JP6883241B2 - Current sensor - Google Patents

Description

The present invention relates to a current sensor that measures the current flowing through a conductor.

In recent years, hybrid vehicles and electric vehicles equipped with a motor and an inverter have become widespread. In order to properly control the rotation of such a motor, it is important to measure the current flowing through the motor. Therefore, conventionally, techniques for measuring the current flowing through such a motor have been studied (for example, Patent Documents 1 and 2).

Patent Document 1 describes a laminated unit in which a plurality of power cards accommodating a semiconductor element and a plurality of coolers are laminated. As a power card, this laminated unit includes a voltage converter that boosts the DC voltage of the battery and an inverter that converts the boosted DC voltage into an AC voltage.

In Patent Document 2, a bus bar is passed through the center of a core having a gap, and the magnetic flux of the core that changes according to the current flowing through the bus bar is detected by a sensor element arranged in the gap to detect the current. A current sensor is described. In this current sensor, the core and the bus bar are attached to the core holder in advance, the core holder in which the core and the bus bar are attached is covered with resin, and the core and the bus bar are integrated by the core holder.

Japanese Unexamined Patent Publication No. 2016-11117 Japanese Unexamined Patent Publication No. 2013-242294

Here, in a hybrid vehicle or an electric vehicle, the number of boosting parts (for example, a reactor) or a motor may differ depending on the vehicle. When the stacking unit described in Patent Document 1 is used for such an application, it is necessary to newly design each time the number of stacking power cards and coolers (hereinafter referred to as “stacking number”) is adjusted to the variation. , There is room for cost reduction. Further, even in the technique described in Patent Document 2, as in the case of the laminated unit described in Patent Document 1, it is necessary to design each time when application to the above application is considered, and there is room for cost reduction. is there.

Therefore, there is a demand for a current sensor that can be realized at low cost even when the number of boosting parts and motors differs depending on the vehicle.

The characteristic configuration of the current sensor according to the present invention is such that a plurality of bus bars on which a three-phase current flowing through a three-phase rotating electric machine to be measured is energized and the plurality of bus bars are individually surrounded along the circumferential direction. The first unit includes a core, a first unit accommodating the plurality of bus bars and the core, and a substrate on which a detection element for detecting the density of the magnetic current collected by the core is mounted . The fixing portion has a fixing portion to which the substrate is fixed, and the fixing portion is within a range defined by half the pitch of the bus bars adjacent to each other among the plurality of bus bars with respect to the bus bar adjacent to the fixing portion. lies in the fact that that provided to.

With such a feature configuration, the first unit can be a common element and the second unit can be a variable element. Therefore, for example, when the number of three-phase rotating electric machines is one, the current sensor is configured with one first unit housed in the second unit, and the number of three-phase rotating electric machines is two. In the case, the current sensor is configured with the two first units housed in the second unit, and when the number of three-phase rotating electric machines is three, the three first units are used as the second unit. By configuring the current sensor in the housed state, it is possible to flexibly respond to the variation of the system in which the current sensor is used. Therefore, according to this current sensor, even if the number of boosting parts and motors differs depending on the vehicle, the first unit can be shared, so that it is not necessary to redesign the first unit. .. Therefore, the cost related to the design can be reduced. Further, by sharing the first unit, the member management cost can be reduced, and it can be realized at a low cost.

Further, with such a configuration, even when a plurality of first units are arranged side by side to form the second unit, the pitch between all the bus bars can be made uniform. Therefore, for example, it is possible to easily connect to the terminal of the three-phase rotary electric machine.

Further, it is preferable that the detection element is mounted on the substrate according to the number of bus bars to which the three-phase current to be measured is energized.

With such a configuration, by appropriately setting the positioning of the substrate and the core, a plurality of detection elements can be simultaneously arranged at appropriate positions with respect to the core.

Further, it is preferable that the pitch of the bus bars adjacent to each other among the plurality of bus bars is the same pitch as the terminals of the inverter of the cooling unit in which the power card accommodating the plurality of electronic components and the plurality of coolers are laminated. Is.

