JP6878083B2 - Current detector - Google Patents

Description

The present invention relates to a current detection device, and more particularly to a current detection device that detects a current flowing through a bus bar.

Rotating electric machines used in hybrid vehicles and electric vehicles are equipped with three bus bars for three-phase AC power supplies (U-phase, V-phase, and W-phase) for electrical connection with the outside. Then, the rotating electric machine is controlled by detecting the current flowing through the bus bar. As a device for detecting the current flowing through the bus bar, a current provided with three C-shaped magnetic material blocks (magnetron collecting cores) surrounding each bus bar and three magnetic-electric conversion elements arranged in a C-shaped notch. The detection device is described in, for example, Patent Document 1.

In addition, in order to reduce the size of the rotary electric machine, it is required to narrow the pitch between the bass bars, and accordingly, it is also necessary to reduce the size of the current detection device. A coreless current sensor that detects the current of the bus bar is also adopted.

Japanese Unexamined Patent Publication No. 2010-002277

The current detection device described in Patent Document 1 is difficult to miniaturize because it requires a magnetic collecting core for the bus bar of each phase. Further, since there is a magnetic collecting core, the number of parts is large and it is difficult to reduce the cost.

On the other hand, since the coreless current sensor does not use a magnetic collecting core, it can be miniaturized, but when detecting the current flowing through the bus bar of a predetermined phase, it is affected by the magnetic flux of the current flowing through the bus bar of another phase. This effect causes a detection error, and it becomes difficult to detect a current with high accuracy.

Therefore, an object of the present invention is to suppress the influence of magnetic flux from a bus bar of another phase and perform highly accurate current detection.

The current detection device of the present invention is arranged parallel to the first direction, and has a plurality of bus bars extending in a second direction orthogonal to the first direction and currents flowing through the bus bars. The magnetic-electric conversion element to be detected and a pair of magnetic shields arranged so as to sandwich the bus bar and the magnetic-electric conversion element in a third direction orthogonal to the first direction and the second direction. Each bus bar has a narrow portion cut out from the side surface, and the narrow portion is located at a position not facing the adjacent narrow portion and at a position close to one of the magnetic shields. The electromagnetic conversion element is arranged, and is characterized in that the narrow portion is arranged between the narrow portion and the magnetic shield on the side where the narrow portion is close to each other.
In the current detection device of the present invention, the narrow portion of each bus bar may be formed by cutting out only one end side of each bus bar.

According to the present invention, it is possible to suppress the influence of magnetic flux from the bus bar of another phase and perform highly accurate current detection. In particular, in a coreless current detection device that does not use a magnetic collecting core, it is possible to perform highly accurate current detection and to reduce the size of the device.

It is a circuit diagram of a rotary electric machine. It is a perspective view which shows the schematic structure of the current detection apparatus in 1st Embodiment. FIG. 2 is a cross-sectional view taken along the line aa of FIG. FIG. 3 is a cross-sectional view taken along the line bb of FIG. FIG. 3 is a cross-sectional view taken along the line cc of FIG. It is a characteristic diagram which superposed the characteristics of the currents IW and IV. It is a characteristic diagram which shows the simulation result of the magnetic flux distribution in the aa cross section of FIG. It is a characteristic diagram which shows the simulation result of the magnetic flux distribution in the bb cross section of FIG. It is a perspective view which shows the schematic structure of the current detection apparatus in 2nd Embodiment. It is a top view of the magnetic shield in the 2nd Embodiment. It is a perspective view which shows the schematic structure of the current detection apparatus in 3rd Embodiment. It is a side view of the bus bar in the third embodiment.

FIG. 1 is a schematic circuit diagram of a rotary electric machine 1 in which the current detection device 6 according to the first embodiment is used. As shown in FIG. 1, the rotary electric machine 1 includes a DC power supply 2, an inverter 3, and a motor generator 4. The inverter 3 and the motor generator 4 are electrically connected by a bus bar B.

The inverter 3 includes a power conversion unit 5 that converts direct current into alternating current, a current detection device 6 provided in the bus bar B, and a control device 7 that controls the power conversion unit 5. The power conversion unit 5 is composed of a circuit including a MOS transistor, a diode, and the like. The current detection device 6 detects the current flowing through the bus bar B and outputs the detected current value to the control device 7. The detailed configuration of the current detection device 6 will be described later.

The control device 7 controls the power conversion unit 5 based on the current value input from the current detection device 6 to control the rotational drive of the motor generator 4.

