JP2011075536A - Current detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current detecting device composed of fewer magnetic sensors. <P>SOLUTION: A magnetic sensor 10 detects magnetic field vectors caused by currents applied to a first bus bar 11 and a second bus bar 12 or their resultant magnetic vector to be exact. Current values applied to the bus bars 11 and 12 can be detected by the single magnetic sensor 10 based on the magnetic vector detected, thereby the single magnetic sensor 10 can detect all three phase currents. This is because, based on known two phase currents, the other one can be estimated, thus enabling the detection of the current applied to each of bus bars 11-13 by using the fewer magnetic sensors 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a current detection device.

  2. Description of the Related Art Conventionally, a current detection device that detects a current applied to a driving three-phase AC motor such as an electric vehicle is known. Specifically, DC power from the battery is converted into three-phase AC power by an inverter. The AC power generated by this inverter is applied to the motor via the power supply line (bus bar) of each phase. Each bus bar is provided with a magnetic sensor that detects a change in a magnetic field generated by a current flowing through the bus bar. Here, the greater the current flowing through the bus bar, the stronger the generated magnetic field. In this way, the magnetic sensor can detect the value of the current flowing through each bus bar and the current phase by utilizing the fact that there is a fixed relationship between the current and the magnetic field, such as the strength of the magnetic field being proportional to the current. (For example, refer to Patent Document 1).

  In the current detection device described in Patent Document 1, each bus bar is provided with a magnetic sensor. That is, a total of three magnetic sensors are required. Here, as shown in FIG. 2, the phases of the alternating current are shifted by 120 degrees. Therefore, for example, as shown in Patent Document 2, a configuration in which two-phase currents are detected by two magnetic sensors and the remaining one phase is estimated from a phase shift is known. It has been.

JP 2004-61217 A JP 2001-33989 A

  In the current detection device of Patent Document 2, at least two or more magnetic sensors are required to detect a three-phase alternating current. Particularly in recent years, with the demand for miniaturization of various electronic devices, there is a demand for a more compact current detection device incorporated therein.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a current detection device including fewer magnetic sensors.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to the first aspect of the present invention, in the current detection device that detects current flowing in the plurality of bus bars corresponding to each phase of the plurality of phases of AC power, at least adjacent to the plurality of bus bars provided at intervals. A magnetic field generated by a current flowing between the two adjacent bus bars and being installed at a position that forms a predetermined angle with respect to a straight line connecting the bus bars when viewed from the axial direction of the bus bars. The gist thereof is to provide a magnetic sensor that detects a vector and detects the value of an alternating current flowing through the two adjacent bus bars based on the detected magnetic field vector.

  According to this configuration, the magnetic sensor detects a magnetic field vector generated by a current flowing through two adjacent bus bars, more precisely, a combined magnetic field vector thereof. Based on the detected magnetic field vector, a single magnetic sensor can detect the value of current flowing through both bus bars. For example, in the case of three-phase alternating current, it is possible to detect all three-phase currents with a single sensor. This is because if two-phase currents are known, the remaining one phase can be estimated based on these. In this way, it is possible to detect the value of the current flowing through the plurality of bus bars with even fewer magnetic sensors.

The gist of the invention described in claim 2 is that, in the current detection device according to claim 1, the number of phases of the alternating current is three.
According to this configuration, it is possible to detect the currents of all the phases of the three-phase AC power, which is widely used as the driving power of a rotational power source such as a motor, with a single magnetic sensor. Specifically, the magnetic sensor detects a magnetic field vector generated by flowing two-phase alternating current through two adjacent bus bars. For example, by decomposing the magnetic field vector into components, the value of the current flowing through both bus bars can be detected. Based on the value of the current flowing through both bus bars, the value of the current flowing through the remaining one bus bar can be estimated. This is because the three-phase alternating current is detected with a phase shift of 120 degrees in the current waveform of each phase. In this way, it is possible to detect the value of the current flowing through the three bus bars with a single magnetic sensor.

  According to a third aspect of the present invention, in the current detection device according to the first or second aspect, the magnetic sensor is located on a vertical bisector connecting a line between two adjacent bus bars. Its gist is that it is installed at a position of 45 degrees with respect to a line segment connecting two bus bars.

  In the same configuration, the magnetic sensor is installed on a vertical bisector of a line segment connecting adjacent bus bars so that the magnetic sensor is equally affected by the magnetic field due to the current flowing in both bus bars to be detected. Can do. Here, around each bus bar, a magnetic field is formed in the circumferential direction with the current flowing direction as the central axis. For this reason, by installing the magnetic sensor at a position that forms 45 degrees with respect to the straight line connecting the bus bars, the direction of the magnetic field by one bus bar and the direction of the magnetic field by the other bus bar can be orthogonalized. Thereby, the direction of the magnetic vector detected by the magnetic sensor rotates in the circumferential direction by a predetermined angle every predetermined time. Therefore, calculations such as component decomposition related to the magnetic field vector can be simplified, and current values can be detected with the same accuracy for both bus bars.

