic field is performed using the circuit elements of the first amplifier 31 to the seventh amplifier 61 has been shown as an example of the external magnetic field detection circuit 11. However, the present invention is not limited to this, and the external magnetic field detection circuit may employ a circuit element configuration other than that shown in FIG. 10 as long as it can perform a process related to the detection of a magnetic field from a busbar that is the detection target, and current detection including correction for canceling external magnetic fields from busbars other than the detection target.

[0088] Next, a fourth embodiment will be described. In the fourth embodiment, an example of a current detection circuit and an example of an external magnetic field detection circuit will be described for a case where the multiple external magnetic fields include an external magnetic field from the first bus bar 101a and an external magnetic field from a source other than the bus bar, such as the earth's magnetic field, which is a parallel magnetic field.

[0089] Figure 11 is a diagram showing the relationship between the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 and the first bus bar 110a and an external magnetic field 7 from other than the bus bar when the multiple external magnetic fields that affect the second current sensor 100b according to embodiment 4 include an external magnetic field from the first bus bar 101a and an external magnetic field from other than the bus bar.

[0090] 11 , the multiple external magnetic fields that affect the second current sensor 100b may include an external magnetic field from the first bus bar 101a and an external magnetic field 7 from sources other than the bus bar. In such a case, the voltage V (mV) of the detection signal of the first magnetic detection element 21 is expressed by the following equation (4). The voltage V (mV) of the detection signal of the second magnetic detection element 22 is expressed by the following equation (5). The voltage V (mV) of the detection signal of the third magnetic detection element 23 is expressed by the following equation (6).

[0091] V1 = S1 Bn1 I1 + S1 B1 I2 + S1 Bm (4) V2 = S2 Bn2 I1 + S2 B2 I2 + S2 Bm (5) V3 = S3 Bn3 I1 + S3 B3 I2 + S3 Bm (6) In the above formulas (4), (5), and (6), Bm is a uniform external magnetic field (mT) such as the earth's magnetic field. Regarding formulas (4), (5), and (6), the explanation of the common points with the above formulas (1), (2), and (3) will not be repeated.

[0092] As shown in Figure 11, when the multiple external magnetic fields that affect the second current sensor 100b include an external magnetic field from the first busbar 101a and an external magnetic field 7 from sources other than the busbar, the components of the external magnetic field from the third busbar 101c in the above equations (1), (2), and (3) can be replaced with the components of the external magnetic field 7 from sources other than the busbar, as shown in the above equations (4), (5), and (6).

[0093] Therefore, when the multiple external magnetic fields that affect second current sensor 100b include the external magnetic field from first bus bar 101a and the external magnetic field 7 from sources other than the busbar, a current detection circuit that outputs a detection voltage V obtained by performing a correction in equation (5) to cancel the component of the external magnetic field from first bus bar 101a and a correction to cancel the component of the external magnetic field 7 from sources other than the busbar can be configured based on the same technical concept as current detection circuit 10 in Fig. 7. Use of such a current detection circuit can improve the detection accuracy of the current flowing through the busbar to be detected, even when external magnetic fields generated by multiple external magnetic field sources, including the external magnetic field 7 from sources other than the busbar, act on first to third magnetic detection elements 21 to 23.

[0094] Furthermore, if the multiple external magnetic fields that affect the second current sensor 100b include an external magnetic field from the first bus bar 101a and an external magnetic field 7 from a source other than the bus bar, it is possible to construct an external magnetic field detection circuit that detects the external magnetic field based on the same technical idea as the external magnetic field detection circuit 11 of Figure 10.

[0095] Next, a fifth embodiment will be described. In the fifth embodiment, after current sensors such as the first current sensor 100 a, the second current sensor 100 b, and the third current sensor 100 c are mounted, a current is detected by the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 in the test mode described above, and the gain of amplifiers such as the first amplifier 31 to the seventh amplifier 61 can be adjusted according to the detected current value in the test mode.

[0096] (Configuration in Test Mode) FIG. 12 is a diagram showing the external output states of the detection signals of the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 in the test mode according to the fifth embodiment.

[0097] 12 , there are provided an external output path 81 for outputting the detection signal from the first magnetic detection element 21 to the outside of the current sensor, an external output path 82 for outputting the detection signal from the second magnetic detection element 22 to the outside of the current sensor, and an external output path 83 for outputting the detection signal from the third magnetic detection element 23 to the outside of the current sensor. When the test mode is executed, the gains of the first magnetic detection element 21, the second magnetic detection element 22, and the third magnetic detection element 23 are set to 1.

