JPS5853868B2 - Magnetic sensor for measuring iron loss of magnetic materials - Google Patents

Description

Detailed Description of the Invention The present invention measures the iron loss of a magnetic material by correlating the iron loss of the magnetic material with the stress or residual strain acting on the magnetic material. The present invention relates to a magnetic sensor for measuring iron loss of a magnetic material used in a device for determining stress or residual strain acting on the magnetic material.

As shown in FIG. 1, a conventional magnetic sensor 1 is constructed by winding a primary coil (excitation coil) 3 and a secondary coil (output secondary voltage coil) 4 around an iron core 2 having a U-shaped cross section.

When this magnetic sensor 1 is pressed against a measurement point on the surface of the magnetic material 50 where the iron loss is to be measured and the primary coil 3 is excited with single-phase alternating current, the magnetic flux from the iron core 2 is transferred to the magnetic material 50 as shown by the arrow. A closed magnetic path is formed in which the iron flows through the iron core 2 and returns to the iron core 2 again.

At this time, the primary voltage is controlled to keep the output voltage induced in the secondary coil 4 constant, and the primary coil 3 is connected to the current terminal of a wattmeter (not shown), and the secondary coil 4 is connected to the current terminal of the wattmeter (not shown). The iron loss is measured by connecting it to the voltage terminal of a wattmeter, and the stress or residual strain acting on the magnetic material 5 can be determined from the predetermined relationship between the iron loss and the stress or residual strain. .

However, since the primary coil 3 of the magnetic sensor 1 is normally excited by single-phase alternating current, the attractive force between the magnetic sensor 1 and the magnetic material 50 whose iron loss is to be measured is proportional to the square of the magnetic flux generated in the primary coil 3. However, when the instantaneous value of the current is zero, the magnetic flux is zero, so the attractive force is also zero, and the magnetic sensor 1 moves from the measurement point due to the vibration generated by the single-phase alternating current, and the magnetic sensor 1 and the magnetic Since the contact state between the materials 50, especially the air gap, changes, the measured values vary and the iron loss at the correct measurement point cannot be measured.The present invention is a magnetic sensor for measuring iron loss of magnetic materials. This was done in order to prevent the magnetic sensor from moving due to vibrations, so that even if the instantaneous value of the excitation current becomes zero, the magnetic sensor's attractive force does not become zero, and the magnetic sensor always acts on the attractive force. The present invention provides a magnetic sensor that is held at a measurement point and can always accurately measure iron loss at the measurement point.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a perspective view of a magnetic sensor for measuring iron loss of a magnetic material according to the present invention, and FIG. 3 is a view taken in the direction of arrow A in FIG.

In the figure, a magnetic sensor for measuring iron loss of magnetic materials (hereinafter abbreviated as magnetic sensor) 6 of the present invention is composed of an iron core 1, a coil 8, a secondary coil 9, and shaded coils 10 and 11.

That is, the iron core 7 is made of a laminated iron core or a ferrite core with a substantially U-shaped cross section, and two magnetic pole portions thereof are provided with notches 12 and 13, respectively, to form a magnetic pole 14 and a salient magnetic pole 15° 16, The secondary coil 9 is attached to the magnetic pole 14, the salient magnetic pole 15,
A primary coil 8 is provided in close contact with the outside of the secondary coil 9 and the shade coils 10 and 11, each of which is wound with a shade coil 10, 11.

Since the magnetic sensor 6 of the present invention has the above-described configuration, when the primary coil 8 is now excited with single-phase alternating current, the transformer action due to the alternating magnetic flux in the iron core 7 causes two waves to be applied to the shaded coils 10 and 11. The next short circuit current flows.

Due to the principle of transformers, this secondary short-circuit current
Since it acts to prevent changes in the magnetic flux in the salient magnetic pole 15.16 portion, the magnetic flux in the salient magnetic pole 15.16 portion
It changes later than the change in magnetic flux in the 0 portion.

Therefore, when the primary coil 8 is excited with single-phase alternating current, the magnetic pole 1
Since there is a phase difference between the magnetic flux flowing through the magnetic material (not shown) through the magnetic material 4 and the magnetic flux flowing into the magnetic material through the salient magnetic poles 15 and 16 having the shaded coils, there is also a phase difference in the attractive force. Even if the instantaneous value of the excitation current of the primary coil 8 becomes zero, both attraction forces will not become zero at the same time.
.

Therefore, the magnetic sensor 6 is not moved by vibration and is held at the measurement point.

Further, since the magnetic flux of the shaded coil does not intersect with the secondary coil, it does not affect the secondary coil 9 and is not related to the measured iron loss.

In the above embodiment, the case where two salient magnetic poles and therefore two shaded coils were provided was explained.
It is obvious that it can be made into individual pieces.

As described above, if the magnetic sensor of the present invention is used, even if the instantaneous value of the excitation current of the magnetic sensor's primary coil becomes zero, the attractive force will not become zero even if the instantaneous value of the excitation current of the magnetic sensor's primary coil becomes zero. Since the sensor does not move due to vibration, it does not cause any change in the air gap, and the rounded coil does not affect the secondary coil, so the correct iron loss can be measured.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of iron loss measurement using a conventional magnetic sensor, Fig. 2 is a perspective view of an embodiment of the present invention, and Fig. 3 is an illustration of A in Fig. 2.
It is an arrow view. 6...Magnetic sensor, 7...Iron core, 8.
...Primary coil, 9...Secondary coil, 1
0, 11... Bear coil, 12, 13...
...Notch, 14...Magnetic pole, 15.16.
... Salient magnetic pole.

Claims (1)

[Claims] 1. A notch is provided in two magnetic pole parts of an iron core having a substantially U-shaped cross section to form a magnetic pole and at least one small salient magnetic pole, and a secondary coil is connected to the magnetic pole and to the salient magnetic pole. 1. A magnetic sensor for measuring iron loss of a magnetic material, characterized in that a primary coil is provided in close contact with the outside of the secondary coil and the shaded coil.