With such a configuration, the pitch of the bus bar in the first unit and the pitch of the bus bar in the second unit can be set to the same pitch as the terminals of the inverter. Therefore, the bus bar of the current sensor and the terminal of the inverter can be easily connected, and the current sensor can be easily assembled to the cooling unit.

It is a perspective view of a current sensor. It is a top view of the current sensor. It is sectional drawing of the line III-III of FIG. It is a top view of the first unit. It is sectional drawing of the VV line of FIG. It is a top view of the 1st unit which a current sensor for two three-phase rotary electric machines has. It is a top view of the current sensor for two three-phase rotary electric machines.

The current sensor according to the present invention is configured to be able to measure the current flowing through the bus bar. Here, when a current flows through the conductor, a magnetic field is generated with the conductor as the axis according to the magnitude of the current, and a magnetic flux is generated by the magnetic field. This current sensor detects the density of such magnetic flux (magnetic flux density) and measures the current (current value) flowing through the bus bar based on the detected magnetic flux density.

FIG. 1 shows a perspective view of the current sensor 1 according to the present embodiment. For ease of understanding, the direction in which the bus bar 2 penetrating the current sensor 1 extends is the A direction, the direction in which the plurality of bus bars 2 are lined up is the B direction, and the direction orthogonal to both the A direction and the B direction is set. Let it be in the C direction. FIG. 2 shows a view (top view) of the current sensor 1 viewed from the C direction, and FIG. 3 shows a view (side view) of the current sensor 1 viewed from the A direction. Hereinafter, it will be described with reference to FIGS. 1 to 3. The current sensor 1 includes a bus bar 2, a core 10, a first unit 20, a second unit 30, and a substrate 40.

The bus bar 2 is energized with a three-phase current flowing through a three-phase rotating electric machine to be measured. The bus bar 2 is used for connecting a three-phase rotary electric machine (general term for a three-phase motor) (not shown) and a terminal of an inverter that energizes the three-phase rotary electric machine. Three-phase rotating electric machines are used as power sources for hybrid vehicles and electric vehicles. The inverter converts the DC power output from the battery or the like into AC power. The bus bar 2 supplies the voltage and current converted into AC power by such an inverter to the three-phase rotary electric machine. Therefore, in the present embodiment, the bus bar 2 is composed of three as shown in FIGS. 1 to 3. The current sensor 1 measures the current (three-phase current) flowing through such a plurality of bus bars 2.

The core 10 is arranged so as to individually surround the plurality of bus bars 2 along the circumferential direction. In the present embodiment, the core 10 is configured to have a plurality of groove portions 11 and a partition wall portion 12 that separates the groove portions 11 adjacent to each other. Further, outer wall portions 13 are provided on both outer sides of the plurality of groove portions 11. In the present embodiment, as shown in FIGS. 1 to 3, the core 10 is configured to have three groove portions 11. Therefore, the core 10 of this embodiment has two partition walls 12. Such a core 10 is made of a magnetic material. The core 10 according to the present embodiment is formed by laminating flat plates made of a metal magnetic material having a groove 11 in the direction A of FIGS. 1 to 3. The metal magnetic material is a soft magnetic metal, and corresponds to an electromagnetic steel plate (silicon steel plate), permalloy, or the like. As such a magnetic material, for example, a non-oriented electrical steel sheet can be used. Of course, other electromagnetic steel sheets can also be used. The core 10 is formed by punching out such a metal magnetic material. The core 10 can also be formed by sintering a powdered magnetic material.

As shown in FIGS. 1 to 3, a corresponding bus bar 2 is inserted through each groove 11. Therefore, the core 10 surrounds each of the plurality of bus bars 2 along the circumferential direction. By surrounding each of the bus bars 2 along the circumferential direction in this way, the core 10 can easily collect the magnetic flux generated around the bus bar 2. In the present embodiment, the core 10 is described as having a plurality of groove portions 11 and a partition wall portion 12 that separates the groove portions 11 adjacent to each other, but each of the plurality of bus bars 2 is individually configured. (One core 10 may be provided so as to surround one bus bar 2). In such a case, the A-direction view of one core 10 may be formed in a U-shape, or the A-direction view may be C-shaped.

