JP2020134497A - Current sensor - Google Patents

Abstract

To provide a multi-phase integrated current sensor with multiple openings of different shapes, which can be configured using inexpensive linear bus bars even when a pitch of bus bars to be detected changes.SOLUTION: A current sensor provided herein is configured to be compatible with multiple bus bar pitches by horizontally widening openings of left and right phases using an opening of a center phase as a reference. Gaps of left and right cores 3a, 3c are wider than a gap of a center phase core 3b.SELECTED DRAWING: Figure 5

Description

The present invention relates to the structure of a multi-phase integrated current sensor that detects a multi-phase current.

In the conventional current sensor, in order to detect the current of the bus bar, a C-shaped core that collects the magnetic flux generated by the current in the gap, a magnetic sensitive element that is inserted into the gap of the core and detects the magnetic flux density, and them are used. It is composed of a case provided with an opening for holding and passing a bus bar.

In a three-phase integrated current sensor that detects the current of a three-phase motor or the like, the C-shaped core, a magnetic sensitive element, and a case are usually used so that the currents of three bus bars arranged in the horizontal direction can be detected at the same time. The three openings are arranged side by side in the horizontal direction, and the three openings have the same size so that a predetermined bus bar can penetrate (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-139556 (Page 10, Fig. 3)

As described above, the bus bars arranged in the horizontal direction in the conventional current sensor are preferably arranged according to the terminal pitch dimension of the power converter that generates the current detected by the current sensor, but the terminals of the power converter The pitch dimensions are not unified. For example, the terminal pitches of the predetermined same rated products are 47 mm for company A, 48 mm for company B, and 41 mm and 31 mm for company C. Therefore, if there is no current sensor having openings of the same pitch, a straight bus bar cannot form a current path from the power converter to the current sensor.
In this case, in order to form a current path from the power converter to the opening of the current sensor, it is necessary to take a method that is not economical compared to using a straight bus bar, such as using a crank-shaped bus bar. ..

The present invention has been made to solve the above problems, and provides a multi-phase integrated current sensor capable of detecting the current of a linear bus bar having a different bus bar pitch with one type of current sensor. The purpose is to do that.

The current sensor of the present invention has a C-shaped core that collects magnetic flux generated by currents to be detected flowing through a plurality of non-flexible conductors, and a magnetic detection element that is inserted into a gap between the cores to detect the magnetic flux for each conductor. The plurality of cores have different magnetic path lengths and different gap dimensions, and the gap dimensions of cores having a longer magnetic path length than the others are longer than the others.

According to the present invention, it is possible to detect a plurality of conductor pitches with one type of current sensor, and it is not necessary to adjust the conductors to a predetermined pitch. Further, since it is not necessary to newly develop a current sensor according to the pitch to be used, it is possible to inexpensively configure a power conversion device and a device using the current sensor.

FIG. 6 is an external view of the current sensor according to the first embodiment of the present invention when the bus bar pitch is narrow. FIG. 6 is an external view of the current sensor according to the first embodiment of the present invention when the bus bar pitch is wide. FIG. 5 is a perspective view when the current sensor according to the first embodiment of the present invention is used when the bus bar pitch is narrow. FIG. 5 is a perspective view when the current sensor according to the first embodiment of the present invention is used when the bus bar pitch is wide. The internal structural drawing of the current sensor of Embodiment 1 of this invention. The bus bar is in the state when it passes through the center of the core opening. The figure which showed the gap dimension of the core of the current sensor of Embodiment 1 of this invention.

