JP4105470B2 - Three-phase AC rotating electric machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-phase AC motor and a three-phase AC generator (hereinafter referred to as a three-phase AC rotating electric machine), and more particularly, in a three-phase AC rotating electric machine provided with a neutral point leading wire, the neutral point leading wire TECHNICAL FIELD
[0002]
[Prior art]
Conventionally, a system has been proposed in which a neutral point lead wire is connected to a neutral point of a coil winding of a three-phase AC rotating electric machine and further connected to another device. For example, Japanese Patent Laid-Open No. 10-337047 proposes a system in which a battery is connected to a neutral point and a capacitor is connected to a power supply line of an inverter that controls each phase current of the motor. In the system of this publication, by superimposing an alternating current on a current other than each phase current flowing through the neutral point, the battery voltage can be used for charging the capacitor using the motor coil, and the motor is driven. Can be done as usual.
[0003]
[Problems to be solved by the invention]
In the system in which other devices are connected to the neutral point, including the example of the above-mentioned publication, there is a problem that fluctuations in the current flowing through the neutral point lead line affect the connected devices. Japanese Patent Laid-Open No. 10-285879 discloses a technique for arranging a reactor on the power source side of an inverter in a system for supplying electric power from the inverter to the power source side in order to prevent harmonics generated by the inverter from being transmitted to the power source side. Is disclosed.
[0004]
The present invention has been made to solve the above-described problems, and it is an object of the present invention to suppress fluctuations in current flowing through a neutral point lead wire provided in a three-phase AC generator.
[0005]
[Means for Solving the Problems]
To attain the above object, a three-phase AC rotary electric machine according to the present invention has a substantially cylindrical stator core, the inner periphery the stator core are arranged magnetic poles at predetermined intervals in the circumferential direction, between the magnetic poles A three-phase AC rotating electrical machine in which a three-phase winding is housed in a slot that is a part, with one end connected to the neutral point of the three-phase winding and the other point connected to an external device A lead wire having a neutral lead wire through which power is supplied to the external device via the neutral lead wire, and a part of the neutral lead wire is a part of the rotating electrical machine. It is a neutral point winding that is encased in the magnetic pole part of the stator core, which is the iron core of the three-phase winding, and placed in the slot .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a cross section of the three-phase AC rotating electric machine of the present embodiment, in particular, 1/8 turn. The stator 10 has a stator core 14 in which magnetic poles 12 are arranged at a predetermined interval in the circumferential direction on the inner periphery of a substantially cylindrical shape. A space between the magnetic poles 12 is referred to as a slot 16 and accommodates conductive wires constituting the windings 18 and 20. The winding 18 corresponds to each of the three phases, and the winding 20 is connected to a neutral point as will be described in detail later. A cylindrical or cylindrical rotor 22 is disposed inside the stator 10. The rotor 22 includes a rotor core 26 including permanent magnets 24 arranged around the circumference thereof at a predetermined interval in the circumferential direction.
[0007]
When a current is passed through each of the three-phase windings 18 of the stator 10 at a predetermined phase, a rotating magnetic field is generated inside the stator 10, and the rotor 22 is rotated by the interaction between the rotating magnetic field and the permanent magnet 24.
[0008]
FIG. 2 shows the configuration of the windings of the rotating electrical machine of the present embodiment shown in FIG. As shown in the figure, in the present embodiment, windings 18U, 18V, and 18W corresponding to the respective star-connected phases, that is, the U, V, and W phases are provided. Hereinafter, when it is not necessary to distinguish the phase for each winding, the description will be made simply by describing the winding 18. In the present embodiment, a neutral point lead wire 30 is connected to the neutral point 28, and a neutral point winding 20 is provided on this lead wire. A current (Iu + Iv + Iw) corresponding to the sum of the phase currents (Iu, Iv, Iw) flows through the lead line. As shown in FIG. 1, the neutral point winding 20 is housed in the slot 16 together with each phase winding 18, and shares the stator core 14, which is an iron core, with each phase winding 18.
