JP7248837B2 - Rotating electric machine, rotating electric motor drive system, and electric vehicle - Google Patents

Description

The present invention relates to a rotating electrical machine, a rotating electrical machine drive system, and an electric vehicle equipped with the rotating electrical machine.

2. Description of the Related Art A driving motor, which is a rotating electric machine used in electric vehicles such as electric vehicles and electric railway vehicles, is required to have a large output. In particular, drive motors are required to have a wide operating range such as high torque at low speed and low torque at high speed. Furthermore, in addition to these characteristics, the motor for driving an electric vehicle is required to reduce vibration and noise. In order to reduce vibration and noise, reduction of torque pulsation in an embedded magnet type motor is an issue.

On the other hand, conventionally, the technique described in Patent Document 1 is known. In the present technology, the magnetoresistive change portion is provided at a position displaced from the q-axis of the rotor core in the circumferential direction. In such a rotor, the phases of generated torque pulsations are almost exactly opposite between the regions having the magnetoresistive change portions and the regions not having them. Therefore, by alternately arranging the regions having the magnetoresistive change portions and the regions not having them, the torque pulsation received by the entire rotor can be reduced.

JP 2010-98830 A

In the conventional technology described above, the leakage magnetic flux of the permanent magnet passes through the d-axis core portion near the end of the permanent magnet. Furthermore, the q-axis magnetic flux due to the q-axis current of the motor passes through the d-axis core portion. Therefore, the d-axis core portion is magnetically saturated. When the d-axis core portion is magnetically saturated, the effective magnetic pole width of the permanent magnet changes, so the phase of torque pulsation changes. The range of magnetic saturation in the d-axis core differs depending on the amount of q-axis current, that is, the load state. It is difficult to sufficiently reduce the torque pulsation because the phases are not diametrically opposed.

Accordingly, the present invention provides a rotating electric machine capable of reducing torque pulsation over a wide operating range, a rotating electric motor drive system, and an electric vehicle equipped with the rotating electric machine.

In order to solve the above-described problems, a rotating electric machine according to the present invention includes a stator and a rotor having a rotor core facing the stator, the rotor core having a V-shaped magnet insert. A d-axis core having a hole and arranged on the outer peripheral side with respect to the magnet insertion hole, an inner peripheral side core arranged on the inner peripheral side with respect to the magnet insertion hole, and adjacent to the d-axis core in the circumferential direction A permanent magnet is inserted into the magnet insertion hole, the d-axis core is connected to the inner peripheral side core by a bridge part, and the rotor core has a cross section of one pole pitch angle τp The d-axis core, which has a plurality of types of shapes, is connected to the inner peripheral core by a first bridge portion adjacent to one of both ends of the magnet insertion hole and a second bridge portion adjacent to the other end of the magnet insertion hole. The distance L1 between the first bridge portion side end of the axial core and the magnetic pole center is greater than the distance L2 between the connecting portion between the first bridge portion and the d-axis core and the magnetic pole center, A distance L3 between the end on the second bridge portion side and the magnetic pole center is longer than a distance L4 between the connecting portion between the second bridge portion and the d-axis core and the magnetic pole center.

In order to solve the above-described problems, a rotating electrical machine drive system according to the present invention includes a rotating electrical machine that drives a load, and a power conversion device that drives the rotating electrical machine, wherein the rotating electrical machine is a rotating electrical machine according to the present invention. It is a rotating electric machine.

In order to solve the above problems, an electric vehicle according to the present invention includes a rotating electric machine, a battery, and a power conversion device that converts DC power of the battery into AC power and supplies the AC power to the rotating electric machine, The torque of the rotating electrical machine is transmitted to the wheels via the transmission, and the rotating electrical machine is the rotating electrical machine according to the present invention.

In order to solve the above problems, an electric railway vehicle according to the present invention includes a rotating electric machine and wheels driven by the rotating electric machine via gears, wherein the rotating electric machine is a rotating electric machine according to the present invention. is.

