JP2014165935A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor capable of preventing generation of a shaft voltage with a simple structure while reducing the amount of insulation material used and the cost.SOLUTION: The electric motor includes: a motor main body; a stator having a stator coil which is wound in a slot in a stator core being interposed by a slot insulation paper and is fixed to the motor main body; and a rotor which is disposed including a predetermined air gap from the stator with a rotary shaft rotatably supported by the motor main body via a bearing. An inverter device controls to drive the stator coil. A holding groove is formed in a portion of the slot at a predetermined dimension inner side from the end at the rotor side in the stator core to insert a wedge of an electrical insulation material into the holding groove to be held thereby.

Description

  Embodiments described herein relate generally to an electric motor.

  In an electric motor that requires variable speed operation, such as an induction motor, an inverter device has been used for ease of use and economy. In addition, for the purpose of reducing the noise of induction motors, the carrier frequency of inverter devices has been set higher. For this reason, a common mode voltage is included in the unbalanced component of the output voltage of the inverter device, and is applied to the stator coil of the induction motor that is driven, thereby causing the rotor of the induction motor to be based on electrostatic induction. Voltage (axis voltage) is generated. When this shaft voltage increases, current (shaft current) flows through the bearing supporting the rotor's rotating shaft, causing corrosion called electrolytic corrosion, which deteriorates the durability of the bearing. It is necessary to take measures to prevent the occurrence of

  Therefore, conventionally, the shield between the stator and the rotor is electrostatically shielded to eliminate or disperse the floating capacitance to suppress the generation of the shaft voltage. However, the configuration is complicated. There is. In order to cope with such a situation, an insulator (interposer) having a thickness larger than that of a normal wedge is inserted and disposed on the slot opening side of the stator slot, and is accommodated in the slot. There has also been a proposal to suppress the stray capacitance by making the distance between the end of the stator coil on the slot opening side and the rotor equal to or greater than a predetermined dimension. There is a problem that a large amount is necessary and the cost becomes high.

JP 2012-244872 A

  In view of the above, an electric motor is provided that has a simple configuration and that can reduce the amount of the insulator used and suppress the increase in cost while suppressing the generation of shaft voltage.

  The electric motor of the present embodiment includes a fuselage, a stator that is fixed to the fuselage, and a stator coil is wound in a slot of the stator core via a slot insulating paper, and the stator and a predetermined The rotor is disposed with an air gap, the rotor is rotatably supported on the airframe via a bearing, and the stator coil is driven and controlled by an inverter device. A holding groove is provided in a portion of the slot that has a predetermined dimension on the inner side of the slot from the rotor-side end surface of the stator core, and a wedge made of an electrically insulating material is inserted and held in the holding groove. .

The expanded sectional view of the slot part by a 1st embodiment Diagram showing the stator and rotor schematically Block diagram schematically showing the drive circuit of the electric motor Figure 1 equivalent figure by reference form

(First embodiment)
Hereinafter, a first embodiment applied to an induction motor will be described with reference to FIGS. 1 to 3. As shown in FIG. 2, the stator 1 of the induction motor M includes a stator core 2 in which a U-phase coil 3, a V-phase coil 4, and a W-phase coil 5, which are three-phase stator coils, are wound. It is configured. The stator iron core 2 has a cylindrical shape in which a plurality of iron core materials formed by, for example, punching electromagnetic steel sheets into a ring shape by pressing or the like are laminated, and a U-phase coil 3 and a V-phase are provided on the inner peripheral side thereof. A plurality of, for example, 36 slots 6 into which the coil 4 and the W-phase coil 5 are inserted are formed. Each U-phase coil 3, V-phase coil 4, and W-phase coil 5 is configured by winding a coil wire 7 (see FIG. 1) such as an enameled wire in which a conductor such as a copper wire is coated with an insulating coating. In this embodiment, a U-phase coil 3, a V-phase coil 4, and a W-phase coil 5 are sequentially attached to the stator core 2 from the radially outer peripheral side toward the inner peripheral side.

