CN111466003B

CN111466003B - Reactor with current sensor

Info

Publication number: CN111466003B
Application number: CN201880079983.9A
Authority: CN
Inventors: 青木弘利; 稻田宪弘
Original assignee: Tamura Corp
Current assignee: Tamura Corp
Priority date: 2017-12-18
Filing date: 2018-10-11
Publication date: 2021-09-07
Anticipated expiration: 2038-10-11
Also published as: CN111466003A; WO2019123790A1; JP2019110202A; JP7049749B2

Abstract

Provided is a reactor with a current sensor, which can maintain a linear relationship between a magnetic flux density and an input electromotive force. The annular core (11) has two leg sections (1a) arranged in parallel and two yoke sections (1b) arranged so as to connect the ends of the two leg sections (1 a). The coil (2) is attached to at least one of the leg sections (1 a). The sensor core (3) protrudes outward from the annular core (11) beyond the outer peripheral surface of the annular core (11) at the corner between the leg (1a) and the yoke (1 b). The notch (3a) is provided in the sensor core (3). A magnetic field detection element (5) of the current sensor is mounted in the cutout portion (3 a).

Description

Reactor with current sensor

Technical Field

The present invention relates to a reactor with a current sensor having a function of detecting a current flowing through a coil.

Background

In recent years, environmentally friendly vehicles such as EVs (electric vehicles) and HEVs (hybrid vehicles) have been developed for environmental protection. These vehicles are systems in which a motor is driven by electricity, and a high-voltage battery, a control unit, and the motor are combined. The control unit includes a reactor therein, and a current sensor is used to detect a current applied to the reactor. In order to cope with higher efficiency of environmentally friendly vehicles, it is inevitable to reduce the size and weight of the unit, but the reactor and the current sensor are generally separate, which is disadvantageous in terms of demand.

In order to solve such a problem, for example, a reactor with a current sensor as shown in patent document 1 is proposed. In the reactor of patent document 1, a slit is provided in advance in a part of a core constituting the reactor, a magnetic field detection element of a current sensor is disposed inside the slit, and a coil is wound around the outside of the slit. Patent document 1 also describes a structure in which a hole is formed in the core or a magnetic field detection element is disposed on the outer peripheral surface of the core, instead of the slit. In such a conventional technique, when the reactor is operated, the current flowing through the coil generates a magnetic flux in the core, and therefore the magnetic flux is detected by the magnetic field detection element, and the current sensor can detect the value of the current flowing through the coil.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5252207

Disclosure of Invention

Problems to be solved by the invention

The reactor described in patent document 1 is a so-called UU core in which both ends of the core are curved in an arc shape, and therefore the direction of the magnetic flux passing through the core is almost identical to the curved shape of the core. In general, the magnetic flux is formed in a ring shape with respect to its generation source (coil in the case of a reactor), and passes through a path having the smallest magnetic resistance and the shortest. In the structure of patent document 1, the main magnetic field is formed in the substantially O-shaped magnetic path generated by the UU core, but for the above reason, the magnetic flux concentrates on the innermost side of the core, and the magnetic flux density of this portion becomes high, and tends to gradually decrease as it approaches the outer peripheral portion. However, since the outer peripheral portion of the UU core has an arc shape, the magnetic flux density is high even in the outer peripheral portion of the core, and saturation is likely to occur when the current flowing through the coil increases.

Therefore, in the conventional technique in which a magnetic field detection element is provided on a part of the UU core or on the outer peripheral surface of the core as in patent document 1, as shown in the left graph of fig. 9, the input magnetomotive force to the magnetic field detection element increases as the current flowing through the coil increases, and the relationship between the magnetic flux density and the input magnetomotive force does not show a linear proportional relationship. As a result, the accuracy of the detection value of the current sensor is lowered.

The present invention has been made to solve the above-described problems of the prior art. An object of the present invention is to provide a reactor with a current sensor, in which an iron core for mounting the current sensor (hereinafter, referred to as a sensor iron core) is provided in a portion where a magnetic flux density is lower than a magnetic flux density of a leg portion during operation of the reactor, thereby ensuring linearity between the magnetic flux density and an input magnetomotive force and improving detection accuracy of a coil current.

