JP6589703B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine.

  As a rotating electrical machine that outputs torque using the magnetic flux of a permanent magnet, a rotating electrical machine that can vary the amount of effective magnetic flux generated by the permanent magnet is known. For example, Patent Document 1 discloses a rotating electric machine having a stator around which an armature winding is wound and a rotor that is rotatably provided through the stator and a gap. A structure is described in which field magnets having two different polarities are alternately arranged in the rotation direction, each being divided into a first rotor and a second rotor.

  From such a structure, the rotating electrical machine described in Patent Document 1 operates the second rotor in accordance with changes in torque and rotational speed, and the polarity of the permanent magnet of the first rotor and the permanent magnet of the second rotor. By changing the positional relationship with the polarity, the effective magnetic flux amount by the permanent magnet can be adjusted. At this time, the rotating electrical machine described in Patent Document 1 changes the positional relationship between the polarity of the permanent magnet of the first rotor and the polarity of the permanent magnet of the second rotor according to the control signal input to the actuator. Control is performed so that the two rotors are positioned in a predetermined state.

JP 2010-246196 A

  However, the rotating electrical machine described in Patent Document 1 requires an actuator and a control device for controlling the actuator in order to position the second rotor in a predetermined state as described above. Further, since the second rotor is mechanically moved so that the first rotor and the second rotor have a predetermined positional relationship, precise control is required. For this reason, the magnetic flux of the permanent magnet cannot be varied with a low-cost configuration.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a rotating electrical machine that can vary the magnetic flux of a permanent magnet with a low-cost configuration.

  In order to achieve the above object, the present invention provides a rotating electrical machine including a stator having an armature coil and a rotor having a permanent magnet, wherein the stator includes a plurality of concentrated windings of the armature coil. The rotor has a stator tooth, and the rotor includes a plurality of rotor teeth in which the permanent magnet is included, and an induction coil wound around the rotor tooth on the stator side with respect to the permanent magnet. A magnetic path member is disposed between the adjacent rotor teeth via a gap, and the permanent magnets adjacent in the circumferential direction are arranged on the magnetic path member based on an induced current generated in the induction coil. A variable field coil capable of adjusting the amount of magnetic flux that is short-circuited between them is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the rotary electric machine which can vary the magnetic flux of a permanent magnet with a low-cost structure can be provided.

FIG. 1 is a partial cross-sectional perspective view of a rotating electrical machine according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the rotating electrical machine according to one embodiment of the present invention cut along a plane orthogonal to the rotation axis. FIG. 3 is a diagram showing a magnetic flux distribution of second-order spatial harmonics generated in the rotating electrical machine according to the embodiment of the present invention and its magnetic flux vector. FIG. 4 is a schematic diagram showing the connection of the induction coil, variable field coil, and diode in the rotating electrical machine according to the embodiment of the present invention. FIG. 5 is a schematic diagram showing a path of magnetic flux when the rotor of the rotating electrical machine according to the embodiment of the present invention is rotating at a low speed. FIG. 6 is a diagram showing the amount of magnetic flux when the rotor of the rotating electrical machine according to the embodiment of the present invention is rotating at a low speed. FIG. 7 is a schematic diagram showing a path of magnetic flux when the rotor of the rotating electrical machine according to the embodiment of the present invention is rotating at a high speed. FIG. 8 is a diagram showing the amount of magnetic flux when the rotor of the rotating electrical machine according to the embodiment of the present invention is rotating at a high speed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 to 8 are diagrams illustrating a rotating electrical machine according to an embodiment of the present invention.

  As shown in FIG. 1 and FIG. 2, the rotating electrical machine 1 includes a stator 10 having a three-phase armature coil 11 of W phase, V phase, and U phase that generates magnetic flux when energized, and magnetic flux generated in the stator 10. A rotor 20 that rotates by passage and a magnetic path member 30 are provided. In FIG. 2, the armature coil 11 is not shown.

(Stator)
The stator 10 is fixed to a motor case (not shown). The stator 10 includes an annular stator core 12 made of a magnetic material having a high magnetic permeability. A plurality of stator teeth 13 protruding inward in the radial direction are formed on the stator core 12 along the circumferential direction.