According to the present invention, it is possible to reduce the torque pulsation of the rotary electric machine over a wide operating range. This makes it possible to reduce noise and vibration caused by torque pulsation even when the load fluctuates in a rotary electric machine drive system, an electric vehicle including an electric vehicle and an electric railway vehicle.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 shows the overall configuration of a rotating electrical machine that is Embodiment 1. FIG. 2 shows the configuration of the rotor in FIG. 1; 4 shows a configuration of a rotor of a rotating electric machine that is a modification of the first embodiment; 4 is a perspective view showing the configuration of the rotor in Example 1. FIG. It is a perspective view which shows the structure of the rotor in a modified example. FIG. 11 is a perspective view showing the configuration of a rotor in another modified example; 3 shows the configuration of a rotor in a rotating electrical machine as a comparative example. 3 shows the flow of magnetic flux through the peripheral core portion of the permanent magnet under low load for Comparative Example and Example 1. FIG. 3 shows the flow of magnetic flux passing through the peripheral core portion of the permanent magnet under high load for Comparative Example and Example 1. FIG. FIG. 2 is a cross-sectional view of the stator and rotor in the first embodiment taken along a plane perpendicular to the rotation axis; 4 shows parameters representing the cross-sectional shape of the rotor core in Example 1. FIG. 2 shows a schematic configuration of a rotary electric machine drive system that is Embodiment 2. FIG. 3 shows a schematic configuration of an electric vehicle that is Embodiment 3. FIG. 4 shows a schematic configuration of an electric railway vehicle that is Embodiment 4. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings according to Examples 1 to 3 below. In each figure, the same reference numbers denote the same components or components with similar functions.

Embodiment 1 FIG. 1 shows the overall configuration of a rotating electrical machine that is Embodiment 1 of the present invention. FIG. 1 is a cross-sectional view on a plane parallel to the rotating shaft of the rotary electric machine. Note that the rotating electrical machine of the first embodiment is an embedded magnet type permanent magnet synchronous motor.

As shown in FIG. 1, the rotating electric machine 1 includes a stator 10, a rotor 30 rotatably supported radially inwardly of the stator 10, a shaft 90 fixed to the rotor 30, the stator 10 and a frame 5 covering the rotor 30 . The rotor 30 faces the stator 10 via a gap 100 (air gap). The stator 10 includes a stator winding 21 wound in a stator slot (“22” in FIG. 10), which will be described later.

FIG. 2 shows the configuration of the rotor 30 in FIG. FIG. 2 is a cross-sectional view on a plane perpendicular to the rotation axis.

In FIG. 2, the rotor 30 rotates around the rotation axis X. As shown in FIG. In the following description, unless otherwise specified, the terms “inner peripheral side” and “outer peripheral side” refer to the closer side and the farther side with respect to the rotation axis X, respectively. Further, the term "radial direction" means the direction of a straight line perpendicular to the rotation axis X, and the term "circumferential direction" means the direction of rotation about the rotation axis X.

As shown in FIG. 2 , the rotor 30 is composed of a rotor core 40 made of a magnetic material and a shaft 90 that is a rotating shaft of the rotor 30 and passes through the rotor core 40 . Also, the rotor 30 has an even number of magnetic poles (eight in FIG. 2). Each magnetic pole has at least one (one in FIG. 2) magnet insertion hole 50 . Permanent magnets 70 are housed in the magnet insertion holes 50 to form magnetic poles.

The rotor core 40 has an inner peripheral core 110 arranged on the inner peripheral side with respect to the magnet insertion holes 50 and a d-axis core 41 arranged on the outer peripheral side with respect to the magnet insertion holes 50 . The surface of the d-axis core 41 facing the stator is arcuate. Note that this arc is radially convex toward the rotor. The inner peripheral core 110 and the d-axis core 41 of each magnetic pole are referred to as a first bridge portion 61 and a second bridge portion 62 adjacent to both ends of the magnet insertion hole 50 in the width direction, which are part of the rotor core 40 . Mechanically coupled by at least two bridges. The first bridge portion 61 is located away from the magnetic pole center C along one circumferential direction (counterclockwise in FIG. 2) and adjoins one end of the magnet insertion hole 50 in the width direction. The second bridge portion 62 is located away from the magnetic pole center C along the other circumferential direction (clockwise in FIG. 2) and is adjacent to the other end of the magnet insertion hole 50 in the width direction. The magnet insertion hole 50 is defined by a space defined by the first bridge portion 61 , the second bridge portion 62 , the inner core 110 and the d-axis core 41 .

