JPH10322989A - Induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in insulation, such as corona discharge, from being caused by the application of a high voltage due to surge produced by an inverter, using a large coil winding for concentric winding on the voltage input side in each phase, and arranging the windings, so that the voltage input- side windings in each phase are not positioned in adjacent slots. SOLUTION: For phase-U windings extending from a terminal U to a terminal X, the first winding is placed in a slot 1, the second winding is placed in a slot 11, the third winding is placed in a slot 23, the fourth winding is placed in a slot 13, and so on. Phase-V windings similarly extends from a terminal V to a terminal Y. A coil core with a large slot pitch is used for the first winding of the concentric windings on the voltage input terminal side in each phase, sand a small coil core is used for the second winding and the second one from the voltage input terminal side. For slots 11 in the phase-U and phase- V, the windings are brought into contact with each other and cross each other, when they get out of the adjacent slots. Both are the second windings, and shared voltage is cut in half and a surge voltage is reduced to 40% or less in proximity to the commercial frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and medium-sized three-phase induction motor for general industrial use driven by an inverter, and more particularly, to a winding for preventing a surge generated by the inverter from generating corona discharge or the like. And a three-phase induction motor with improved reliability.

[0002]

2. Description of the Related Art In general, windings of the above-mentioned three-phase induction motor are formed by concentrically winding an enamelled insulated wire, and respectively having U, V, W
The windings of the phase are sequentially stored in the slots of the stator.
The concentric winding used here is a winding in which a plurality of windings are wound between two slots which are spaced apart from each other. It has excellent workability and is widely used.

Here, the number of windings of each phase of the concentric winding is determined by the rating of the motor, etc., but the same winding is arranged at an electrically symmetric position, and usually one or two windings correspond to two or three windings. Is the most common, and although very rare, there may be four or more. Since there are a plurality of concentric windings corresponding to one winding, the winding pitches, that is, the winding forms are different from each other. The names of the windings at this time are referred to as first, second and third windings (hereinafter abbreviated) in order from the voltage connection side (U, V, W phase input terminal side) windings. From the viewpoint of ease of installation, a winding having a small winding pitch (winding form) is used as the first winding, and then the second and third windings and the winding pitch (winding form) are sequentially increased.

When a winding is inserted into a slot, for example, first, second and third windings of the U-phase are inserted simultaneously,
The phase winding and the W phase winding are sequentially inserted.
In this case, after inserting the U-phase winding, the V-phase winding is inserted, and the V-phase first winding is inserted into a slot adjacent to the U-phase first winding. Similarly, the W-phase first winding and the W-phase first winding are inserted into adjacent slots, respectively, and the W-phase first winding is inserted into the adjacent slot.

Accordingly, the first windings of each phase are inserted into adjacent slots, and cross each other and come into contact with each other. Naturally, insulating paper etc. is inserted between the windings of each phase so that they do not come in contact with each other, but they intersect near the slot, so it is not possible to securely insert the insulating paper etc. to bind the windings. Structurally difficult, it is virtually impossible to make both windings completely non-contact.

FIG. 2 and FIG. 3 briefly explain this. FIG. 2 shows an example in which four concentric windings for each phase are arranged in a total of 24 slots in a stator of a conventional three-phase induction motor. The U-phase first winding has slot numbers 2 and 1
1 and the second winding is inserted into slot numbers 1 and 12. On the other hand, the V-phase first winding has slot numbers 10 and 1
9 and the second winding is inserted in slot numbers 9 and 20. Accordingly, the U-phase first winding and the V-phase first winding are adjacent slots of slot numbers 11 and 10. This means that the windings of each other intersect each other in an attractive manner, as is evident in the schematic view of the slot end in FIG.
It is difficult to completely separate both windings including workability.

