JPS63217957A - Squirrel-cage induction synchronous motor - Google Patents

Abstract

PURPOSE:To improve the synchronous characteristic and to increase the synchronizing torque of a squirrel-cage induction synchronous motor by narrowing a magnetic path of teeth of recess poles only at the part of the tooth corresponding to the inner slots of double squirrel-cage slots. CONSTITUTION:Double squirrel-cage slots 2, 2' are formed on the outer periphery of a rotor core 1, slits 3 are formed, and projecting and recess poles 4, 5 are formed. The slot 2' formed at the pole 5 is widely formed in width at the inside with respect to the slot 2 formed at the pole 4, thereby narrowing the width of the tooth 6 to narrow the magnetic path of this part. Thus, the difference of the magnetic resistance of the magnetic path 8 of the pole 5 from the magnetic path 6 of the pole 4 is increased to increase a synchronous torque. Since the magnetic flux passes the outer periphery to generate a torque at the conductor in the outer slot at the time of starting, the starting characteristic is not reduced thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synchronous motor, and particularly to a squirrel cage induction synchronous motor that is high in performance, highly productive, and inexpensive.

[Conventional technology]

A squirrel-cage induction synchronous motor has a squirrel-cage winding on the outer periphery of the rotor, and slits are provided in the iron core to form convex and concave poles, making it a synchronous motor.When starting, it operates as an induction motor. During operation, it operates as a reaction type synchronous motor. The so-called synchronous pull-in torque and escape torque of this type of motor are proportional to the difference in magnetic resistance between the convex pole and the concave pole, so in order to increase this difference, in addition to the slit, the tooth at the center of the concave pole is U.S. Patent No. 321058 with cut tip
There are 4 etc. However, on the other hand, if there is a difference in magnetic resistance between the convex pole part and the concave pole part, cogging will occur in the starting torque, and if the difference in magnetic resistance becomes large, the starting torque will increase significantly and the starting characteristics will be significantly degraded. Therefore, although the above-mentioned known examples have excellent operating characteristics, they have the disadvantage of very poor starting characteristics. Since this type of motor operates as an induction motor when starting, the starting characteristics can be improved by increasing the secondary resistance, but during operation, the resistance becomes excessive and the synchronous torque decreases. Therefore, a proposal has been made, for example, in Japanese Utility Model Application Laid-Open No. 60-141667, to use a double squirrel cage rotor that has a large change in effective resistance between startup and operation. Although this method greatly improves the starting characteristics, it has the disadvantage that the synchronous torque is inferior to the above example.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has the disadvantage that, while it is excellent in either the synchronous torque or the starting characteristic, the performance of the other is inferior.

The object of the present invention is its main characteristics as a synchronous motor.

The object of the present invention is to provide a high-performance synchronous motor with excellent synchronization characteristics and starting characteristics.

[Means for solving problems]

The above purpose is to improve the starting characteristics as a double squirrel cage rotor, and to increase the difference in magnetic resistance between the convex and concave poles by narrowing the magnetic path of the teeth in the concave pole part, and to improve the synchronization characteristics at the same time. This is achieved by measuring.

[Effect]

By narrowing the magnetic path of the teeth of the concave pole part only in the tooth subdivision corresponding to the inner slot of the double squirrel cage slot, the synchronization properties can be improved without sacrificing the starting properties.

In other words, the magnetic flux during startup passes through the outer periphery, so there is no effect even if the magnetic path is narrowed in the inner part.On the other hand, the magnetic flux during operation passes deeply into the inner part, but since the magnetic path is narrowed in the concave pole part, it is not affected by the convex pole part. The difference in magnetic resistance of the concave pole portion becomes large, and the synchronous torque can be increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment corresponding to claim 2, in which a double squirrel cage slot 2 and a slit 2', which is a feature of the present invention, are provided on the outer periphery of a rotor core 1, and a slit 3 is provided. A convex pole portion 4 and a concave pole portion 5 are formed. In contrast to the double squirrel cage slot 2 provided in the convex pole portion 4, the slot 2' provided in the concave pole portion 5, which is a feature of the present invention, is formed wider on the inner side, thereby narrowing the width of the teeth 6. The magnetic path in the lever part is narrowed. Therefore, the difference in magnetic resistance between the magnetic path 7 of the convex pole portion 4 and the magnetic path 8 of the sun-facing pole portion 5 becomes large, and the synchronous torque can be increased. On the other hand, during starting, the magnetic flux passes through the outer circumferential side and generates torque by the conductor in the outer slot, so the starting characteristics do not deteriorate as a result. Therefore, both the synchronizing torque and the starting torque can be greatly improved. Note that the reason why the slot 2' of the concave pole portion 5 is shallow is to make the slot area the same.