The invention according to claim 4 is the current detection device according to any one of claims 1 to 3,
The magnetic sensor includes a rotating magnetic field detecting element capable of detecting a rotating magnetic field indicated by the direction of the magnetic field vector, and a magnetic field strength detecting element capable of detecting a magnetic field intensity indicated by the length of the magnetic field vector. That is the gist.

  In the same configuration, the rotating magnetic field detecting element detects a rotating magnetic field indicated by the direction of the magnetic field vector, and the magnetic field strength detecting element detects a magnetic field intensity indicated by the length of the magnetic field vector. Accordingly, it is possible to detect the rotating magnetic field and the magnetic field intensity more quickly than when detecting the rotating magnetic field and the magnetic field intensity in the magnetic field vector by a single detection element.

  According to a fifth aspect of the present invention, in the current detection device according to any one of the first to fourth aspects of the present invention, the current detection device includes a connection cord provided at both ends with plugs connected to a power supply source and a power supply target. When one of the plugs is provided with the plurality of bus bars and the magnetic sensor, and the plugs are connected to the power supply and the power supply target, power is supplied from the power supply through the connection cord including the bus bar. The gist is to be transmitted to the power supply target.

  According to this configuration, a plurality of bus bars and magnetic sensors are provided on the plug. Therefore, when the power supply and the power supply target are electrically connected, both plugs need only be connected to the power supply and the power supply target. Therefore, for example, compared with the case where the bus bar is fastened to the power supply and the power supply target with screws or the like, the man-hour related to the connection between the power supply and the power supply target can be reduced.

  According to the present invention, the current detection device can be configured with fewer magnetic sensors.

The block diagram of the motor drive current detection apparatus in 1st Embodiment. Waveform diagram of current of three-phase AC power. AA sectional view taken on the line AA of FIG. The schematic diagram which showed the magnetic field vector around the bus-bar and magnetic sensor in 1st Embodiment. The schematic diagram which showed the synthetic magnetic field vector which the magnetic sensor in 1st Embodiment detects. The schematic diagram which showed the magnetic field vector by which the synthetic | combination magnetic field vector in 1st Embodiment was decomposed | disassembled. The block diagram of the magnetic sensor in 2nd Embodiment. AA line sectional view of Drawing 1 which arranged a plurality of magnetic sensors in other embodiments. The block diagram of the motor drive current detection apparatus in 3rd Embodiment. BB sectional drawing of FIG. The CC sectional view taken on the line of FIG.

(First embodiment)
Hereinafter, a first embodiment in which a current detection device according to the present invention is embodied in a motor drive current detection device will be described with reference to FIGS.

  As shown in FIG. 1, the motor drive current detection device detects a current applied from the battery 5 to the motor 7. Specifically, the battery 5 applies a direct current to the inverter 6. The inverter 6 converts the DC power from the battery 5 into three-phase AC power for driving the motor 7. Here, the three-phase AC power is an AC current or an AC voltage of three systems (U-phase, V-phase, W-phase) particularly used for driving the motor. The U-phase, V-phase, and W-phase alternating current waveforms are sine waves that are 120 degrees out of phase as shown in the graph of FIG.

  The inverter 6 is connected to the motor 7 via first to third bus bars 11 to 13 which are power supply lines to the motor 7. The first to third bus bars 11 to 13 are made of a conductive material such as copper. The inverter 6 supplies the generated U-phase AC power to the first bus bar 11, V-phase AC power to the second bus bar 12, and W-phase AC power to the third bus bar 13. The motor 7 is rotated by electric power supplied from the bus bars 11 to 13.

  As shown in FIG. 1, a magnetic sensor 10 is installed between the first bus bar 11 and the second bus bar 12. As the magnetic sensor 10 in the present embodiment, a sensor that can detect a rotating magnetic field and a magnetic field strength, such as a Hall element and an MR element (magnetoresistance element), is used.

  Specifically, as shown in FIG. 3, the first to third bus bars 11 to 13 having a circular cross section are arranged at equal intervals in the horizontal direction. The magnetic sensor 10 is located above the center between the first bus bar 11 and the second bus bar 12. Precisely, the straight line connecting the center Ou of the first bus bar 11 and the center Os of the magnetic sensor 10 is orthogonal to the straight line connecting the center Ov of the second bus bar 12 and the center Os of the magnetic sensor 10. That is, by connecting the centers Ou, Ov, Os of the magnetic sensor 10, the first bus bar 11, and the second bus bar 12 with straight lines, the magnetic sensor 10 is installed at a position where an isosceles right triangle is formed. Further, as shown in FIG. 1, the magnetic sensor 10 includes an arithmetic circuit 10a. The arithmetic circuit 10 a performs various calculations based on the magnetic field detection results, and outputs the calculation results to the control device 8 via the connection lines 20 and 21. The control device 8 outputs a command signal to the inverter 6 and drives the motor 7 via the inverter 6. The calculation method by the calculation circuit 10a will be described in detail later.

