JPS60226751A - Permanent magnet rotor type synchronous motor - Google Patents

Abstract

PURPOSE:To improve the starting characteristic of a synchronous motor by composing a cylindrical permanent magnet rotor magnetized in the same direction as an alternating magnetic field generated between poles of a stator of permanent magnets of different magnetic flux density. CONSTITUTION:An armature winding 10 connected with an AC power source is wound on a stator core 9. A permanent magnet rotor 6 is disposed through an air gap 11 at the end of the core 9. The rotor 6 is a cylindrical permanent magnet rotor magnetized in the same direction as an alternating magnetic field generated between poles of a stator, and a permanent magnet 7 of high magnetic density higher than the permanent magnet of a base is partly buried along the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a permanent magnet rotor type synchronous motor that can be used with an AC power source as a rotational power source for small household appliances and the like.

Conventional configuration and its problems The starting method of a synchronous motor is generally one using starting torque based on the principle of an induction motor.
Some small rotors with an oW or less are made of a single permanent magnet as a rotor. This rotor has a small and lightweight rotor, has a low rate of inertia with respect to rotational motion of the rotor, and therefore has good ability to follow the rotational speed of the rotor. Therefore, if the motor is energized without using the starting torque based on the principle of an induction motor, the motor can be instantly brought up to the synchronous speed due to rotational vibration.

FIG. 4 shows a conventional example of such a synchronous motor, in which 1 is a cylindrical permanent magnet rotor rotatably supported by a shaft 4 and magnetized as shown, 2 is a stator core, and 3 is a cylindrical permanent magnet rotor. is the armature winding connected to the AC power source. The direction of rotation of this synchronous motor is not fixed, and it can rotate either clockwise or counterclockwise, and when it starts, an alternating magnetic field is generated between the magnetic poles of the stator 2 by the armature winding 3, causing the permanent magnet to rotate. This is because the child 1 receives a magnetic attraction and repulsion force, starts instantaneously or in small increments of reversal vibration, and as this increases, it begins to rotate in synchronization with the alternating magnetic field. Then, at the first moment when the armature winding 3 is energized, a large vibration shock is applied to the permanent magnet rotor 1, and in order to maintain and increase the vibration and make it easier to start, the magnetic pole part of the stator core 2 and the permanent magnet The air gaps 5 between the rotors 1 are intentionally made non-uniform as shown. When the armature i-wire 3 is not energized, the permanent magnet rotor 1 is stopped toward the narrower gap between it and the stator core 2, and when the armature winding 3 is energized, the stator Since the direction of the alternating magnetic field generated between the magnetic poles and the direction of the magnetic axis of the permanent magnet rotor 1 are misaligned, a large excitation force can be obtained. However, after starting, there is no effect due to the non-uniformity of the air gap 5, but rather the air gap 6 becomes larger on average, causing adverse effects such as a reduction in maximum output, worsening of temperature rise, and reduction in efficiency.

OBJECTS OF THE INVENTION It is an object of the present invention to solve such conventional problems and to obtain a permanent magnet rotor type synchronous motor that improves startability without impairing various characteristics of the motor.

Structure of the Invention In order to achieve the above object, the permanent magnet rotor type synchronous motor of the present invention makes the air gap between the magnetic poles of the stator and the permanent magnet rotor uniform, or minimizes the non-uniformity of the air gap, and improves the air gap. By reducing the magnetic flux of the permanent magnet rotor to the minimum mechanically safe level, the magnetic flux of the permanent magnet rotor is efficiently transferred to the stator side, maintaining various characteristics as an electric motor, and improving startability.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a permanent magnet rotor type synchronous motor according to the present invention. Reference numeral 6 is a cylindrical permanent magnet rotor, and a part of it has a permanent magnet rotor attached to the base body along the axial direction as shown in the figure. A permanent magnet 7 having a higher magnetic flux density than the magnet 6 is embedded.

8 is a shaft, 9 is a stator core, and 10 is an armature winding connected to an AC power source. The permanent magnets 6, 7 are magnetized in the same direction as shown, and the gap 11 between the stator poles and the permanent magnet rotor is of uniform width. Figure 2 is a graph showing the distribution of surface magnetic flux density on the circumferential surface of this permanent magnet rotor. The angle ψ expressed as degrees is taken, and the vertical axis is the surface magnetic flux density B. FIG. 3 is an enlarged view of the main part of FIG. 1.

When the armature winding 1o is not energized, the permanent magnet rotor remains tilted as shown in the figure, with the high magnetic flux density magnets 7 attracting the stator magnetic poles.

When the armature winding 10 is energized in this state, an alternating magnetic field is generated between the stator magnetic poles, and the permanent magnet rotor receives an attractive and repulsive force.
The repulsive forces Fa and Fd acting on points become torques that rotate the permanent magnet rotor clockwise, and the repulsive forces Fb acting on points b and c
, Fo are the torques to rotate counterclockwise.

As shown in Figure 2, the magnetic flux density on the circumference of the permanent magnet rotor at these four points is lower than points a and d, so the repulsive forces Fa and Fd are weaker than the repulsive forces Fb and Fo. , υThe torque that attempts to rotate it counterclockwise increases.Also, when it is attracted, the torque that attempts to rotate it clockwise increases, and the permanent magnet rotor is easily subjected to excitation force due to the alternating magnetic field. It can be started.

Effects of the Invention As is clear from the above explanation, the permanent magnet rotor type synchronous motor of the present invention can ensure startability without intentionally widening the air gap, and by reducing the air gap to the maximum / hour limit, By making the uniform air gap as small as possible and using the composite permanent magnet rotor of the present invention in combination, the magnetic flux of the permanent magnet rotor can be effectively utilized, resulting in a small size and high output. Still, the base permanent magnet is a commonly used inexpensive material such as ferrite, and the high magnetic flux density part is made of rare earth cobalt, but the high magnetic flux density part only needs to be small in volume, so it is cost-effective. The high magnetic flux density portion is not only effective at startup, but also contributes to an increase in output by supplying magnetic flux to the stator in the same way as the permanent magnets during operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a permanent magnet rotor type synchronous motor according to the present invention, and FIG. 2 is a graph showing the distribution of surface magnetic flux density of the permanent magnet rotor of the permanent magnet rotor type synchronous motor according to the present invention. , Figure 3 is an enlarged view of the main part of Figure 1, and Figure 4 is a schematic diagram showing a conventional example. Name of agent: Patent attorney Toshio Nakao and one other person No. 1
Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) An armature winding connected to an AC power supply, a magnetic path of an alternating magnetic field generated by this armature winding, and a stator having a magnetic pole part, and a rotatable structure between the stator's magnetic poles. It has a cylindrical permanent magnet rotor that is journalled and magnetized in the same direction as the alternating magnetic field generated between the magnetic pole parts of the stator, and the permanent magnet rotor is a permanent magnet rotor composed of permanent magnets with different magnetic flux densities. Child type synchronous motor. (2) The permanent magnet rotor type synchronous motor according to claim 1, wherein the gap between the magnetic poles of the permanent magnet rotor and the stator is uniform. (3) The permanent magnet rotor is composed of two types of permanent magnets. A permanent magnet with a high magnetic flux density is also embedded, and in this arrangement, the directions of the magnetic axes of the two types of permanent magnets are the same, and the position where the permanent magnet with a high magnetic flux density is embedded is the center of the magnetic pole of the permanent magnet in the base body. The distance between high magnetic flux density permanent magnets embedded in one magnetic pole of the permanent magnet of the base body is 180 degrees in electrical angle. A permanent magnet rotor type synchronous motor according to claim 1 or 2.