Rotary electric machine

Abstract

A rotary electric machine (100) is provided with a stator (1) and a rotor (2). The stator (1) has a stator core (10) and an armature winding (13). The armature winding (13) includes winding parts (A, B, C) corresponding to three phases. The winding part (A, B, C) of each phase is configured such that coil pairs each composed of two mechanically adjacent coils face each other with respect to the rotation axis of the rotor (2). In the armature winding (13), two coils constituting a coil pair are arranged in parallel with each other, each coil being arranged in parallel with one coil and in series with the other coil of a coil pair of the same phase which is opposite with respect to the rotation axis of the rotor (2), thereby forming a double-Y connection with neutral points (N) of the Y connections being connected via a constant voltage source circuit (200).

Description

rotating electrical machines

[0001] The present disclosure relates to a rotating electric machine.

[0002] Conventionally, permanent magnet rotating electric machines have been widely used as drive motors. For example, Patent Document 1 discloses a motor equipped with a consequent pole rotor in which a plurality of magnets are embedded at intervals in the circumferential direction of a rotor core, and salient poles integrally formed with the rotor core are arranged with gaps between the magnets.

[0003] JP 2012-110213 A

[0004] When used in applications such as electric vehicles, industrial equipment, and air conditioners, drive motors are required to output high torque by strengthening the magnetic field of the magnet at low rotation speeds, and to alleviate voltage saturation by weakening the magnetic field of the magnet at high rotation speeds in order to achieve a wide operating range. However, the motor disclosed in Patent Document 1 cannot adjust the magnetic field flux of the magnet, and therefore cannot achieve a wide operating range.

[0005] The present disclosure has been made in view of the above, and aims to provide a rotating electric machine that can adjust the field magnetic flux of a magnet and achieve a wide operating range.

[0006] To solve the above-mentioned problems and achieve the object, the present disclosure provides a rotating electric machine including a cylindrical stator and a rotor disposed inside the stator. The stator includes a stator core having an annular core back and twelve teeth protruding radially inward from the core back, and an armature winding wound around each of the teeth. The armature winding has winding portions corresponding to three phases. Each phase winding portion is configured such that a coil pair consisting of two mechanically adjacent coils faces the rotor's rotation axis. The armature winding has two coils arranged in parallel with each other, and each coil is connected in parallel with one coil of the same-phase coil pair facing the rotor's rotation axis and in series with the other coil, forming a double Y-connection, with the neutral points of each Y-connection connected via a constant voltage source circuit. A field current supplied from the constant voltage source circuit flows through the armature winding, generating a field magnetic flux.

[0007] The rotating electric machine according to the present disclosure has the advantage that it is possible to adjust the field magnetic flux of the magnet and to realize a wide operating range.

[0008] 4 is a diagram showing the direction of the field current flowing through the coil in the direction of the field magnetic flux shown in FIG. 4; a wiring diagram of the armature winding of a modified example 1 of the rotating electric machine according to the first embodiment; a diagram showing the configuration of a modified example 2 of the rotating electric machine according to the first embodiment; a diagram showing the configuration of a modified example 3 of the rotating electric machine according to the first embodiment; a diagram showing the configuration of a modified example 4 of the rotating electric machine according to the first embodiment; a diagram showing the configuration of a rotating electric machine according to the second embodiment;

[0009] Hereinafter, a rotating electric machine according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] 1 is a plan view schematically illustrating the configuration of a rotating electric machine according to embodiment 1. As shown in Fig. 1, a rotating electric machine 100 according to embodiment 1 is a radial gap type rotating electric machine including a cylindrical stator 1 and a rotor 2 disposed inside the stator 1.

[0011] The stator 1 includes a stator core 10 having an annular core back portion 11 and twelve teeth 12 protruding radially inward from the core back portion 11, and an armature winding 13 wound around the teeth 12. The armature winding 13 is connected to a three-phase power supply (not shown).

