JP2007274798A - Permanent-magnet rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent-magnet rotating electric machine that can satisfy output torque while reducing cogging torque and a torque ripple. <P>SOLUTION: The problem cam be solved such that: permanent magnets are arranged in multiple layers in the circumferential direction, a non-magnetic region is adjacent to at least the outside of the radial direction of each magnet that is positioned outside a magnet pole, the non-magnetic region is adjacent to at least the inside of the radial direction of each magnet that is positioned inside the magnetic pole, and each magnet positioned inside the magnetic pole is smaller in width and larger in thickness than each magnet positioned outside the magnet pole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a permanent magnet type rotating electrical machine including a rotor in which permanent magnets are embedded in multiple layers at intervals in the circumferential direction of a rotor core, and a stator core having distributed winding coils.

  As an electric motor used for driving an electric vehicle, in particular, an electric vehicle (EV) or a hybrid vehicle (HEV), it is desired that the electric motor be small and light and highly efficient. With the development of high-performance magnet materials in recent years, permanent magnet motors have become the mainstream, focusing on the fact that drive motors for electric vehicles (especially EVs and HEVs) can be made smaller, lighter and more efficient than induction motors and reluctance motors. It has become.

  In the permanent magnet motor, a large amount of magnetic flux can be generated without passing a large current, and the characteristics can be exhibited particularly in a high torque region at a low speed.

  The characteristic rotor structure of an electric vehicle, particularly an electric motor used for EV or HEV drive, etc. is embedded with a permanent magnet embedded in a laminated silicon steel sheet in consideration of iron loss generation, high voltage generation countermeasures, permanent magnet retention, etc. Permanent magnet type rotating electric machines of the type are becoming mainstream.

  On the other hand, there is a problem that torque ripple and cogging torque, which are sources of vibration or noise of the motor, are large.

  In Patent Document 1, this kind of torque ripple and cogging torque is provided on the outer side of a pair of permanent magnets embedded in a rotor core in a V shape, and nonmagnetic paths adjacent to each other in the circumferential direction are provided. It is described that the pair of non-magnetic path end portions adjacent to each other in the formation portion are reduced by forming them in different shapes with respect to the pair of non-magnetic path end portions adjacent in the circumferential direction.

JP-A-2005-312102 Japanese Patent No. 3172506

  However, although Patent Document 1 has an effect of reducing torque ripple and cogging torque, output torque is not considered.

  The present invention provides a permanent magnet type rotating electrical machine that can reduce the cogging torque and the torque ripple and satisfy the output torque.

  Here, the present invention is a stator core in which a stator winding is wound around a plurality of tooth portions extending in the circumferential direction at equal intervals in the circumferential direction, and opposed to the stator with a rotation gap, In a permanent magnet type rotating electrical machine having a rotor core in which a magnetic pole portion is formed by embedding a plurality of permanent magnets whose polarities are alternately magnetized in the circumferential direction, the permanent magnets are arranged in multiple layers in the circumferential direction. Each of the magnets located outside is adjacent to at least the radially outer side of the nonmagnetic region, and each of the magnets located inside the magnetic pole is adjacent to at least the radially inner side of the nonmagnetic region and located inside the magnetic pole. The magnet is characterized in that it is narrower and thicker than each magnet positioned outside the magnetic pole.

  In the present invention, it is preferable to form a nonmagnetic region on the radially outer side of each magnet located outside the magnetic pole.

  In the present invention, it is preferable to form nonmagnetic regions on both sides in the radial direction of each magnet located outside the magnetic pole.

  In the present invention, it is preferable to form nonmagnetic regions on both sides in the radial direction of each magnet positioned outside the magnetic pole, and to form nonmagnetic regions on both sides in the radial direction of each magnet positioned inside the magnetic pole.

  In this invention, it is preferable to arrange | position each magnet located inside and outside a magnetic pole in V shape via a nonmagnetic area | region.

  In this invention, it is preferable to arrange | position each magnet located inside and outside a magnetic pole in U shape via a nonmagnetic area | region.

  In the present invention, the nonmagnetic region is preferably a hole penetrating the rotor core.