[0009]
3 and 4 are views showing a state in which the windings 18 and 20 are unfolded. FIG. 3 shows windings 18 for each phase, U-phase winding 18U is shown by a solid line, V-phase winding 18V is a one-dot chain line, and W-phase winding 18W is a two-dot chain line. It is shown. More specifically, each phase has a configuration in which two sets of four windings 18 connected in series are arranged in parallel. The lead wire is configured by connecting a plurality of windings 20 in series. The plurality of neutral point windings 20 are arranged so that magnetic fluxes generated from each other cancel each other. FIG. 5 is a diagram showing the torque generated when only the neutral point winding 20 is energized. As shown, this torque has a period of 120 electrical degrees and cancels each other out. Therefore, the magnetic flux formed by the neutral point winding 20 does not act on the rotor 22 during operation of the rotating electrical machine, that is, does not become disturbance torque that disturbs the rotation of the rotor 22.
[0010]
FIG. 6 is a diagram showing the ripple reduction effect of the neutral point current by the reactor formed by the neutral point winding 20. A broken line indicates a neutral point current in a state where no reactor is provided in the neutral point lead line 30, and a solid line indicates a current when a reactor is provided. In this case, it can be seen that the ripple current is reduced to about ¼ in amplitude by providing the reactor.
[0011]
In the above embodiment, the reactor provided on the neutral lead-out line is configured to use the stator core, but the stator core can also be used for the reactor used in the external circuit. This example will be described below.
[0012]
7 and 8 show a configuration in which a low-voltage battery boosts the voltage by a booster circuit and drives the electric motor 40. FIG. 7 shows a general circuit configuration. The voltage of the battery 42 is boosted by a booster circuit (DC-DC converter) 46 including a reactor 44 and supplied to the electric motor 40 via the inverter 48. FIG. 8 shows a configuration in which the reactor 44 is replaced with a reactor 50 using a stator core. According to the configuration of FIG. 8, a space for providing the reactor is not necessary, and the entire system can be downsized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a rotating electrical machine according to an embodiment.
FIG. 2 is a diagram showing a winding configuration of the rotating electrical machine of the present embodiment.
FIG. 3 is a development view of windings of the rotating electrical machine of the present embodiment.
FIG. 4 is a development view of a neutral point winding of the rotating electrical machine of the present embodiment.
FIG. 5 is a diagram showing torque when only a neutral point winding is energized.
FIG. 6 is a diagram illustrating a ripple reduction effect of neutral point current by providing a neutral point winding.
FIG. 7 is a diagram showing an example of a system having an external reactor.
8 is a diagram showing an example in which the reactor shown in FIG. 7 is configured using a core of a rotating electrical machine.
[Explanation of symbols]
10 stators, 12 magnetic poles, 14 stator cores, 16 slots, 18 windings for each phase, 20 neutral point windings, 28 neutral points, 30 neutral point lead wires.

Claims (3)

A three-phase AC rotating electric machine having a substantially cylindrical stator core, in which magnetic poles are arranged at predetermined intervals in the circumferential direction on the inner circumference of the stator core, and three-phase windings are housed in slots between the magnetic poles. There,
  A neutral point lead wire having one end connected to a neutral point of the three-phase winding and the other end connected to an external device, and power is supplied to the external device via the neutral point lead wire. Has a neutral point leader,
  The neutral point lead wire is a neutral point winding part of which is encased in the magnetic pole part of the stator core, which is the iron core of the three-phase winding of the rotating electrical machine,
Three-phase AC rotating electric machine.   2. The three-phase AC rotating electric machine according to claim 1, wherein a plurality of the neutral point windings are provided, and the generated magnetic fluxes are arranged to cancel each other.   The three-phase AC rotating electric machine according to claim 2, wherein the plurality of neutral point windings are connected in series.

Images