The magnet material of the permanent magnet 70 may be any magnet material such as ferrite, neodymium, and samarium-cobalt. Moreover, although the permanent magnet 70 of the first embodiment has a rectangular cross section in FIG. 2, it is not limited to this and may have an arc shape. Furthermore, the magnet insertion hole 50 may be filled with a bond magnet (plastic magnet, rubber magnet, etc.) by injection. Also, the permanent magnet 70 per pole may be divided into a plurality of pieces in the radial direction or the circumferential direction.

As the magnetic material forming the rotor core 40, a laminate of magnetic steel plates laminated with an electrical insulator is preferably applied in order to reduce eddy current loss generated in the rotor core 40. FIG. A solid (bulk) magnetic material may be used to reduce material and processing costs. Further, it may be configured by compression-molding a powder magnetic material such as a powder magnetic core, or may be configured by an amorphous metal or a nanocrystalline material. The rotor core 40 is fixed to the shaft 90 by means of adhesion, welding, press fitting, shrink fitting, or the like. If the rotor core 40 is made of solid (bulk) magnetic material, the rotor core 40 and the shaft 90 may be integrally molded.

In FIG. 2, the cross-sectional shape of the magnet insertion hole 50 is rectangular. Other shapes such as a V shape and a substantially circular arc shape may be used.

The stator core 20 and frame 5 are fixed using methods such as gluing, welding, press-fitting, and shrink fitting.

In rotor core 40 , q-axis cores 46 are provided adjacent to both ends of d-axis core 41 in the circumferential direction. That is, each q-axis core 46 is located between two d-axis cores 41 adjacent in the circumferential direction. Approximately V-shaped grooves 120 (air gaps) are located on both sides of the q-axis core 46 in the circumferential direction, and the grooves 120 separate the d-axis core 41 and the q-axis core 46 in the circumferential direction. Also, in the groove portion 120 , both ends of the d-axis core protrude from the positions of the first bridge portion 61 and the second bridge portion 62 toward the q-axis core 46 in the circumferential direction. In the first embodiment, the lengths of these projecting portions are different between two d-axis cores 41 adjacent to each other with one q-axis core 46 interposed therebetween.

In addition, in the first embodiment, the outermost diameter of the d-axis core 41 and the outermost diameter of the q-axis core 46 are substantially equal. In addition, the thickness of the first and second bridge portions 61 and 62 in the circumferential direction is thinner than the thickness of the distal end portion of the circumferential projecting portion of the d-axis core 41 . The eight permanent magnets 70 forming the magnetic poles have the same thickness in the radial direction and the same width in the circumferential direction. Furthermore, the radial and circumferential dimensions of the magnet insertion hole 50 are also the same.

The first bridge portion 61 and the second bridge portion 62 are located on both radial sides of the magnetic pole center C and are separated from each other. The first bridge portion 61 and the d-axis core 41 are connected in the circumferential direction to the tip of one overhanging portion of the d-axis core 41, that is, the d-axis core end portion 42 of the d-axis core 41 in the circumferential direction on the first bridge portion 61 side. are connected at a connecting portion 81 located closer to the magnetic pole center C than the magnetic pole center C. In addition, the second bridge portion 62 and the d-axis core 41 are arranged in the circumferential direction at the tip of the other projecting portion of the d-axis core 41, that is, at the circumferential direction d-axis core end of the d-axis core 41 on the second bridge portion 62 side. They are connected at a connecting portion 82 located closer to the magnetic pole center C than the portion 42 . In addition, in the first embodiment, the distance between each d-axis core end portion 42 and the q-axis core 46 is substantially constant.