Next, the current detection device 6 will be described with reference to FIGS. 2 to 5. FIG. 2 is a perspective view showing a schematic configuration of the current detection device 6. Further, the XYZ coordinate system is shown in each figure, and each direction will be described using the XYZ coordinate system. The X direction (second direction) indicates the extending direction of the bus bar B, the Y direction (first direction) indicates the direction of parallel arrangement of the bus bar B, and the Z direction (third direction) indicates the current detection device 6. Indicates the vertical direction of.

The current detection device 6 includes a bus bar B including U-phase, V-phase, and W-phase bus bars BU, BV, and BW, magnetic and electrical conversion elements SU, SV, and SW that detect the currents of the bus bars BU, BV, and BW, respectively, and magnetic electricity. It is provided with a pair of magnetic shields 10 and 11 that suppress magnetic interference with the conversion elements SU, SV, and SW.

The bus bars BU, BV, and BW are arranged parallel to each other in the Y direction and extend in the X direction. The magnetic shields 10 and 11 are arranged so as to sandwich the bus bar BU, BV, BW and the magnetron conversion elements SU, SV, SW from both the upper and lower sides in the Z direction. The magnetic shield 10 is shown by a virtual line in order to show the arrangement configuration of the bus bar BU, BV, BW and the magnetron conversion elements SU, SV, SW.

The magnetic shields 10 and 11 are formed of, for example, a magnetic material such as iron or ferrite having a high magnetic permeability, and have a flat plate shape capable of covering the bus ba BU, BV, BW and the magnetron conversion elements SU, SV, SW. is there. Further, the magnetic shield 11 is provided with substrates PU, PV, and PW on which the magnetron conversion elements SU, SV, and SW are mounted.

The magnetron conversion elements SU, SV, and SW detect the magnetic flux generated when a current flows through the bus bar BU, BV, and BW, and calculate the corresponding current value. As the magnetron conversion elements SU, SV, and SW, Hall elements, MI elements (magnetic impedance elements), MR elements (magneto resistance elements), and the like can be used.

Next, the configurations of the bus bars BU, BV, and BW will be described in detail. The bus bars BU, BV, and BW are formed of a flat metal plate elongated in the X direction. The bus bars BU, BV, and BW are arranged parallel to the Y direction so that their wide side surfaces face each other.

The bus bars BU, BV, and BW have wide portions BUL, BVL, and BWL, and narrow portions BUS, BVS, and BWS formed by cutting out the wide portions BUL, BVL, and BWL from the width direction. The cross-sectional area of the narrow portion BUS, BVS, BWS is smaller than the cross-sectional area of the wide portion BUL, BVL, BWL. Further, the cross-sectional areas of the wide portions BUL, BVL, and BWL are the same as each other, and the cross-sectional areas of the narrow portions BUS, BVS, and BWS are also the same.

The wide portion BUL, BVL, BWL and the narrow portion BUS, BVS, BWS are arranged in a staggered pattern. That is, the narrow portion BUS is arranged so as not to face the adjacent narrow portion BVS, and the narrow portion BVS is arranged so as not to face the adjacent narrow portion BWS. In other words, the narrow portions BUS, BVS, and BWS are arranged in a substantially V shape when viewed from the Z direction. Further, the narrow portion BUS, BVS, BWS is a part for detecting the current flowing through the bus bur BU, BV, BW, and the narrow portion BUS, BVS, BWS is a wide portion BUL, BVL, BWL except for the narrow portion BUS, BVS, BWS. (See Busba BV in FIG. 2).

FIG. 4 shows a cross-sectional view taken along the line bb of FIG. In FIG. 4, the reference numeral WLC indicates the center line of the wide portion BWL. Further, the reference numeral WSC indicates the center line of the narrow portion BWS. The center line WSC of the narrow portion BWS is closer to the magnetic shield 11 side by a distance DW with respect to the center line WLC of the wide portion BWL. That is, the narrow portion BWS is arranged offset to the magnetic shield 11 side with respect to the wide portion BWL. Regarding this point, referring to FIG. 3, the narrow portion BWS has a distance H1 between the magnetic shields 10 and 11 and a distance H2 (distance H1> distance) between the magnetic shields 10 and the magnetic shield 11. It becomes H2) and is arranged close to the magnetic shield 11.

A magnetron conversion element SW is arranged between the narrow portion BWS and the magnetic shield 11. As shown in FIG. 3, the magnetron conversion element SW is arranged so as to face the narrow portion BWS so that the magnetic sensing direction faces the Y direction.