Next, a method for detecting the current flowing through the bus bars 11 to 13 by the magnetic sensor 10 when power is supplied from the battery 5 to the motor 7 will be described.
When a current is passed through each of the bus bars 11 to 13, a magnetic field corresponding to the value of the current passed through the bus bars 11 to 13 is generated around the bus bars 11 to 13 (right-hand rule). Here, as described above, an alternating current whose phase is shifted by 120 degrees flows through each of the bus bars 11 to 13. Therefore, the value of the current flowing through each bus bar 11 to 13 changes every moment. As the current value increases or decreases, the magnetic field (precisely, the intensity) formed around the bus bars 11 to 13 increases or decreases.

  FIG. 4 shows, as an example, a magnetic field formed around the first bus bar 11 and the second bus bar 12 at time t1 in FIG. At time t1, the absolute value of the current flowing through the first bus bar 11 is greater than the absolute value of the current flowing through the second bus bar 12. Also, the values of the currents flowing through both bus bars 11 and 12 are different between plus and minus, and the current flows through the first bus bar to the front side of the page of FIG. 4, and the second bus bar 12 passes through the back of the page of FIG. Current flows to the side. In FIG. 4, the magnetic field formed around the first bus bar 11 and the second bus bar 12 is represented by a magnetic field vector indicated by an arrow. In the magnetic field vector, the full length of the arrow represents the strength of the magnetic field, and the direction represents the direction of the magnetic field. That is, the magnetic field vector is an index indicating the magnetic field strength and the rotating magnetic field. Since a current flows through the first bus bar 11 toward the front side of the sheet of FIG. 4, the magnetic field vector is directed counterclockwise around the first bus bar 11. On the other hand, since a current flows through the second bus bar 12 on the back side of the sheet of FIG. 4, the magnetic field vector is directed clockwise around the second bus bar 12.

  In addition, since a current having an absolute value larger than that of the second bus bar 12 is passed through the first bus bar 11, the range of the magnetic field formed with the energization of the first bus bar 11 is the energization of the second bus bar 12. It becomes a wider range than the magnetic field formed.

  Further, as can be seen from the length of the arrow indicating the magnetic field vector, the strength of the magnetic field formed in the vicinity of the first bus bar 11 is larger than the magnetic field strength formed in the vicinity of the second bus bar 12. And as it leaves | separates from both bus bars 11 and 12, it becomes small. In this example, the magnetic field generated by energizing the first bus bar 11 extends to the second bus bar 12.

  As described above, the waveform of the current flowing through each bus bar 11 to 13 is a sine wave. Therefore, the value of the current flowing through each bus bar 11 to 13 changes with the passage of time. For this reason, as the value of the current passed through each bus bar 11-13 increases or decreases, the magnetic field strength also increases or decreases. That is, the length of the magnetic field vector changes with time.

  Moreover, the value of the current passed through each of the bus bars 11 to 13 takes a positive value or a negative value around zero with the passage of time. Therefore, a current can flow through each of the bus bars 11 to 13 in both the left and right directions in FIG. Thus, the direction of the magnetic field vector also changes in accordance with the change in the direction of the current flowing through each bus bar 11-13.

  As described above, the length and direction of the magnetic field vectors around the bus bars 11 to 13 change from moment to moment. Along with this, the direction of the magnetic field vector around the magnetic sensor 10 also changes. As described above, the magnetic sensor 10 is provided so that the intervals between the first bus bar 11 and the second bus bar 12 are equal. For this reason, the magnetic sensor 10 receives the change of the magnetic field formed in the periphery of the 1st bus bar 11 and the 2nd bus bar 12 equally.

  As shown in FIG. 5, the magnetic sensor 10 has a Bv axis and a Bu axis that are orthogonal to each other. The Bu axis extends in a direction along the magnetic field vector generated from the first bus bar 11, and the Bv axis extends in a direction along the magnetic field vector generated from the second bus bar 12. In other words, as shown in FIG. 3, the Bv axis extends in a line direction connecting the center Ou of the first bus bar 11 and the center Os of the magnetic sensor 10, and the Bu axis is the center Ov of the second bus bar 12 and the center of the magnetic sensor 10. It extends in the direction of the line connecting Os. A magnetic field formed by the first bus bar 11 when energized is applied to the Bu axis, and a magnetic field formed by the second bus bar 12 when energized is applied to the Bv axis.

