JP2018207726A - Current sensor - Google Patents

Abstract

To provide a current sensor capable of measuring a current flowing over a three-phase rotational machine and an inverter at high precisely while activating performance of a detection element.SOLUTION: A current sensor 1 comprises: a plurality of bus bars 10 which is arranged in parallel so as to be adjacent in each three-phase rotational machine 2 in a predetermined pitch across each of connection terminals of the plurality of three-phase rotational machines 2 and each of the connection terminals of an inverter 3 with a plurality of cooling functions; a plurality of cores 20 arranged so as to surround each bus bar 10 along a peripheral direction while displacing a position to an extended direction of each bus bar 10 in each of the three-phase rotational machines from the plurality of bus bars 10; and a plurality of detection elements 40 that detects density of a magnetic flux in which the plurality of cores 20 is magnetized. The core 20 arranged so as to surround the bus bar 10 in which the maximum current flows from the bus bars 10 connected to the plurality of three-phase rotational machines 2 is arranged in the inverter 3 side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current sensor that measures current flowing through a plurality of three-phase rotating electrical machines and a plurality of inverters with a cooling function.

  In recent years, hybrid vehicles and electric vehicles equipped with a motor and an inverter have become widespread. In order to appropriately 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 in such a motor have been studied (for example, Patent Documents 1 and 2).

  Patent Document 1 describes a stacked unit configured by stacking a plurality of power cards accommodating semiconductor elements and a plurality of coolers. 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 in accordance with the current flowing through the bus bar is detected by a sensor element disposed in the gap, thereby detecting 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 a state where the core and the bus bar are attached is covered with resin, and the core and the bus bar are integrated with the core holder.

Japanese Unexamined Patent Publication No. 2016-111167 JP 2013-242294 A

  The current sensor is provided between the inverter that converts the frequency of the input electric power and the three-phase rotating electric machine, and the current sensor is provided on the bus bar that connects the inverter and the three-phase rotating electric machine. For this reason, the core and the detection element provided in the current sensor are greatly affected by the heat (Joule heat) generated according to the current flowing through the bus bar. In general, the detection element is formed using a semiconductor, and its characteristics change (temperature drift) by receiving heat. Therefore, the technique described in Patent Document 1 accurately detects the current flowing through the bus bar. In such a case, the control of the three-phase rotating electrical machine may be adversely affected.

  In the technique described in Patent Document 2, the current detection units are arranged in a staggered manner, but the current detection units are arranged on the inverter side and the three-phase rotating electrical machine side, respectively. When the inverter has a cooling function, the periphery of the inverter has a high thermal conductivity and is easily dissipated, but at least one phase of the current detection unit is disposed on the three-phase rotating electrical machine side. Therefore, it is assumed that the influence of temperature on the current detection unit arranged on the three-phase rotating electrical machine side becomes large. Therefore, the amount of temperature change of the phase arranged on the three-phase rotating electrical machine side becomes large, which may adversely affect the control of the three-phase rotating electrical machine. Further, the detection element has a heat resistant temperature, and it is necessary to control the temperature based on the temperature of the phase arranged on the three-phase rotating electric machine side in order to keep the heat resistant temperature. As a result, the other phases are used in a temperature range that does not reach the heat-resistant temperature, and thus the ability of the detection element may not be fully utilized.

  Therefore, there is a demand for a current sensor that can accurately measure the current flowing between the three-phase rotating electrical machine and the inverter while utilizing the capability of the detection element.

  A characteristic configuration of the current sensor according to the present invention is a current sensor that measures a current flowing through each of a plurality of three-phase rotating electrical machines and a plurality of inverters with a cooling function, and each of the plurality of three-phase rotating electrical machines. And a plurality of bus bars arranged side by side so as to be adjacent to each of the three-phase rotating electrical machines at a predetermined pitch across the connection terminals of the plurality of inverters, and among the plurality of bus bars, For each of the three-phase rotating electrical machines, a plurality of cores arranged so as to surround the bus bar along the circumferential direction by shifting the position in the bus bar extending direction, and the density of magnetic flux collected by the plurality of cores. A plurality of detection elements for detection, and a core disposed so as to surround a bus bar through which a maximum current flows among bus bars connected to the plurality of three-phase rotating electrical machines is disposed on the inverter side In .

  The inverter with a cooling function has a structure in which the thermal conductivity is large and the heat is easily radiated by the cooler. On the other hand, since the bus bar that penetrates the current sensor is connected to the terminal of the inverter, the heat (Joule heat) generated in the bus bar is radiated to the cooler, and this heat radiation effect becomes larger as the distance from the cooler is shorter. . Therefore, with the above-described characteristic configuration, it is possible to suppress a temperature increase in the core and in the vicinity of the core by disposing the core disposed on the inverter side so as to surround the bus bar through which the maximum current flows. For this reason, since the temperature rise of the detection element which detects the density of the magnetic flux which arises in a core can also be suppressed, it becomes possible to make temperature drift small. Therefore, according to the current sensor, the current flowing between the three-phase rotating electric machine and the inverter can be accurately measured while utilizing the capability of the detection element, and the controllability of the three-phase rotating electric machine can be maintained. Is possible.