Further, the bus bar BU has the same configuration as the bus bar BW, and the narrow portion BUS is arranged so as to be offset toward the magnetic shield 11 side with respect to the wide portion BUL, and magnetic electric conversion is performed on the portion facing the narrow portion BUS. The element SU is arranged.

As shown in FIGS. 2 and 5, the narrow portion BVS of the bus bar BV is arranged at a different position from the narrow portion BWS of the bus bar BW, but the narrow portion BVS is similar to the narrow portion BWS of the bus bar BW. The magnetic shield 11 side is offset with respect to the wide portion BVL, and the magnetron conversion element SV is arranged at a portion facing the narrow portion BVS. In FIGS. 4 and 5, other bus bars are not shown in order to avoid complication of the drawings.

Next, the influence of the magnetic flux from the other-phase bus bar when detecting the magnetic flux of the self-phase bus bar will be described. Here, the influence of the magnetic flux from the bus bar BV (other phase) when detecting the magnetic flux of the bus bar BW (self-phase) will be described, but the same applies to the relationship between the other bus bar BU and BV.

In FIGS. 4 and 5, the centers of the currents flowing through the bus bars BV and BW are schematically shown as currents IV and IW, respectively. As shown in FIG. 4, the current IW passes through the center line WSC in the narrow portion BWS and passes through the center line WLC in the wide portion BWL. In this way, the current IW also flows in a state of being offset toward the magnetic shield 11 side.

Then, the current IW flowing through the narrow portion BWS is detected by the magnetron conversion element SW. Since the narrow cross-sectional area of the narrow portion BWS is small, the current IW flows in a concentrated manner. Therefore, a large magnetic flux is generated in the narrow portion BWS. The magnetron conversion element SW detects this magnetic flux and converts it into a current value. At this time, the magnetron conversion element SW detects the magnetic flux of the Y-direction component indicated by the arrow in FIG.

On the other hand, as shown in FIG. 5, the current IV passes through the center line VLC in the wide portion BVL and passes through the center line VSC in the narrow portion BVS. That is, the current IV flows from the center line VLC along the center line VSC. In this way, the current IV also flows in a state of being offset toward the magnetic shield 11 side.

FIG. 6 shows a state in which the currents IW and IV viewed from the magnetron conversion element SW are superimposed. As shown in FIG. 6, since the position where the current IV flows is separated from the position where the current IW flows by a distance D1 with respect to the magnetron conversion element SW, it is less likely to be affected by the magnetic flux due to the current IV. As a result, the influence of the magnetic flux of the current IV can be suppressed.

The reason for this will be described with reference to FIGS. 7 and 8. FIG. 7 shows the simulation result of the magnetic flux distribution in the Y direction in the cross section aa of FIG. 2, and FIG. 8 shows the simulation result of the magnetic flux distribution in the Y direction in the cross section bb of FIG. In FIGS. 7 and 8, the reference numeral GL indicates a region where the magnetic flux is small, and the reference numeral GH indicates a region where the magnetic flux is large.

In FIG. 7, the magnetic flux in the upper region GH1 of the bus bar BV is the largest, followed by the magnetic flux in the lower region GH2 of the bus bar BV. Further, the magnetic flux is small in the regions near the magnetic shields 10 and 11, and the magnetic fluxes in the regions GL1, GL2, GL3, and GL4 away from the regions GH1 and GH2 are also small. In particular, the magnetic flux in the regions GL3 and GL4 is the smallest.

In FIG. 8, the magnetic flux in the region GH3 above the narrow portion BWS of the bus bar BW and behind the magnetic shield 10 is large. Further, the magnetic flux is small in the region near the magnetic shields 10 and 11, and the magnetic flux in the regions GL5, GL6, and GL7 away from the region GH3 is also small. In particular, the magnetic flux in the region GL6 is the smallest. In FIGS. 7 and 8, the magnetron conversion element SW is shown by a alternate long and short dash line.

As can be seen from the relationship between the magnetron conversion element SW shown in FIG. 6 and the currents IW and IV, and the simulation results shown in FIGS. 7 and 8, the position of the magnetron conversion element SW is far from the position where the current IV flows, and the current IV It is less susceptible to the magnetic flux generated by. That is, the magnetron conversion element SW is located in the region GL4 in FIG. 7, and is located in the region GL6 in FIG. As described above, the magnetron conversion element SW is arranged at a position where the influence of the magnetic flux due to the current IV flowing through the bus bar BV is small.