[0012] The armature winding 13 has three-phase winding sections: winding section A corresponding to phase A, winding section B corresponding to phase B, and winding section C corresponding to phase C. Winding section A corresponding to phase A includes coils A1, A2, A3, and A4. Winding section B corresponding to phase B includes coils B1, B2, B3, and B4. Winding section C corresponding to phase C includes coils C1, C2, C3, and C4. In the winding sections A, B, and C of each phase, a coil pair consisting of two mechanically adjacent coils faces the rotation axis of the rotor 2. In winding section A corresponding to phase A, the coil pair consisting of two mechanically adjacent coils A1 and A2 and the coil pair consisting of two mechanically adjacent coils A3 and A4 face the rotation axis of the rotor 2. In the winding section B corresponding to the B phase, a pair of two mechanically adjacent coils, B1 and B2, and a pair of two mechanically adjacent coils, B3 and B4, face each other across the rotation axis of the rotor 2. In the winding section C corresponding to the C phase, a pair of two mechanically adjacent coils, C1 and C2, and a pair of two mechanically adjacent coils, C3 and C4, face each other across the rotation axis of the rotor 2.

[0013] Furthermore, the two coils that make up a coil pair are wound in opposite directions. Specifically, coils A1 and A2 are wound in opposite directions. Coils A3 and A4 are wound in opposite directions. Coils B1 and B2 are wound in opposite directions. Coils B3 and B4 are wound in opposite directions. Coils C1 and C2 are wound in opposite directions. Coils C3 and C4 are wound in opposite directions.

[0014] The rotor 2 has a cylindrical rotor core 20, a shaft 21 made of a magnetic material and inserted through the center of the rotor core 20 as a rotating shaft, and permanent magnets 22 arranged at intervals along the circumferential direction of the rotor core 20. As an example, the rotor 2 is a surface magnet type in which the permanent magnets 22 are attached in an annular shape to the outer circumferential surface of the rotor core 20. The rotor 2 is a consequent pole type in which permanent magnets 22 with north poles and iron pole portions 23 with south poles formed by the rotor core 20 without any permanent magnets 22 are arranged alternately along the circumferential direction of the rotor core 20. The rotor 2 has a 10-pole structure with five permanent magnets 22 and five iron pole portions 23. That is, in the rotating electric machine 100 according to the first embodiment, the ratio of the number of magnetic poles of the rotor 2 to the number of slots of the stator 1 is 10:12.

[0015] FIG. 2 is a cross-sectional perspective view taken along the line II-II in FIG. 1 , showing the state in which the frame and brackets are installed. Note that some hatching is omitted in FIG. 2 to make the flow of field magnetic flux easier to see. As shown in FIG. 2 , the rotating electric machine 100 further includes a cylindrical frame 3 to which the stator 1 is fixed, and brackets 4 attached to both ends of the frame 3 in the direction of the rotational axis of the rotor 2. The frame 3 and brackets 4 are made of magnetic material. The stator 1 and rotor 2 are housed inside the cylindrical frame 3. The outer peripheral surface of the stator 1 is fixed to the inner wall surface of the frame 3. The outer wall surface of the frame 3 serves as a cooling source. The frame 3 and the stator core 10 are electrically connected. The bracket 4 rotatably holds the shaft 21 and closes the openings at both ends of the frame 3. Of the two brackets 4 attached to both ends of the frame 3, only one bracket 4 is shown in FIG. 2 . The bracket 4 is fixed to the frame 3 with fastening members such as bolts (not shown).

[0016] 3 is a connection diagram of the armature winding of the rotating electric machine according to the first embodiment. As shown in Fig. 3, the armature winding 13 has two coils that make up a coil pair connected in parallel with each other, and each coil is connected in parallel with one coil that faces radially with respect to the rotation axis of the rotor 2, of the in-phase coil pair that faces with respect to the rotation axis of the rotor 2, and in series with the other coil, forming a double Y connection.

[0017] Specifically, in the case of the winding section A corresponding to phase A, coils A1 and A2 constituting a coil pair are connected in parallel. Coils A3 and A4 constituting a coil pair are connected in parallel. Coil A1 is connected in parallel with coil A3, one of the coil pairs that face each other across the rotational axis of the rotor 2, and is connected in series with the other coil A4. Similarly, coil A2 is connected in parallel with coil A4, one of the coil pairs that face each other across the rotational axis of the rotor 2, and is connected in series with the other coil A3. The same applies to winding section B corresponding to phase B and winding section C corresponding to phase C.