  In addition, among the plurality of detection elements, the detection element that detects the density of the magnetic flux collected by the core arranged so as to surround the bus bar through which the maximum current flows is located at a position where the distance from the inverter is uniform. It is preferable that they are arranged.

  With such a configuration, the cooling effect of the cooler on the detection element can be made uniform. Therefore, since the temperature drift of the detection element can be made uniform for each three-phase rotating electrical machine, the current flowing through the three-phase rotating electrical machine and the inverter can be measured with higher accuracy.

It is a perspective view of a current sensor. It is a top view of a current sensor. It is sectional drawing of the III-III line of FIG.

  The current sensor according to the present invention is configured 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 an axis according to the magnitude of the current, and a magnetic flux is generated by the magnetic field. The current sensor detects the density of the 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 is a perspective view of a current sensor 1 according to this embodiment. In order to facilitate understanding, the direction in which the bus bar 10 extending through the current sensor 1 extends is defined as the A direction, the direction in which the plurality of bus bars 10 are arranged is defined as the B direction, and the direction orthogonal to both the A direction and the B direction is defined as the direction. C direction. FIG. 2 shows a view (top view) of the current sensor 1 viewed from the direction C, and FIG. 3 shows a cross-sectional view taken along line III-III in FIG. Hereinafter, a description will be given with reference to FIGS. The current sensor 1 includes a bus bar 10, a core 20, and a detection element 40.

  Here, as shown in FIG. 2, the current sensor 1 measures the current flowing through each of the plurality of three-phase rotating electrical machines 2 and the plurality of inverters 3 with a cooling function. Therefore, a plurality of bus bars 10 are provided across the connection terminals of the plurality of three-phase rotating electrical machines 2 and the connection terminals of the plurality of inverters 3. In the present embodiment, an example in which there are two three-phase rotating electrical machines 2 and two inverters 3 will be described. The three-phase rotating electrical machine 2 corresponds to, for example, a motor 2A that serves as a power source for a hybrid vehicle or an electric vehicle, or a generator 2B that generates electric power. The inverter 3 converts the frequency of input power, for example. The bus bar 10 performs power transmission between the three-phase rotating electrical machine 2 and the inverter 3. In this embodiment, since there are two three-phase rotating electrical machines 2 and two inverters 3 each, the bus bar 10 is composed of six as shown in FIGS. The current sensor 1 uses the current (three-phase current) flowing through the plurality of bus bars 10 as a measurement target.

  Each of the two three-phase rotating electrical machines 2 is provided with three connection terminals of a U-phase terminal, a V-phase terminal, and a W-phase terminal, and each of the two inverters 3 has a U-phase terminal, a V-phase terminal, and a W-phase terminal. Three connection terminals of phase terminals are provided. The U-phase terminal of one of the two three-phase rotating electrical machines 2 (motor 2A) and the U-phase terminal of one of the two inverters 3 (inverter 3A) are connected by one bus bar 10 (hereinafter referred to as “bus bar 10A”). The V-phase terminal of the one three-phase rotating electrical machine 2 (motor 2A) and the V-phase terminal of the one inverter 3 (inverter 3A) are connected by one bus bar 10 (hereinafter referred to as “bus bar 10B”). The W-phase terminal of the one three-phase rotating electrical machine 2 (motor 2A) and the W-phase terminal of the one inverter 3 (inverter 3A) are connected by one bus bar 10 (hereinafter referred to as “bus bar 10C”).

  The U-phase terminal of the other (generator 2B) of the two three-phase rotating electrical machines 2 and the U-phase terminal of the other (inverter 3B) of the two inverters 3 constitute one bus bar 10 (hereinafter referred to as “bus bar 10D”). The V-phase terminal of the other three-phase rotating electrical machine 2 (generator 2B) and the V-phase terminal of the other inverter 3 (inverter 3B) are connected to one bus bar 10 (hereinafter referred to as “bus bar 10E”). The W-phase terminal of the other three-phase rotating electrical machine 2 (generator 2B) and the W-phase terminal of the other inverter 3 (inverter 3B) are connected to one bus bar 10 (hereinafter referred to as “bus bar 10F”). Connected by

  The plurality of bus bars 10 are juxtaposed so as to be adjacent to each other for each three-phase rotating electrical machine 2 at a predetermined pitch. As shown in FIG. 2, “arranged in parallel at a predetermined pitch” means that the six bus bars 10 are arranged side by side so that the intervals P between two adjacent bus bars 10 are equal. Adjacent to each three-phase rotating electrical machine 2 means that in this embodiment, the bus bar 10A, the bus bar 10B, and the bus bar 10C connected to the motor 2A are arranged in order, and the bus bar 10D, the bus bar 10E connected to the generator 2B, It means that the bus bars 10F are arranged in order. In FIG. 2, the interval between the bus bar 10C and the bus bar 10D is shown as the interval P, but the interval P may not be the interval between the bus bar 10C and the bus bar 10D.