[0007]

Here, when an inverter generating a variable speed frequency and a variable voltage is used as a drive power source for an induction motor, the voltage generated by opening and closing a semiconductor element mounted on the inverter is equal to the input voltage of the inverter. It is considered that a voltage corresponding to the peak value of the commercial AC voltage supplied to the side is generated. When the output voltage of the inverter is applied to the motor, the voltage generated by the inverter is about twice as large as the surge voltage, although it depends on the switching time of the semiconductor element and the length of the cable from the inverter to the motor. It is considered that the voltage may be applied to the motor terminal.

Therefore, for example, when a motor having a rated voltage of 440 V is driven by an inverter, a high voltage due to an inverter surge of about 1,250 V is expected to be applied to terminals of each phase of the motor. This means that a voltage of 1,250 V is applied between the terminals of the U and V phases, and
A similar voltage is applied between the winding and the V-phase first winding. Normally, the breakdown voltage characteristics of an enameled insulated wire used in this type of motor have a value of 10 kV or more in a sample of two or more wires, depending on the enamel coating thickness. Therefore, it is considered that a voltage of about 1,250 V can be sufficiently endured. However, even with two twisted wires, 1,0
It is also known that when a voltage of 00 V or more is applied, a corona discharge is caused to cause breakdown in a relatively short time.

As described above, when an inverter power supply is used, a high voltage due to a surge of 1,000 V or more may be applied between the motor terminals. In order to prevent this, a filter or the like for preventing surge is provided by a motor or the like. Measures have been taken to minimize the surge by interposing the circuit. However, although a filter for surge prevention is effective for attenuating surge, the rated current of the motor also flows through the filter. Installation space is also an issue. Further, when the impedance of the filter is high, the voltage drop cannot be ignored, which may cause a problem in the performance of the motor.

[0010] The present invention has been made in view of the above circumstances, and in an induction motor driven by an inverter, even if a high voltage due to a surge generated by the inverter is applied, a problem of insulation deterioration due to corona discharge or the like to its winding. It is an object of the present invention to provide a three-phase induction motor that does not cause the problem.

[0011]

An induction motor according to the present invention comprises:
In a three-phase AC induction motor in which a stator has a plurality of concentric windings having different winding types, the concentric windings on the voltage input side of each phase are formed as large windings, and the voltage input side windings of each phase are used. The winding is arranged so that the wires do not become adjacent slots.

Further, in the three-phase AC induction motor,
Between the adjacent slots of the concentric windings on the voltage input side of each phase, the second winding and subsequent windings are placed so that the windings on the voltage input side of each phase do not come into direct contact with the portions coming out of the slots. The winding is tightened by interposing one or more slots in which the winding is accommodated.

According to the configuration of the present invention described above, U, V,
W By using concentric windings on the voltage input side of each phase as large windings, it is possible to prevent the first windings on the voltage input side of each phase from being arranged in slots adjacent to each other. Can be. Between the adjacent slots of the first winding of each phase,
By arranging the slots accommodating the windings of the second and subsequent windings, the first windings of each phase come out of the slots,
Direct contact can be avoided.

The surge voltage applied from the output side of the inverter to the input terminals of the plurality of concentric windings of the motor is divided into a first winding, a second winding,. side)
Decay as it proceeds. Therefore, by arranging the primary windings of the plurality of phases having the highest peak values (for example, the U-phase and the V-phase) so as not to contact each other, the problem of application of a high voltage generated in an insulating portion between these windings is solved. Can be avoided.
Therefore, it is possible to prevent the problem of insulation deterioration due to the occurrence of corona discharge, which has been seen in the conventional contact portion between the primary windings, and to provide an induction motor with a highly reliable winding.

[0015]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a winding development view of a stator winding of a two-pole three-phase induction motor according to one embodiment of the present invention. In this stator, 24 slots of slot numbers 1 to 24 are arranged, and each of the U, V, and W phases is divided into four first, second, third, and fourth concentric windings from the input terminal side. A line is placed in that slot. Therefore, each phase is constituted by four concentric windings, each of which accommodates windings in eight slots, and whose output terminals are X, Y, and Z, respectively. U, V, W
The phases are connected in a Y-shape, and terminals X, Y, and Z are short-circuited as neutral points and separately insulated.