  Therefore, as shown in FIG. 5, when an alternating current is passed through each of the bus bars 11 to 13, the magnetic field vector indicated by the arrow applied to the magnetic sensor 10 is centered on the orthogonal point of the Bu axis and the Bv axis. Rotate clockwise. Also, as shown in FIG. 5, the tip of the magnetic field vector applied to the magnetic sensor 10 moves so as to draw a substantially circular locus. Here, the magnetic field vector is a combined magnetic field vector of a magnetic field generated by energizing the first bus bar 11 and a magnetic field generated by energizing the second bus bar 12. For this reason, the arithmetic circuit 10a of the magnetic sensor 10 decomposes the magnetic field vector into components in the Bu axis direction and the Bv axis direction at predetermined time intervals, so that the U phase and V phase flowing in the first bus bar 11 and the second bus bar 12 are obtained. AC current can be calculated.

Hereinafter, a method for calculating the U-phase and V-phase AC currents by the arithmetic circuit 10a will be described in detail.
First, a method of component decomposition of the magnetic field vector will be described. Hereinafter, a magnetic field vector that has not been subjected to component decomposition is represented as a combined magnetic field vector V.

  As shown in FIG. 6, it is assumed that a combined magnetic field vector V having a predetermined angle θ with respect to the Bu axis is detected with the orthogonal point of the Bu axis and Bv axis as the rotation center. The composite magnetic field vector V can be decomposed into components using a trigonometric function. That is, the magnetic field vector Vu in the Bu axis direction is obtained by “synthetic magnetic field vector V × Cos θ”. Further, the magnetic field vector Vv in the Bv-axis direction is obtained by “synthetic magnetic field vector V × Sinθ”.

  When the combined magnetic field vector V in the direction along the Bu axis at the time indicated by the circled numeral 1 in FIG. 5 is detected, since Sin0 ° = 0, the magnetic field vector Vv in the Bv axis direction is zero. Since Cos0 ° = 1, the magnetic field vector Vu in the Bu axis direction is equal to the combined magnetic field vector V. Therefore, the current value of the V phase becomes zero and the current value of the U phase becomes the reference current value Ia corresponding to the length of the magnetic field vector Vu as at the time of the circled number 1 in FIG.

  The synthesized magnetic field vector V at the time indicated by the circled numeral 1 in FIG. 5 is rotated by 45 degrees clockwise after the predetermined time has elapsed and becomes the direction at the time indicated by the circled numeral 2. At this time, the magnetic field vector Vu in the Bu-axis direction is obtained by “synthetic magnetic field vector V × Cos45 °”, and the magnetic field vector Vv in the Bv-axis direction is obtained by “synthetic magnetic field vector V × Sin45 °”. Here, Sin 45 ° and Cos 45 ° are √2 / 2. Accordingly, at this time, the magnetic field vectors Vu and Vv in both axial directions are equal. The U-phase and V-phase current values at this time are obtained based on the reference current value Ia from the length of the combined magnetic field vector V and the ratio of the lengths of the magnetic field vectors Vv and Vu in the Bu-axis and Bv-axis directions. Can do. That is, at the time of the circled number 2 in FIG. 2, the current values of the U phase and the V phase are “reference current value Ia × √2 / 2”.

  The synthesized magnetic field vector V at the time indicated by the circled number 2 in FIG. 5 is rotated by 45 degrees clockwise after the predetermined time has elapsed and becomes the direction at the time indicated by the circled number 3. At this time, since Sin90 ° = 1, the magnetic field vector Vv in the Bv axis direction is equal to the combined magnetic field vector V. Further, since Cos90 ° = 0, the magnetic field vector Vu in the Bu axis direction is zero. Therefore, the current value of the U phase becomes zero and the current value of the V phase becomes the reference current value Ia corresponding to the length of the magnetic field vector Vu as at the time of the circled number 3 in FIG.

In such a procedure, the current values of the U phase and the V phase at each time are obtained and connected by a curve, whereby the waveforms of the alternating currents of the U phase and the V phase as shown in FIG. 2 are obtained.
Here, the length of the magnetic field vector Vu at the time indicated by the circled number 1 in FIG. 5 is not strictly maximum. The length of the magnetic field vector Vu is 180 degrees when the direction of the synthetic magnetic field vector V is rotated by 22.5 degrees counterclockwise from the direction (θ = 0 °) at the time indicated by the circled numeral 1 and 180 degrees from the angle. Sometimes it becomes maximum. Here, when the length of the magnetic field vector Vu is maximum, the peak value which is the maximum value or the minimum value of the value of the U-phase current shown in FIG. 2 is taken.