  The core 20 is disposed so as to surround the bus bar 10 along the circumferential direction by shifting the position in the extending direction of the bus bar 10 for each of the three-phase rotating electrical machines 2 among the plurality of bus bars 10. The phrase “arranged for each three-phase rotating electrical machine 2 among the plurality of bus bars 10” means that the bus bar 10A, the bus bar 10B, the bus bar 10C, and the bus bar 10D, the bus bar 10E, and the bus bar 10F are separately arranged. means. The “extending direction of the bus bar 10” is a direction in which the bus bar 10 is provided from one of the three-phase rotating electrical machine 2 and the inverter 3 to the other, and specifically corresponds to the A direction in FIGS. .

  Here, in the present embodiment, the core 20 includes a plurality of groove portions 21 and a partition wall portion 22 that separates the groove portions 21 adjacent to each other. In addition, outer walls 23 are provided on both outer sides of the plurality of grooves 21. In the present embodiment, as shown in FIGS. 1 to 3, the core 20 includes three groove portions 21. Therefore, the core 20 of the present embodiment has two partition walls 22. Such a core 20 is made of a magnetic material. The core 20 according to the present embodiment is formed by laminating a flat plate made of a metal magnetic body having a groove portion 21 in the direction A of FIGS. The metal magnetic body is a soft magnetic metal and corresponds to an electromagnetic steel plate (silicon steel plate), permalloy, or the like. For example, a non-oriented electrical steel sheet can be used as such a magnetic body. Of course, other electromagnetic steel sheets can also be used. The core 20 is configured by punching such a metal magnetic material. The core 20 can also be configured by sintering a powder magnetic material.

  As shown in FIGS. 1 to 3, the corresponding bus bar 10 is inserted into each groove portion 21. Therefore, the core 20 surrounds each of the plurality of bus bars 10 along the circumferential direction. As described above, the core 20 surrounds each of the bus bars 10 along the circumferential direction, so that the magnetic flux generated around the bus bar 10 can be easily collected. In the present embodiment, the core 20 has been described as having a plurality of groove portions 21 and a partition wall portion 22 that separates the adjacent groove portions 21 from each other. However, the core 20 is individually provided for each of the plurality of bus bars 10. (It may be provided so that one core 20 surrounds one bus bar 10). In this case, the core 20 may be formed so that the A direction view is U-shaped, or the A direction view may be C-shaped.

  A plurality (two in this embodiment) of such cores 20 are provided as shown in FIGS. One of the two cores 20 (hereinafter referred to as “core 20A”) is disposed so as to surround the bus bar 10A, bus bar 10B, and bus bar 10C along the circumferential direction, and the other of the two cores 20 (hereinafter referred to as “core 20B”). Are arranged so as to surround the bus bar 10D, the bus bar 10E, and the bus bar 10F along the circumferential direction.

  In the current sensor 1, a core 20 arranged so as to surround the bus bar 10 through which the maximum current flows among the bus bars 10 connected to the plurality of three-phase rotating electrical machines 2 is arranged on the inverter side. In the present embodiment, a motor 2A and a generator 2B are exemplified as the plurality of three-phase rotating electrical machines 2. The bus bar 10 includes bus bars 10A, 10B, and 10C connected to terminals of the motor 2A, and bus bars 10D, 10E, and 10F connected to terminals of the generator 2B. The bus bar 10 through which the maximum current flows refers to the bus bar 10 through which the largest current flows among the bus bars 10A, 10B, 10C, 10D, 10E, and 10F. In this embodiment, the bus bars 10A, 10B, and 10C connected to the motor 2A. Suppose that In this case, as shown in FIG. 2, the core 20A disposed so as to surround the bus bars 10A, 10B, and 10C is disposed on the inverter 3 side, and the core 20B disposed so as to surround the bus bars 10D, 10E, and 10F. It arrange | positions at the three-phase rotary electric machine 2 (generator 2B) side.

  The core 20 is disposed at the position as described above, and is molded with the bus bar 10 inserted therethrough. Thereby, at least a part of each of the bus bar 10 and the core 20 is included in the resin. It is preferable that at least a recess 50 (described later) is formed in the groove 21 described above. Hereinafter, the bus bar 10 and the core 20 integrated by resin molding will be referred to as a resin molding unit 60 and described.