[0018] In the rotating electric machine 100 according to the first embodiment, the neutral point N of each Y-connection is open, and the open ends are connected by a constant voltage source circuit 200. The constant voltage source circuit 200 is configured such that the neutral points N of the Y-connections are connected via a DC power supply 201. In the rotating electric machine 100, the field current supplied by the constant voltage source circuit 200 circulates through the winding portions A, B, and C of each phase. In the example shown in FIG. 3 , in the winding portion A corresponding to the A-phase, the field current circulates in the order of coil A3, coil A2, coil A1, and coil A4, as indicated by the dashed-dotted arrow X. In the winding portion B corresponding to the B-phase, the field current circulates in the order of coil B3, coil B2, coil B1, and coil B4, as indicated by the solid-line arrow Y. In addition, in winding section C corresponding to phase C, the field current circulates in the order of coil C3, coil C2, coil C1, and coil C4, as indicated by dashed arrow Z. Note that by reversing the flow of the field current, in winding section A corresponding to phase A, the field current circulates in the order of coil A4, coil A1, coil A2, and coil A3. The same applies to the field current circulating in winding section B corresponding to phase B and the field current circulating in winding section C corresponding to phase C.

[0019] Fig. 4 is an explanatory diagram showing an example of the direction of field magnetic flux in the rotating electric machine according to the first embodiment. The white arrows shown in Fig. 4 indicate the direction of the field magnetic flux. Fig. 5 is an explanatory diagram showing the direction of the field current flowing through the coil in the direction of the field magnetic flux shown in Fig. 4. The white arrows shown in Fig. 5 indicate the direction of the field current circulating in the winding portion of each phase.

[0020] As shown in Fig. 4, the field flux generated by the field current supplied from the constant voltage source circuit 200 and circulating in the windings A, B, and C of each phase is linked to each of the teeth 12 in the same direction in the radial direction of the stator 1. In the case shown in Fig. 4, the field flux is linked to the inside of each tooth 12 in the radial direction. As shown by the solid arrows in Fig. 2, the flow of the field flux in the teeth 12 is directed toward the inside of the rotor 2. The field flux that has flowed through the teeth 12 flows in the axial direction of the shaft 21, passes through the bracket 4, and returns to the frame 3. As shown in FIG. 5, the field flux oriented as shown in FIG. 4 is generated when the field current circulates in the order of coil A3, coil A2, coil A1, and coil A4 in winding section A corresponding to phase A, the field current circulates in the order of coil B3, coil B2, coil B1, and coil B4 in winding section B corresponding to phase B, and the field current circulates in the order of coil C3, coil C2, coil C1, and coil C4 in winding section C corresponding to phase C.

[0021] 5 , the field current circulating through each phase generates a field flux directed radially inward in each tooth portion 12, i.e., a field flux in a direction that forms a north pole in the iron pole portion 23. This cancels out the magnetic flux of the south pole in the iron pole portion 23, reducing the magnetic flux density of the rotating magnetic field in the gap between the stator 1 and the rotor 2. As a result, voltage saturation can be alleviated during high-speed rotation.

[0022] Next, a case will be described in which a field current flows so as to generate a field flux radially outward from each tooth portion 12, i.e., so as to generate a field flux in the opposite direction to the white arrows shown in Fig. 4. An S pole is formed in the iron pole portion 23 of the rotor 2 by the permanent magnet 22. By flowing a field current in the opposite direction to the direction of the white arrows shown in Fig. 5, a field flux is generated in the direction that forms an S pole in the iron pole portion 23. This strengthens the field flux of the S pole in the iron pole portion 23. As a result, the magnetic flux density of the rotating magnetic field in the air gap between the stator 1 and the rotor 2 increases, and torque can be increased.

