JP2626852B2 - AC synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in rotational characteristics of an AC synchronous motor.

[0002]

2. Description of the Related Art FIG. 1 shows a main configuration of an AC synchronous motor 1. The AC synchronous motor 1 includes a permanent magnet rotor 2 and a stator 3 surrounding the rotor 2. The rotor 2 is constituted by a cylindrical permanent magnet, and is in a state in which N poles and S poles are alternately magnetized in the circumferential direction. The stator 3 includes a plurality of main poles 4 and auxiliary poles 5 surrounding the rotor 2 in, for example, a four-split state, and a single-turn coil 6 for exciting these main poles 4 and auxiliary poles 5.
It is composed of The auxiliary pole 5 is arranged with a mechanical phase difference α with respect to the main pole 4, and is combined with the shading coil 7 for improving startability.

Next, FIG. 2 shows a conventional magnetizing method for the rotor 2. The rotor 2 is arranged concentrically with respect to the cylindrical magnetized yoke 8 and magnetized so as to alternately form N poles and S poles in the circumferential direction. Here, the maximum value of the amount of magnetization in the circumferential direction of the magnetization yoke 8 is, as shown in FIG.
The N pole and the S pole are set to be the same.

In such an AC synchronous motor 1, an abnormal vibration rotation phenomenon called "oscillation" appears during rotation. Such abnormal rotation characteristics cause problems such as instability and noise during steady-state rotation after the initial startup. FIG. 4 shows the rotation characteristics together with the rotation angle of the rotor 2 with respect to the passage of time (leading angle of the power supply waveform) at this time. As is apparent from the figure, the rotation trajectory at this time rotates in the forward direction in synchronization with the power supply waveform while returning in the reverse direction for a certain time. Such a phenomenon is caused by the rotor 2
Is considered as a kind of resonance phenomenon occurring between the inertia of the motor and the rotational torque.

FIG. 5 shows an abnormal rotation region on a graph of a power supply voltage with respect to a power supply frequency. From this graph, the range of the usable normal rotation region is a portion surrounded by two abnormal rotation regions. Commercial power frequency 50/60 [H
z] In the case of common use, the usable normal rotation area is narrow, so that it is difficult to set the area. The usable normal rotation region is determined by the gap between the rotor 2 and the stator,
It does not change even if the inertia of the motor and the specifications of the single-turn coil 6 are changed.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a practically usable normal rotation range of an AC synchronous motor of this kind and obtain stable rotation characteristics.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the inventor, as a result of trial and error, gives periodic strength to reluctance torque as a result of trial and error in the process of changing the components of the AC synchronous motor 1. It was found out that the abnormal rotation area can be moved by the above. The present invention expands the range of the normal rotation region that can be used practically by making the circumferentially magnetized amount of the permanent magnet rotor 2 undulate based on the above findings. Here, the undulation of the amount of magnetization in the circumferential direction is usually given as a sine wave in order to avoid a sudden change in rotational unevenness, and the peak difference of the undulation is set in the range of 10 to 30%.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the basic structure of an AC synchronous motor 1 is basically the same as that of FIG. here,
The rotor 2 of the permanent magnet is formed with undulation in the amount of magnetization in the circumferential direction. FIG. 6 shows a change in the amount of magnetization of the permanent magnet in the circumferential direction of the rotor 2. The magnetized state is N pole and S
The poles are alternately repeated, and the waveform is preferably sinusoidal. And the peak is
One round of the rotor 2 is formed with one cycle of undulation, and the peak difference [(b / a) × 100] between the maximum value a and the minimum value b of the same pole is 13 to 23%. The range is preferably set in the range of 10 to 30%. Such a setting range of the peak difference is necessary in order to reduce the variation in the starting characteristics to a range that can be used practically.

In this manner, the change in the reluctance torque of the permanent magnet with respect to the rotor 2 is caused by a sinusoidal wave on the amount of magnetization of each pole in the process of magnetizing the circumferential surface of the rotor 2, for example, one round of 24 poles. It is set by giving strength, that is, swell. Such a magnetized state is set by disposing the center of the rotor 2 eccentric by an amount corresponding to the swell of the magnetized amount with respect to the center of the magnetized yoke 8 as shown in FIG. it can. The undulation of the magnetization amount is given as one cycle for one round of the circumferential surface of the rotor 2, but can be set to one cycle or more.

FIG. 8 shows the rotation region characteristics of the power supply voltage with respect to the power supply frequency according to the present invention. According to the present invention, since the two abnormal rotation regions are separated in the direction of frequency,
The normal rotation area is expanding.

[0011]

According to the present invention, the frequency range of the commercial power supply is 50/60 [H
z], a stable rotation characteristic can be obtained, and the air gap, the inertia of the rotor, and the use of the winding can be afforded. Moreover,
Since such improvement of the rotation characteristics can be realized without changing the mechanical components of the AC synchronous motor, there is no change in the size or shape of each part, and it can be easily dealt with by changing the magnetization method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of an AC synchronous motor.

FIG. 2 is an explanatory diagram of a conventional magnetizing method.

FIG. 3 is a graph of the amount of magnetization in a circumferential direction of a conventional rotor.

FIG. 4 is a graph of a rotation characteristic of a rotor.

FIG. 5 is a graph of a conventional rotation region.

FIG. 6 is a graph of the amount of magnetization in the circumferential direction of the rotor of the present invention.

FIG. 7 is an explanatory diagram of a magnetizing method of the present invention.

FIG. 8 is a graph of a rotation region.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC synchronous motor 2 Rotor 3 Stator 4 Main pole 5 Complementary pole 6 Single winding coil 7 Shading coil 8 Magnetization yoke

Claims (3)

(57) [Claims] 1. An AC synchronous motor having a permanent magnet rotor, wherein the amount of magnetization in the circumferential direction of the rotor is undulated. 2. The AC synchronous motor according to claim 1, wherein the undulation is sinusoidal. 3. The peak difference of undulation is 10 to 30.
2. The AC synchronous motor according to claim 1, wherein [%] is set.