Means for solving the problems

The reactor with a current sensor according to the present invention is characterized by having the following configuration.

(1) And an annular core having two leg portions arranged in parallel and two yoke portions arranged so as to connect end portions of the two leg portions to each other.

(2) And a coil attached to at least one of the legs.

(3) And a sensor core provided at a corner of the leg portion and the yoke portion at a portion where a magnetic flux density is lower than that of the leg portion.

(4) And a notch portion provided in the sensor core.

(5) And a magnetic field detection element of the current sensor mounted in the cutout portion.

The present invention also includes the following modes.

(6) The sensor core is provided at a position bulging toward the outer periphery of the annular core than an arc surface connecting outermost peripheral surfaces of the two leg portions and an outermost peripheral surface of the yoke portion.

(7) The notch is provided so as to intersect the direction of the magnetic flux passing through the annular core.

(8) The sensor iron core and the annular iron core are arranged in a split mode and fixed on the surface of the annular iron core through a heat insulation sheet.

Effects of the invention

According to the present invention, since the sensor core is provided in a portion where the magnetic flux density at the corner of the annular core is low, even if the current flowing through the coil is large, the sensor core is less likely to be saturated, linearity between the magnetic flux density and the input magnetomotive force is ensured, and the accuracy of detecting the current flowing through the core by the magnetic field detection element provided in the sensor core portion is improved.

Drawings

Fig. 1 is a perspective view showing embodiment 1.

Fig. 2 is an enlarged perspective view of the sensor core portion of embodiment 1 as viewed from above.

Fig. 3 is an enlarged perspective view of the sensor core portion of embodiment 1 as viewed from below.

Fig. 4 is a plan view showing embodiment 1.

Fig. 5 is a plan view showing the magnetic flux density of the core according to embodiment 1.

Fig. 6 is a plan view showing embodiment 2.

Fig. 7 is a plan view showing embodiment 3.

Fig. 8 is a plan view showing embodiment 4.

Fig. 9 is a graph comparing the current sensing characteristics of the present invention with those of the prior art.

Detailed Description

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

[1 ] embodiment 1 ]

(1) Structure of the product

The reactor of the present embodiment includes: an annular core 1 having a quadrangular opening at the center thereof; and a coil 2 attached to the annular core 1. The annular core 1 includes two leg portions 1a arranged in parallel and two yoke portions 1b arranged to connect end portions of the two leg portions 1a to each other, and coils 2 are attached to outer peripheries of the two leg portions 1 a.

In the present embodiment, the annular core 1 is formed by abutting leg portions 1a of two U-shaped cores, each having one-half length of the leg portion 1a on both sides of one yoke portion 1b, with a center gap therebetween. The coil 2 is formed by winding one flat conductor so as to be folded back halfway to form mounting portions 2a for the two leg portions 1a, and when the two U-shaped cores are butted, the leg portions 1a of the annular core 1 are inserted inside the mounting portions 2 a. Lead portions 2b are provided at both ends of the coil 2, and the lead portions 2b connect the coil 2 to an external power supply.

At the corner of the leg portion 1a and the yoke portion 1b, a sensor core 3 is provided at a portion of the leg portion 1a where the coil 2 is not mounted, the portion having a magnetic flux density lower than the highest magnetic flux density. For example, the sensor core 3 is provided at a position bulging toward the outer periphery of the annular core 1 from an arc surface connecting the outermost peripheral surface A, B of the two leg portions 1a and the outermost peripheral surface C of the yoke portion 1 b.

In the present embodiment, the annular core 1 is formed by obliquely chamfering the corner portions of the leg portion 1a and the yoke portion 1b formed in a square shape, and therefore, the edge core 1c portion bulging toward the outer periphery than the arc surface is formed. That is, as shown in fig. 5, since the substantially O-shaped magnetic path formed by the annular core 1 is concentrated on the inside at the corner portion, the edge core 1c portion becomes the outside with respect to the magnetic path, and the magnetic flux density becomes relatively small. Therefore, the sensor core 3 is provided in the edge core 1c portion, and the edge core 1c portion is located outside the magnetic path having a high magnetic flux density formed in an arc shape.