  Similarly, the length of the magnetic field vector Vv at the time indicated by the circled number 3 is not strictly maximum. The length of the magnetic field vector Vv is maximized when it is rotated by 22.5 degrees clockwise from the orientation (θ = 90 °) indicated by the round numeral 3 and when it is rotated 180 degrees from that angle. Here, when the length of the magnetic field vector Vv is the maximum, the peak value which is the maximum value or the minimum value of the value of the V-phase current shown in FIG. 2 is taken.

  The reference current value Ia is obtained based on the maximum current value that can be supplied to the motor 7. This value is set in advance based on the motor specifications and the like. That is, the reference current value Ia is determined from the relationship of the reference current value Ia: the maximum current value = the length of the combined magnetic field vector V at the time indicated by the circled numbers 1, 2, or 3 in FIG. 5: the maximum length of the combined magnetic field vector V. It can be calculated.

  The calculation results (Iu, Iv) of the arithmetic circuit 10 a are output to the control device 8 via the connection lines 20 and 21. Based on the calculation result of the magnetic sensor 10, the control device 8 estimates a W-phase AC current that is 120 degrees out of phase from the U-phase and V-phase AC currents. Then, the control device 8 performs various determinations such as whether there is an abnormality in the power supply status to the motor 7 based on the waveform of each phase, etc., and outputs a command signal to the inverter 6 to control the drive of the motor 7. .

As described above, according to the embodiment described above, the following effects can be obtained.
(1) The magnetic sensor 10 detects magnetic field vectors generated by currents flowing through the first bus bar 11 and the second bus bar 12, more precisely, their combined magnetic field vectors. Based on the detected magnetic field vector, the single magnetic sensor 10 can detect the value of the current flowing through both the bus bars 11 and 12. As a result, the current of all three phases can be detected by the single magnetic sensor 10. This is because if two-phase currents are known, the remaining one phase can be estimated based on these. In this way, it is possible to detect the value of the current flowing through each of the bus bars 11 to 13 with fewer magnetic sensors 10.

  (2) Since the magnetic sensor 10 is installed on a perpendicular bisector connecting the centers Ou and Ov of the first bus bar 11 and the second bus bar 12, the magnetic sensor 10 is detected by both bus bars 11. , 12 can be evenly affected by the magnetic field due to the current flowing through them. Here, around the bus bars 11 to 13, a magnetic field directed in the circumferential direction with the current flowing direction as the central axis is formed. For this reason, the magnetic sensor 10 is installed at a position that forms an angle of 45 degrees with respect to the straight line connecting the bus bars 11 and 12 when viewed from the axial direction of the bus bars 11 to 13. The direction of the magnetic field by the second bus bar 12 can be made orthogonal. Thereby, the direction of the magnetic vector detected by the magnetic sensor 10 rotates in the circumferential direction by a predetermined angle every predetermined time. Therefore, calculations such as component decomposition relating to the magnetic field vector can be simplified, and current values can be detected with the same accuracy for both bus bars 11 and 12.

(Second Embodiment)
Hereinafter, a second embodiment of the motor drive current detection device according to the present invention will be described. In the current detection device of this embodiment, the configuration of the magnetic sensor 10 is different from that of the first embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment. Note that the current detection device of this embodiment has substantially the same configuration as the current detection device of the first embodiment shown in FIG.

  As shown in FIG. 7, the magnetic sensor 10 includes an MR (magnetoresistive effect) element 15 corresponding to a rotating magnetic field detecting element and a GMR (giant magnetoresistive effect) element 16 corresponding to a magnetic field strength detecting element. In the present embodiment, the arithmetic circuit 10a is omitted.

  The MR element 15 can detect a rotating magnetic field corresponding to the direction of the synthetic magnetic field vector V in the first embodiment. Specifically, the MR element generates a voltage corresponding to the direction of the magnetic vector applied to itself. That is, the MR element 15 detects a magnetic field vector in the Bv axis direction and outputs a signal (voltage value) Sv corresponding to the direction to the control device 8. The MR element 15 detects a magnetic field vector in the Bu-axis direction and outputs a signal (voltage value) Su corresponding to the direction to the control device 8. Both signals Su and Sv at this time are sinusoidal waves having the same period, although the amplitude is different from the U-phase and V-phase alternating currents shown in FIG.

  The GMR element 16 can detect a magnetic field intensity corresponding to the length of the combined magnetic field vector V in the first embodiment. Specifically, the GMR element 16 detects the magnetic field strength at every predetermined time interval and outputs a signal (voltage value) So corresponding to the magnetic field strength to the control device 8. The control device 8 can calculate the U-phase and V-phase AC currents shown in FIG. 2 by multiplying the waveforms of the signals Su and Sv by the amplitude based on the signal So.