  According to the present invention, it is possible to provide a permanent magnet type rotating electrical machine that can satisfy the output torque while reducing the cogging torque and the torque ripple.

  Further, according to the present invention, it is possible to obtain a permanent magnet type rotating electric machine with low torque ripple, and it is possible to obtain an electric vehicle with low vibration and low noise.

  Hereinafter, the configuration of the permanent magnet type rotating electrical machine according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3 and FIG. 6. Here, as an example, a rotating electrical machine will be described as an example of a permanent magnet motor having a distributed winding structure as a stator and an 8-pole rotor pole. First, the overall configuration of the permanent magnet type rotating electrical machine according to the present embodiment will be described with reference to FIGS. 1 and 2.

  The same reference numerals used in the drawings indicate the same parts and have the same functions.

  As shown in FIGS. 1 and 2, the permanent magnet type rotating electrical machine 1 includes a stator 2, a rotor 3, and end brackets 4A and 4B. The stator 2 includes a stator core 4 formed by laminating magnetic steel plates and a stator winding 5. The rotor 3 includes a rotor core 6 formed by laminating magnetic steel plates like the stator core, and a shaft 7 that penetrates and is fixed to the rotation center of the core. The rotor 3 is rotatably held by bearings 8A and 8B attached to the end brackets 4A and 4B via a shaft 7.

  In addition, although the outer periphery of the stator core 4 is an open type in consideration of heat dissipation, it may be forcedly cooled by using a hermetic type depending on the application.

  A magnetic pole position detector PS for detecting the position of the rotor 3 and a position detector E are provided on the shaft 7 of the rotor 3. A rotating magnetic field is generated by applying a three-phase current to the stator winding 5 in accordance with the rotor position detected by the magnetic pole position detector PS and the position detector E. Magnetic attraction and repulsive force generated between the rotating magnetic field and the permanent magnets 9, 10, 11, and 12 attached to the rotor 3 are generated to generate continuous rotating force. Here, by appropriately selecting the phase of the current, control is performed so that the combined torque of the torque by the permanent magnets 9, 10, 11, and 12 and the reluctance torque by the auxiliary salient pole 61 is maximized in the low speed and large torque region. The

  On the other hand, in the high-speed region where the induced voltage of the permanent magnet is equal to or higher than the motor terminal voltage (battery voltage), the current vector is advanced so that the permanent magnet 9, 10, 11, 12 is centered by the stator winding current. Weak field control is performed so that the rotating magnetic field acts as a demagnetizing force. This effectively reduces the magnetic flux of the permanent magnets 9, 10, 11, and 12, thereby reducing the iron loss of the rotating electrical machine and enabling highly efficient operation.

Next, as shown in FIG. 2, the stator core 4 includes an annular yoke portion 41 and an iron core tooth portion 42. By forming the iron core tooth portion 42, a slot 43 for accommodating the stator winding 5 is formed between the adjacent iron core tooth portions 42. Here, the stator winding 5 is wound with a general three-phase (U-phase, V-phase, W-phase) distributed winding. The number of the iron core teeth 42 is 48, and the number of the slots 43 is 48. The number of stator tooth portions (saliency poles) 42 per phase is sixteen.

  As shown in FIGS. 2 and 3, the rotor core 6 has insertion holes 9A for the permanent magnets 9, 10, 11, and 12 arranged at equal intervals in the circumferential direction and in a V shape in multiple layers in the circumferential direction. , 10A, 11A, 12A. The number of poles of the rotor 3 is 8 and the insertion holes 9A and 10A are provided with 4 pieces per pole and 32 pieces. For example, the permanent magnets 9 and 10 inserted into the four insertion holes 9A and 10A have the same polarity, thereby constituting one pole. For example, when the polarities of the permanent magnets 9 and 10 are S poles, the polarities of the permanent magnets 11 and 12 adjacent in the circumferential direction are N poles, and the polarities are alternating in the circumferential direction. The first insertion holes 9A, 10A, 11A, and 12A are arranged so as to be line-symmetric with respect to the radial direction of the rotor core 6, and are opposed to the outer insertion holes 9A and 11A and the inner insertion holes 10A. 12A are arranged in a V shape with an opening angle of 40 degrees toward the outer peripheral surface. Therefore, since four permanent magnets 9 and 10 are disposed per magnetic pole, the magnetic flux density per magnetic pole can be increased.