Embodiment 1
FIG. 1 is an external view of the current sensor 1 according to the first embodiment of the present invention when the bus bars 2a, 2b, 2c having a narrow pitch P1 are passed through the openings 6a, 6b, 6c of the current sensor 1. 3 is a perspective view thereof. FIG. 2 is an external view when the bus bars 2a, 2b, 2c having a wide pitch P2 are passed through the openings 6a, 6b, 6c of the current sensor 1, and FIG. 4 is a perspective view thereof.
In FIG. 3, the power conversion device 7 controls the frequency and magnitude of the three-phase voltage and current, outputs the power to the output terminals 8a, 8b, and 8c, and the three-phase motor via the bus bars 2a, 2b, and 2c connected to them. It is connected to (not shown). The central opening 6b of the current sensor 1 has a quadrangular shape through which the bus bar 2b can penetrate, and the left and right openings 6a and 6c have a quadrangular shape long in the horizontal direction. The output terminals 8a, 8b, and 8c of the power conversion device 7 have a narrow pitch P1, and the bus bars 2a and 2c are arranged unevenly on the opening 6b side in the frame of the openings 6a and 6c.
In FIG. 4, the output terminals 10a, 10b, and 10c of the power conversion device 9 have a wide pitch P2, and the bus bars 2a and 2c are arranged unevenly outside the frame of the openings 6a and 6c.

FIG. 5 is an internal structural diagram of the current sensor 1. The cores 3a, 3b, and 3c have a C-shape arranged so as to surround the openings 6a, 6b, and 6c, and the cores 3a, 3c arranged on the left and right are larger than the cores 3b arranged in the center. It is longer in the horizontal direction. The magnetic sensing elements 4a, 4b, and 4c are fixed to the printed circuit board 5 so as to be inserted into the gaps between the cores 3a, 3b, and 3c, and the output signal thereof is detected and output by an electronic circuit (not shown).

FIG. 6 shows the gap size of the core. The gap size of the left and right cores 3a and 3c is W2, the gap size of the central core 3b is W1, and W1 <W2.

According to the present embodiment, in order to provide a wider space in the horizontal direction than the central core 3b, the deterioration of the magnetic saturation characteristics of the cores 3a and 3c caused by lengthening the core magnetic path lengths of the left and right cores 3a and 3c is deteriorated. By widening the gap dimension W2, the magnetic resistance of the cores 3a and 3c can be increased to improve the magnetic resistance, and the detection error of the magnetic sensing elements 4a and 4c can be reduced.

By setting the gap dimension W1 narrower than the gap dimension W2 to the central core 3b having a short magnetic path length, a large magnetic flux density generated in the gap portion can be obtained. The magnetic sensing element 4b outputs a voltage proportional to the magnetic flux density generated in the gap, and is used by amplifying it to a desired voltage by an electronic circuit configured in the same integrated circuit as the magnetic sensing element or on a printed substrate. However, since the voltage generated by the magnetic sensing element 4b can be increased by increasing the magnetic flux density, the amplification factor of the electronic circuit can be decreased. As a result, the amplification of errors generated from the magnetic sensing element and the electronic circuit can be reduced, so that the design, component selection, and adjustment of the electronic circuit can be simplified and the cost can be reduced.

In the present embodiment, the cases where the pitches of the three bus bars 2a, 2b, and 2c are the same are shown, but different pitches in which the dimensions of P1 and P2 are combined may be used. Further, although the openings 6a, 6b, and 6c are rectangular, they may be circular or elliptical as long as the bus bar can penetrate. Further, although the current sensor 1 shows a three-phase integrated type, it may be a two-phase integrated type having only openings 6a and 6b.

1: Current sensors 2a to 2c: Bus bars 3a to 3c: Core (magnetic material)
4a to 4c: Magnetic sensitive element 5: Printed substrate 6a to 6c: Opening 7: Power conversion device with narrow output terminal pitch 8a to 8c: Output terminal of power conversion device 7: Power conversion device 10a to wide output terminal pitch 10c: Output terminals P1 and P2 of the power converter 9: Bus bar pitch W1, W2: Gap size of the core

Claims (2)

A current sensor that detects the current flowing through multiple non-flexible conductors.
A C-shaped core that collects the magnetic flux generated by the detected current,
A plurality of sets of magnetic detection elements inserted into the gaps of the core to detect the magnetic flux are provided for each conductor.
A current sensor characterized in that the plurality of cores have different magnetic path lengths and different gap dimensions, and the gap dimensions of cores having a longer magnetic path length than others are longer than others. The plurality of non-flexible conductors are three bus bars arranged on the same surface, and the magnetic path lengths of the cores arranged on both outer sides of the cores are larger than the magnetic path lengths of the cores arranged in the center. The current sensor according to claim 1, wherein the current sensor is long.

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