According to the connections shown in FIG. 1 or FIG.
A rotation driving magnetic field of a pole is formed, and a rotor (not shown) is driven to rotate.

Here, the U-phase winding is arranged from the U terminal, the first winding is arranged in slots 1 and 12, and the second winding is arranged in slot 2
And 11, the third winding is located in slots 23 and 14, the fourth winding is located in slots 24 and 13, X
The terminal has been reached. Similarly, for the V-phase winding, the first winding is arranged in slots 9 and 20, the second winding is arranged in slots 10 and 19, and the third winding is arranged in slots 7 and 2 from the V terminal.
2 and the fourth winding is located in slots 8 and 21, leading to the Y terminal. That is, the winding of the first winding on the voltage input terminal side of the concentric winding of each phase is a winding having a large slot pitch, and the second winding from the voltage input terminal side is a small winding of the winding winding. And

The three-phase voltages supplied from the inverter are applied to terminals U, V and W. Therefore, the surge voltage generated by the inverter that supplies the voltage to the U, V, and W phase windings is first applied to the U, V, and W phase input terminals. Here, the first windings on the voltage input side of each phase are slot numbers 1 and 12 in the case of U phase, and 9 and 20 in the case of V phase. Therefore, the closest slot numbers of the voltage input winding are 12 and 9.

At this time, the U and V phase slots 11 and 10 are adjacent to each other. As a result, the windings completely cross each other when they come out of the slot, but the two windings share a shared voltage of about half the voltage near the commercial frequency and a surge voltage of 40% or less. For this reason, even an enamel insulated wire can fully withstand. The surge voltage of the inverter output is directly applied to the slots 12 and 9,
The U-phase and V-phase second windings inserted into the first and the first 10 can be formed and tightened with the second windings interposed therebetween, thereby enabling a sufficient distance to withstand a surge voltage.

In order to see the effect of improving the withstand voltage of the stator winding by the winding structure of the present invention, an inverter output voltage is applied to each of the winding input terminals U, V, W to observe the corona generation state and the like. did. The motor to be tested is a conventional motor and a machine having the winding structure of the present invention.
It was confirmed that the surge voltage at this time was about 1,350 V. As a result, it was observed that corona of 50 pC or more frequently occurred in the conventional product, but corona of 50 pC or more was not observed in the machine having the winding structure of the present invention.

Although the above-described embodiment relates to a three-phase induction motor, the winding structure of the present invention can be similarly applied to a two-phase induction motor. Further, the winding structure of the present invention can be similarly applied to a synchronous motor.

[0023]

As described above, according to the present invention, corona generation due to a surge voltage can be prevented by arranging the concentric windings on the voltage input side of each phase away from adjacent slots. . Thus, it is possible to provide an inverter-driven induction motor with improved reliability by preventing insulation deterioration of the winding.

[Brief description of the drawings]

FIG. 1 is a development view of slots and windings according to an embodiment of the present invention. However, illustration of the ZW phase is omitted.

FIG. 2 is a development view of a conventional slot and winding of the present invention. However, illustration of the ZW phase is omitted.

FIG. 3 is a schematic view of a slot end for clarifying a positional relationship between windings.

[Explanation of symbols]

 1 winding 2 slot U, V, W each phase and its input terminal X, Y, Z each phase output terminal

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazutaka Yoshida 4-1-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Ebara Densan Co., Ltd.

Claims (2)

[Claims] 1. A three-phase AC induction motor having a stator having a plurality of concentric windings having different winding forms, wherein a concentric winding on a voltage input side of each phase is a large winding, and each phase has a large winding. Wherein the windings are arranged such that the voltage input side windings do not form adjacent slots. 2. In the three-phase AC induction motor, the concentric windings of the voltage input side of each phase do not come into direct contact with each other at the portions coming out of the slots. 2. The induction motor according to claim 1, wherein the windings are tightened by interposing one or more slots in which the second and subsequent windings are accommodated between the slots adjacent to each other.