FIG. 4 shows a top view of the first unit 20, and FIG. 5 shows a cross-sectional view taken along the line VV of FIG. As shown in FIGS. 4 and 5, the first unit 20 accommodates a plurality of bus bars 2 and core 10. In the present embodiment, the plurality of bus bars 2 are three bus bars 2. The first unit 20 is configured by including at least a part of each of these three bus bars 2 and the core 10 with a resin. The groove portion 11 described above may be filled with resin so that at least a recess 43 (described later) is formed. It is preferable that such a first unit 20 is formed by resin molding.

Returning to FIGS. 1 to 3, the second unit 30 accommodates the first unit 20 according to the number of three-phase rotary electric machines. In this embodiment, there is only one three-phase rotary electric machine. Therefore, the second unit 30 accommodates one first unit 20. It is preferable that such a second unit 30 is formed by resin molding with the first unit 20 included.

The substrate 40 is mounted with a detection element 41 that detects the density of the magnetic flux collected by the core 10. The detection element 41 is provided in the opening portion of each groove portion 11 of the core 10 and detects the density (magnetic flux density) of the magnetic flux generated in the opening portion. As described above, in this embodiment, three cores 10 are provided. Therefore, three detection elements 41 are mounted on the substrate 40. As such a detection element 41, a known Hall IC or magnetoresistive sensor (MR element) may be used. Further, as each detection element 41, in order to reduce the detection error included in the detection result of the magnetic flux density, it is preferable to use one manufactured by the same process, preferably one manufactured in the same lot.

In the present embodiment, the substrate 40 is mounted with the detection elements 41 according to the number of bus bars 2 to which the three-phase current to be measured is energized. In this embodiment, as described above, the three detection elements 41 are provided. These three detection elements 41 are mounted on one substrate 40.

The substrate 40 is fixed to the first unit 20. Therefore, the first unit 20 is provided with a fixing portion 42 to which the substrate 40 is fixed. In this embodiment, the substrate 40 is fixed to the first unit 20 via screws 50. Therefore, in the present embodiment, the fixing portion 42 corresponds to a screw hole into which the screw 50 is screwed.

The fixing portion 42 is provided within a pitch-defined range of half the pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2 with respect to the bus bar 2 adjacent to the fixing portion 42. In this embodiment, two fixing portions 42 are provided so as to be separated from each other. The bus bar 2 adjacent to the fixed portion 42 is the bus bar 2 closest to each other in FIG. 2 from the fixed portion 42. For ease of understanding, if the two fixing portions 42 are fixed portions 42A and 42B and the bus bars 2 are bus bars 2A, 2B and 2C, the bus bar 2A corresponds to the bus bar 2 adjacent to the fixing portion 42A and is fixed. The bus bar 2C corresponds to the bus bar 2 adjacent to the portion 42B.

The pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2 corresponds to the distance P1 between the bus bar 2A and the bus bar 2B and the distance P2 between the bus bar 2B and the bus bar 2C. Therefore, the half pitch corresponds to half the length of the interval P1 and half the length of the interval P2. In the present embodiment, the interval P1 and the interval P2 are configured by the same interval P. Therefore, the fixed portion 42A is provided within the range defined by the distance P / 2 from the bus bar 2A, and the fixed portion 42B is provided within the range defined by the distance P / 2 from the bus bar 2C. With this configuration, the first unit 20 can be compactly configured.

It should be noted that the pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2 is configured to be the same pitch as the terminals of the inverter of the cooling unit in which the power card containing the plurality of electronic components and the plurality of coolers are stacked. Suitable. As a result, the bus bar 2 of the current sensor 1 can be easily connected to the terminal of the inverter, and the current sensor 1 can be easily assembled to the cooling unit.

Such a first unit 20 is formed by resin molding as described above. At this time, it is preferable that the first unit 20 is provided with a screw hole as the fixing portion 42. Further, a recess 43 into which the detection element 41 is inserted is also provided. The detection element 41 mounted on the substrate 40 is in a state of being inserted into the recess 43 when the substrate 40 is fixed to the second unit 30. The recess 43 may be provided so that the detection element 41 is arranged at a position where the magnetic flux passing through the groove 11 of the core 10 can be detected with high accuracy.

