JP2002272067A - Squirrel-cage rotor and motor using the squirrel-cage rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a squirrel-cage rotor which allows improvement of synchronizing torque. SOLUTION: The squirrel-cage rotor comprises a rotor core having magnets built therein in the axial direction, a plurality of conductors inserted into the individual conductor grooves in the rotor core, and end rings. The magnets are arranged in cylindrical shape, and the conductor grooves are so formed that the conductor grooves positioned on the boundary lines between the magnetic poles of the rotor core are deeper than the other conductor grooves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cage rotor and an electric motor using the cage rotor. For more information,
The present invention relates to an induction synchronous motor having both functions of an induction motor and a synchronous motor.

[0002]

2. Description of the Related Art Conventionally, as an energy-saving motor, a brushless motor (magnet type synchronous motor) using magnets for magnetic poles has been used as an energy-saving motor.
Has been put to practical use. However, this motor does not start even when directly connected to a commercial polyphase AC power supply (mainly three-phase), and requires a control device (driver). In addition, a means for detecting the magnetic pole is required as a control circuit of the control device, which is practically costly and does not spread. In contrast, induction motors are widely used because they are easy to start and inexpensive. But,
Since an induction motor requires an exciting current, there is a problem that the efficiency is inferior to a brushless motor which does not require an exciting current by using a magnet.

[0003] In recent years, an induction synchronous motor with a built-in magnet, which is a motor having the characteristics of both motors, has been developed. For example, as shown in FIG.
There is an induction synchronous motor with a built-in magnet in which 0 is embedded in a cage rotor 51. In this motor, the stator 52 includes a plurality of teeth 5.
3 and a yoke portion 54 connecting the roots of the teeth 53, and have a substantially cylindrical shape. A three-phase winding 56 is provided in a plurality of conductor grooves 55 formed between the plurality of teeth 53. The rotor 51 has a substantially cylindrical shape that is substantially coaxial with the stator 52, has four rotor magnetic poles facing the inner peripheral surface of the stator 52, and is rotatable about a shaft 57. It is supported by bearings (not shown). Rotor 51
Are supported by a plurality of conductors 59 inserted into the conductor grooves 58 and are provided with four permanent magnet burying holes 60 penetrating in the axial direction.
A flat permanent magnet 50 is buried therein. This permanent magnet 50 is magnetized to the N pole and the S pole as shown.
The conductor 58 is a conductor such as copper or aluminum,
The difference in the track characteristics due to the resistance is the same as in a general induction motor. The rotor 51 rotates when its rotor magnetic pole attracts or repels the rotating magnetic pole formed by the winding of the stator 52 due to the rotating magnetic field formed by the current flowing through the stator winding 56. Therefore, by embedding the permanent magnet 50 in the rotor 51, high efficiency is realized by utilizing both the magnet torque and the reluctance torque.

[0004]

In a conventional induction synchronous motor, a rotor has a built-in prismatic magnet (N pole and S pole), and cage teeth are formed on teeth of an outer stator. Structurally, the poles of the magnet form pole pieces, and the boundaries of the poles are narrow. For this reason, the magnetic flux which short-circuits directly between magnetic poles is restricted, and a convex polarity is maintained.

[0005] However, this induction synchronous motor starts up as an induction motor at start-up and rotates as a synchronous machine at high speed. However, when accelerating, magnetic flux saturation occurs around the boundary between the magnetic poles. Therefore, it is a cause of lowering the synchronization torque.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a cage rotor capable of improving the synchronization torque and an electric motor using the cage rotor.

[0007]

According to a first aspect of the present invention, there is provided a cage rotor having a rotor core in which a magnet is built in an axial direction.
A plurality of conductors inserted into each conductor groove of the rotor core,
A cage rotor including an end ring, wherein the magnet is arranged in a cylindrical shape, and a conductor groove located on a line of a magnetic pole boundary of the rotor core is formed as a groove deeper than other conductor grooves. It is characterized by being done.

According to a third aspect of the present invention, there is provided an induction synchronous motor including a cage rotor according to the first aspect and a stator having a multi-phase winding disposed on a stator core.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a cage rotor according to the present invention;

FIG. 1 is a sectional view of an essential part showing an embodiment of a cage rotor and an induction synchronous motor according to the present invention, FIG. 2 is a diagram showing torque-input characteristics, and FIG. 3 is a diagram showing torque-current characteristics. FIG. 4 is a cross-sectional view of a main part showing a cage rotor according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view of main parts showing a basket rotor according to still another embodiment of the present invention. is there.

As shown in FIG. 1, an induction synchronous motor according to one embodiment of the present invention includes a cylindrical stator 1 incorporated in a housing (not shown), and a stator 1.
And a basket-shaped rotor 2 that is inserted through the cage.

The stator 1 includes a stator core 3 and a three-phase winding 6 formed on the inner periphery of the stator core 3 and arranged in, for example, a conductor groove 5 between 24 teeth 4. , And each phase of the three-phase winding is distributed winding every six pitches.

