JPS60219947A - Permanent magnet type synchronous motor - Google Patents

Abstract

PURPOSE:To obtain a motor which has high magnetization reduction resistance and torque performance, high speed response and ready generative brake, and small size and weight by forming the pole of the rotor by securing two or more types of permanent magnets of different magnetizing characteristics. CONSTITUTION:An armature winding is wound in a slot 2 of a stator core in which electromagnetic steel plates are laminated to form a stator 1. On the other hand, two types or more permanent magnets 31, 3b are secured to the outer periphery of a shaft 4 to form a rotor, the rotor is disposed in the bore side of the statot 1 through an air gap, thereby constructing a synchronous motor. In this case, a permanent magnet having high coercive force is used as a permanent magnet 3a of the side near the stator 1, and a permanent magnet having magnetic flux density is used preferably a permanent magnet 3b of the shaft 4 side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a permanent magnet type synchronous motor having field magnets formed from permanent magnets with different magnetization characteristics.

[Background technology of the invention]

Conventionally, the stator of a general synchronous motor has been constructed by laminating magnetic steel plates, slots are provided in the plates, and armature windings are wound thereon, and the rotor is constructed by fixing permanent magnets evenly distributed around the outer periphery of the shaft.

A structural diagram of a lO-pole synchronous motor is shown in Figure 1.

1 is a stator, 2 is a slot, 3 is a permanent magnet, 4 is a shaft, and U, V, and W are armature windings, and each phase of armature current that flows through them and creates a rotating magnetic field is shown.

[Problems with background technology]

By the way, when this synchronous motor is used as an AC servo motor, a high-speed response is required and a large armature current flows. Another feature of this type of motor is that it can perform dynamic braking during power outages.

In this case as well, an armature current several times the rated current flows.

Therefore, the permanent magnet must be able to withstand the demagnetizing force of the armature current.

For this purpose, conventionally, a permanent magnet with a high coercive force Ho has been used as a permanent magnet material.

However, in this case, a material with a high coercive force H6 has a characteristic of having a low residual magnetic flux density Br, which has the disadvantage that the induced voltage EMF becomes low, and therefore the generated torque as a synchronous motor becomes small.

On the other hand, if a permanent magnet with a high residual magnetic flux density Br (low coercive force H6) is used, the induced voltage EMF characteristics will improve and the performance of the generated torque will improve, but the demagnetization resistance will be poor. Although it is conceivable to increase the demagnetization resistance by increasing the thickness of the permanent magnet, the amount of permanent magnets required increases, thus increasing the cost and making magnetization difficult.

FIG. 2 shows a magnetization characteristic diagram of a permanent magnet.

21 is the magnetization characteristic of a permanent magnet with a low residual magnetic flux density Br and a high coercive force H6, and 22 is a permanent magnet with a high residual magnetic flux density Br (
This is the magnetization characteristic of a permanent magnet with low coercive force H6.

Furthermore, Fig. 3 shows the demagnetizing force distribution due to an armature current 5 times the rated value, Fig. 4 shows an enlarged view of the permanent magnet part, and Fig. 5 shows a detailed view of the demagnetizing force distribution of the permanent magnet. .

Arrow a indicates demagnetization, arrow s indicates magnetization, C indicates rotor rotation direction,
d is the magnetization direction of the permanent magnet, e is a region where large demagnetization occurs, and f is a region where magnetization occurs.

The rear portion of the rotor in the rotational direction C receives a large demagnetizing force.

Further, FIG. 6 shows the operating points on the magnetization characteristics of an example of a conventional synchronous motor using a permanent magnet material with a high coercive force Hc (low residual magnetic flux density Br).

Further, FIG. 7 shows the operating point on the magnetization characteristics of the other side of a conventional synchronous motor using a permanent magnet with a low coercive force H6 and a high residual magnetic flux density Br.

As is clear from the figure, there is a portion where the operating point exceeds the inflection point, which distorts the induced voltage EMF waveform and causes torque ripple.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the prior art and to provide a permanent magnet type synchronous motor in which the permanent magnet portion of the rotor is made of materials having different magnetization characteristics.

[Summary of the invention]

In the present invention, the permanent magnet portion of the rotor is made of at least two kinds of materials having different magnetization characteristics, for example, a permanent magnet with a low residual magnetic flux density Br (high coercive force H6) and a permanent magnet with a high residual magnetic flux density Br and low coercive force H6. This permanent magnet type synchronous motor is composed of permanent magnets, has high demagnetization resistance, has a large induced voltage EMF, and therefore has good torque performance.