  Slots 14 that are groove-like spaces are formed between stator teeth 13 that are adjacent in the circumferential direction. A radial direction shows the direction orthogonal to the direction where the rotating shaft of the rotor 20 extends | stretches. The radially inward side indicates a side close to the rotation axis of the rotor 20 in the radial direction. The outer side in the radial direction indicates a side far from the rotation axis of the rotor 20 in the radial direction. The circumferential direction indicates a circumferential direction around the rotation axis of the rotor 20. The radial direction is shown in the radial direction around the rotation axis.

  In each slot 14 of the stator core 12, a three-phase armature coil 11 of W phase, V phase, and U phase is arranged along the circumferential direction of the stator core 12. Each of the W-phase, V-phase, and U-phase armature coils 11 is wound around the stator teeth 13 by concentrated winding.

  Thus, the stator 10 has a plurality of stator teeth 13 around which the armature coils 11 are concentratedly wound. The stator 10 generates a rotating magnetic field that rotates in the circumferential direction when a three-phase alternating current is supplied to the armature coil 11. Magnetic flux generated in the stator 10 (hereinafter, this magnetic flux is referred to as “main magnetic flux”) is linked to the rotor 20. Thereby, the stator 10 can rotate the rotor 20.

  As described above, the stator 10 has the armature coil 11 concentratedly wound around the stator teeth 13. For this reason, when three-phase alternating current is supplied to the armature coil 11, the stator 10 generates a harmonic rotating magnetic field that is asynchronous with the rotation of the rotor 20 in addition to the rotating magnetic field that rotates in synchronization with the rotation of the rotor 20. To do. This harmonic rotating magnetic field includes second-order spatial harmonics in the stationary coordinate system (third-order time harmonics in the synchronous rotating coordinate system). Therefore, the harmonic component is superimposed on the magnetic flux generated in the stator 10.

(Rotor)
The rotor 20 is disposed on the radially inner side of the stator core 12 so that the outer peripheral surface faces the inner peripheral surface of the stator core 12. The rotor 20 includes an annular rotor core 21 and an induction coil 22.

  The rotor core 21 is made of a magnetic material having a high magnetic permeability, and is fixed so as to be integrally rotatable with respect to the rotating shaft of the rotor 20. In the rotor core 21, a plurality of rotor teeth 23 protruding from the rotor core 21 outward in the radial direction are formed at predetermined intervals along the circumferential direction of the rotor core 21. The rotation axis of the rotor 20 is fixed to the inner peripheral surface of the rotor core 21 and extends in a direction orthogonal to the radial direction of the rotor core 21. Hereinafter, the direction in which the rotation axis of the rotor 20 extends is referred to as the axial direction.

  The rotor teeth 23 are provided with permanent magnets 24. The permanent magnet 24 is composed of, for example, a neodymium magnet (Nd—Fe—B magnet), and is included in the rotor teeth 23. The permanent magnet 24 is disposed on the rotor teeth 23 so that the direction of the magnetic flux is the radial direction. The permanent magnets 24 are arranged so that the polarities of the rotor teeth 23 adjacent in the circumferential direction are reversed. As the permanent magnet 24, a pair of permanent magnets that are arranged in a V shape in each rotor tooth 23 may be used.

  The induction coil 22 is wound around each rotor tooth 23 on the stator 10 side with respect to the permanent magnet 24. The induction coil 22 is wound so as to surround the side surface of the distal end portion 23 a of the rotor tooth 23.

  The induction coil 22 generates an induction current based on a harmonic component superimposed on the magnetic flux generated on the stator 10 side. Specifically, when a three-phase alternating current is supplied to the armature coil 11 and a rotating magnetic field is generated in the stator 10, the harmonic component magnetic flux generated on the stator 10 side is linked to the induction coil 22. Thereby, the induction coil 22 induces an induced current.