  Each of the U-phase coil 3, the V-phase coil 4, and the W-phase coil 5 is composed of a plurality of, for example, four (four poles) unit coils 3a, 4a, and 5a. Each of the four unit coils 3a, 4a, 5a is connected in series, one terminal of each series circuit is connected to the power supply terminal of each phase, and the other terminal of each series circuit is Connected to neutral point. That is, the stator core 2 is wound with a stator coil (U-phase coil 3, V-phase coil 4, W-phase coil 5) star-connected between the power terminals of each phase.

  The squirrel-cage rotor 8 includes a rotor iron core 9 and a rotating shaft 10 provided on the inner peripheral side of the rotor iron core 9. The rotor core 9 is formed by laminating a plurality of annular cores made of electromagnetic steel plates and integrally bonding them, and has a cylindrical shape. The rotor 8 is arranged in the field space of the stator 1 with a predetermined air gap between the outer peripheral surface thereof and the inner peripheral surface of the stator 2, and is rotatable with respect to the stator 1. ing. The rotary shaft 10 passes through the rotor core 9 in the stacking direction of the core material, and is fixed to the rotor core 9. A large number of conductors 9a are embedded in the outer peripheral portion of the rotor core 9 along the circumferential direction, and these are short-circuited by end rings (not shown).

  As shown in FIG. 3, the machine body 11 of the induction motor M includes a cylindrical frame 12 and bearing brackets 13 and 14 attached to openings at both ends thereof. The stator 1 is fitted and fixed to the inner peripheral surface of the frame 12, and the rotary shaft 10 of the rotor 8 is supported by bearing brackets 13 and 14 via ball bearings which are not shown. A cooling fan (not shown) is attached to the end of the rotating shaft 10 of the rotor 8 on the side opposite to the bearing bracket 13 that is on the bearing bracket 13 side.

Here, the winding process of the stator coils (U-phase coil 3, V-phase coil 4, W-phase coil 5) of each phase provided in the stator core 2 will be briefly described with reference to FIG. .
As shown in FIG. 1, the slot 6 of the stator core 2 has a slot insulating paper 15 affixed to the inner wall thereof, so that each phase stator coil (U-phase coil 3,. Slot insulation is provided to insulate between the V-phase coil 4 and W-phase coil 5) and the stator core 2 (inner wall of the slot 6).

  The slot 6 of the stator core 2 is a semi-closed slot and has an opening 6a on the rotor 8 side. First, the U-phase coil 3 is inserted and wound into the slot 6 which is insulated from the slot through the opening 6a. That is, the U-phase coil 3 is wound in the slot 6 via the slot insulating paper 15. Here, the coil wire 7 constituting the U-phase coil 3 has a diameter (size) of a copper wire as a conductor set to, for example, 0.75φ and is accommodated in 52 pieces per slot 6. Both end portions of the slot insulating paper 15 are overlapped so as to be doubled on the opening 6 a side in the slot 6.

  In the slot 6, the pair of holding grooves 16 are opposed to a portion having a predetermined dimension L 1, for example, 3.5 mm, from the end surface of the stator core 2 on the rotor 8 side to the inside of the slot 6 (in the radial direction). A thin plate-like wedge 17 made of an electrical insulating material is inserted and held in the holding groove 16 from the axial direction. By inserting and holding the wedge 17 in the holding groove 16, the coil wire 7 in the slot 6 is restricted from moving toward the opening 6a. In this case, the width dimension of the holding groove 16 is set to 0.5 mm, for example. Further, the wedge 17 is formed in a thin plate shape by bonding a polyester film and a PET (polyethylene terephthalate) non-woven fabric, for example, and the thickness dimension is slightly smaller than 0.5 mm, for example, so that it can be inserted into the holding groove 16. Is set to Note that the wedge 17 may be formed of a glass mat laminate molded product as long as it is made of an electrical insulating material. As a result of the above configuration, when the dimension of the air gap G between the inner peripheral surface of the stator core 2 of the stator 1 and the outer peripheral surface of the rotor core 9 of the rotor 8 is 0.3 mm, for example, the stator The distance L2 for stray capacitance between the end face on the opening 6a side of the U-phase coil 3 housed in one slot 6 and the inner peripheral surface of the rotor core 9 of the rotor 8 is, for example, It is set to 4.0 mm or more.