[0098] The external output path 81 is provided as a path branching off from the output terminal of the first amplifier 31. The external output path 82 is provided as a path branching off from the output terminal of the second amplifier 32. The external output path 83 is provided as a path branching off from the output terminal of the third amplifier 33.

[0099] Each of the external output paths 81, 82, and 83 is provided with a switch or the like for switching the output path between the signal path connected to the next amplifier, and when the test mode is executed, the output path is switched by the switch or the like and an output signal of the corresponding amplifier is supplied. By providing such external output paths 81, 82, and 83, in the test mode, the detection signal from the first magnetic detection element 21, the detection signal from the second magnetic detection element 22, and the detection signal from the output terminal of the third amplifier 33 are output to the outside of the current sensor.

[0100] The sensitivities S1, S2, and S3 and the coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 are set at the time of design. Of these data, the coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 are values ​​that change depending on the distance between the bus bar to be detected and the magnetic detection element. When the current sensor is installed at an actual installation site, the optimal values ​​may be determined at the installation site.

[0101] In order to further improve the detection accuracy of the voltage V indicating the detection value of the current sensor, the detection signal from the first magnetic detection element 21, the detection signal from the second magnetic detection element 22, and the detection signal from the output terminal of the third amplifier 33 can be obtained outside the current sensor in test mode at the installation site, and the coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 corresponding to the installation state of the current sensor at the site can be determined, and the gain of amplifiers such as the first amplifier 31 to the seventh amplifier 61 mentioned above can be adjusted according to the results.

[0102] For example, when setting the gains of the first amplifier 31 to the seventh amplifier 61 using equations (1) to (3), an optimum coefficient that reflects reality can be found based on the detection signal from the first magnetic detection element 21, the detection signal from the second magnetic detection element 22, and the detection signal from the output terminal of the third amplifier 33 obtained in the test mode, and the gain of the amplifier can be adjusted based on the coefficient, as follows:

[0103] The coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 can be calculated, for example, using the following procedure: First, a constant current I1 is passed through only the first bus bar 101a. As a result, in equations (1) to (3), voltages V1 = S1·Bn1·I1, V2 = S2·Bn2·I1, and V3 = S3·Bn2·I1 are output to the outside. In this case, since the sensitivities S1, S2, and S3 and the current I1 are known, the coefficients B1, B2, and B3 can be calculated using the following relationship: V1 = S1·Bn1·I1, V2 = S2·Bn2·I1, and V3 = S3·Bn2·I1. Similarly, if a constant current I2 is passed through only the second bus bar 101b, the coefficients Bn1, Bn2, and Bn3 can be calculated using the same principle. Similarly, when a constant current I3 is passed through only the third bus bar 101c, the coefficients Bm1, Bm2, and Bm3 can be calculated based on the same principle.

[0104] In such a test mode, once the coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 corresponding to the actual installation site are determined, the gains of the aforementioned first amplifier 31 to seventh amplifier 61 need to be adjusted to change to values ​​that reflect these coefficients.

[0105] (Configuration of the circuit that adjusts the gain of the amplifiers) Next, a description will be given of a circuit that adjusts the gain of the first amplifier 31 to the seventh amplifier 61. Fig. 13 is a circuit diagram showing an example of an adjustment circuit 200 that can adjust the gain of each of the first amplifier 31 to the seventh amplifier 61 according to the fifth embodiment. The adjustment circuit 200 is a circuit that can adjust parameters such as gain for circuit elements such as the first amplifier 31 to the seventh amplifier 61 in an analog circuit configured by the first amplifier 31 to the seventh amplifier 61.

[0106] Referring to FIG. 13 , adjustment circuit 200 includes memory 201 and resistor selection circuit 202. Memory 201 stores the gain value of the amplifier to be adjusted. Memory 201 is connected to an input device (not shown) provided externally to the current sensor. A person adjusting the gain of the amplifier inputs data of the adjusted gain from the input device. The gain data input from the input device is stored in memory 201. Resistor selection circuit 202 is a digital circuit that reads out the gain data stored in memory 201 and adjusts the resistance value of a resistor connected to the non-inverting input terminal of amplifier 96 by turning on / off switches 810 to 840 provided in amplifier 96 in order to set the gain corresponding to the read gain data in amplifier 96.