[0023] As described above, the rotating electric machine 100 according to the first embodiment can adjust the field flux density by controlling the field current supplied from the constant voltage source circuit 200 and circulating through the windings A, B, and C of each phase. That is, the rotating electric machine 100 strengthens the field flux of the permanent magnets 22 during low-speed rotation, thereby increasing the magnetic flux density of the rotating magnetic field in the air gap between the stator 1 and the rotor 2 and outputting high torque. Meanwhile, the rotating electric machine 100 weakens the field flux of the permanent magnets 22 during high-speed rotation, thereby decreasing the magnetic flux density of the rotating magnetic field in the air gap between the stator 1 and the rotor 2 and alleviating voltage saturation. Furthermore, iron loss during high-speed rotation can be suppressed, and copper loss due to the weakened field current can be reduced. Therefore, the rotating electric machine 100 according to the first embodiment can achieve a wide operating range as a drive motor for applications such as electric vehicles, industrial equipment, and air conditioners.

[0024] Furthermore, for example, in the prior art, an armature winding that generates a rotating magnetic field and a field winding that generates a field magnetic field are wound around the teeth of a stator. However, this complicates the winding process during manufacturing, thereby reducing productivity. Furthermore, the field winding reduces the space factor of the armature winding, which may increase winding resistance. On the other hand, the rotating electric machine 100 according to the first embodiment has a configuration in which only the armature winding 13 is wound around the teeth 12 of the stator 1, which does not complicate the winding process during manufacturing and thus reduces productivity degradation. Furthermore, the rotating electric machine 100 according to the first embodiment can utilize a stator 1 in which, for example, the number of magnetic poles of the rotor 2 and the number of slots of the stator 1 are in a 10:12 series, thereby improving productivity.

[0025] Furthermore, the rotating electric machine 100 according to the first embodiment is of a consequent pole type, and the amount of permanent magnets 22 can be reduced compared to conventional permanent magnet motors, which reduces costs and is effective in avoiding resource procurement risks.

[0026] FIG. 6 is a wiring diagram of the armature windings of a first modified example of the rotating electric machine according to the first embodiment. The rotating electric machine 100A shown in FIG. 6 has a constant voltage source circuit 200 in which the neutral point N of each Y-connection is open and each open end is connected via a diode 202. In this case, the sum of the number of turns of the coils of the same phase in one Y-connection of the double Y-connection is different from the sum of the number of turns of the coils of the same phase in the other Y-connection. Specifically, the sum of the number of turns of the A-phase coils A1 and A4 in one Y-connection is different from the sum of the number of turns of the A-phase coils A2 and A3 in the other Y-connection. Similarly, the sum of the number of turns of the B-phase coils B1 and B4 in one Y-connection is different from the sum of the number of turns of the B-phase coils B2 and B3 in the other Y-connection. Similarly, the sum of the number of turns of the C-phase coils C1 and C4 in one Y-connection is different from the sum of the number of turns of the C-phase coils C2 and C3 in the other Y-connection.

[0027] As a result, in the rotating electric machine 100A, an AC current is generated in the winding section A corresponding to phase A due to the difference in back electromotive force generated between coils A1 and A4 and coils A2 and A3, and a DC component that becomes field current is extracted by half-wave rectification by diode 202. In the winding section A corresponding to phase A, the field current circulates in the order of coils A4, A1, A2, and A3, as indicated by the dashed-dotted arrow X. Similarly, DC components that become field current are extracted in the winding section B corresponding to phase B and the winding section C corresponding to phase C. In the winding section B corresponding to phase B, the field current circulates in the order of coils B4, B1, B2, and B3, as indicated by the solid-line arrow Y. In the winding section C corresponding to phase C, the field current circulates in the order of coils C4, C1, C2, and C3, as indicated by the dashed-line arrow Z. That is, the rotating electric machine 100A can achieve the same effect as the rotating electric machine 100 in which each open end of the neutral point N of each Y-connection is connected via the DC power supply 201.