The sensor core 3 is provided separately from the leg portion 1a and the yoke portion 1b so as to cut the edge core 1c portion of the annular core 1, and is fixed to the outer periphery of the annular core 1 with a gap in which the heat insulating sheet 4 is interposed. In this case, the sensor core 3 and the annular core 1 may be formed in a shape in which they are partially connected to each other by providing the gap halfway in the cross section of the annular core 1, instead of completely separating the sensor core 3 and the annular core 1 by the gap.

The sensor core 3 is provided with a notch 3a so as to intersect the direction of the magnetic flux passing through the annular core 1. The cutout portion 3a is a slit formed vertically downward from the upper surface of the sensor core 3. A magnetic field detection element 5 such as a hall element is mounted in the cutout portion 3 a. The lead wire 6 extending from the magnetic field detection element 5 passes through the cutout portion 3a and protrudes toward the surface of the sensor core 3.

The current sensor has: a substrate (not shown) connected to the lead wires 6 and supporting the magnetic field detection element 5; and a connector (not shown) provided integrally with the substrate. An electronic component such as an ASIC (application specific integrated circuit) that processes a signal from the magnetic field detection element 5 is provided on the substrate, and an output portion of the electronic component is connected to an external device via a connector.

The annular core 1, the sensor core 3, and the coil 2 are housed in a case 7 made of metal such as aluminum or resin. A filler 8 such as resin is filled in a gap between the case 7 and the annular core 1 and the coil 2. A current sensor is fixed to a position of the upper edge portion of the case 7 facing the sensor core 3 by means of screw fixation, adhesion, fitting, or the like.

(2) Action and Effect

In the present embodiment, when the coil 2 is energized, the current generates a magnetic field in the annular core 1, and functions as a reactor. At the same time, the sensor core 3 provided at the corner of the annular core 1 also generates a leakage flux due to the influence of the current flowing through the coil 2, and the magnetic field detection element 5 provided in the notch 3a of the sensor core 3 detects the leakage flux. Since the leakage magnetic flux of the sensor core 3 portion is proportional to the current flowing through the coil 2, the magnetic field detection element 5 can measure the magnitude of the current flowing through the coil 2 and function as a current sensor.

In this case, since the sensor core 3 is provided in a portion where the magnetic flux density is lower than that of the leg portion 1a at the corner portion of the leg portion 1a and the yoke portion 1b, the sensor core 3 does not saturate during the reactor operation, and the input magnetomotive force and the magnetic flux density of this portion show a linear proportional relationship as shown in the right graph of fig. 9, and the current flowing through the coil 2 by the magnetic field detection element 5 can be detected with high accuracy. Further, since the sensor core 3 is provided at a position bulging toward the outer periphery of the annular core 1 from the arc surface connecting the outermost peripheral surfaces of the two leg portions 1a and the outermost peripheral surface of the yoke portion 1b, although the magnetic flux density of the sensor core 3 itself is low, a magnetic path from the leg portion 1a to the core portion is sufficiently secured inside the arc surface, and therefore, the operational characteristics of the reactor are not adversely affected.

Further, since the sensor core 3 is provided to the annular core 1 with the heat insulating sheet 4 interposed therebetween, heat generated when energized from the coil 2 is not transmitted through the annular core 1, and there is no concern of thermal destruction of the magnetic field detection element 5 or reduction in detection accuracy, and the device selection range of the magnetic field detection element 5 is expanded.

[2 ] other embodiments ]

The present invention is not limited to the above embodiments, and for example, includes other embodiments described below.

(1) As in embodiment 2 shown in fig. 6, instead of being formed separately from the leg portion 1a and the yoke portion 1b of the annular core 1, the core may be provided integrally with the corner portion of the annular core 1 without providing a gap or a notch.