[0107] 13, amplifier 96 is a representative example of the first amplifier 31 to the seventh amplifier 61. An input signal is supplied to the non-inverting input terminal of amplifier 96 from input signal line 80 via resistor 90 (resistance value R0). The inverting input terminal (-) of amplifier 96 is, for example, grounded. Resistors 91 (resistance value R1), 910 (resistance value R10), 92 (resistance value R2), 920 (resistance value R20), 93 (resistance value R3), 930 (resistance value R30), 94 (resistance value R4), and 940 (resistance value R40) are connected in series between the non-inverting input terminal (+) of amplifier 96 and output signal line 85 of amplifier 96.

[0108] A resistor 91 and a switch 810 are connected in parallel between resistors 90 and 910. A resistor 92 and a switch 820 are connected in parallel between resistors 910 and 920. A resistor 93 and a switch 830 are connected in parallel between resistors 920 and 930. A resistor 94 and a switch 840 are connected in parallel between resistors 930 and 940.

[0109] In this configuration, when all of the switches 810 to 840 are turned on, the gain of the amplifier 96 is set to (R10+R20+R30+R40) / R0. Then, the resistor selection circuit 202 appropriately selects the on / off states of the switches 810 to 840 in accordance with the gain data stored in the memory 201, thereby adjusting the gain of the amplifier 96 to the gain corresponding to the gain data stored in the memory 201. Each of the first amplifier 31 to the seventh amplifier 61 has a configuration similar to that of the amplifier 96 shown in FIG. 13, which allows the gain setting to be adjusted individually.

[0110] The configuration shown in FIG. 13 makes it possible to adjust the gains of the first amplifier 31 to the seventh amplifier 61, so that when coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 corresponding to the actual installation site are determined in test mode, the gains of the first amplifier 31 to the seventh amplifier 61 can be adjusted to change to values ​​that reflect these coefficients.

[0111] In this way, in test mode, coefficients B1, B2, B3, Bn1, Bn2, Bn3, Bm1, Bm2, and Bm3 corresponding to the actual installation site are determined, and the gains of the first amplifier 31 to the seventh amplifier 61 are adjusted to values ​​that reflect these coefficients, thereby further improving the detection accuracy of the voltage V that indicates the detection value of the current sensor in accordance with the conditions of the actual installation site of the current sensor.

[0112] In the fifth embodiment, an example is shown in which a plurality of resistors for adjusting the gain of the amplifier 96 are connected in series. However, this is not limiting, and a configuration in which a plurality of resistors for adjusting the gain of the amplifier 96 are connected in parallel may also be adopted.

[0113] Furthermore, the adjustment of the gain of the amplifier 96 according to the fifth embodiment may be used to adjust the gain of the first amplifier 31 to the seventh amplifier 61 included in the external magnetic field detection circuit 11 for detecting the external magnetic field according to the third embodiment.

[0114] [Additional Notes] Next, features of the embodiments of the present disclosure will be summarized.

[0115] <1> The magnetic field detection device includes at least three magnetic field detection elements (first magnetic field detection element 21, second magnetic field detection element 22, third magnetic field detection element 23) that detect a magnetic field generated by a current flowing through a bus bar (second bus bar 110b), and a current detection circuit (current detection circuit 10) that outputs a detection signal of a current flowing through the bus bar in response to a detection signal of a magnetic field output from the at least three magnetic field detection elements (first magnetic field detection element 21, second magnetic field detection element 22, third magnetic field detection element 23), wherein the at least three magnetic field detection elements (first magnetic field detection element 21, second magnetic field detection element 22, third magnetic field detection element 23) are provided at positions that are different in distance in one direction from the bus bar (second bus bar 110b), and each magnetic field detection element detects a magnetic field generated from the bus bar (second bus bar 110b) as well as a magnetic field generated from a plurality of external magnetic field sources other than the bus bar (first bus bar 110a, third bus bar 110c, or external magnetic field 7), The current detection circuit (current detection circuit 10) performs signal processing in response to the magnetic field detection signals output from the at least three magnetic field detection elements (first magnetic detection element 21, second magnetic detection element 22, third magnetic detection element 23), correcting the magnetic field detection signals to cancel out the magnetic fields generated from the multiple external magnetic field sources, and outputting the corrected detection signals as detection signals of the current flowing through the bus bar (second current sensor 100b).

