Rotary electric machine and drive method for rotary electric machine

Abstract

Provided is a rotary electric machine that meets a required maximum performance and improves efficiency in a low-torque region without an increase in size.　A rotary electric machine (1) has a first rotary drive unit (200) and a second rotary drive unit (300) that share a rotary shaft (20). The first rotary drive unit is a radial gap–type rotary drive unit that comprises a first stator (220) and a first rotor (210), and the second rotary drive unit is an axial gap–type rotary drive unit that comprises a second stator (330) and a second rotor (310) that includes a second rotor core (311) and a second rotor magnet (312) and is fastened to the rotary shaft on the first rotary drive unit side of the second stator at a gap in the axial direction.

Description

Rotating electric machine and method for driving the rotating electric machine

[0001] The present disclosure relates to a rotating electric machine and a method for driving the rotating electric machine.

[0002] Rotating electric machines used in electric vehicles are required to have high performance in terms of the maximum torque and maximum output necessary to drive the vehicle. However, general rotating electric machines that meet these requirements have a problem of reduced efficiency in the low torque and low output ranges where actual use is frequent. In particular, efficiency is reduced in the low torque range due to stator iron loss caused by field magnetomotive force and carrier harmonic iron loss caused by inverter drive. For this reason, it has been difficult for general rotating electric machines to satisfy both maximum performance and high efficiency in the low torque range.

[0003] As a conventional rotating electric machine that addresses such problems, a rotating electric machine has been disclosed that improves efficiency in the low torque range by providing two rotational drive units on one rotating shaft (see, for example, Patent Documents 1 and 2).

[0004] Special table No. 2021-534717 Publication No. 2020-501484

[0005] In conventional rotating electric machines, magnetic interference occurs between two rotary drive units when the two rotary drive units are operated. This magnetic interference causes the magnetic flux of one rotary drive unit to interlink with the iron core of the other rotary drive unit, resulting in loss. This reduces the effectiveness of improving efficiency in the low torque range. Increasing the distance between the two rotary drive units to avoid magnetic interference increases the size of the rotating electric machine.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a rotating electric machine that satisfies the required maximum performance without increasing the size and has improved efficiency in the low torque range.

[0007] The rotating electric machine according to the present disclosure includes a frame, a rotating shaft rotatably supported by the frame, and first and second rotary drive units built into the frame and sharing the rotating shaft. The first rotary drive unit is a radial gap type rotary drive unit including a first stator having a first annular stator core fixed to the frame and a plurality of first stator coils mounted on the first stator core, and a first rotor fastened to the rotating shaft and having a first rotor core disposed radially from the first stator via a gap and the first rotor coils mounted on the first rotor core. The second rotary drive unit is an axial gap type rotary drive unit including a second stator fixed to the frame and a second rotor fastened to the rotating shaft and having a second rotor core disposed axially on the first rotary drive unit side of the second stator via a gap and a second rotor magnet mounted on the second rotor core.

[0008] In the rotating electric machine disclosed herein, the second rotary drive unit is an axial gap type rotary drive unit that includes a second stator fixed to the frame, a second rotor core fastened to the rotating shaft and arranged axially on the first rotary drive unit side of the second stator via a gap, and a second rotor having a second rotor magnet installed on the second rotor core, so that the required maximum performance can be met without increasing the size and efficiency can be improved in the low torque range.

[0009] FIG. 1 is a cross-sectional view of a rotating electric machine according to embodiment 1. FIG. 2 is a cross-sectional view of a first stator according to embodiment 1. FIG. 3 is a side view of a load-side second rotor according to embodiment 1. FIG. 4 is a diagram for explaining the operation of a rotating electric machine according to embodiment 1. FIG. 5 is a cross-sectional view of a rotating electric machine according to embodiment 2. FIG. 6 is a cross-sectional view of a first rotor according to embodiment 2. FIG. 7 is a cross-sectional view of a rotating electric machine according to embodiment 3. FIG. 8 is a cross-sectional view of a first rotor according to embodiment 3. FIG. 9 is a cross-sectional view of a rotating electric machine according to embodiment 4. FIG. 10 is a cross-sectional view of a second stator according to embodiment 4. FIG. 11 is a cross-sectional view of a rotating electric machine according to embodiment 5. FIG. 12 is a cross-sectional view of a rotating electric machine according to embodiment 6.