Next, an embodiment corresponding to claim 3 will be described with reference to FIG. A double squirrel cage slot 12 is provided on the outer periphery of the rotor core 11, and the slit 13 forms a convex pole part 14 and a concave pole part 15. The concave pole part is provided with a small hole 16 in the tooth portion corresponding to the inner slot, which is a feature of the present invention, for reducing the magnetic path, so that the convex pole part's magnetic path 17 and the concave pole part's magnetic path 18 are provided. This further increases the difference in magnetic resistance. As a result, a large synchronizing torque can be obtained, and since the small hole 16 is provided at a position corresponding to the inner slot portion, magnetic flux passes through the outer circumference at the time of starting, so the starting torque does not decrease. Very large synchronizing torque and starting torque can be obtained. This embodiment also operates as a double squirrel cage induction motor by removing the slits 13 and small holes 16, so the expensive mold for punching out the single rotor core can be used in common with the induction motor, and the feature is that it can be manufactured at low cost. It is something that you have.

Next, the following table shows a comparison between the characteristics of the synchronous motor using the rotor according to the embodiment of the present invention and the characteristics of a conventional synchronous motor.

Note that each synchronous motor is a 100W capacitor run type synchronous motor, and only the rotor is changed for comparison. The upper row in the column of the above table shows the value at 50 Hz, and the lower row shows the value at 60 Hz.

The embodiments of the present invention have been described above.According to the present invention, the problem of low starting torque, which is a basic drawback of this type of synchronous motor, is not only solved, but also the starting torque and productivity are sacrificed. The practical effect is very great because the synchronization characteristics can be greatly improved without any additional damage.

〔Effect of the invention〕

As described above, according to the present invention, even if the magnetic resistance of the concave pole part is increased to maximize the synchronous torque, the starting torque does not decrease, and the starting torque is further increased due to the double squirrel cage structure. Therefore, very large synchronous torque and starting torque can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a rotor core showing an embodiment of the present invention;
FIG. 2 similarly shows a plan view of another embodiment. 1.11... Rotor core, 2, 12... Double squirrel cage slot, 3, 13... Slit, 4, 14... Convex pole part, 5.15... Concave pole part, 6...teeth, 16...
Small holes 1, 7° 17... Convex pole magnetic path, 8, 18... Concave pole magnetic path. 11. ,'

Claims (1)

[Claims] 1. A large number of slots are provided on the outer periphery of the cylindrical rotor core, conductors are arranged therein, both ends of the conductors are connected to each other by short-circuit rings, and a plurality of slots are provided in the rotor core. In a squirrel cage induction synchronous motor in which a convex pole and a concave pole are formed by providing a slit, the slot is made into a double squirrel cage shape, and
A squirrel-cage induction synchronous motor characterized in that the magnetic path of the tooth portion corresponding to the inner slot portion of the double squirrel-cage slot of the concave pole is narrower than the tooth portion of the convex pole portion. 2. The squirrel cage induction synchronous motor according to claim 1, characterized in that the inner slot of the double squirrel cage slot of the concave pole is formed shallow and wide to narrow the magnetic path. synchronous motor. 3. The squirrel cage induction synchronous motor according to claim 1, characterized in that small holes are provided in the teeth corresponding to the inner slots of the double squirrel cage slot of the concave pole to narrow the magnetic path. Squirrel cage induction synchronous motor.