[0028] FIG. 7 is a plan view schematically illustrating the configuration of a second modified example of the rotating electric machine according to the first embodiment. The rotating electric machine 100B of the second modified example illustrated in FIG. 7 has an embedded-magnet rotor 2 in which permanent magnets 22 are embedded inside the rotor core 20. The other configurations are the same as those of the rotating electric machines 100 and 100A described above. The rotor 2 illustrated in FIG. 7 includes two permanent magnets 22 in pairs, with each pair of permanent magnets 22 having a north pole and an iron pole portion 23 formed by the rotor core 20 and having a south pole alternately arranged in the circumferential direction of the rotor core 20. Embedding the permanent magnets 22 inside the rotor core 20 reduces eddy current loss generated in the permanent magnets 22. Furthermore, the amount of permanent magnets 22 can be increased, thereby increasing the magnetic flux.

[0029] FIG. 8 is a plan view schematically illustrating the configuration of a third modification of the rotating electric machine according to the first embodiment. The rotating electric machine 100C of the third modification shown in FIG. 8 has a rotor 2 with a 14-pole structure, including seven permanent magnets 22 and seven iron pole portions 23. That is, in the rotating electric machine 100C of the third modification, the number of magnetic poles of the rotor 2 and the number of slots of the stator 1 are in a 14:12 ratio. In this case, compared to the rotor 2 shown in FIG. 1 , the position of the winding portion B corresponding to the B phase and the position of the winding portion C corresponding to the C phase are interchanged. Note that the rotor 2 of the rotating electric machine 100C of the third modification is not limited to a surface magnet type in which the permanent magnets 22 are annularly attached to the outer circumferential surface of the rotor core 20, but may be an embedded magnet type in which the permanent magnets 22 are embedded inside the rotor core 20, as shown in FIG. 7 .

[0030] FIG. 9 is a plan view schematically illustrating the configuration of a fourth variation of the rotating electric machine according to the first embodiment. The solid arrows on the permanent magnets 22 a, 22 b illustrated in FIG. 9 indicate the directions of the magnetic flux of the permanent magnets 22 a, 22 b. The rotating electric machine 100 according to the first embodiment is not limited to the consequent-pole configuration illustrated in FIG. 1. For example, as in a rotating electric machine 100D according to a fourth variation illustrated in FIG. 9, a configuration in which the north-pole permanent magnets 22 a and the south-pole permanent magnets 22 b are alternately arranged along the circumferential direction of the rotor core 20 may be used. A flux barrier 24 is formed between adjacent north-pole permanent magnets 22 a and south-pole permanent magnets 22 b so as to increase or decrease the magnetic flux of either the north or south pole. The rotor 2 of the rotating electric machine 100D of variant example 4 is not limited to an embedded magnet type in which the permanent magnets 22a, 22b are embedded inside the rotor core 20, but may also be a surface magnet type in which the permanent magnets 22a, 22b are attached in a ring shape to the outer peripheral surface of the rotor core 20.

[0031] Furthermore, the rotating electric machines 100, 100A, 100B, 100C, and 100D according to the first embodiment are not limited to the radial gap type shown in Fig. 1, and may be of an axial gap type. When the rotating electric machines 100, 100A, 100B, 100C, and 100D according to the first embodiment are applied to the axial gap type, the annular field winding provided in the conventional axial gap type can be omitted.

[0032] Second Embodiment Next, a rotating electric machine 101 according to the second embodiment will be described. Fig. 10 is a plan view schematically showing the configuration of a rotating electric machine according to the second embodiment. The white arrows shown in Fig. 10 indicate the direction of field magnetic flux. Furthermore, reference numeral 25 shown in Fig. 10 indicates magnetic flux lines. Fig. 11 is an explanatory diagram showing the direction of field current flowing through the coil in the direction of the field magnetic flux shown in Fig. 10. The white arrows shown in Fig. 11 indicate the direction of field current circulating in each phase. The stator 1 of the rotating electric machine 101 according to the second embodiment has 12 slots.