  The detection element 40 is mounted on the substrate 30 and detects the density of magnetic flux collected by the plurality of cores 20. The detection element 40 is provided in the opening part of each groove part 21 of the core 20, and detects the density (magnetic flux density) of the magnetic flux which arises in an opening part. As described above, in this embodiment, two cores 20 are provided. Therefore, a plurality (six in this embodiment) of detection elements 40 are mounted on the substrate 30. Such a detection element 40 may be a known Hall IC or magnetoresistive element (MR element). Further, each detection element 40 may be manufactured by the same process, preferably manufactured by the same lot, in order to reduce the detection error included in the detection result of the magnetic flux density.

  The substrate 30 is fixed to the resin molding unit 60. For this reason, the resin molding unit 60 is provided with a fixing portion 61 to which the substrate 30 is fixed. In the present embodiment, the substrate 30 is fixed to the resin molding unit 60 via screws 70. Therefore, in the present embodiment, the fixing portion 61 corresponds to a screw hole into which the screw 70 is screwed. As shown in FIG. 2, the fixing portion 61 is provided between two bus bars 10 adjacent to each other. In the present embodiment, two fixing portions 61 are provided apart from each other.

  By configuring the current sensor 1 as described above, since the inverter 3 is provided with a cooling function, it is possible to cool Joule heat generated in the bus bars 10A, 10B, and 10C. Therefore, an increase in the ambient temperature of the detection element 40 provided in the core 20 can be suppressed, and a temperature drift in the electrical characteristics of the detection element 40 can be reduced.

  In particular, among the plurality of detection elements 40 described above, the detection element 40 that detects the density of magnetic flux collected by the core 20 disposed so as to surround the bus bar 10 through which the maximum current flows has a distance from the inverter 3. It is preferable to arrange them at uniform positions. Thereby, the cooling effect by the cooling function provided in the inverter 3 can be made uniform with respect to the detection element 40. Therefore, the temperature drift in the electrical characteristics of the detection element 40 can be further reduced.

[Other Embodiments]
In the above embodiment, the motor 2A and the generator 2B are described as examples of the plurality of three-phase rotating electrical machines 2, but the number of the plurality of three-phase rotating electrical machines 2 may be three or more. Further, all the three-phase rotating electrical machines 2 may be motors 2A, and all the three-phase rotating electrical machines 2 may be generators 2B.

  In the above embodiment, the bus bar 10 through which the maximum current flows among the bus bars 10 connected to the plurality of three-phase rotating electrical machines 2 is described as being the bus bars 10A, 10B, and 10C connected to the motor 2A. When the flowing bus bar 10 is the bus bars 10D, 10E, and 10F connected to the generator 2B, the core 20B may be disposed on the inverter 3B side, and the core 20A may be disposed on the motor 2A side.

  In the above embodiment, among the plurality of detection elements 40, the detection element 40 that detects the density of the magnetic flux collected by the core 20 arranged so as to surround the bus bar 10 through which the maximum current flows has a single distance from the inverter 3. Although it has been described that it is preferable to arrange in such a position, the detection element 40 may not be arranged in a position where the distance from the inverter 3 is uniform.

  In the above-described embodiment, it has been described that six detection elements 40 are mounted on the substrate 30. However, the detection elements 40 are individually mounted on the substrate 30, that is, as many substrates 30 as the detection elements 40 are prepared. It is also possible to configure so that one detection element 40 is mounted on one substrate 30.

  The present invention can be used for a current sensor that measures current flowing through a plurality of three-phase rotating electrical machines and a plurality of inverters with a cooling function.

1: Current sensor 2: Three-phase rotating electric machine 3: Inverter 10: Bus bar 20: Core 40: Detection element

Claims (2)

A current sensor that measures current flowing through each of a plurality of three-phase rotating electrical machines and a plurality of inverters with a cooling function,
A plurality of bus bars arranged in parallel so as to be adjacent to each of the three-phase rotating electrical machines at a predetermined pitch across the connecting terminals of the plurality of three-phase rotating electrical machines and the connecting terminals of the plurality of inverters. When,
Among the plurality of bus bars, for each of the three-phase rotating electrical machines, a plurality of cores arranged so as to surround the bus bar along the circumferential direction by shifting the position in the bus bar extending direction,
A plurality of detection elements for detecting the density of magnetic flux collected by the plurality of cores,
A current sensor in which a core disposed so as to surround a bus bar through which a maximum current flows among bus bars connected to the plurality of three-phase rotating electrical machines is disposed on the inverter side.   Among the plurality of detection elements, the detection element for detecting the density of magnetic flux collected by the core arranged so as to surround the bus bar through which the maximum current flows is arranged at a position where the distance from the inverter is uniform. The current sensor according to claim 1.

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