[0010] Hereinafter, a rotating electric machine according to an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the same reference numerals in the various drawings indicate the same or corresponding parts.

[0011] Embodiment 1. Figure 1 is a cross-sectional view of a rotating electric machine according to embodiment 1. Figure 1 is a cross-sectional view in a direction parallel to a rotating shaft, which will be described later. In the rotating electric machine 1 of this embodiment, the rotating shaft is connected to a load (not shown) on the right side of Figure 1. Therefore, in Figure 1, the right side is referred to as the load side, and the left side is referred to as the anti-load side.

[0012] The rotating electric machine 1 of this embodiment includes a first rotary drive unit 200 disposed on the load side and a second rotary drive unit 300 disposed on the counter-load side. The first rotary drive unit 200 and the second rotary drive unit 300 are housed in a single frame 100 and share a single rotating shaft 20. The rotating shaft 20 is rotatably supported relative to the frame 100 by a load-side bearing 30 and a counter-load-side bearing 40. The load-side end of the rotating shaft 20 extends to the outside of the frame 100 and is connected to the load. Hereinafter, the direction parallel to the rotating shaft 20 is referred to as the axial direction, the direction perpendicular to the rotating shaft 20 is referred to as the radial direction, and the direction in which the rotating shaft 20 rotates is referred to as the circumferential direction. The inner diameter side refers to the direction radially approaching the rotating shaft 20, and the outer diameter side refers to the direction radially away from the rotating shaft 20.

[0013] The frame 100 is composed of a cylindrical central frame 101 that covers the radially outer sides of the first rotary drive unit 200 and the second rotary drive unit 300, a load-side plate 102 that covers the load-side end of the central frame 101, and a counter-load-side plate 103 that covers the counter-load-side end. A resolver rotor 51, which is a rotational position sensor that detects the rotational position of the rotating shaft 20, is fastened to the counter-load-side end of the rotating shaft 20. A resolver stator 52 is fastened to the counter-load-side plate 103 and is disposed across a gap from the resolver rotor 51. A resolver cover 53 that covers the resolver rotor 51 and the resolver stator 52 is attached to the counter-load-side plate 103.

[0014] The first rotary drive unit 200 is an induction machine and is disposed on the load side within the rotating electric machine 1. The first rotary drive unit 200 has a first rotor 210 fastened to the rotating shaft 20 and a first stator 220 fastened to the central frame 101. The first rotor 210 and the first stator 220 are disposed with a radial gap between them. The first rotor 210 is composed of a first rotor core 211 having an annular shape fastened to the rotating shaft 20, and a first rotor coil 212. Although not shown, the first rotor core 211 has an annular main body and 59 teeth protruding radially outward from the main body. The first rotor coil 212 is a cage conductor disposed in slots, which are spaces between the teeth.

[0015] 2 is a cross-sectional view of the first stator according to this embodiment. The first stator 220 is composed of a first stator core 221 having an annular shape fastened to the central frame 101 and a first stator coil 222. The first stator core 221 has an annular main body and 48 teeth protruding radially inward from the main body. The first stator coil 222 is wound around the teeth in a distributed winding manner. The first rotation drive unit 200 configured in this manner is an eight-pole radial gap squirrel-cage induction machine. Note that a radial gap type refers to a structure in which a gap exists between the rotor and stator in the radial direction.