  When the U-phase coil 3 is wound, the V-phase coil 4 is wound in a slot 6 different from that where the U-phase coil 3 is wound so that the electrical angle with the U-phase coil 3 is shifted by 120 °. Subsequently, the W-phase coil 5 is wound in a slot 6 different from the position where the V-phase coil 4 is wound so that the electrical angle with the V-phase coil 4 is shifted by 120 °. In this case, wedges 17 are also arranged in the slot 6 around which the V-phase coil 4 is wound and the slot 6 around which the W-phase coil 5 is wound.

  Next, the configuration of the drive circuit of the induction motor M will be briefly described with reference to FIG. The induction motor M according to an embodiment having the slot cross-sectional structure shown in FIG. 1 has three phases and four poles, can be used with a rated output of 1.5 kW, and a voltage-frequency (400/400/440 V-50 / 60/60 Hz). It is a specification. The inverter device 18 includes a DC power supply circuit composed of a rectifier circuit and a smoothing circuit, an inverter circuit formed by connecting IGBTs serving as semiconductor switching elements with a three-phase bridge, and a control circuit serving as control means.

  In the inverter device 18, the DC power supply circuit has an AC power supply terminal connected to an AC power supply 19 having a voltage of 400 V and 60 Hz, creates a DC drive power supply and a DC control power supply, and applies a DC drive power supply voltage to the DC input terminal of the inverter circuit. The DC control power supply voltage is supplied to the control circuit. The inverter circuit creates a three-phase AC power supply by PWM control and supplies it to the power supply terminals of each phase of the stator coil of the stator 1 via the output reactor 20 from the three-phase output terminals. The control circuit performs PWM control on the inverter circuit based on a predetermined condition.

  In the present embodiment, as shown in FIG. 1, a pair of holding grooves 16 are provided in a portion of the slot 6 that has a predetermined dimension L1 inside the slot 6 from the end surface on the rotor 8 side of the stator core 2. Then, a wedge 17 made of an electrically insulating material is inserted into the holding groove 16, and the opening 6a side of the U-phase coil 3 (V-phase coil 4, W-phase coil 5) housed in the slot 6 of the stator 1 is disposed. The distance L2 for stray capacitance between the end face of the rotor and the inner peripheral surface of the rotor core 9 of the rotor 8 was set to 4.0 mm or more, and the stray capacitance between them was reduced. Therefore, the shaft voltage can be reduced. Thereby, generation | occurrence | production of the electric corrosion in a bearing (ball bearing) can be prevented, and the lifetime of a bearing can be extended significantly. In addition, the holding groove 16 can be provided in the slot 6 of the stator 1, and the wedge 17 can be inserted and disposed in the holding groove 16. Furthermore, since the position of the wedge 17 can be held at the position of the holding groove 16, unlike the conventional case where the position of the coil wire 7 is regulated by the thickness of the interposed body, the amount of insulator used can be reduced and the cost is increased. Can also be suppressed.

  Moreover, in the said embodiment, the diameter (size) of the copper wire in the coil wire 7 of the U-phase coil 3 (V-phase coil 4 and W-phase coil 5) accommodated in one slot 6 is the temperature of the induction motor M. Since it is set to the thinnest size that satisfies the rising standard, a space for placing the wedge 17 in the slot 6 can be secured without changing the dimensions of the stator core 2 including the slot 6. .

(Reference form)
FIG. 4 shows a reference form. In this reference form, in the stator core 2, the shape of the opening 22a side of the slot 22 is different from the above embodiment. Specifically, in order to ensure a large distance from the opening 22a of the slot 22 to the inside of the slot 22, the radial dimension L3 of the slot chip portion 23 is set larger than that in the case of FIG. In this case, the slot chip portion 23 is a portion protruding in the circumferential direction in order to narrow the circumferential width of the opening 22 a with respect to the circumferential width of the slot 22. In this case, the radial dimension L3 of the slot chip portion 23 is set to 4 mm or more. A wedge 24 is inserted into the slot 22 so as to be positioned on the opening 22a side. Note that the slot insulating paper 15 is not overlapped at both ends, the opening 22a side is opened, and has a U-shape when viewed from the axial direction. The wedge 24 is disposed so as to block the open portion of the slot insulating paper 15 from the opening 22a side.