  FIG. 3 shows the distribution of magnetic flux of the second-order spatial harmonics generated on the stator 10 side and its magnetic flux vector. As shown in FIG. 3, most of the magnetic flux of the second spatial harmonic generated on the stator 10 side is linked to the tip 23 a of the rotor teeth 23. Therefore, in the present embodiment, the induction coil 22 is wound so as to surround the side surface of the distal end portion 23 a of the rotor tooth 23, so that more second-order spatial harmonic magnetic flux is linked to the induction coil 22. be able to.

(Magnetic path member)
The magnetic path member 30 guides a part of the magnetic flux of the permanent magnet 24 so as to short-circuit between the rotor teeth 23 adjacent in the circumferential direction. Specifically, the magnetic path member 30 leads a part of the magnetic flux generated by the permanent magnet 24 magnetized to the N pole to the permanent magnet 24 magnetized to the S pole as a short-circuit magnetic flux.

  The magnetic path members 30 are respectively disposed on the q axes (see FIG. 4) between the rotor teeth 23 adjacent in the circumferential direction. The magnetic path member 30 is disposed between the rotor teeth 23 facing in the circumferential direction via a gap G.

  The magnetic path member 30 is held on the rotating shaft of the rotor 20 or the rotor core 21 via a bracket or a connecting member (not shown) made of a nonmagnetic material such as resin. Therefore, the magnetic path member 30 rotates integrally with the rotation of the rotor 20.

  When the magnetic path member 30 is held on the rotating shaft or rotor core 21 of the rotor 20 without using a non-magnetic material, the magnetic coupling between the magnetic path member 30 and the rotating shaft or rotor core 21 of the rotor 20 is minimized. It is preferable to connect with each other in a state.

  As described above, the magnetic path member 30 is disposed on the q axis in a state of being magnetically shielded from the rotor teeth 23 of the rotor core 21. Thereby, the fall of salient pole ratio is prevented and the fall of reluctance torque is prevented.

  The magnetic path member 30 is formed by laminating a plurality of electromagnetic steel plates in the axial direction. The magnetic path member 30 may be formed of a dust core obtained by compressing and hardening a fine ferromagnetic powder.

  The magnetic path member 30 includes a core portion 31 extending in the circumferential direction, and a pair of opposed portions 32 protruding outward in the radial direction from both ends of the core portion 31 in the circumferential direction. The core portion 31 and the pair of opposed portions 32 are integrally formed.

  A variable field coil 35 is concentratedly wound around the core portion 31 in a toroidal shape in the axial direction. The variable field coil 35 is a coil that can adjust the amount of short-circuit magnetic flux that is short-circuited between adjacent permanent magnets 24 according to the magnitude of the induced current generated in the induction coil 22. The adjacent permanent magnets 24 are the permanent magnets 24 included in each of the rotor teeth 23 adjacent in the circumferential direction.

  The variable field coil 35 is toroidally wound around the magnetic path member 30 so as to form a magnetic pole in a direction in which the magnetic flux is short-circuited between the adjacent permanent magnets 24. Thereby, when the direct current rectified by the rectifier circuit 40 to be described later is supplied, the variable field coil 35 generates an induced magnetic flux in a direction in which the magnetic flux is short-circuited between the adjacent permanent magnets 24, and the magnetic path member A magnetic pole is formed on 30. That is, the magnetic path member 30 is magnetized according to the direction of the induced magnetic flux generated by the variable field coil 35.

  Specifically, when a direct current is supplied to the variable field coil 35, as shown in FIG. 7, the magnetic path member 30 is magnetized to the N pole on the S pole permanent magnet 24 side, and the N pole permanent magnet. The 24 side is magnetized to the south pole. As a result, a part of the magnetic flux of the N-pole permanent magnet 24 is short-circuited to the S-pole permanent magnet 24 via the magnetic path member 30.

  The amount of induced magnetic flux generated by the variable field coil 35 is adjusted according to the magnitude of the direct current supplied to the variable field coil 35. By adjusting the amount of the induced magnetic flux, the amount of short-circuit magnetic flux between the adjacent permanent magnets 24 is adjusted.

  The amount of induced magnetic flux increases as the direct current supplied to the variable field coil 35 increases and the number of turns of the variable field coil 35 increases. The number of turns of the variable field coil 35 is set to the number of turns obtained experimentally in advance.