The cage rotor 2 is fixed to a rotating shaft 7 rotatably supported by a pair of bearings (not shown) mounted on the housing. This cage rotor 2
A rotor core 9 having a magnet 8 built in the axial direction, a plurality of copper or aluminum rod-shaped conductors 11 inserted into respective conductor grooves 10 of the rotor core 9, And an end ring (not shown) attached to both ends for short-circuiting the conductor 11.

The rotor core 9 includes an outer basket-shaped core 9a.
And an inner magnetic path core 9b. The magnet 8 is composed of four magnet pieces 8a, 8b, 8c, and 8d each having a fan shape, a tile shape, or an arc shape. A predetermined gap is provided in the circumferential direction between them, and they are arranged in a cylindrical shape. That is, the rotor core 9 in the basket-shaped rotor 2 of the present embodiment is configured such that the four-pole magnet 8 composed of the magnet pieces 8a to 8d divided into four parts has an outer diameter surface on the inner diameter surface of the cage iron core 9a. It has a structure in which the inner diameter surface is fitted to the outer diameter surface of the magnetic path core 9b while being fitted.

A conductor groove 12 located on a line corresponding to a boundary between adjacent magnet pieces 8a to 8d, which is a magnetic pole boundary of the basket-shaped iron core 9a, is formed as a deeper groove larger than the other conductor grooves 10. I have. The conductor groove 12 having this deep groove can be formed to be as long as 0.5 to 1.0 mm from the inner diameter surface of the cage iron core 9a. The conductor groove 12 of this deep groove
Thus, a barrier is formed in the magnetic path, so that a fan-shaped magnetic pole piece is attached to the rotor magnetic pole (N pole, S pole).

The size distribution between the stator 1 and the cage-shaped rotor 2 can be appropriately selected. However, it is preferable that the magnetic flux densities of the respective yoke portions and the tooth portions have substantially the same value. preferable. This is because if the balance between the magnetic flux densities of the cage iron core 9a and the magnetic path iron core 9b of the cage rotor 2 is poor, characteristic deterioration occurs due to saturation of one magnetic flux.

In this embodiment, the cage rotor 2 rotates at a synchronous speed determined by the number of poles of the stator winding and the power supply frequency when the magnet is a field during synchronization. Further, in the case of a step-out when the load of the electric motor temporarily increases and the synchronous rotation speed is lost, or when starting or accelerating other than the synchronous operation, the cage rotor 2
Rotates with the induced current, and synchronizes again when the load is restored. Therefore, the induction-synchronous motor according to the present embodiment has both functions of the induction motor and the synchronous motor, and does not require secondary excitation during synchronization, that is, high torque and high efficiency because the rotor becomes a field. Electric motor.

Next, the induction synchronous motor shown in FIG. 1 will be described based on an embodiment, but the present invention is not limited to only this embodiment.

Example 1 An electric motor (Example) using a cage rotor and a stator incorporating a four-pole cylindrical magnet (cylindrical magnet) composed of four magnet pieces was prepared. Then, an electric motor (comparative example) was prepared in which the same stator was replaced with a cage-type rotor in which only a conventional rotor incorporates a conventional four-pole plate-like magnet (a prismatic magnet).

Then, the voltage was set to 200 V and the number of revolutions was set to 1800 rpm, and a torque test (load test) for the current and the input was performed. The results are shown in Table 1 and FIGS.

[0021]

[Table 1]

As shown in FIGS. 2 and 3, it can be seen that the synchronizing torque of this embodiment is higher than that of the comparative example except for a small current value. In addition, although the magnet amount of the magnet in the comparative example is about 1.3 times as large as the magnet amount of the magnet in the present embodiment, the present embodiment is superior. It can be seen that the above advantage is also shown.

Embodiment 2 Next, a torque of 4 kg-c was applied to the above embodiment and a comparative example.
m, and a voltage change test was performed. Table 2 shows the results.

[0024]

[Table 2]

From the results of the torque-voltage characteristics, the voltage (17) for efficiently generating a constant torque (4 kg-cm) with the minimum input (76 W) and the current (0.291 A).
0V) exists. This voltage is in a range that does not cause loss of synchronism.

Therefore, if the operation is performed by applying a voltage that minimizes the input, an energy-saving operation that minimizes power consumption can be performed. Thereby, the electric motor in the present embodiment is:
It can be seen that a controller (such as a control circuit) that detects the voltage that minimizes the input enables energy-saving operation.