[0016] The second rotary drive unit 300 is a permanent magnet synchronous rotating machine and is arranged on the anti-load side within the rotating electric machine 1. The second rotary drive unit 300 has a load-side second rotor 310 and an anti-load-side second rotor 320 fastened to the rotating shaft 20, and a second stator 330 fastened to the central frame 101. The load-side second rotor 310 is arranged on the axial load side of the second stator 330 via a gap. The anti-load-side second rotor 320 is arranged on the axial anti-load side of the second stator 330 via a gap.

[0017] The load side second rotor 310 is composed of a disk-shaped load side second rotor core 311 fastened to the rotating shaft 20, and a load side second rotor magnet 312. The load side second rotor magnet 312 is embedded in the surface of the load side second rotor core 311 facing the second stator 330. The load side second rotor magnets 312 are fan-shaped, and 24 of them are arranged at equal intervals in the circumferential direction, with the north poles and south poles alternately facing in the axial direction.

[0018] Fig. 3 is a side view of the load side second rotor 310 according to this embodiment, as viewed from the second stator 330 side. The load side second rotor 310 has 24 load side second rotor magnets 312 arranged at equal intervals in the circumferential direction on a disk-shaped load side second rotor core 311.

[0019] The counter-load side second rotor 320 is composed of a disk-shaped counter-load side second rotor core 321 fastened to the rotating shaft 20, and a counter-load side second rotor magnet 322. The counter-load side second rotor magnet 322 is embedded in the surface of the counter-load side second rotor core 321 facing the second stator 330. The counter-load side second rotor magnets 322 are fan-shaped, and 24 of them are arranged at equal intervals in the circumferential direction, with the north poles and south poles alternately facing in the axial direction. The side surface of the counter-load side second rotor 320 seen from the second stator 330 side is similar to the side surface of the load side second rotor 310 shown in FIG. 3.

[0020] The load side second rotor magnet 312 of the load side second rotor 310 and the anti-load side second rotor magnet 322 of the anti-load side second rotor 320 are arranged so that the magnetic poles of the magnets at the same circumferential position face each other with their north and south poles facing the second stator 330.

[0021] The second stator 330 is composed of a second stator base 331 having an annular shape fastened to the central frame 101, and a second stator coil 332. The second stator base 331 has 72 slots formed at equal intervals of 5 mechanical degrees in the circumferential direction. The second stator coil 332 is wound around these 72 slots at a pitch of 6 slots. The second rotary drive unit 300 configured in this manner is an axial gap type permanent magnet synchronous rotating machine. Note that an axial gap type is a structure in which a gap exists between a disk-shaped rotor and a stator in the axial direction.

[0022] Here, the materials will be described. The frame 100, the rotating shaft 20, the second stator 330, and the second stator base 331 are non-magnetic, such as aluminum or resin. These components are preferably made of a non-conductive material, such as resin, to prevent eddy current loss due to magnetic flux fluctuations. The first rotor core 211, the first stator core 221, the load-side second rotor core 311, and the counter-load-side second rotor core 321 are magnetic, such as laminated electromagnetic steel sheets. The first rotor coil 212, the first stator coil 222, and the second stator coil 332 are formed by winding conductors made of, for example, copper, aluminum, or iron. The load-side second rotor magnet 312 and the counter-load-side second rotor magnet 322 are permanent magnets, such as rare earth magnets.

[0023] Next, the operation of the rotating electric machine according to this embodiment will be described. Fig. 4 is a diagram showing the operation of the rotating electric machine according to this embodiment. In Fig. 4, the horizontal axis represents the rotation speed, and the vertical axis represents the torque. Also, S ＭＡＸ is the maximum rotation speed of the rotating electrical machine 1, S Ｈ is the threshold value for the high rotation speed side, S Ｌ is the threshold value for the low rotation speed side, and S Ｌ <S Ｈ <S ＭＡＸ Furthermore, T ＭＡＸ is the maximum torque of the rotating electrical machine 1, T Ｈ is the threshold value on the high torque side, T Ｌ is the threshold value on the low torque side, and T Ｌ <T Ｈ <T ＭＡＸis.