In each magnetic pole portion, if the distance between the d-axis core end portion 42 on the first bridge portion 61 side and the magnetic pole center C is L1, and the distance between the connecting portion 81 and the magnetic pole center C is L2, then L1 is greater than L2 (L2<L1). Here, the distance between a certain portion and the magnetic pole center C is the length of a perpendicular drawn from the certain portion to the imaginary center line (one-dot chain line in FIG. 2) indicating the magnetic pole center C, that is, the distance between the certain portion and the imaginary center line. It is the length of the shortest line segment that connects (the same applies to "distance" described below). Further, when the distance between the d-axis core end portion 42 on the second bridge portion 62 side and the magnetic pole center C is L3, and the distance between the connecting portion 82 and the magnetic pole center C is L4, L3 is larger than L4 (L4 <L3). In addition, in the first embodiment, L1=L3 and L2=L4 in one d-axis core. In two d-axis cores 41 located on both sides in the circumferential direction of one q-axis core 46 and adjacent to each other, the sizes of L1 and L3 are different, and the sizes of L2 and L4 are the same.

As shown in FIG. 2, the rotor 30 is, so to speak, an aggregate of parts having a substantially fan-shaped cross section for one pole pitch (τp). Here, τp is a value obtained by dividing 360 degrees for one rotation of the rotor by the number of poles. In Example 1, the number of poles is 8, so τp=45 degrees. In the first embodiment, as described above, between the two d-axis cores 41 adjacent to each other, the distance (L1) between the d-axis core end 42 and the magnetic pole center C in the circumferential direction of the d-axis core 41 is different. Therefore, the rotor 30 has two types of cross-sectional shapes for one pole pitch, and these two types of shapes are alternately arranged in the circumferential direction. The number of types of cross-sectional shapes is not limited to two types, and a plurality of types may be used.

In addition, in the present Example 1, the shape of the groove part 120 also differs between two types of cross-sectional shapes. Specifically, the q-axis core 46 in the case where the substantially flat portion of the outermost peripheral portion of the q-axis core 46, that is, the direction from the rotation axis X toward the outer periphery of the rotor 30 along the radial direction is the height direction. The size of the angle (obtuse angle in FIG. 2) formed by the substantially flat portion at the top of the groove 120 and the slope of the inner wall of the groove portion 120 continuing to the edge of the substantially flat portion differs between the two types of cross-sectional shapes that are in contact with each other.

FIG. 3 shows the configuration of a rotor of a rotating electrical machine that is a modification of the first embodiment. FIG. 3, like FIG. 2, is a cross-sectional view taken along a plane perpendicular to the axis of rotation.

As shown in FIG. 3 , in this modification, the d-axis core end portion 42 and the q-axis core end portion 47 in the circumferential direction of the substantially flat portion in the outermost peripheral portion of the q-axis core 46 are connected by a bridge portion 63 . It is The bridge portion 63 closes the opening of the groove portion 120 along the direction of the rotation axis. In addition, in this modification, the surfaces of the d-axis core 41, the q-axis core 46, and the bridge portions 63 facing the stator form continuous smooth cylindrical surfaces. As a result, it is possible to reduce noise (wind noise) and mechanical loss (windage loss) generated during rotation due to uneven portions on the surface of the rotor facing the stator.

In this modified example, the bridge portion 63 is continuous with the d-axis core 41 and the q-axis core 46 and is made of the same magnetic material as the d-axis core 41 and the q-axis core 46 . In addition, the radial thickness of the bridge portion 63 is thinner than the thickness of the distal end portion of the circumferential overhang portion of the d-axis core 41, and is equivalent to the circumferential thickness of the first and second bridge portions 61 and 62, for example. .

FIG. 4 is a perspective view showing the configuration of the rotor in Example 1. FIG.