[0033] The armature winding 13 shown in Figure 10 has three-phase winding sections: winding section A corresponding to phase A, winding section B corresponding to phase B, and winding section C corresponding to phase C. Winding section A corresponding to phase A includes coils A1, A2, A3, and A4. Winding section B corresponding to phase B includes coils B1, B2, B3, and B4. Winding section C corresponding to phase C includes coils C1, C2, C3, and C4. In the winding sections A, B, and C of each phase, a coil pair consisting of two mechanically adjacent coils faces the rotation axis of the rotor 2. In winding section A corresponding to phase A, the coil pair consisting of two mechanically adjacent coils A1 and A2 and the coil pair consisting of two mechanically adjacent coils A3 and A4 face the rotation axis of the rotor 2. In the winding section B corresponding to the B phase, a pair of two mechanically adjacent coils, B1 and B2, and a pair of two mechanically adjacent coils, B3 and B4, face each other across the rotational axis of the rotor 2. In the winding section C corresponding to the C phase, a pair of two mechanically adjacent coils, C1 and C2, and a pair of two mechanically adjacent coils, C3 and C4, face each other across the rotational axis of the rotor 2. All of these coils are wound in the same direction.

[0034] As an example, the rotor 2 is a surface magnet type in which permanent magnets 22 are attached in an annular shape to the outer peripheral surface of the rotor core 20. The rotor 2 is a consequent pole type in which permanent magnets 22 with north poles and iron pole portions 23 with south poles formed by the rotor core 20 without any permanent magnets 22 are alternately arranged in the circumferential direction of the rotor core 20. The rotor 2 in the second embodiment has a 20-pole structure with ten permanent magnets 22 and ten iron pole portions 23. In other words, the rotating electric machine 101 according to the second embodiment generates torque as a 20-pole permanent magnet motor.

[0035] As shown in FIG. 11 , the armature winding 13 has two coils constituting a coil pair connected in parallel with each other, and each coil is connected in series with one coil of the in-phase coil pair that faces radially relative to the rotational axis of the rotor 2 and in parallel with the other coil, forming a double Y-connection. Specifically, in the case of the A-phase winding section A, coils A1 and A2 constituting the coil pair are connected in parallel. Coils A3 and A4 constituting the coil pair are connected in parallel. Coil A1 is connected in series with coil A3, one of the coils in the coil pair that faces radially relative to the rotational axis of the rotor 2, and in parallel with coil A4, the other of the coils in the coil pair that face radially relative to the rotational axis of the rotor 2. Similarly, coil A2 is connected in series with coil A4, one of the coils in the coil pair that faces radially relative to the rotational axis of the rotor 2, and in parallel with coil A3, the other of the coils in the coil pair that face radially relative to the rotational axis of the rotor 2. The same applies to the winding section B corresponding to the B phase and the winding section C corresponding to the C phase.

[0036] In the rotating electric machine 101 according to the second embodiment, the neutral point N of each Y-connection is open, and the open ends are connected by a constant voltage source circuit 200. The constant voltage source circuit 200 is configured such that the neutral points N of each Y-connection are connected via a DC power supply 201. In the rotating electric machine 101, the field current supplied by the constant voltage source circuit 200 circulates through the windings A, B, and C of each phase. In the example shown in FIG. 11 , in the winding corresponding to phase A, the field current circulates in the order of coil A4, coil A2, coil A1, and coil A3. In the winding corresponding to phase B, the field current circulates in the order of coil B4, coil B2, coil B1, and coil B3. In the winding corresponding to phase C, the field current circulates in the order of coil C4, coil C2, coil C1, and coil C3. By reversing the flow of the field current, the field current circulates in the order of coil A3, coil A1, coil A2, and coil A4 in the winding corresponding to phase A. The same applies to the field current circulating through winding section B corresponding to phase B and the field current circulating through winding section C corresponding to phase C.

[0037] In the rotating electric machine 101 according to the second embodiment, a field current supplied from the constant voltage source circuit 200 flows in the direction of the white arrows shown in FIG. 11 and circulates through the windings A, B, and C of each phase, generating a field flux in the direction of the white arrows shown in FIG. 10 . The field flux interlinks adjacent teeth 12 in opposite directions in the radial direction of the stator 1. This field flux forms a fixed magnetic field of six pole pairs (12 poles in total). As the rotor 2 rotates, the six-pole fixed magnetic field formed by the field flux is flux-modulated by the ten iron pole portions 23, generating a rotating magnetic field of four pole pairs, which is the ten poles of the iron pole portions 23 minus the six pole pairs of the fixed magnetic field. The rotating magnetic field of these four pole pairs synchronizes with the rotating magnetic field of the armature to generate torque. As a result, the torque of the 20-pole permanent magnet motor is boosted.