[Embodiments of the invention]

A front view in cross section of one embodiment of the present invention is shown in FIG.
As shown in the figure.

The same reference numerals indicate the same or corresponding parts in all drawings.

The stator IVC, in which electromagnetic iron plates are laminated, has one slot 2 per pole and one phase, into which an armature winding is wound.

The 0-tata part is a permanent magnet with different magnetization characteristics, which is evenly distributed around the outer periphery of the shaft B and fixed in two pole layers with 7 poles each, that is, with a low residual magnetic flux density Br and a coercive force H6.
Permanent magnet with high 3. and a permanent magnet 3b having a high residual magnetic flux density Br and a low coercive force Ho.

The operating point on the magnetization characteristics of the synchronous motor according to the present invention is
It is shown in the figure.

As can be seen in the figure, the part that undergoes large demagnetization is handled by the permanent magnet 3a with a high coercive force H6, and the amount of magnetic flux is handled by the permanent magnet 3b with a high residual magnetic flux density Br.

Note that FIG. 10 shows an induced voltage EMF waveform that is a substitute characteristic for torque performance.

10 is a characteristic of only the permanent magnet 3a, 101) is a characteristic of only the permanent magnet 3b, and 101) is a characteristic of only the permanent magnet 3b.

As described above, from the operating points on the permanent magnet magnetization characteristics shown in FIGS. As seen in the figure, the induced voltage gMF is also large (therefore, an electric motor with high torque performance can be obtained).

FIG. 11 shows a front sectional view showing the main parts of another embodiment of the present invention.

In (a), the rotation direction C of the rotor is only clockwise, but (
In b), (C), and (d), the rotation direction C may be either clockwise or counterclockwise.

In other words, in the structure shown in FIG. 10, the part that is strongly subjected to armature reaction is made up of permanent magnets 3a with a high coercive force H6, and the other parts are made up of permanent magnets 3b with a high residual magnetic flux density Br.

〔Effect of the invention〕

Thus, according to the present invention, it is possible to obtain a servomotor that has high demagnetization resistance and high torque performance, and thus has high-speed response and easy dynamic braking.

In addition, since the permanent magnets can be made thinner, the amount of permanent magnets required is reduced, and magnetization is easier during the manufacturing process, making it possible to obtain a small, lightweight, and low-cost synchronous motor.

[Brief explanation of drawings]

Figure 1 is a structural diagram of a conventional example, Figure 2 is a magnetization characteristic diagram of a permanent magnet, Figure 3 is a distribution diagram of demagnetizing force due to armature current, Figure 4 is an enlarged view of the permanent magnet part, and Figure 5 is a diagram of the magnetization characteristics of a permanent magnet. A detailed diagram of the demagnetizing force distribution of the permanent magnet, Fig. 6 is an operating point diagram on the magnetization characteristic of an example of a conventional synchronous motor, Fig. 7 is an operating point diagram on the magnetization characteristic of the other side, and Fig. 8 is the main FIG. 9 is a diagram of operating points on the magnetization characteristics of the synchronous motor according to the present invention; FIG. 10 is a comparison diagram of induced voltage waveforms;
1(a), (b), (C), and (d) are front sectional views showing essential parts of other embodiments of the present invention. 1... Stator 2... Slot 3... Permanent magnet 3a... Permanent magnet 3b with low residual magnetic flux density Br and high coercive force H6... High Br ( Permanent magnet 4 with low Ho...
·shaft. Applicant's agent Kiyoshi Inomata Figure 1 Figure 2 Ei (KG) 5432 1 H (K Oe) Figure 5 Figure 6 H (K ER5) H (K De) Figure 8 ( ) ((KDc) Figure 10

Claims (1)

[Claims] 1. Laminated electromagnetic steel plates with slots on the inner periphery of the stator are arranged on the stator around which the armature winding is wound, and on the outer periphery of the shaft. , a permanent magnet type synchronous motor characterized by having a rotor with two or more fixed permanent magnets with different magnetization characteristics. 2. A permanent magnet with high coercive force is placed on the stator side, and the residual magnetic flux density A permanent magnet type synchronous motor according to claim 1, comprising a rotor having a tall permanent magnet fixed to the shaft side.