  As described above, since the direction of the magnetic field vector V (rotating magnetic field) and the magnetic field strength can be separately detected with respect to the magnetic field at the position where the magnetic sensor 10 is installed, the arithmetic circuit 10a performs the operation in the first embodiment. This eliminates the need for operations such as component decomposition. Therefore, the magnetic sensor 10 can output the detection result to the control device 8 more quickly, and thus can detect the current value quickly. Further, since the arithmetic circuit 10a is not required for the magnetic sensor 10, a motor drive current detection device with a simpler configuration can be obtained.

As mentioned above, according to embodiment described, in addition to the effect of (1)-(2) of 1st Embodiment, there can exist the following effects.
(3) The MR element 15 detects the rotating magnetic field indicated by the direction of the magnetic field vector, and the GMR element 16 detects the magnetic field strength indicated by the length of the magnetic field vector. Therefore, as compared with the case where the rotating magnetic field and the magnetic field strength in the magnetic field vector are detected by a single detecting element, calculation such as component decomposition becomes unnecessary, so that the rotating magnetic field and the magnetic field strength can be detected quickly.

(Third embodiment)
Hereinafter, a third embodiment of the motor drive current detection device according to the present invention will be described. The current detection device of this embodiment is different from both of the above embodiments in that the connection between the inverter 6 and the motor 7 can be connected by a plug. Hereinafter, a description will be given focusing on differences from the first embodiment. Note that the current detection device of this embodiment has substantially the same configuration as the current detection device of the first embodiment shown in FIG.

  As shown in FIG. 9, a control device 8 is built in the inverter 6. A connection cord 55 is connected between the inverter 6 and the motor 7. The connection cord 55 includes a first plug 51 connected to the inverter 6, a second plug 52 connected to the motor 7, and three connection lines 54 connecting the plugs 51 and 52. These connection lines 54 are bundled by being covered with a coating (not shown).

  As shown in FIG. 10, the first plug 51 is molded in a columnar shape from the first to third bus bars 11 to 13 and the magnetic sensor 10 with a resin material. The first to third bus bars 11 to 13 are arranged at positions that form equilateral triangles by connecting the centers Ou, Ov, and Or of the bus bars 11 to 13 with line segments.

  Further, as shown in FIG. 11, the first and third bus bars 11 and 13 are formed so as to protrude toward the inverter 6 side. Similarly, the second bus bar 12 protrudes toward the inverter 6 side. On the other hand, the inverter 6 is formed with an insertion port 58 into which the first to third bus bars 11 to 13 are inserted. Inside each insertion port 58, connection terminals 59 a and 59 b are provided that enable electrical connection between the bus bars 11 to 13 inserted into the insertion port 58 and the inverter 6. The connection terminals 59a and 59b face each other in the vertical direction. The connection terminal 59a is formed by bending a plate-shaped metal material inward at the tip. The connection terminal 59b is formed in a flat plate shape. The first to third bus bars 11 to 13 can be inserted between the connection terminals 59a and 59b. The bus bars 11 to 13 inserted between the connection terminals 59a and 59b are prevented from being pulled out from the insertion port 58 by the elastic force of the bent portion of the connection terminal 59a. In addition, the contact pressure between the connection terminals 59a and 59b and the bus bars 11 to 13 is secured by the elastic force. In a state where each bus bar 11-13 is inserted into each insertion port 58 (between both connection terminals 59a, 59b), the inverter 6 and the first to third bus bars 11-13 are electrically connected. Become.

  Similarly to the above embodiment, the line segment connecting the center Ou of the first bus bar 11 and the center Os of the magnetic sensor 10 is orthogonal to the line segment connecting the center Ov of the second bus bar 12 and the center Os of the magnetic sensor 10. The magnetic sensor 10 is installed at the position. Thereby, like the said embodiment, it becomes possible to detect the electric current of all three phases with the single magnetic sensor 10.

  As shown in FIG. 11, the magnetic sensor 10 is embedded in the first plug 51. The connection lines 20 and 21 connected to the magnetic sensor 10 go out from the side surface of the first plug 51. A connector 56 is connected to the outer ends of the connection lines 20 and 21. The connector 56 is inserted into an insertion port 57 formed in the inverter 6. Thereby, the magnetic sensor 10 and the control device 8 are electrically connected, and the calculation result of the magnetic sensor 10 (more precisely, the calculation circuit 10a) is transferred to the control device 8 provided in the inverter 6 through the connection lines 20 and 21. Is output.

  In FIG. 9, each of the bus bars 11 to 13 and the inverter 6 are illustrated as being connected via a connection line indicated by a solid line, but this shows an electrical connection relationship. The bus bars 11 to 13 are inserted into the insertion ports 58 of the inverter 6 so that the bus bars 11 to 13 are connected to the inverter 6 through both connection terminals 59a and 59b.