As shown in FIG. 4, the rotor 30 of the first embodiment has one rotor core. In the rotor 30, a first cross-sectional shape 131 and a second cross-sectional shape 132 having different core shapes in the vicinity of the permanent magnets, i.e., two types of cross-sectional shapes corresponding to a pitch of one pole (τp), are substantially fan-shaped. It has a cross-sectional shape. The first cross-sectional shape 131 and the second cross-sectional shape 132 are alternately arranged in the circumferential direction of the rotor 30 . Since there is only one rotor core shown in the drawing, the cross-sectional shape of the rotor 30 along the rotation axis direction is the same at each part of the rotor 30 .

In the first embodiment, τp=45 degrees. Therefore, when the first cross-sectional shape 131 and the second cross-sectional shape 132 are alternately arranged one by one as shown in the drawing, the rotor 30 has four first cross-sectional shapes 131 and four second cross-sectional shapes 132, thus a total of eight substantially fan-shaped cross-sectional shapes with equal τp.

FIG. 5 is a perspective view showing the configuration of a rotor in a modified example of the first embodiment.

In the variant of FIG. 5, two rotor cores are coaxially fixed to a shaft ("90" in FIG. 1), not shown. Therefore, the rotor 30 has, so to speak, two rotor parts. In one rotor portion, eight first cross-sectional shapes 131 are arranged in the circumferential direction as substantially fan-shaped cross-sectional shapes corresponding to one pole pitch (τp (=45 degrees)). In addition, in the other rotor portion, a second rotor portion having a substantially fan-shaped cross-sectional shape corresponding to the same one-pole pitch (τp (=45 degrees)) has a core shape different from the first cross-sectional shape 131 in the vicinity of the permanent magnets. 8 cross-sectional shapes 132 are arranged in the circumferential direction. Furthermore, the two rotor portions are arranged such that the first cross-sectional shape 131 of one rotor portion and the second cross-sectional shape 132 of the other rotor portion are entirely overlapped with each other. be done.

Therefore, in the rotor 30 of this modified example, the first cross-sectional shape 131 and the second cross-sectional shape 132 are different from each other in the core shape near the permanent magnets (such as the dimensions of the circumferential extension of the d-axis core). , are arranged in the rotation axis direction of the rotor 30 . Note that the same cross-sectional shape (either the first cross-sectional shape 131 or the second cross-sectional shape 132) is arranged in one circumferential direction.

FIG. 6 is a perspective view showing the configuration of the rotor in another modified example of the first embodiment.

In the variant of FIG. 6, the rotor 30 comprises two rotor parts, like the variant of FIG. On the other hand, the rotor section has a first cross-sectional shape 131 and a second cross-sectional shape 132 having different core shapes in the vicinity of the permanent magnets, that is, two types of substantially fan-shaped cross-sectional shapes corresponding to one pole pitch (τp). has a cross-sectional shape of The first cross-sectional shape 131 and the second cross-sectional shape 132 are alternately arranged in the circumferential direction of one rotor portion. In the other rotor portion, a third cross-sectional shape 133 and a fourth cross-sectional shape 134 having different core shapes in the vicinity of the permanent magnets as substantially fan-shaped cross-sectional shapes corresponding to one pole pitch (τp), i.e. It has two types of cross-sectional shapes. The third cross-sectional shape 133 and the fourth cross-sectional shape 134 are alternately arranged in the circumferential direction of the other rotor portion. Furthermore, the two rotor parts are arranged such that the first cross-sectional shape 131 of one rotor part and the third cross-sectional shape 133 of the other rotor part overlap each other over the entire cross-sectional shape, and The second cross-sectional shape 132 of one rotor portion and the fourth cross-sectional shape 134 of the other rotor portion are arranged so that the entire surface of each cross-sectional shape overlaps with each other.

Here, the first cross-sectional shape 131 and the fourth cross-sectional shape 134 are the same. Also, the second cross-sectional shape 132 and the third cross-sectional shape 133 are the same. Therefore, in the modification of FIG. 6, two types of cross-sectional shapes (two types of 131 and 132 or two types of 133 and 134) are arranged in the circumferential direction, and two types of cross-sectional shapes are arranged in the direction of the rotation axis. (Two types 131 and 133, or two types 132 and 134) are arranged.