(2) In embodiment 1, the four corner portions of the annular core 1 have the same shape, but only one or two corner portions may be provided so as to bulge outward on the outer peripheral side and the sensor core 3 may be provided in the corner portions. In the annular core 1 having the arc-shaped yoke portion 1b described in patent document 1, as in embodiment 3 shown in fig. 7, a sensor core 3 may be fixed to the outer peripheral surface of the annular core 1 as a separate body instead of bulging the corner of the annular core 1.

(3) The notch 3a in which the magnetic field detection element 5 is disposed may be formed from the outer peripheral side of the annular core 1 toward the core interior, in addition to the upper surface side of the annular core 1 toward the core interior. The notch 3a is preferably provided at right angles to the direction of the magnetic flux passing through the sensor core 3, but is not necessarily required to be at right angles depending on the characteristics of the magnetic flux detection element, and may be a circular hole or the like other than the slit shape shown in the figure. Further, the notch 3a and the magnetic flux detection element need not be located entirely outside the arc shown in fig. 4, and the notch 3a and a part of the magnetic flux detection element may be located inside the arc.

(4) The sensor core 3 may not necessarily be provided in the outermost peripheral portion of the corner portion as long as it maintains a minimum cross-sectional area for the main magnetic path so as not to affect the performance of the reactor. As in embodiment 4 shown in fig. 8, the sensor core 3 may be provided at a position shifted toward the leg portion 1a or the yoke portion 1b from the outermost peripheral portion of the corner portion.

(5) The ring-shaped core 1 may be formed by combining two U-shaped cores, or may be formed by combining four core materials constituting the leg portion 1a and the yoke portion 1b in a ring shape. The leg portion 1a and the yoke portion 1b need not be separate members, and may be formed of a plurality of core materials connected with a gap therebetween.

(6) In the annular core 1 having the different cross-sectional areas of the leg portion 1a and the yoke portion 1b, the position of the notch portion 3a may be determined so that a cross-sectional area substantially equal to that of a member having a small cross-sectional area (that is, the leg portion 1a or the yoke portion 1b) is left at the corner of the annular core 1. Since the main magnetic flux passes through the cross-sectional area portion left at the corner portion, the sensor core 3 portion provided with the notch portion 3a is not saturated, and linearity of the input magnetomotive force of the sensor core 3a portion can be ensured.

Industrial applicability

Since the sensor core is provided in a portion where the magnetic flux density at the corner of the annular core is low, even if the current applied to the coil is increased, the sensor core is less likely to be saturated, linearity between the magnetic flux density and the input magnetomotive force is ensured, and accuracy of detection of the current applied to the core by the magnetic field detection element provided in the sensor core portion is improved.

Description of the reference symbols

1: an annular iron core; 1 a: a leg portion; 1 b: a yoke portion; 1 c: an edge iron core; 2: a coil; 2 a: an installation part; 2 b: a lead-out section; 3: a sensor core; 3 a: a cut-out portion; 4: a heat insulating sheet; 5: a magnetic field detection element; 6: a wire; 7: a housing; 8: and (4) filling materials.

Claims

1. A reactor with a current sensor, comprising:

an annular core having two leg portions arranged in parallel and two yoke portions arranged so as to connect end portions of the two leg portions to each other;

a coil attached to at least one of the legs;

a sensor core provided at a corner portion between the leg portion and the yoke portion, the sensor core being a peripheral core having a magnetic flux density lower than that of the leg portion and being positioned outside a magnetic path having a magnetic flux density higher than that of the arc shape;

a notch portion provided in the sensor core; and

and a magnetic field detection element of the current sensor mounted in the cutout portion.

2. The reactor with current sensor according to claim 1,

the sensor core is provided at a position bulging toward the outer periphery of the annular core than an arc surface connecting the outermost peripheral surfaces of the two leg portions and the outermost peripheral surface of the yoke portion.

3. The reactor with current sensor according to claim 1,

the notch is provided so as to intersect the direction of the magnetic flux passing through the annular core.

4. The reactor with a current sensor according to claim 1 or 2,

the sensor iron core and the annular iron core are arranged in a split mode and fixed on the surface of the annular iron core through a heat insulation sheet.