  Further, the magnet insertion holes 9A, 10A, 11A, and 12A form magnetic pole pieces 62, 63, 64, and 65 on the outer peripheral portions of the permanent magnets 9 and 10, respectively. A magnetic circuit is formed by causing the magnetic flux generated by the magnetic flux 12 to flow toward the stator 2 through a rotation gap between the rotor 3 and the stator 2.

  Here, the shape and arrangement of the permanent magnets 9, 10, 11, 12 will be described.

  As described above, the permanent magnets 9, 10, 11, and 12 arranged at equal intervals in the circumferential direction for each magnetic pole penetrate the rotor core 6 in the axial direction, and each insertion hole 9A is formed in a multilayer V shape. , 10A, 11A, 12A and fixed by an adhesive or the like.

Here, the arrangement structure of the permanent magnets constituting one pole will be described with reference to FIG. 3. The outer magnets of the two-layer structure permanent magnets arranged in a line-shape and V-shape with respect to the magnetic pole center. 9 is an opening angle of approximately 80 degrees and is located around the outer periphery of the rotor core 6. Magnetic spaces 9b, 9c, and 9d for preventing leakage magnetic flux are formed between both ends of the magnet in the radial direction and the inner end of the magnet. The above-mentioned spaces 9b and 9c are formed with the other spaces 9d1 and 0d together with the formation of the magnet insertion hole 9A in order to punch out a laminated steel sheet with a punching press, and are dimensioned so that the magnet cannot move in the circumferential direction and the radial direction. It fits perfectly.

  Next, the permanent magnets 10 located on the inner side are paired like the magnets to form the inner magnets 10 and are arranged in parallel with the outer magnets. The magnet is mounted in a magnet insertion hole 10A previously punched into a trapezoidal shape when viewed from the circumferential direction. Therefore, in a state where a magnet having a square cross section is mounted, magnetic spaces 10b and 10c are formed at both ends in the radial direction as in the case of the magnet. 10d is a magnetic space formed in the outer periphery of the rotor core 6 at the center of the magnetic pole to prevent leakage of effective magnetic flux.

  The inner magnet is provided to improve the rotational torque of the electric motor, but it takes into account that the d-axis current that flows during field weakening, which is a problem specific to the magnet electric motor, flows and the demagnetizing action acts on the inner magnet. Must. Therefore, in this structure, a magnet having a larger magnetomotive force than that of the outer magnet that is less affected by the demagnetizing action is used.

  In a specific embodiment, the outer magnet 9 has a circumferential thickness of 4 mm, whereas the inner magnet 10 has a circumferential thickness of 5.5 mm. Since the magnet thickness is proportional to the demagnetizing force, it can be said that the inner magnet 10 is 1.375 times stronger than the outer magnet 9 and is strong against demagnetization. By adopting such a configuration, the demagnetizing force of the inner magnet 10 is 1.375 times larger than that of the outer magnet 9 even if the demagnetizing action is exerted on the inner magnet 10 due to the d-axis current that flows during field weakening. The motor can be strong against demagnetization.

  This situation is also apparent from the output torque characteristic diagram shown in FIG. That is, FIG. 6 is a comparison diagram of output characteristics when the configuration of the single-layer magnet raised as the prior art of the present application is the conventional technology, and shows the range shown in FIG. 3 (electric rotation angle 0 to 180 degrees). In particular, by providing the inner magnet 10, the output improvement in the range of electrical rotation angles of 60 to 120 degrees is remarkable.

  Further, if the inner magnet 10 is arranged in parallel with the outer magnet 9 with the current physique, the outer magnet 9 can be made 0.73 times thinner than the inner magnet 10, so there is an advantage that the amount of magnets can be reduced accordingly.