  The direct current supplied to the variable field coil 35 is adjusted according to the magnitude of the induced current generated in the induction coil 22. Thus, the magnetic flux amount of the short-circuit magnetic flux is adjusted according to the magnitude of the induced current generated in the induction coil 22. Further, the induced current generated in the induction coil 22 increases as the rotational speed of the rotor 20 increases. Therefore, the magnetic flux amount of the short-circuit magnetic flux increases as the rotational speed of the rotor 20 increases.

  The pair of opposed portions 32 protrudes radially outward from both ends in the circumferential direction of the core portion 31, and the protruding ends are positioned at least radially outward of the permanent magnet 24. It has become. Thereby, the area of the magnetic path member 30 facing the rotor teeth 23 is larger than that of the magnetic path member without the facing portion 32. Therefore, when a direct current is supplied to the variable field coil 35, a large amount of magnetic flux can be guided from the permanent magnet 24 to the magnetic path member 30.

  A gap G having a predetermined size is formed as a high magnetic resistance region between the facing portion 32 and the rotor teeth 23. The gap G is such that when the direct current is not supplied to the variable field coil 35, the magnetic flux of the permanent magnet 24 does not flow between the rotor teeth 23 and the magnetic path member 30, or a minute amount even if it flows. It is a big size. The gap G is set to a size such that the magnetic flux of the permanent magnet 24 flows between the rotor tooth 23 and the magnetic path member 30 when a direct current is supplied to the variable field coil 35.

(Rectifier circuit)
The rotating electrical machine 1 includes a rectifier circuit 40 that rectifies an alternating induced current induced by the induction coil 22 into a direct current and supplies the rectified current to the variable field coil 35.

  As shown in FIG. 4, the rectifier circuit 40 includes two diodes D1 and D2 as rectifier elements, and a closed circuit in which the diodes D1 and D2, the two induction coils 22, and the two variable field coils 35 are connected. It is configured as.

  The diodes D1 and D2 are provided on the rotor 20 in a state of being housed in a diode case (not shown), for example. The diodes D1 and D2 may be mounted inside the rotor 20.

  In the rectifier circuit 40, the AC induced current generated in the two induction coils 22 is rectified by the diodes D1 and D2, and the rectified DC current is supplied to the two variable field coils 35 connected in series. Supplied as The two variable field coils 35 generate an induced magnetic flux when supplied with a direct current.

(Operation of rotating electrical machine)
Next, the operation of the rotating electrical machine 1 according to the present embodiment will be described with reference to FIGS. 5, 6, 7, and 8.

  As described above, the rotating electrical machine 1 according to the present embodiment is a permanent magnet type synchronous motor that includes the permanent magnet 24 in the rotor 20 and outputs torque using the magnetic flux of the permanent magnet 24.

  In the conventional permanent magnet type synchronous motor, since the magnetic flux of the permanent magnet is constant, the counter electromotive force generated in the armature coil of the stator is increased by the magnetic flux of the permanent magnet as the rotational speed of the rotor increases. When the rotational speed of the rotor reaches a certain rotational speed, the back electromotive force generated in the armature coil becomes equal to the power supply voltage of the permanent magnet type synchronous motor. As a result, no more current can flow through the permanent magnet type synchronous motor. As a result, the rotational speed of the rotor cannot be increased.

  Conventionally, in order to solve such problems, field weakening control has been performed in which a counter electromotive force generated in the armature coil is equivalently reduced by passing a current that cancels the magnetic flux generated by the permanent magnet through the armature coil of the stator.

  However, this field weakening control generates a magnetic flux that does not contribute to torque because a current is supplied to generate a magnetic flux in a direction that cancels the magnetic flux of the permanent magnet. This has led to a decrease in efficiency.