[0024] As shown in FIG. 4, the rotating electrical machine 1 of this embodiment has a torque that varies from 0 to T Ｌ The rotating electric machine 1 is driven only by the second rotary drive unit 300 until the rotation speed is increased from 0 to S Ｌ In the region up to and including torque T Ｌ From T Ｈ The rotating electric machine 1 is driven only by the first rotary drive unit 200 until the rotation speed reaches 0. Ｌ In the region up to and including torque T Ｈ From T ＭＡＸ Up to this point, the rotation is driven by both the first rotation drive unit 200 and the second rotation drive unit 300.

[0025] The rotating electric machine 1 has a rotation speed of S Ｌ From S Ｈ In the region up to and including torque T Ｌ From T Ｈ The rotating electric machine 1 is driven only by the first rotary drive unit 200 up to the constant output curve of S. Ｌ From S ＭＡＸ In the region up to and including torque T Ｈ From the constant power curve of T ＭＡＸ 1. The rotary drive unit 200 and the rotary drive unit 300 are both driven up to the constant output curve .

[0026] In the rotating electric machine of this embodiment, when both rotational drive units are driven, the torque distribution is such that the second rotational drive unit 300 always provides the torque T Ｌ The first rotary drive unit 200 outputs the remaining required torque. Ｌ is the maximum torque that the second rotary drive unit 300 can output, and T Ｈ is the maximum torque that the first rotary drive unit 200 can output. ＭＡＸ =T Ｌ +T Ｈ and T ＭＡＸ is the maximum torque that the rotating electrical machine 1 can output. Ｌ is the maximum torque T Ｌ is the maximum rotation speed at which the Ｈis the maximum rotational speed at which the first rotary drive unit 200 and the second rotary drive unit 300 can generate maximum torque.

[0027] When the rotating electric machine 1 is used in a region where the drive modes are switched between the first rotary drive unit 200 and the second rotary drive unit 300, frequent drive mode switching may occur. Providing a hysteresis characteristic to the borderline indicating the switching region shown in Figure 4 can prevent frequent drive mode switching. For example, when torque increases and decreases across the borderline, setting the threshold value that is the borderline for torque decrease to 95% of the threshold value that is the borderline for torque increase can prevent frequent drive mode switching.

[0028] First, a case where the rotating electric machine 1 is driven only by the second rotary drive unit 300 will be described. In the rotating electric machine 1, the torque is T Ｌ In the following cases, the motor is driven only by the second rotary drive unit 300, which is an axial gap type permanent magnet synchronous rotating machine, and therefore it is possible to reduce iron loss caused by PWM carrier harmonics that occur when the second rotary drive unit 300 is inverter-driven, thereby improving efficiency in the low torque range.

[0029] Furthermore, the second rotary drive unit 300 has permanent magnets as field sources in the load side second rotor 310 and the anti-load side second rotor 320, but because the second stator base 331 of the second stator 330 is made of a non-magnetic material, no stator iron loss occurs due to the rotating magnetic field generated by the rotor field. This allows the efficiency of the rotating electric machine 1 to be improved.

[0030] When only the second rotary drive unit 300 is driven, the first rotary drive unit 200 also rotates in conjunction with it, but since the first rotary drive unit 200 is an induction motor, no electromagnetic loss occurs due to the interlocking rotation.

[0031] Next, we will explain the case where the rotating electric machine 1 is driven solely by the first rotary drive unit 200. In this rotating electric machine, the region where the rotating electric machine is driven solely by the first rotary drive unit 200, which is a squirrel-cage induction machine, is not a low-torque region where efficiency is low. Therefore, efficiency degradation in the low-torque region can be suppressed. Furthermore, when only the first rotary drive unit 200 is driven, the second rotary drive unit 300 also rotates in conjunction with the first rotary drive unit 200. However, although the second rotary drive unit 300 is provided with a permanent magnet as a field source, the second stator base 331 of the second stator 330 is made of a non-magnetic material, so stator iron loss due to the rotating magnetic field generated by the rotor field is not generated. This improves the efficiency of the rotating electric machine 1.