[0116] <2> The current sensor (second current sensor 100b) described in <1>, wherein the current detection circuit (current detection circuit 10) identifies the magnitude of the magnetic field generated from the plurality of external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) according to the output difference of the magnetic field detection signals output from the at least three magnetic field detection elements (first magnetic detection element 21, second magnetic detection element 22, third magnetic detection element 23), and performs correction to cancel the magnetic field generated from the plurality of external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) by subtracting a value according to the identified magnetic field magnitude from the signal value of the magnetic field detection signal.

[0117] <3> The current detection circuit (current detection circuit 10) is a current sensor (second current sensor 100b) described in <1> or <2>, in which signal processing including correction to cancel magnetic fields generated from the multiple external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) is performed by an analog circuit.

[0118] <4> The current sensor (second current sensor 100b) described in <3> further comprising an adjustment circuit (adjustment circuit 200) that adjusts parameters (gains) of circuit elements (first amplifier 31 to seventh amplifier 61) included in the analog circuit.

[0119] <5> The at least three magnetic field detection elements (first magnetic detection element 21, second magnetic detection element 22, third magnetic detection element 23) include a first magnetic field detection element (first magnetic detection element 21), a second magnetic field detection element (second magnetic detection element 22), and a third magnetic field detection element (third magnetic detection element 23), and the current detection circuit (current detection circuit 10) includes: a first amplifier (first amplifier 31) that amplifies a detection signal of the first magnetic field detection element; a second amplifier (second amplifier 32) that amplifies a detection signal of the second magnetic field detection element; a third amplifier (third amplifier 33) that amplifies a detection signal of the third magnetic field detection element; a fourth amplifier (fourth amplifier 41) that amplifies a difference between an output signal of the second amplifier and an output signal of the third amplifier; a fifth amplifier (fifth amplifier 42) that amplifies a difference between an output signal of the first amplifier and an output signal of the third amplifier; and a sixth amplifier (sixth amplifier 51) that amplifies an output signal of the fifth amplifier. a seventh amplifier (seventh amplifier 61) that amplifies a difference between an output signal of the fourth amplifier and an output signal of the sixth amplifier; the first amplifier (first amplifier 31), the second amplifier (second amplifier 32), the third amplifier (third amplifier 33), the fourth amplifier (fourth amplifier 41), and the fifth amplifier (fifth amplifier 42) perform a correction to cancel a magnetic field generated from a first external magnetic field (first bus bar 110a); and the sixth amplifier (sixth amplifier 51) and the seventh amplifier (seventh amplifier 61) perform a correction to cancel a magnetic field generated from a second external magnetic field (third bus bar 110c or external magnetic field 7). The current sensor (second current sensor 100b) according to any one of <1> to <4>.

[0120] <6> The current sensor (second current sensor 100b) according to any one of <1> to <5>, further including an external magnetic field detection circuit (external magnetic field detection circuit 11) that, in response to detection signals output from the at least three magnetic field detection elements (first magnetic field detection element 21, second magnetic field detection element 22, third magnetic field detection element 23), corrects the magnetic field detection signals to cancel a magnetic field generated from any one of the plurality of external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) and a magnetic field generated from the bus bar (second bus bar 110b), and outputs the corrected detection signal as a detection signal of a magnetic field generated from any one of the external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7).

[0121] <7> The current sensor (second current sensor 100b) according to <6>, wherein the external magnetic field detection circuit (external magnetic field detection circuit 11) identifies the magnitude of the magnetic field generated from any of the external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) and the magnetic field generated from the bus bar according to an output difference between the magnetic field detection signals output from the at least three magnetic field detection elements (first magnetic detection element 21, second magnetic detection element 22, third magnetic detection element 23), and subtracts a value according to the identified magnitude of the magnetic field from the signal value of the magnetic field detection signal, thereby performing a correction to cancel the magnetic field generated from any of the external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) and the magnetic field generated from the bus bar (second bus bar 110b).

[0122] <8> The current sensor (second current sensor 100b) described in <7>, wherein the external magnetic field detection circuit (external magnetic field detection circuit 11) uses an analog circuit to perform signal processing including correction to cancel the magnetic field generated from any of the external magnetic field sources (first bus bar 110a, third bus bar 110c, or external magnetic field 7) and the magnetic field generated from the bus bar (second bus bar 110b).