Further, the substrate 40 on which the detection element 41 is mounted is also provided with a hole 44, and the substrate 40 is placed in the first unit 20 via the screw 50 in a state where the hole 44 and the screw hole (fixing portion 42) are aligned with each other. It is fastened and fixed to.

[Other Embodiments]
In the above embodiment, the example in which the second unit 30 accommodates one first unit 20 has been described, but the second unit 30 can also be configured to accommodate a plurality of first units 20. .. FIG. 6 shows a top view of the first unit 20 included in the two current sensors 1 for a three-phase rotary electric machine. In this case, as shown in FIG. 6, two first units 20 are used according to the number of three-phase rotary electric machines. The first unit 20 is resin-molded in a state of being provided according to the pitch of the terminals of the three-phase rotary electric machine or the power card to which the current sensor 1 is connected, and is housed in the second unit 30 as shown in FIG. .. As described above, according to the current sensor 1, it is only necessary to standardize the first unit 20 and increase or decrease the number according to the environment in which the current sensor 1 is provided, so that the first unit 20 does not need to be redesigned. .. In addition, the member management cost can be reduced. Therefore, the current sensor 1 can be realized at low cost. Further, since the fixed portion 42 is provided for the bus bar 2 adjacent to the fixed portion 42 within a range defined by a pitch of half the pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2, a plurality of fixed portions 42 are provided. Even if one unit 20 is provided adjacent to each other, the pitch between all the bus bars 2 can be made uniform.

In the above embodiment, the fixed portion 42 of the first unit 20 has a range defined by half the pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2 with respect to the bus bar 2 adjacent to the fixed portion 42. Although it has been described that it is provided inside, the fixing portion 42 can be provided regardless of the pitch of the bus bars 2 adjacent to each other.

In the above embodiment, it has been described that the substrate 40 is mounted with the detection elements 41 according to the number of bus bars 2 to which the three-phase current to be measured is energized, but the substrate 40 is related to the number of bus bars 2. It is also possible to mount a number of detection elements 41 that do not.

In the above embodiment, one substrate 40 is fixed to one first unit 20, but one substrate 40 can be fixed to a plurality of first units 20.

In the above embodiment, the pitch of the bus bars 2 adjacent to each other among the plurality of bus bars 2 is the same pitch as the terminals of the inverter of the cooling unit in which the power card containing the plurality of electronic components and the plurality of coolers are stacked. However, this is just an example. Therefore, the pitch of the bus bar 2 can be configured to match the pitch of the connection terminals of other devices, or can be configured independently of the pitch of the connection terminals.

In the above embodiment, the substrate 40 has been described as being fixed to the first unit 20, but it may be configured to be fixed to the second unit 30.

The present invention can be used in a current sensor that measures the current flowing through a conductor.

1: Current sensor 2: Bus bar 10: Core 20: 1st unit 30: 2nd unit 40: Substrate 41: Detection element 42: Fixed part

Claims (3)

Multiple bus bars to which the three-phase current flowing through the three-phase rotating electric machine to be measured is energized,
A core arranged so as to individually surround the plurality of bus bars along the circumferential direction,
A first unit accommodating the plurality of bus bars and the core,
A second unit accommodating the number of the three-phase rotary electric machines and the first unit, and
A substrate on which a detection element that detects the density of magnetic flux collected by the core is mounted, and
Equipped with a,
The first unit has a fixing portion to which the substrate is fixed.
The fixing portion, to the bus bars adjacent to the fixing unit, the current sensor that provided within the range defined by half the pitch of the pitch of the adjacent bus to each other among the plurality of bus bars. The current sensor according to claim 1 , wherein the detection element is mounted on the substrate according to the number of bus bars to which the three-phase current to be measured is energized. Pitch of the bus bars adjacent to each other among the plurality of bus bars, according to claim 1 or a power card plurality of electronic components are accommodated a plurality of coolers is the same pitch as the terminals of the inverter cooling units stacked 2. The current sensor according to 2.

Images