[0032] Furthermore, when the axial distance between the first rotary drive unit 200 and the second rotary drive unit 300 is shortened, the rotating magnetic field generated between the first rotor 210 and the first stator 220 of the first rotary drive unit 200 intersects with the load-side second rotor core 311 of the second rotary drive unit 300. However, since the rotating magnetic field generated by the first rotary drive unit 200 rotates at the same rotational speed as the load-side second rotor core 311, it does not become an alternating magnetic field within the load-side second rotor core 311. As a result, no iron loss occurs in the load-side second rotor core 311. Therefore, efficiency does not decrease even when the axial distance between the first rotary drive unit 200 and the second rotary drive unit 300 is shortened. As a result, the rotating electric machine of this embodiment can be prevented from becoming large.

[0033] Furthermore, the load-side second rotor core 311 of the second rotary drive unit 300 is disposed closer to the first rotary drive unit 200 than the second stator 330. The second rotary drive unit 300 and the first rotary drive unit 200 rotate synchronously. Therefore, the load-side second rotor core 311 shields the rotating magnetic field of the first rotary drive unit 200, so that the rotating magnetic field of the first rotary drive unit 200 does not interlink with the second stator 330. As a result, the rotary electric machine 1 of this embodiment can improve efficiency without increasing its size.

[0034] Finally, a case where the rotating electric machine 1 is driven by both the first rotary drive unit 200 and the second rotary drive unit 300 will be described. The second rotary drive unit 300 has a second stator base 331 made of a non-magnetic material and rotates using a field magnet of a permanent magnet, and has high efficiency. In a region where the rotating electric machine 1 is driven by both the first rotary drive unit 200 and the second rotary drive unit 300, the highly efficient second rotary drive unit 300 always generates maximum torque, thereby improving the maximum performance of the rotating electric machine 1.

[0035] In a rotating electrical machine configured in this manner, it is possible to satisfy the required maximum performance without increasing the size and to improve efficiency in the low torque range.

[0036] Note that the control of second rotary drive unit 300, which is a permanent magnet synchronous rotating machine, is greatly influenced by the rotational position. In the rotating electric machine of this embodiment, resolver rotor 51, which serves as a rotational position sensor, is disposed at the end of rotating shaft 20 on the anti-load side. Therefore, because resolver rotor 51 is disposed in the vicinity of second rotary drive unit 300, it is less susceptible to the influence of torsion of rotating shaft 20, and the controllability of second rotary drive unit 300 can be improved.

[0037] Embodiment 2. In the rotating electric machine according to embodiment 1, the first rotary drive unit is an eight-pole radial gap squirrel-cage induction machine. In the rotating electric machine according to embodiment 2, the first rotary drive unit is configured as a synchronous reluctance motor.

[0038] Fig. 5 is a cross-sectional view of a rotating electric machine according to this embodiment. The configuration of the rotating electric machine according to this embodiment is similar to that of the rotating electric machine according to embodiment 1 shown in Fig. 1, except that the configuration of first rotary drive unit 200 is different from that of the first rotary drive unit according to embodiment 1. First rotor 210 according to this embodiment is composed only of an annular first rotor core 211 fastened to rotating shaft 20. This first rotor core 211 has a plurality of slits 213 formed therethrough in the axial direction.

[0039] FIG. 6 is a cross-sectional view of a first rotor according to this embodiment. FIG. 6 is a cross-sectional view in a direction perpendicular to the rotation axis. As shown in FIG. 6, first rotor 210 according to this embodiment has a plurality of slits 213 formed in first rotor core 211. These slits 213 serve as flux barriers that form salient poles facing the inner diameter side. Eight sets of these flux barriers are formed at equal intervals in the circumferential direction. That is, in rotating electric machine 1 according to this embodiment, first rotary drive unit 200 is configured as a synchronous reluctance motor.