Like the rotor shown in FIGS. 4 to 6, a plurality of types of cross-sectional shapes with different core shapes near the permanent magnets are arranged in the circumferential direction of the rotor as a substantially fan-shaped cross-sectional shape for one pole pitch (τp). and the direction of the rotation axis, or in both directions, the state of the magnetic flux distribution is different in the portions having different cross-sectional shapes in either of these directions. If the state of magnetic flux distribution differs, the phase of torque ripple will differ. As a result, torque pulsations at portions with different cross-sectional shapes cancel each other out, and torque pulsations in the rotating electric machine can be reduced. Furthermore, according to the first embodiment, as will be described later, torque pulsation can be reduced in a wide operating range (load range) of the rotary electric machine.

The action and effects of the first embodiment will be described below.

FIG. 7 shows the configuration of a rotor in a rotating electrical machine that is a comparative example of the first embodiment. This FIG. 7 shows a cross-sectional view in a plane perpendicular to the rotation axis of the rotor.

As shown in FIG. 7, in this comparative example, the position of the d-axis core end portion 42, the positions of the first and second bridge portions 61 and 62, the d-axis core end portion 42 and the first and second bridge portions The positions of the connection portions 81 and 82 of 61 and 62 match. That is, in this comparative example, the d-axis core 41 does not have a portion that protrudes in the circumferential direction from the positions of the connecting portions 81 and 82 .

FIG. 8 shows the flow of magnetic flux passing through the peripheral core portion of the permanent magnet at low load for the comparative example and the first embodiment. Note that FIG. 8 is a partial cross-sectional view taken along a plane perpendicular to the rotation axis of the rotor.

As shown in FIG. 8, leakage magnetic flux 150 passes through the d-axis core end 42 in the comparative example and the example. The leakage flux 150 can increase until either the bridge portions 61, 62 or the d-axis core end 42 becomes magnetically saturated and the relative permeability becomes approximately unity. Therefore, both the bridge portions 61 and 62 and the d-axis core end portion 42 are in a high magnetic flux density state. Area A in FIG. 8 indicates a high magnetic flux density area (the same applies to FIG. 9 described later).

As shown in FIG. 8, in a low load state, the amount of q-axis magnetic flux 160 is small even when the d-axis core end 42 is in a high magnetic flux density state. can pass through the d-axis core end 42 .

FIG. 9 shows the flow of magnetic flux through the peripheral core portion of the permanent magnet under high load for the comparative example and the first embodiment. FIG. 9 is a partial cross-sectional view similar to FIG.

As shown in FIG. 9, in the comparative example, in a high-load state, the leakage flux 150 and the q-axis flux 160 at the d-axis core end 42 are superimposed so that the d-axis The core end 42 is magnetically saturated. Therefore, part of the q-axis magnetic flux 160 cannot pass through the d-axis core end portion 42 and escapes to the stator 10 while avoiding the high magnetic flux density region A.

Here, according to the knowledge obtained by the present inventor, the phase of torque pulsation at each magnetic pole depends on the opening angle τd (see FIG. 10) in the circumferential direction from one end to the other end of the d-axis core 41. , when the d-axis core end 42 is magnetically saturated, the effective opening angle τd is narrowed, resulting in a change in the state of torque pulsation generation. Therefore, even if the opening angle τd is set so as to reduce the torque ripple under low load, the effective opening angle τd is narrowed under high load, so there is a possibility that the torque ripple cannot be reduced. That is, in the comparative example, even if torque pulsation can be reduced at a certain operating point, it is difficult to reduce torque pulsation over a wide operating range.

In contrast, in Example 1 of the present invention, since the d-axis core has overhanging portions at both ends thereof, as shown in FIG. There is a portion through which the leakage flux 150 passing through 62 does not pass. That is, even if the bridge portions 61 and 62 are magnetically saturated by the leakage magnetic flux 150, the magnetic flux density of the d-axis core end portion 42 does not increase to the extent that the d-axis core end portion 42 is magnetically saturated. Therefore, the q-axis magnetic flux 160 can pass through the d-axis core end portion 42 even in a high-load state as in a low-load state, so the effective opening angle τd is substantially constant regardless of the load state. be. Therefore, according to this embodiment, torque ripple can be reduced in a wide operating range from low load to high load.