[0038] On the other hand, in the rotating electric machine 101 according to the second embodiment, the field current supplied from the constant voltage source circuit 200 flows in the direction opposite to that of the white arrows shown in Fig. 11 and circulates through the windings A, B, and C of each phase, generating a field flux in the direction opposite to that of the white arrows shown in Fig. 10. This generates a negative torque, reducing the torque of the 20-pole permanent magnet motor, making it possible to suppress back electromotive force and alleviate voltage saturation during high-speed rotation.

[0039] As described above, the rotating electric machine 101 according to the second embodiment can adjust the field flux density by controlling the field current supplied from the constant voltage source circuit 200 and circulating through the windings A, B, and C of each phase. That is, the rotating electric machine 101 strengthens the field flux of the permanent magnets 22 during low-speed rotation, thereby increasing the magnetic flux density of the rotating magnetic field in the air gap between the stator 1 and the rotor 2 and outputting high torque. Meanwhile, the rotating electric machine 101 weakens the field flux of the permanent magnets 22 during high-speed rotation, thereby decreasing the magnetic flux density of the rotating magnetic field in the air gap between the stator 1 and the rotor 2 and alleviating voltage saturation. Furthermore, iron loss during high-speed rotation can be suppressed, and copper loss due to a weakened field current can be reduced. Therefore, the rotating electric machine 101 according to the second embodiment can achieve a wide operating range as a drive motor for applications such as electric vehicles, industrial equipment, and air conditioners. Furthermore, unlike the rotating electric machine 100 of embodiment 1, the rotating electric machine 101 of embodiment 2 does not need to use the shaft 21 and frame 3 as a magnetic path, so there is no loss that occurs in the shaft 21 and frame 3, and efficiency can be improved.

[0040] FIG. 12 is a wiring diagram of the armature windings of a modified example of the rotating electric machine according to the second embodiment. The rotating electric machine 101A shown in FIG. 12 is configured to include a constant-voltage source circuit 200 in which the neutral point N of each Y-connection is open and each open end is connected via a diode 202. In this case, the sum of the number of turns of the coils of the same phase in one Y-connection of the double Y-connection is different from the sum of the number of turns of the coils of the same phase in the other Y-connection. Specifically, the sum of the number of turns of the A-phase coils A1 and A3 in one Y-connection is different from the sum of the number of turns of the A-phase coils A2 and A4 in the other Y-connection. Similarly, the sum of the number of turns of the B-phase coils B1 and B3 in one Y-connection is different from the sum of the number of turns of the B-phase coils B2 and B4 in the other Y-connection. Similarly, the sum of the number of turns of the C-phase coils C1 and C3 in one Y-connection is different from the sum of the number of turns of the C-phase coils C2 and C4 in the other Y-connection.

[0041] As a result, in the rotating electric machine 101A, an AC current is generated in the winding section A corresponding to phase A due to the difference in back electromotive force generated between coil A1 and coil A3 and coil A2 and coil A4, and a DC component that becomes a field current is extracted by half-wave rectification by diode 202. Similarly, a DC component that becomes a field current is extracted in the winding section B corresponding to phase B and in the winding section C corresponding to phase C. In other words, the rotating electric machine 101A can obtain the same effect as the rotating electric machine 101 in which the open ends of the neutral point N of each Y-connection are connected via the DC power supply 201.

[0042] The rotating electric machines 101, 101A according to the second embodiment may be configured as an embedded magnet rotor 2 in which the permanent magnets 22 are embedded inside the rotor core 20, as shown in Fig. 7, for example. Embedding the permanent magnets 22 inside the rotor core 20 reduces eddy current loss generated in the permanent magnets 22. Furthermore, the amount of permanent magnets 22 can be increased, thereby increasing the magnetic flux.