[0040] The rotating electric machine 1 of this embodiment is driven in the same manner as the rotating electric machine of embodiment 1. Therefore, like the rotating electric machine of embodiment 1, it is possible to satisfy the required maximum performance without increasing the size and to improve efficiency in the low torque range.

[0041] Embodiment 3. In the rotating electric machine according to embodiment 1, the first rotary drive unit is an eight-pole radial gap squirrel-cage induction machine. In the rotating electric machine according to embodiment 3, the first rotary drive unit is configured as a switched reluctance motor.

[0042] 7 is a cross-sectional view of a rotating electric machine according to this embodiment. The configuration of the rotating electric machine according to this embodiment is similar to the configuration of the rotating electric machine according to the first embodiment shown in FIG. 1, except for the configuration of first rotary drive unit 200, which is different from the configuration of the first rotary drive unit according to the first embodiment.

[0043] The first stator 220 in the rotating electric machine of this embodiment is composed of a first stator core 221 having an annular shape fastened to the central frame 101, and a first stator coil 222. Although not shown, the first stator core 221 has an annular main body and 12 teeth protruding radially inward from the main body. The first stator coil 222 is wound around the teeth in a concentrated winding manner.

[0044] The first rotor 210 of this embodiment is composed only of a first rotor core 211 fastened to the rotating shaft 20. This first rotor core 211 is composed of a circular ring-shaped main body and eight protrusions 214 protruding radially outward from the main body.

[0045] Fig. 8 is a cross-sectional view of a first rotor according to this embodiment. Fig. 8 is a cross-sectional view in a direction perpendicular to the rotation axis. As shown in Fig. 8, first rotor 210 according to this embodiment has eight protrusions 214 that protrude radially outward from the annular main body of first rotor core 211. The eight protrusions 214 are formed at equal intervals in the circumferential direction. That is, in rotating electric machine 1 according to this embodiment, first rotary drive unit 200 is configured as a switched reluctance motor.

[0046] The rotating electric machine 1 of this embodiment is driven in the same manner as the rotating electric machine of embodiment 1. Therefore, like the rotating electric machine of embodiment 1, it is possible to satisfy the required maximum performance without increasing the size and to improve efficiency in the low torque range.

[0047] Embodiment 4. In the rotating electric machine according to embodiment 1, the second rotary drive unit is an axial gap type permanent magnet synchronous rotating machine that does not have a magnetic body in the stator. In the rotating electric machine according to embodiment 4, the second rotary drive unit has a magnetic body stator.

[0048] 9 is a cross-sectional view of a rotating electric machine according to this embodiment. The configuration of the rotating electric machine according to this embodiment is similar to the configuration of the rotating electric machine according to the first embodiment shown in FIG. 1, except for the configuration of second rotary drive unit 300, which is different from the configuration of the second rotary drive unit according to the first embodiment.

[0049] 10 is a cross-sectional view of a second stator according to this embodiment. The second stator 330 in the rotating electric machine of this embodiment is composed of a second stator core 333 having an annular shape fastened to the central frame 101, and a second stator coil 332. The second stator core 333 is composed of a magnetic material. The second stator core 333 has 48 teeth through which magnetic flux passes in the axial direction, and a teeth connection portion that connects these 48 teeth at their axial center. The circumferential width of the teeth connection portion is smaller than the circumferential width of the teeth. The second stator coil 332 is wound around the teeth.

[0050] In the rotating electric machine of this embodiment, second rotary drive unit 300 has second stator core 333 made of a magnetic material, so iron loss occurs due to PWM carrier harmonics that are generated when second rotary drive unit 300 is inverter-driven. Furthermore, when only first rotary drive unit 200 is driven, second rotary drive unit 300 also rotates in conjunction with it, which generates stator iron loss due to a rotating magnetic field. Therefore, the efficiency of the rotating electric machine of this embodiment is lower than that of the rotating electric machine of embodiment 1.