In addition, in the modification shown in FIG. 3 described above, a leakage magnetic flux path passing through the bridge portion 63 may occur. However, the bridge portion 63 is circumferentially farther from the end of the permanent magnet 70 than the bridge portions 61 and 62, and the radial thickness of the bridge portion 63 is greater than the radial thickness of the ends of the overhanging portions. It is thin and about the same as the circumferential thickness of the bridge portions 61 and 62 . Therefore, the magnetic resistance of the leakage magnetic flux path passing through the bridge portion 63 is greater than the magnetic resistance of the leakage magnetic flux path passing through the bridge portions 61 and 62 . As a result, most of the leakage magnetic flux (“150” in FIGS. 8 and 9) passes through the leakage magnetic flux path passing through the bridge portions 61 and 62 . Therefore, the state of the magnetic flux flow is the same as that shown in FIGS. 8 and 9, and the third modification can also reduce torque pulsation over a wide operating range.

On the other hand, in the first embodiment, the bridge portion 63 is not provided, and the d-axis core 41 and the q-axis core 46 are not connected in the circumferential direction, but are separated in the circumferential direction by the gap formed by the groove portion 120. The path of the magnetic flux is substantially limited to the path passing through the bridge portions 61 and 62, and the magnetic flux density of the d-axis core end portion 42 is prevented from increasing due to leakage flux passing through other paths. Therefore, according to the first embodiment, it is possible to reliably reduce torque pulsation over a wide operating range.

The cross-sectional shape of the rotor of the first embodiment will be described in more detail below.

FIG. 10 is a cross-sectional view of the stator and rotor in the rotating electrical machine of Example 1, taken along a plane perpendicular to the rotation axis. For simplification of the drawing, the stator windings 21 (FIG. 1) wound in the stator slots 22 are omitted. 10, the rotor 30 has 8 poles and the stator 10 has 48 slots. The combination of the number of poles and the number of slots is not limited to 8 poles and 48 slots as in the first embodiment, and can be set as appropriate.

The momentary torque of each magnetic pole depends on the positional relationship between the d-axis core end 42 and the stator teeth 25 . For example, the slot combination affects the order of the torque ripple component, and in the case of 8 poles and 48 slots as shown in FIG. 10, the 12th order component is the main torque ripple component.

Also, the phase of the torque ripple component depends on the positional relationship between the d-axis core end portion 42 and the stator teeth 25 . When the positional relationship between the d-axis core end portion 42 and the stator teeth 25 facing the d-axis core end portion 42 is the same for each magnetic pole, the phases of the torque pulsations at each magnetic pole substantially match. For example, as shown in FIG. 10, if the slot pitch angle of the stator 10 is τs, two different cross-sectional shapes (131 and 132 in FIG. When the difference in the opening angle τd in the circumferential direction is 2τs, the phases of the torque pulsations at the magnetic poles substantially match.

10, in each magnetic pole portion, the distance between the d-axis core end portion 42 in the circumferential direction on the first bridge portion 61 side of the d-axis core 41 and the magnetic pole center ("C" in FIG. 2) is L1, and d Assuming that the distance between the d-axis core end 42 and the magnetic pole center in the circumferential direction of the axial core 41 on the side of the second bridge 62 is L3, L1=L3 (see FIG. 11 described later). On the other hand, when L1≠L3, when the difference in τd between the two types of cross-sectional shapes is τs and the facing positions of the d-axis core end 42 and the stator teeth 25 are the same, the torque pulsation at each magnetic pole phases are almost the same.

Therefore, by making the difference between the maximum value and the minimum value of τd smaller than τs in a plurality of types (two types in the first embodiment) of cross-sectional shapes having different shapes, the torque pulsation caused by the slot combination of each magnetic pole can be reduced. The phase can be shifted, and torque ripple can be reduced.

