JPS63242157A - Permanent magnet rotor for synchronous motor - Google Patents

Abstract

PURPOSE:To reduce an armature reaction reactance, by making the magnetization side section of permanent magnets thinner, and by making the demagnetization side section thicker. CONSTITUTION:To the central shaft of the magnet of a pole N, the magnet 2b of the left half is made thicker, and the magnet 2a of the right half is made thinner. In the same manner, on the magnet of a pole S, a magnet 3a is made thinner, and a magnet 3b is made thicker. Generally on the magnet of a large capacity, in many cases, the magnet is divided in the rotor shaft direction and in the circumferential direction, and also in this case, for the magnets 2b, 3b on the demagnetization side, thicker magnet pieces are used, and for the magnets 2a, 3a on the magnetization side, thinner magnet pieces are used to be fitted with adhesives. Besides, in order to permit the magnet outer-diameters to coincide with each other, inside the thinner magnets 2a, 3a, the spacers 6 of magnetic units are used. As a result, even on the demagnetization side, because of the thicker magnets 2b, 3b, an armature reaction reactance is reduced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a permanent magnet rotor for a synchronous motor.

(Prior Art) The structure of a conventional permanent magnet type synchronous motor is shown in the sectional view of FIG. The rotor A has permanent magnets 2 and 3 attached to the outer periphery of the rotor shaft l, with N and S poles respectively.
The rotor shaft 1 serves as a pole and serves as a magnetic path for these to create a magnetic field. The stator I (consists of an armature core 4 and, for example, armature coils 5a, 5b, and 5c in the case of three phases, and a rotating magnetic field is generated by the three-phase alternating current flowing through these armature coils. For example, if the direction of the current flowing through the armature coil 5a (other coils are omitted) is as shown in the figure, and the phase rotation of the armature winding is clockwise, then
The rotor Δ rotates clockwise.

In this case, in a servo motor or the like, the armature reaction becomes a biased magnetism because the torque relationship is controlled so that the armature current and the field magnetic flux are out of phase by 90 degrees. For this reason, for example, in the magnetic circuit of the permanent magnet 2 shown in FIG.
The left side of the axis X passing through the center of is the demagnetizing side, as shown by the arrow, and the right side is the magnetizing side. Therefore, on the magnetization side, magnetic saturation occurs, making it difficult for the magnetic flux to pass through, and the armature reaction reactance becomes small. On the contrary, on the demagnetizing side, since there is no magnetic saturation, the armature reaction reactance is almost constant and does not become small. For this reason, if the reactance remains large, the armature winding will have a large actance drop, and there is a problem in that the current required to generate torque cannot flow in a high rotation range. Furthermore, in order to suppress such armature reaction, it is conceivable to make the permanent magnets sufficiently thick, but this poses a problem of increasing the cost of these magnets.

(Problems to be Solved by the Invention) An object of the present invention is to provide a permanent magnet rotor for a synchronous motor that can reduce armature reaction reactance.

(Means for solving the problem) Regarding the field permanent magnet attached to the outer periphery of the rotor shaft, the part that becomes the magnetizing side due to the armature reaction due to the armature current of the corresponding armature winding. Make the magnet thinner, and make the part of the magnet thicker on the demagnetizing side.

(Function) In the magnetic circuit on the magnetizing side of the permanent magnet, even if the thickness of the magnet is made thinner, the armature reaction reactance becomes small due to magnetic saturation.
In addition, the thickness of the magnet in the magnetic circuit on the demagnetizing side is increased, so there is no magnetic saturation, but the armature reaction reactance is small.
In either case, the armature reaction reactance becomes smaller.

(Embodiment) FIG. 1 is a sectional view of an embodiment of a permanent magnet rotor according to the present invention, showing a two-pole case, and its basic lateral movement is the same as that of the conventional rotor shown in FIG. However, the thickness of the magnet is not uniform. Looking at the N-pole magnet in FIG. 1, with respect to the central axis of the magnet, the left half of the magnet 2b is thick, and the right half of the magnet 2a is thin. Similarly, regarding the S-pole magnets, the magnet 3a is thin and the magnet 3b is thick.

Normally, large-capacity magnets are manufactured by dividing the magnet in both the rotor axial direction and the circumferential direction, so in this case as well,
Thick magnet pieces are used for the magnets 2b and 3b on the demagnetizing side, thin magnet pieces are used for the magnets 2a and 3a on the increasing side, and these are attached with an adhesive or the like. In this case, in order to match the outer diameters of the magnets, a magnetic spacer 6 is used inside the thin magnets 2a and 3a, and these are bonded together with an adhesive. As a result, the armature reaction reactance becomes small even on the demagnetizing side because of the thick magnets 2b and 2a.

In the above-mentioned embodiment, a three-phase two-pole synchronous motor was described, but the same applies to cases where the number of phases and the number of poles are different from this.

(Effect of the invention) The thickness of the field permanent magnet attached to the outer periphery of the rotor shaft is made different between the magnetizing side and the demagnetizing side, and on the magnetizing side, the armature reaction reactance is reduced by magnetic saturation using a thinner magnet than before. By making the magnet thicker on the demagnetizing side, the armature reaction reactance can be reduced even if magnetic saturation cannot be achieved, and The armature reaction reactance is almost the same as using a thick magnet, and the characteristics in the high rotation range are improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the permanent magnet rotor of the present invention;
FIG. 2 is a sectional view of a synchronous motor using a conventional permanent magnet rotor. In the figure,

Claims (1)

[Claims] In a permanent magnet rotor of a synchronous motor in which permanent magnets for field are attached to the outer periphery of the rotor shaft, armature reaction due to armature current of the corresponding armature winding is applied to each permanent magnet. A permanent magnet rotor for a synchronous motor, characterized in that the magnets in the magnetizing side are thinner and the magnets in the demagnetizing side are thicker.