Next, a method for manufacturing the first plug 51 will be briefly described.
First, as shown in FIG. 11, the resin member 60 is formed by molding the end of the first to third bus bars 11 to 13 opposite to the inverter 6 with a resin material. Separately, the resin member 61 is formed by molding the magnetic sensor 10 with a resin material. The resin member 61 is formed with a through hole 63 through which the first to third bus bars 11 to 13 can be inserted. Then, the first to third bus bars 11 to 13 are inserted through the through holes 63 of the resin member 61. Here, the engagement protrusion 65a formed on the outer peripheral edge of the surface where the resin member 60 contacts the resin member 61 is engaged with the engaged portion 65b formed on the outer periphery of the front end of the resin member 61. The resin members 60 and 61 are fixed. Thus, the manufacture of the first plug 51 is completed. The second plug 52 is formed by molding a connection terminal (not shown) to which an end of the connection line 54 opposite to the first plug 51 is connected with resin.

  Therefore, when connecting the inverter 6 and the motor 7, it is only necessary to manually connect the first plug 51 to the inverter 6 and the second plug 52 to the motor 7. Thereby, the connection work of the inverter 6 and the motor 7 becomes easy. As a connection mode of the inverter 6 and the motor 7, for example, it is conceivable that the inverter 6 and the motor 7 are directly connected by the bus bars 11-13. However, in this case, it is necessary to fasten the inverter 6 and the bus bars 11 to 13 and the bus bars 11 to 13 and the motor 7 with screws. In this respect, according to the present example, such a fastening work with screws can be omitted, and therefore, the number of connection steps can be reduced as compared with the case where the bus bar is fastened with screws.

  When the power of the battery 5 is supplied to the motor 7, the battery 5 corresponds to a power supply and the motor 7 corresponds to a power supply target. When the battery 5 is charged as the motor 7 is driven, the motor 7 corresponds to a power supply and the battery 5 corresponds to a power supply target.

As mentioned above, according to embodiment described above, in addition to the effect of (1)-(3) of both the said embodiment, there can exist the following effects.
(4) The first plug 51 is provided with the first to third bus bars 11 to 13 and the magnetic sensor 10. Therefore, when connecting the inverter 6 and the motor 7, it is only necessary to connect the first plug 51 to the inverter 6 and connect the second plug 52 to the motor 7. Therefore, for example, compared to the case where the first to third bus bars 11 to 13 are fastened to the inverter 6 and the motor 7 with screws or the like, the man-hour related to the connection between the inverter 6 and the motor 7 can be reduced.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
-In 3rd Embodiment, when the 1st plug 51 is seen from a bus-bar axial direction, 1st-3rd bus-bars 11-13 are each center Ou, Ov, Or of 1st-3rd bus-bars 11-13. Is placed at a position where an equilateral triangle is formed. However, for example, as shown in FIG. 3, the first plug 51 may be formed in a state where the first to third bus bars 11 to 13 are arranged in a line. In this case, the first plug 51 is formed in a rectangular parallelepiped shape, for example.

In the third embodiment, the magnetic sensor 10 is provided in the first plug 51, but the magnetic sensor 10 may be provided in the second plug 52.
In the second embodiment, the MR element 15 is provided as the rotating magnetic field detecting element. However, as long as the rotating magnetic field can be detected, not only the MR element 15 but also a Hall element or the like may be used. Similarly, the GMR element 16 is provided as the magnetic field strength detection element. However, as long as the magnetic field strength can be detected, not only the GMR element 16 but also a Hall element or the like can be used.

  In the first to third embodiments, the magnetic sensor 10 can detect the three-phase alternating current flowing through the bus bars 11 to 13. However, as long as the AC current has a plurality of phases, the AC current is not limited to three-phase AC current. For example, in a motor driven by supplying six-phase AC power, the AC current of each phase flowing through each bus bar can be detected. Also good. In this case, the value of the current flowing through all the bus bars can be detected by three magnetic sensors for a total of six bus bars. If the current waveform is estimated based on the assumed phase shift, it is possible to detect the value of the current flowing through all the bus bars with a smaller number of magnetic sensors.