[0123] <9> The current sensor (second current sensor 100b) described in <8> further comprising an adjustment circuit (adjustment circuit 200) that adjusts parameters (gains) of circuit elements (first amplifier 31 to seventh amplifier 61) included in the analog circuit.

[0124] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0125] 21 First magnetic detection element, 22 Second magnetic detection element, 23 Third magnetic detection element, 110a First bus bar, 110b Second bus bar, 110c Third bus bar, 10 Current detection circuit, 100a First current sensor, 100b Second current sensor, 100c Third current sensor, 200 Adjustment circuit.

Claims

1. At least three magnetic field detection elements for detecting a magnetic field generated by a current flowing through the bus bar; a current detection circuit that outputs a detection signal of a current flowing through the bus bar in response to a detection signal of a magnetic field output from the at least three magnetic field detection elements; the at least three magnetic field detection elements are provided at positions with different distances from the bus bar in one direction, and each of the magnetic field detection elements detects a magnetic field generated from the bus bar as well as a magnetic field generated from a plurality of external magnetic field sources other than the bus bar; The current detection circuit performs signal processing in which, in response to the magnetic field detection signals output from the at least three magnetic field detection elements, a correction is made to the magnetic field detection signals to cancel the magnetic fields generated from the multiple external magnetic field sources, and the corrected detection signals are output as detection signals of the current flowing through the bus bar.

2. 2. The current sensor according to claim 1, wherein the current detection circuit identifies a magnitude of the magnetic field generated from the multiple external magnetic field sources in accordance with an output difference between the magnetic field detection signals output from the at least three magnetic field detection elements, and performs a correction to cancel the magnetic fields generated from the multiple external magnetic field sources by subtracting a value corresponding to the identified magnitude of the magnetic field from the signal value of the magnetic field detection signal.

3. 3. The current sensor according to claim 1, wherein the current detection circuit performs signal processing including correction for canceling the magnetic fields generated from the plurality of external magnetic field sources by an analog circuit.

4. The current sensor according to claim 3 , further comprising an adjustment circuit that adjusts parameters of circuit elements included in the analog circuit.

5. the at least three magnetic field detection elements include a first magnetic field detection element, a second magnetic field detection element, and a third magnetic field detection element; The current detection circuit includes: a first amplifier that amplifies a detection signal of the first magnetic field detection element; A second amplifier that amplifies a detection signal of the second magnetic field detection element; a third amplifier that amplifies a detection signal of the third magnetic field detection element; a fourth amplifier that amplifies a difference between an output signal of the second amplifier and an output signal of the third amplifier; a fifth amplifier that amplifies a difference between an output signal of the first amplifier and an output signal of the third amplifier; a sixth amplifier that amplifies an output signal of the fifth amplifier; a seventh amplifier that amplifies a difference between an output signal of the fourth amplifier and an output signal of the sixth amplifier; performing a correction to cancel a magnetic field generated from a first external magnetic field source by the first amplifier, the second amplifier, the third amplifier, the fourth amplifier, and the fifth amplifier; 3. The current sensor according to claim 1, wherein the sixth amplifier and the seventh amplifier perform a correction to cancel a magnetic field generated from a second external magnetic field source.

6. 3. The current sensor according to claim 1, further comprising an external magnetic field detection circuit that, in response to detection signals output from the at least three magnetic field detection elements, corrects the magnetic field detection signal to cancel a magnetic field generated from one of the multiple external magnetic field sources and a magnetic field generated from the bus bar, and outputs the corrected detection signal as a detection signal of a magnetic field generated from another one of the multiple external magnetic field sources.

7. 7. The current sensor according to claim 6, wherein the external magnetic field detection circuit identifies a magnitude of the magnetic field generated from any of the external magnetic field sources and the magnetic field generated from the bus bar in accordance with an output difference between the magnetic field detection signals output from the at least three magnetic field detection elements, and performs a correction to cancel the magnetic field generated from any of the external magnetic field sources and the magnetic field generated from the bus bar by subtracting a value corresponding to the identified magnitude of the magnetic field from the signal value of the magnetic field detection signal.

8. 8. The current sensor according to claim 7, wherein the external magnetic field detection circuit uses an analog circuit to perform signal processing including correction for canceling the magnetic field generated from any one of the external magnetic field sources and the magnetic field generated from the bus bar.

9. The current sensor according to claim 8 , further comprising an adjustment circuit that adjusts parameters of circuit elements included in the analog circuit.