  As a result of the above configuration, when the dimension of the air gap G between the inner peripheral surface of the stator core 2 of the stator 1 and the outer peripheral surface of the rotor core 9 of the rotor 8 is 0.3 mm, for example, the stator Between the end face on the opening 22a side of the U-phase coil 3 (V-phase coil 4, W-phase coil 5) housed in one slot 22 and the inner peripheral surface of the rotor core 9 of the rotor 8. The distance L4 for floating capacitance is set to 4.3 mm or more, for example.

  Also in this reference embodiment, the same effect as that of the above embodiment can be obtained. That is, the floating static between the end surface on the opening 22a side of the U-phase coil 3 (V-phase coil 4 and W-phase coil 5) housed in the slot 22 and the inner peripheral surface of the rotor core 9 of the rotor 8 is fixed. Since the distance L4 for electric capacity can be secured to 4.0 mm or more, the floating electrostatic capacity between them can be reduced, and the axial voltage can be reduced. Thereby, generation | occurrence | production of the electric corrosion in a bearing (ball bearing) can be prevented, and the lifetime of a bearing can be extended significantly. In addition, it can be realized with a simple configuration in which the radial dimension of the slot chip portion 23 is set to a predetermined dimension or more. Further, the wedge 24 may have a normal thickness, and unlike the case where the position of the coil wire 7 is regulated by the thickness of the conventional intervention body, the usage amount of the insulator can be reduced and the increase in cost can be suppressed. be able to.

(Other embodiments)
Although the four-pole induction motor has been described in the above embodiment, the number of poles is not limited to this.
In the above embodiment, the stator coils are star-connected, but may be delta-connected.
In the said embodiment, although the example applied to the three-phase induction motor driven by an inverter apparatus was shown, an electric motor is not limited to this. For example, the present invention can be applied to an inner rotor type or outer rotor type permanent magnet synchronous motor.

  As described above, according to the electric motor of the present embodiment, the holding groove is provided in a portion of the slot that has a predetermined dimension from the rotor-side end surface of the stator core to the inside of the slot, and the insulating groove is electrically insulated. A wedge made of material was inserted and held. With this configuration, the distance for the stray capacitance between the end face on the slot opening side of the stator coil housed in the slot and the rotor is set to a predetermined dimension or more, and the stray static electricity between these is set. Since the electric capacity can be reduced, the shaft voltage can be reduced. Thereby, generation | occurrence | production of the electric corrosion in a bearing can be prevented, and the lifetime of a bearing can be extended significantly. In addition, a holding groove can be provided in the slot of the stator, and a simple configuration in which a wedge is inserted and disposed in the holding groove can be realized. Furthermore, since the position of the wedge can be held at the position of the holding groove, unlike the conventional case where the position of the stator coil is regulated by the thickness of the interposed body, the amount of the insulator used can be reduced and the increase in cost can be suppressed. be able to.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 is a stator, 2 is a stator core, 3 is a U-phase coil (stator coil), 4 is a V-phase coil (stator coil), 5 is a W-phase coil (stator coil), 3a, 4a And 5a are unit coils, 6 is a slot, 6a is an opening (slot opening), 7 is a coil wire, 8 is a rotor, 9 is a rotor core, 10 is a rotating shaft, 11 is an airframe, and 15 is slot insulation paper. , 16 is a holding groove, 17 is a wedge, 18 is an inverter device, 22 is a slot, 22a is an opening (slot opening), 23 is a slot tip, and 24 is a wedge.

Claims (2)

The aircraft,
A stator fixed to the fuselage and configured by winding a stator coil through a slot insulating paper in a slot of the stator core;
The stator is disposed with a predetermined air gap, and the rotor includes a rotor on which a rotating shaft is rotatably supported via a bearing,
In the electric motor in which the stator coil is driven and controlled by an inverter device,
In the slot, a holding groove is provided in a portion having a predetermined dimension from the end surface on the rotor side in the stator core to the inner side of the slot, and a wedge made of an electrical insulating material is inserted and held in the holding groove. An electric motor characterized by that.   2. The electric motor according to claim 1, wherein a dimension of the stator iron core from the end surface on the rotor side to the holding groove is 3.5 mm or more.

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