Therefore, as described above, the narrow portion BWS of the bus bar BW is arranged close to the magnetic shield 11 and alternately arranged with the narrow portion BUS of the adjacent bus bar BU, and the magnetic flux conversion element SW is arranged in the narrow portion BWS. By arranging them in the vicinity, the magnetic flux of the bus bar BW can be detected satisfactorily, and the influence of the magnetic flux of the adjacent bus bar BU can be suppressed. As a result, highly accurate current detection can be performed.

Further, since the bus bar B is arranged so as to be sandwiched from both sides in the Z direction by the pair of magnetic shields 10 and 11, it is not necessary to individually surround the bus bar BU, BV, and BW, and the number of magnetic shield parts can be reduced. Also, its size can be reduced. As a result, the current detection device 6 can be miniaturized, and the cost can be reduced by reducing the number of parts. Therefore, it is possible to achieve both high-precision current detection, miniaturization, and cost reduction.

Next, the second embodiment will be described with reference to FIGS. 9 and 10. In the second embodiment, the configurations of the magnetic shields 12 and 13 are different from those of the first embodiment, and the other configurations are the same as those of the first embodiment. Therefore, the configurations of the magnetic shields 12 and 13 will be described. The description of the configuration of is omitted.

As shown in FIG. 10, the magnetic shield 12 has slits 12U, 12V, and 12W in which portions corresponding to the wide portions BUL, BVL, and BWL of the bus bars BU, BV, and BW are cut out, respectively. Similarly, the magnetic shield 13 has slits 13U, 13V, and 13W (see FIG. 9).

Therefore, the distance between the magnetic shields 12 and 13 can be narrowed without interfering with the wide portions BUL, BVL, and BWL of the bus bars BU, BV, and BW. As a result, the size of the current detection device 6 in the Z direction can be reduced. In addition to the effect of the current detection device 6 of the first embodiment, the current detection device 6 can be further miniaturized.

Next, the third embodiment will be described with reference to FIGS. 11 and 12. Since the shape of the bus bar BU, BV, and BW is different from that of the first embodiment and the other configurations are the same as those of the first embodiment, the shape of the bus bar BU, BV, and BW will be described. , Other configurations will be omitted.

As shown in FIGS. 11 and 12, the narrow portions BUS, BVS, and BWS of the bus bars BU, BV, and BW are formed by cutting out one side end side of the wide portions BUL, BVL, and BWL. Therefore, when forming the narrow portions BUS, BVS, and BWS of the bus bars BU, BV, and BW, the notch processing of the bus bars BU, BV, and BW is performed as compared with the bus bars BU, BV, and BW of the first embodiment. Man-hours can be reduced.

That is, in the bus bus BU, BV, BW of the first embodiment, the narrow portion BUS, BVS, BWS is formed by cutting out the wide portion BUL, BVL, BWL from both sides of the wide portion BUL, BVL, BWL. However, since the narrow portion BUS, BVS, BWS of the third embodiment can form the narrow portion BUS, BVS, BWS by cutting out only one side of the wide portion BUL, BVL, BWL. It is possible to reduce the processing man-hours.

1 rotary electric machine, 2 DC power supply, 3 inverter, 4 motor generator, 5 power converter, 6 current detector, 7 controller, 10, 11, 12, 13 magnetic shield, B, BU, BV, BW bus bar, BUL, BVL, BWL wide part, BUS, BVS, BWS narrow part, GH1, GH2, GH3, GL1, GL2, GL3, GL4, GL5, GL6, GL7 region, IV, IW current, PU, PV, PW substrate, SU, SV, SW magnetic conversion element, VLC, VSC, WLC, WSC center line.

Claims (2)

A plurality of bus bars arranged parallel to the first direction and extending in a second direction orthogonal to the first direction, respectively.
A magnetron conversion element that detects the current flowing through the bus bar,
A pair of magnetic shields arranged so as to sandwich the bus bar and the magnetron conversion element in the first direction and the third direction orthogonal to the second direction.
Is equipped with
Each bus bar has a narrow portion cut out from the side surface, and the narrow portion is arranged at a position not facing the adjacent narrow portion and at a position close to one of the magnetic shields.
The magnetron conversion element is arranged between the narrow portion and the magnetic shield on the side where the narrow portion is close to each other.
A current detector characterized by this. In the current detection device according to claim 1,
The narrow portion of each bus bar is formed by cutting out only one end side of each bus bar.
A current detector characterized by this.

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