  Further, in the field weakening control, a harmonic magnetic flux is generated, and therefore the iron loss and electromagnetic vibration of the permanent magnet type synchronous motor may increase due to the harmonic magnetic flux. Further, in the field weakening control, since the magnetic flux in the direction opposite to the magnetic flux of the permanent magnet is generated to suppress the magnetic flux of the permanent magnet, irreversible demagnetization of the permanent magnet may occur. For this reason, it is necessary to use a permanent magnet having a relatively high coercive force, which increases costs.

  When a neodymium magnet is used as the permanent magnet, an eddy current is generated in the permanent magnet due to fluctuations in the external magnetic field by field weakening control, and the permanent magnet generates heat. This heat generation may cause irreversible demagnetization of the permanent magnet. Therefore, it is necessary to add a material such as a rare earth having high heat resistance to the permanent magnet. However, in this case, since the added material such as rare earth becomes an impurity for the permanent magnet, the original performance of the permanent magnet may not be exhibited.

  Therefore, in the rotating electrical machine 1 according to the present embodiment, the amount of magnetic flux linked from the permanent magnet 24 to the stator 10 is adjusted by the action of the magnetic path member 30 and the variable field coil 35 described above without performing field weakening control. Possible configuration. Thereby, the rotary electric machine 1 which concerns on this Embodiment can solve the problem by the field weakening control as mentioned above.

(When rotor is running at low speed)
In the rotating electrical machine 1 according to the present embodiment, when the rotational speed of the rotor 20 is low, the magnetic flux of the harmonic component is not generated in the stator 10 or is very small even if it is generated. For this reason, the variable field coil 35 does not generate an induced magnetic flux, or even if it generates a very small amount.

  Therefore, in the gap G, the magnetic resistance is high, and the magnetic pole member 30 is not formed with the N pole and the S pole. For this reason, the magnetic flux of the N-pole permanent magnet 24 is not short-circuited to the S-pole permanent magnet 24 via the magnetic path member 30 or is only slightly short-circuited. As a result, when the rotational speed of the rotor 20 is low, all or most of the magnetic flux of the permanent magnet 24 is linked to the stator 10 as shown in FIGS.

  Thus, when the rotational speed of the rotor 20 is low, the amount of magnetic flux interlinked from the permanent magnet 24 to the stator 10 can be increased compared to when the rotational speed of the rotor 20 described later is high.

(At high rotor speed)
In the rotating electrical machine 1 according to the present embodiment, when the rotational speed of the rotor 20 is high, a harmonic component magnetic flux is generated in the stator 10. The amount of the harmonic component magnetic flux increases as the rotational speed of the rotor 20 increases.

  This harmonic component magnetic flux interlinks with the induction coil 22 to induce an induced current in the induction coil 22 (see FIG. 2) of the rotor 20, and the induced current is induced by the rectifier circuit 40 (see FIG. 4). Rectified and supplied as a direct current to the variable field coil 35 (see FIG. 2).

  The variable field coil 35 supplied with the direct current generates an induced magnetic flux so that the magnetic flux is short-circuited between the adjacent permanent magnets 24. That is, in the magnetic path member 30, the magnetic poles of the N pole and the S pole are formed so that the magnetic flux is short-circuited between the adjacent permanent magnets 24.

  As a result, a Halbach array in which the magnetization directions of the magnetic path member 30 and the permanent magnet 24 are different by 90 ° is formed. Along with this, the magnetic resistance in the gap G decreases. The Halbach array refers to an array in which magnets are arranged so that the magnetization directions differ by 90 ° between adjacent magnets.

  As described above, when the magnetic resistance in the gap G decreases, as shown in FIGS. 7 and 8, a part of the magnetic flux of the N-pole permanent magnet 24 becomes a short-circuit magnetic flux through the magnetic path member 30 and the S-pole permanent magnet. 24 is short-circuited. Thereby, the magnetic flux of the magnetic flux amount excluding the magnetic flux amount of the short-circuit magnetic flux among the total magnetic flux amount of the permanent magnet 24 is linked to the stator 10. That is, when the rotational speed of the rotor 20 is high, the amount of magnetic flux interlinked from the permanent magnet 24 to the stator 10 is suppressed compared to when the rotational speed of the rotor 20 is low.