[0051] However, in the rotating electric machine of this embodiment, the second rotary drive unit 300 has a second stator core 333 made of a magnetic material, so the torque of the second rotary drive unit 300 can be further improved.

[0052] Furthermore, in the rotating electric machine of this embodiment, the teeth connection portions that connect the teeth of the second stator core 333 in the circumferential direction are small and do not function as a yoke, so there is almost no iron loss caused by the magnetic flux passing through the second stator core 333 in the circumferential direction. Therefore, there is less reduction in efficiency compared to general rotating electric machines.

[0053] Furthermore, load-side second rotor core 311 of second rotary drive unit 300 is arranged closer to first rotary drive unit 200 than second stator core 333. Second rotary drive unit 300 and first rotary drive unit 200 rotate synchronously. Therefore, load-side second rotor core 311 shields the rotating magnetic field of first rotary drive unit 200, so that the rotating magnetic field of first rotary drive unit 200 does not interlink with second stator core 333. As a result, the rotating electric machine 1 of this embodiment can improve efficiency without increasing its size.

[0054] Fifth Embodiment A rotating electric machine according to a fifth embodiment is the rotating electric machine according to the fourth embodiment, except that the anti-load side second rotor is removed.

[0055] Fig. 11 is a cross-sectional view of a rotating electric machine according to this embodiment. The configuration of the rotating electric machine according to this embodiment is similar to the configuration of the rotating electric machine according to embodiment 4 shown in Fig. 9, except for the configuration of second rotary drive unit 300, which differs from the configuration of the second rotary drive unit according to embodiment 4. Second rotary drive unit 300 according to this embodiment has a load-side second rotor 310 fastened to rotating shaft 20 and a second stator 330 fastened to central frame 101. Load-side second rotor 310 is disposed on the axial load side of second stator 330 via a gap.

[0056] The second stator 330 in the rotating electric machine of this embodiment is composed of a second stator core 333 having an annular shape fastened to the central frame 101, and a second stator coil 332. The second stator core 333 is composed of a magnetic material. The second stator core 333 has 48 teeth through which magnetic flux passes in the axial direction, and a teeth connection portion that connects these 48 teeth at the axial end on the anti-load side. The circumferential width of the teeth connection portion is larger than the circumferential width of the teeth. The second stator coil 332 is wound around the teeth.

[0057] In the rotating electric machine of this embodiment, load side second rotor core 311 is arranged closer to first rotary drive unit 200 than second stator core 333. Second rotary drive unit 300 and first rotary drive unit 200 rotate synchronously. Therefore, load side second rotor core 311 shields the rotating magnetic field of first rotary drive unit 200, so that the rotating magnetic field of first rotary drive unit 200 does not interlink with second stator core 333. As a result, rotating electric machine 1 of this embodiment can improve efficiency without increasing the size, similar to embodiment 4.

[0058] Furthermore, in the rotating electric machine of this embodiment, the second rotary drive section does not have a counter-load side second rotor, so the number of parts is reduced and the machine can be made smaller than the rotating electric machine of embodiment 4.

[0059] 12 is a cross-sectional view of a rotating electric machine according to Embodiment 6. The configuration of the rotating electric machine of this embodiment is similar to the configuration of the rotating electric machine of Embodiment 1 shown in FIG. 1, except that the outer diameter of the second rotary drive unit 300 is larger than the outer diameter of the first rotary drive unit 200.

[0060] As shown in Figure 12, in the rotating electric machine 1 of this embodiment, the frame 100 is composed of a cylindrical load side central frame 101a that covers the first rotational drive unit 200 on the radial outside, a cylindrical anti-load side central frame 101b that covers the second rotational drive unit 300 on the radial outside, a load side plate 102 that covers the load side end of the load side central frame 101a, and an anti-load side plate 103 that covers the anti-load side end of the anti-load side central frame 101b.