In the present embodiment, the cage rotor has a built-in four-pole cylindrical magnet composed of four magnet pieces. However, the present invention is not limited to this. As shown in FIG. 4, the rotor core 9 shown in FIG. 1 is shared and two of the four magnet pieces 8a to 8d have two magnet pieces 8a and 8c positioned at the top of the conductor groove 12 of a deep groove. And the two magnet pieces 8b and 8d are connected to the position of the deep groove conductor groove 12 located at the lower part, whereby the cage rotor 21 having a built-in two-pole cylindrical magnet is connected. Obtainable. As described above, if one half (two poles in the present embodiment) of the number of poles (four poles in the present embodiment) of the magnet is an even number, a pair of rotor magnetic poles (N (Pole, S pole) can be shared with the rotor core. Therefore, when the number of poles is an odd number, for example, 6, 10, or 14 poles are excluded. In the case of a common iron core, the dimension is determined by designing with the smaller number of poles. In the opposite case, the countermeasure against saturation is made by increasing the stacking thickness, which is disadvantageous in dimensions.

In the present embodiment, although there is a slight decrease in the synchronizing torque as compared with the previous embodiment, the mold cost of the rotor core is unnecessary. In addition, since the magnet pieces of the magnet can be shared by connecting the same polarity, it is possible to contribute to a reduction in magnet cost.

Next, an induction synchronous motor using a basket-shaped rotary iron core shown in FIG. 4 will be described based on an embodiment, but the present invention is not limited to only this embodiment.

Example 3 An electric motor using a cage rotor and a stator having a built-in two-pole cylindrical magnet was prepared. Next, the torque was set to 4 kg-cm, and a voltage change test was performed. Table 3 shows the results.

[0031]

[Table 3]

From the results of the torque-voltage characteristics, the voltage (17 kg) for efficiently generating a constant torque (4 kg-cm) with the minimum input (153 W) and the current (0.564 A) is obtained.
0V) exists. This voltage is in a range that does not cause loss of synchronism.

Therefore, when the operation is performed by applying the voltage for minimizing the input similarly to the second embodiment, the energy-saving operation for minimizing the power consumption can be performed. Thus, it can be understood that the electric motor according to the present embodiment can perform energy-saving operation by a controller (such as a control circuit) that detects a voltage that minimizes an input.

Further, the cage rotor incorporating the two-pole cylindrical magnet is not limited to the cage rotor shown in FIG. 4, but as shown in FIG. The magnet 32 is built from the two magnet pieces 32a and 32b in the rotor core 31 having a shape in which the conductor groove 12 having a deep groove is provided only in the upper and lower portions (central portion). The cage rotor 33 may be used. In the present embodiment, the rotor core 9 cannot be shared, but the electric motor incorporating the rotor cage rotor 33 has a conductor groove 12 having a deep groove at the center of the polarity (N pole, S pole). Since there is no, the characteristics are slightly improved.

Although a cage rotor having a cage winding and an induction synchronous motor using the cage rotor have been described above, the present invention is not limited to this. The present invention can be applied to a synchronous motor using a cage rotor having no wire. That is, by using a cage rotor from which the cage winding has been removed, the function as an induction motor can be eliminated and the motor can function as a synchronous motor such as a normal brushless motor. However, in this case, since the self-starting property is lost, a control circuit as a brushless motor is required.

In the present invention, three types of motors (induction synchronous motor, synchronous motor, and brushless motor) can be manufactured by sharing the same rotor core, thus reducing the die cost. Thereby, the manufacturing cost of the electric motor can be reduced.

[0037]

As described above, according to the present invention,
Synchronization torque can be improved. Further, a motor having half the number of poles (only an even number) can be manufactured using the same iron core mold.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a cage rotor and an induction synchronous motor according to the present invention.

FIG. 2 is a diagram showing a torque-input characteristic.

FIG. 3 is a diagram showing torque-current characteristics.

FIG. 4 is a cross-sectional view of a main part showing a cage rotor according to another embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a cage rotor according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a main part showing an example of a conventional induction synchronous motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Cage rotor 3 Stator iron core 4 Teeth 5, 10 Conductor groove 6 Three-phase winding 7 Rotation shaft 8 Magnet 8a, 8b Magnet piece, 8c, 8d 9 Rotor core 9a Cage core 9b Magnetic path core 11 conductor 12 deep groove conductor groove

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA01 AA05 AA07 AA09 AB07 AB08 AE06 5H621 AA01 BB07 BB10 GA04 HH01 HH10 5H622 AA01 AA03 CA02 CA05 CA09 CA13 CB01 PP12

Claims (4)

[Claims] 1. A rotor core having a magnet built therein in an axial direction,
A plurality of conductors inserted into each conductor groove of the rotor core,
A cage rotor comprising an end ring, wherein the magnet is arranged in a cylindrical shape, and a conductor groove located on a line of a magnetic pole boundary portion of the rotor core is formed in a groove deeper than other conductor grooves. A basket-shaped rotor that has been made. 2. The cage rotor according to claim 1, wherein one half of the number of poles of the magnet is an even number. 3. The basket-shaped rotor according to claim 1 or 2,
An induction synchronous motor including a stator having a multi-phase winding disposed on a stator core. 4. The induction synchronous motor according to claim 3, further comprising a controller for applying a voltage for minimizing an input to a predetermined torque and minimizing power consumption.