  FIG. 4 shows another embodiment, in which the inner magnet 11 is embedded in accordance with the trapezoidal magnet insertion punching hole 11A, and the inner magnet 11 can be increased in addition to the embodiment, so that the output is further improved. Can do. Since the magnet used here is generally formed using a mold, its shape is arbitrary, and it is free and does not impair productivity.

  FIG. 5 shows still another embodiment, in which the corner of the magnet insertion punching hole 12A of the inner magnet 12 is a curved surface R, and the inner magnet 12 is embedded in accordance with the shape, so that the output can be increased in the same manner as described above. . Further, the centrifugal stress of the magnet that is concentrated on the corner when the rotor rotates can be dispersed along the curved surface R of the corner itself, so that the centrifugal stress concentration at the time of high-speed rotation can be easily avoided.

  By adopting such a configuration, it is possible to rotate at a high speed of 10,000 rpm or more, while the performance characteristics of the present invention described above are obtained at the same time.

  In the above-described embodiments, the V-shaped magnets are arranged in a two-layer structure. However, it is easy to make two or more layers as necessary. Also, the same effect can be obtained with a U-shaped arrangement.

It is a principal part vertical side view of the permanent-magnet-type rotary electric machine by 1st Embodiment of this invention. It is AA arrow sectional drawing in FIG. It is a partially expanded sectional view in FIG. It is a principal part cross-sectional front view of the permanent magnet type rotary electric machine by 2nd Embodiment of this invention. It is a principal part crossing front view of the permanent-magnet-type rotary electric machine by 3rd Embodiment of this invention. FIG. 2 is an output torque characteristic diagram of the permanent magnet type rotating electric machine of FIG. 1.

Explanation of symbols

3 ... Rotor, 4 ... Stator core, 5 ... Stator winding, 6 ... Rotor core, 9, 10, 11,
DESCRIPTION OF SYMBOLS 12 ... Permanent magnet, 9A, 10A, 11A, 12A ... Magnet insertion hole, 9b, 9c, 10b, 10c ... Nonmagnetic area | region, 9d, 10d ... Magnetic space | gap, 61 ... Auxiliary salient pole.

Claims (7)

A stator core in which a stator winding is wound around a plurality of teeth extending at equal intervals in the circumferential direction and in the axial direction;
A rotor core that is opposed to the stator core with a rotation gap and has a magnetic pole portion formed by embedding a plurality of permanent magnets whose polarities are alternately magnetized in the circumferential direction,
The permanent magnets are arranged in multiple layers in the circumferential direction,
Each magnet located outside the magnetic pole is adjacent to a nonmagnetic region at least radially outward,
Each magnet located inside the magnetic pole is adjacent to a nonmagnetic region at least radially inward,
A permanent magnet type rotating electrical machine characterized in that each magnet located inside the magnetic pole is narrower and thicker than each magnet located outside the magnetic pole. In the permanent magnet type rotating electrical machine according to claim 1,
A permanent magnet type rotating electrical machine characterized in that each magnet located outside a magnetic pole has a nonmagnetic region formed outside in the radial direction. In the permanent magnet type rotating electrical machine according to claim 1,
A permanent magnet type rotating electric machine characterized in that each magnet located outside a magnetic pole has a non-magnetic region on both radial sides thereof. In the permanent magnet type rotating electrical machine according to claim 1,
Each magnet located outside the magnetic pole has a non-magnetic region on both sides in the radial direction, and each magnet located inside the magnetic pole also has a non-magnetic region on both sides in the radial direction. Magnet rotating electric machine. In the permanent magnet type rotating electrical machine according to any one of claims 1 to 4,
A permanent magnet type rotating electrical machine characterized in that each magnet located on the outside of the magnetic pole is arranged in a V shape through a non-magnetic region. In the permanent magnet type rotating electrical machine according to any one of claims 1 to 4,
A permanent magnet type rotating electrical machine characterized in that each magnet located on the outside of the magnetic pole is arranged in a U shape through a non-magnetic region. In the permanent magnet type rotating electrical machine according to any one of claims 1 to 6,
A permanent magnet type rotating electrical machine, wherein the non-magnetic region is a hole penetrating the rotor core.

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