[0061] The outer diameter of the counter-load side central frame 101b is larger than the outer diameter of the load side central frame 101a, so that the outer diameter of the second rotary drive unit 300 disposed inside the counter-load side central frame 101b can be larger than the outer diameter of the first rotary drive unit 200 disposed inside the load side central frame 101a.

[0062] In the rotating electric machine configured in this manner, the torque of the second rotary drive unit 300 can be improved, and therefore the torque of the entire rotating electric machine can be improved.

[0063] Although the configurations of the number of poles and the number of slots of the first rotary drive unit and the second rotary drive unit are exemplified in the first to sixth embodiments, the present invention is not limited to these configurations. For example, in the second embodiment, the first rotary drive unit has 8 poles and 48 slots, and the second rotary drive unit has 8 poles and 48 slots, but the first rotary drive unit may have 6 poles and 36 slots, and the second rotary drive unit may have 12 poles and 72 slots.

[0064] Although various exemplary embodiments are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0065] REFERENCE SIGNS LIST 1 Rotating electric machine, 20 Rotating shaft, 30 Load side bearing, 40 Counter-load side bearing, 51 Resolver rotor, 52 Resolver stator, 53 Resolver cover, 100 Frame, 101 Central frame, 101a Load side central frame, 101b Counter-load side central frame, 102 Load side plate, 103 Counter-load side plate, 200 First rotary drive unit, 210 First rotor, 211 First rotor core, 212 First rotor coil, 213 Slit, 214 Protrusion, 220 First stator, 221 First stator core, 222 First stator coil, 300 Second rotary drive unit, 310 Load side second rotor, 311 Load side second rotor core, 312 Load side second rotor magnet, 320 Counter-load side second rotor, 321 Counter-load side second rotor core, 322 counter-load side second rotor magnet, 330 second stator, 331 second stator base, 332 second stator coil, 333 second stator core.

Claims

1. A rotating electric machine having a frame, a rotating shaft rotatably supported by the frame, and first and second rotating drive units built into the frame and sharing the rotating shaft, wherein the first rotating drive unit is a radial gap type rotating drive unit including a first stator having a first stator core of a circular ring shape fixed to the frame and a plurality of first stator coils installed on the first stator core, and a first rotor having a first rotor core fastened to the rotating shaft and disposed radially from the first stator via a gap and a first rotor coil installed on the first rotor core, and the second rotating drive unit is an axial gap type rotating drive unit including a second stator fixed to the frame, and a second rotor having a second rotor core fastened to the rotating shaft and disposed axially on the first rotating drive unit side of the second stator via a gap, and a second rotor magnet installed on the second rotor core.

2. A rotating electric machine according to claim 1, characterized in that the maximum output torque of said second rotary drive section is smaller than the maximum output torque of said first rotary drive section.

3. A rotating electric machine according to claim 1 or 2, characterized in that the outer diameter of the second stator of the second rotary drive unit is larger than the outer diameter of the first stator of the first rotary drive unit.

4. A rotating electric machine according to any one of claims 1 to 3, characterized in that the second stator of the second rotary drive section is made of a non-magnetic material.

5. A rotating electric machine as described in any one of claims 1 to 4, characterized in that the second rotary drive unit further comprises a second rotor fastened to the rotating shaft and located on the opposite side of the second stator to the first rotary drive unit.

6. A rotating electric machine as described in any one of claims 1 to 5, further comprising a rotational position sensor for detecting the rotational position of the rotating shaft, the rotational position sensor being arranged at a position closer to the second rotational drive unit than to the first rotational drive unit.

7. A method for driving a rotating electric machine as claimed in any one of claims 1 to 6, characterized in that when a torque smaller than the maximum output torque of the second rotary drive unit is output, only the second rotary drive unit is driven.

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