[0043] Furthermore, the rotating electric machines 101, 101A according to the second embodiment are not limited to the radial gap type shown in Fig. 10, but may be of an axial gap type. When the rotating electric machines 101, 101A according to the second embodiment are applied to the axial gap type, the annular field winding provided in the conventional axial gap type can be omitted.

[0044] Furthermore, the rotating electric machines 101 and 101A according to the second embodiment are not limited to the 20-pole structure shown in the figure, and may have a structure with other numbers of poles. For example, the rotating electric machines 101 and 101A according to the second embodiment may have a 16-pole structure with eight permanent magnets 22 and eight iron pole portions 23, and may have a configuration in which the position of the winding portion B corresponding to the B phase and the position of the winding portion C corresponding to the C phase are interchanged.

[0045] Furthermore, the rotating electric machines 101 and 101A according to the second embodiment are not limited to the consequent-pole configuration shown in Fig. 10. The rotating electric machines 101 and 101A according to the second embodiment may have a configuration in which north-pole permanent magnets and south-pole permanent magnets are alternately arranged along the circumferential direction of the rotor core 20. In this case, a flux barrier is formed between adjacent north-pole and south-pole permanent magnets so that the magnetic flux of either the north or south pole can be increased or decreased.

[0046] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0047] 1 stator, 2 rotor, 3 frame, 4 bracket, 10 stator core, 11 core back portion, 12 teeth portion, 13 armature winding, 20 rotor core, 21 shaft, 22, 22a, 22b permanent magnet, 23 iron pole portion, 24 flux barrier, 25 magnetic flux lines, 100, 100A, 100B, 100C, 100D, 101, 101A rotating electric machine, 200 constant voltage source circuit, 201 DC power supply, 202 diode, A, B, C winding portion, A1, A2, A3, A4, B1, B2, B3, B4, C1, C2, C3, C4 coil, N neutral point.

Claims

1. A rotating electric machine comprising: a cylindrical stator; and a rotor arranged inside the stator, wherein the stator has a stator core having a circular core back portion and 12 teeth protruding radially inward from the core back portion, and an armature winding wound around each of the teeth, wherein the armature winding has winding portions corresponding to three phases, wherein the winding portions of each phase are configured such that a coil pair consisting of two mechanically adjacent coils faces the rotation axis of the rotor, wherein the two coils constituting the coil pair are connected in parallel to each other, and each of the coils is connected in parallel to one of the coil pairs of the same phase facing the rotation axis of the rotor and in series with the other coil, forming a double Y connection, and the neutral points of each Y connection are connected via a constant voltage source circuit, and wherein a field flux is generated when a field current supplied from the constant voltage source circuit flows through the armature winding.

2. The rotating electric machine described in claim 1, characterized in that the two coils that constitute the coil pair are wound in opposite directions, each of the coils is connected in parallel with one of the coils of the coil pair that faces radially relative to the rotor's rotation shaft and in series with the other coil, and the field magnetic flux links each of the teeth portions in the same direction in the radial direction of the stator.

3. A rotating electric machine as described in claim 1, characterized in that all of the coils are wound in the same direction, each of the coils is in series with one of the coil pairs of the same phase that face each other relative to the rotor's rotation shaft and in parallel with the other coil, and the field magnetic flux links adjacent teeth portions in opposite directions in the radial direction of the stator.

4. A rotating electric machine as claimed in any one of claims 1 to 3, characterized in that the rotor has a rotor core and permanent magnets arranged at intervals along the circumferential direction of the rotor core, and the permanent magnets and the iron pole portions formed by the rotor core are arranged alternately in the circumferential direction of the rotor core.

5. A rotating electric machine as claimed in any one of claims 1 to 4, characterized in that the constant voltage source circuit is configured such that the neutral points of each of the Y connections are connected via a diode, the sum of the number of turns of the coils of the same phase in one of the Y connections of the double Y connections is different from the sum of the number of turns of the coils of the same phase in the other Y connection, and a field magnetic flux is generated by rectifying an AC current circulating in the coils of each phase due to a back electromotive force generated in the coils of each phase by the diode.

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