  Therefore, even if the rotational speed of the rotor 20 is high, field-weakening control can be made unnecessary. For this reason, the iron loss and electromagnetic vibration resulting from the harmonic magnetic flux produced by field weakening control can be prevented.

  Further, since field weakening control is not required, it is not necessary to use a permanent magnet having a high coercive force, and it is not necessary to add a material such as a rare earth having a high heat resistance to the permanent magnet. Thereby, the cost of the rotary electric machine 1 can be reduced.

  Thus, in the rotating electrical machine 1 according to the present embodiment, the amount of magnetic flux interlinking from the permanent magnet 24 to the stator 10 can be adjusted without performing field-weakening control. Specifically, when the rotational speed of the rotor 20 is high, a decrease in efficiency can be prevented. Further, the output can be improved when the rotational speed of the rotor 20 is low.

  As described above, according to the rotating electrical machine 1 of the present embodiment, an induced current is generated by interlinking the harmonic component superimposed on the magnetic flux generated on the stator 10 side with the induction coil 22, and the induced current Is rectified by the rectifier circuit 40 and supplied to the variable field coil 35. Thereby, the magnetic flux amount of the short circuit magnetic flux which short-circuits between the permanent magnets 24 adjacent to the circumferential direction can be adjusted.

  The harmonic component superimposed on the magnetic flux generated on the stator 10 side is obtained by supplying a three-phase alternating current to the armature coil 11 concentratedly wound on the stator 10. For this reason, in order to generate the direct current supplied to the variable field coil 35, a special device such as a DC / DC converter is not required.

  Thus, the rotating electrical machine 1 of the present embodiment adjusts the amount of magnetic flux interlinked from the permanent magnet 24 to the stator 10 with a simple configuration without using a special device such as a DC / DC converter. be able to. As a result, the rotating electrical machine 1 of the present embodiment can vary the magnetic flux of the permanent magnet 24 with a low-cost configuration.

  The rotating electrical machine 1 can be suitably employed as, for example, a vehicle-mounted motor, a wind power generator, or a machine tool motor.

  In the present embodiment, the rotary electric machine 1 is applied to a radial gap type rotary electric machine, but may be applied to an axial gap type rotary electric machine.

  When the ratio of the number of slots 14 of the stator 10 to the number of rotor teeth 23 of the rotor 20, that is, the slot combination of the stator 10 and the rotor 20 is “3: 2”, the rotating electrical machine 1 of the present embodiment The combination of the number of 14 and the number of rotor teeth 23 may be any combination.

  For example, in the example shown in FIGS. 1 and 2, the number of slots 14 is “12” and the number of rotor teeth 23 is “8”. In the examples shown in FIGS. Is a combination of “18” and the number of rotor teeth 23 is “12”, but the slot combination is “3: 2” in any combination.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 Rotating electrical machine 10 Stator 11 Armature coil 13 Stator teeth 20 Rotor 22 Inductive coil 23 Rotor teeth 24 Permanent magnet 30 Magnetic path member 35 Variable field coil 40 Rectifier circuit

Claims (3)

A rotating electric machine comprising a stator having an armature coil and a rotor having a permanent magnet,
The stator is
The armature coil has a plurality of stator teeth wound in a concentrated manner,
The rotor is
A plurality of rotor teeth containing the permanent magnets;
An induction coil wound around the rotor teeth on the stator side of the permanent magnet,
Between the rotor teeth adjacent in the circumferential direction, a magnetic path member is disposed through a gap,
The magnetic path member is provided with a variable field coil capable of adjusting a magnetic flux amount of a magnetic flux that is short-circuited between the permanent magnets adjacent in the circumferential direction based on an induced current generated in the induction coil. A rotating electric machine that is characterized.   2. The rotating electrical machine according to claim 1, further comprising a rectifier circuit that rectifies an alternating induced current induced by the induction coil into a direct current and supplies the rectified current to the variable field coil. The variable field coil is toroidally wound around the magnetic path member, and is provided so as to form a magnetic pole in a direction in which a magnetic flux is short-circuited between the permanent magnets adjacent in the circumferential direction. Item 3. The rotating electrical machine according to Item 2.

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