  In the first to third embodiments, the magnetic sensor 10 is installed at a position where an isosceles right triangle is formed by connecting the first bus bar 11 and the second bus bar 12. However, the installation position of the magnetic sensor 10 is not on the straight line connecting the first bus bar 11 and the second bus bar 12 and detects a change in the magnetic field caused by current flowing through the first bus bar 11 and the second bus bar 12. If possible, the position is not limited to the above position. Here, for example, when the magnetic sensor 10 is installed on a straight line connecting the first bus bar 11 and the second bus bar 12, the Bu axis and the Bv axis exist on the same line, and component decomposition becomes impossible. . In addition, by changing the installation position of the magnetic sensor 10, the detection accuracy of the value of the current flowing through the first bus bar 11 and the second bus bar 12 can be adjusted. That is, when it is desired to detect the value of the current flowing through the first bus bar 11 with higher accuracy, the magnetic sensor 10 is installed at a position close to the first bus bar 11. Thereby, since the magnetic sensor 10 is more strongly affected by the magnetic field formed by energizing the first bus bar 11, it is possible to detect a minute difference in the value of the current flowing through the first bus bar 11, for example. Become.

  In the first to third embodiments, a single magnetic sensor 10 is installed between the first bus bar 11 and the second bus bar 12. However, as shown in FIG. 8, the magnetic sensor 10 is further positioned between the second bus bar 12 and the third bus bar 13 in the same positional relationship as the magnetic sensor 10 installed between the first bus bar 11 and the second bus bar 12. May be installed. In this case, the currents flowing through the bus bars 11 to 13 can be detected with higher accuracy by the two magnetic sensors 10, and even if one of the magnetic sensors 10 becomes undetectable due to a failure or the like. The value of the current flowing through each bus bar 11-13 can be detected. Also in this configuration, the fail safe function can be provided with fewer magnetic sensors 10 as compared with the conventional configuration in which the magnetic sensor 10 is provided in each of the bus bars 11 to 13 to provide the fail safe function.

  In the first to third embodiments, the current value required for driving the motor is detected. However, as long as it is an electrical load, not only the motor but also the value of the current required for driving the load may be detected.

  In the first and third embodiments, the control device 8 estimates the W-phase AC current that is 120 degrees out of phase from the U-phase and V-phase AC currents based on the calculation result of the magnetic sensor 10. . However, the arithmetic circuit 10a may estimate the W-phase AC current. Further, the control device 8 may perform the calculation performed by the calculation circuit 10a. In this case, the arithmetic circuit 10a can be omitted.

Next, the technical idea that can be grasped from the embodiment will be described together with the effects.
(A) The current detection device according to any one of claims 1 to 3, wherein the magnetic sensor is a Hall sensor or an MR sensor.

According to this configuration, the magnetic field vector, that is, the rotating magnetic field and the magnetic field strength can be detected by the Hall sensor or the MR sensor.
(B) The current detecting device according to claim 4, wherein the rotating magnetic field detecting element is a Hall element or an MR element, and the magnetic field intensity detecting element is a Hall element or a GMR element.

  According to this configuration, the rotating magnetic field at the installation position of the magnetic sensor can be detected by using the Hall element or the MR element as the rotating magnetic field detecting element. In addition, by using a Hall element or a GMR element as the magnetic field strength detection element, the magnetic field strength at the installation position of the magnetic sensor can be detected.

  DESCRIPTION OF SYMBOLS 5 ... Battery, 6 ... Inverter, 7 ... Motor, 8 ... Control apparatus, 10 ... Magnetic sensor, 10a ... Arithmetic circuit, 11-13 ... Bus bar, 15 ... MR element, 16 ... GMR element, 51, 52 ... Plug, 55 ... connection cord.

Claims (5)

In the current detection device that detects the current flowing through the plurality of bus bars corresponding to each phase of the multi-phase AC power,
Among the plurality of bus bars provided at intervals, the bus bars are disposed at least between two adjacent bus bars at a predetermined angle with respect to a straight line connecting the bus bars when viewed from the axial direction of the bus bars. And detecting a magnetic field vector generated by a current flowing through the two adjacent bus bars and detecting a value of an alternating current flowing through the two adjacent bus bars based on the detected magnetic field vector. apparatus. The current detection device according to claim 1,
A current detection device in which the number of phases of the alternating current is three. In the current detection device according to claim 1 or 2,
The magnetic sensor is a current detecting device installed at a position on a perpendicular bisector of a line segment connecting two adjacent bus bars and at a position of 45 degrees with respect to a line segment connecting the two bus bars. . In the electric current detection apparatus as described in any one of Claim 1 to 3,
The magnetic sensor includes a rotating magnetic field detecting element capable of detecting a rotating magnetic field indicated by the direction of the magnetic field vector, and a magnetic field strength detecting element capable of detecting a magnetic field intensity indicated by the length of the magnetic field vector. Current detection device. In the electric current detection apparatus as described in any one of Claim 1 to 4,
A plug connected to the power supply and power supply target is provided with a connection cord provided at both ends,
The plurality of bus bars and the magnetic sensor are provided in any one of the both plugs,
A current detection device in which when the plugs are connected to the power supply and the power supply target, power is transmitted from the power supply to the power supply through the connection cord including the bus bar.

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