FIG. 11 shows parameters (L1 to L9) representing the cross-sectional shape of the rotor core in the first embodiment. Note that FIG. 11 is a partial cross-sectional view of the rotor on a plane perpendicular to the rotation axis.

L1 is the distance between the magnetic pole center C and the d-axis core end portion 42 in the circumferential direction on the first bridge portion 61 side of the d-axis core 41 .

L2 is the distance between the connecting portion 81 and the magnetic pole center C;

L3 is the distance between the magnetic pole center C and the d-axis core end portion 42 in the circumferential direction on the second bridge portion 62 side of the d-axis core 41 .

L4 is the distance between the connecting portion 82 and the magnetic pole center C;

L5 is the circumferential width of the opening of the groove portion 120 (gap) on the first bridge portion 61 side. That is, L5 is the distance between the circumferential end of the d-axis core 41 and the edge of the radial outermost periphery c (flat portion) of the q-axis core 46 on the first bridge portion 61 side.

L6 is the circumferential width of the opening of the groove portion 120 (gap) on the second bridge portion 62 side. That is, L6 is the distance between the circumferential end of the d-axis core 41 and the edge of the radially outermost peripheral portion c of the q-axis core 46 on the second bridge portion 62 side.

L7 is the radial distance from the rotation axis X of the radial outermost peripheral portion c of the q-axis core 46 on the first bridge portion 61 side.

L8 is the radial distance from the rotational axis X of the radial outermost peripheral portion c of the q-axis core 46 on the second bridge portion 62 side.

L9 is the distance between the outer peripheral surface of the d-axis core 41 and the outer peripheral surface of the permanent magnet 70 on the magnetic pole center C.

In the first embodiment, since the rotor core has the q-axis core 46, not only magnet torque but also reluctance torque is generated. As described above, the circumferential open angle τd from one end to the other end of the d-axis core end portion 42 is a parameter related to the phase of torque pulsation due to magnet torque. τd changes according to L1 to L4. Therefore, by making one or more of L1 to L4 different in a plurality of types (two types in the first embodiment) of cross-sectional shapes, the phase of torque pulsation due to magnet torque can be made different. In the first embodiment, L1=L3, L2=L4 (where L1>L2, L3>L4) in each magnetic pole portion, and L1 and L3 is different.

Changing one or more of L5 to L8 changes the distribution state of the q-axis magnetic flux, so that the phase of the reluctance torque of each magnetic pole can be varied. Thereby, pulsation of reluctance torque can be reduced.

When L9 is changed, both the magnetic flux amount of the permanent magnet 70 and the q-axis inductance are changed, so that the magnet torque and the reluctance torque can be changed. Therefore, by making L9 different for each cross-sectional shape, the ratio between the pulsating component of the magnet torque and the pulsating component of the reluctance torque of each magnetic pole can be adjusted. Therefore, by shifting the phase of each torque pulsation of the magnet torque and the reluctance torque by L1 to L8 and equalizing the magnitude of each torque pulsation by L9, both pulsation components cancel each other, and the torque pulsation of the entire rotor can be reduced.

L1 to L9 may be different in the circumferential direction of the rotor as in the first embodiment, or may be different in the rotational axis direction or in both the circumferential and rotational axis directions as in the modified examples of FIGS. You can tighten it.

In addition, in the first embodiment, L1=L3, L2=L4, and L1>L2, L3>L4 for each magnetic pole. That is, both ends of the d-axis core protrude from the positions of the first bridge portion 61 and the second bridge portion 62 toward the q-axis core 46 in the circumferential direction. This prevents magnetic saturation at the d-axis core end portion 42 in the circumferential direction of the d-axis core 41, as described above (FIGS. 8 and 9).

In addition, in the first embodiment, the two types of cross-sectional shapes have different L1 and L3, and L2, L4, and L5 to L9 are equal. Therefore, torque pulsation of the magnet torque is reduced. Note that the two types of cross-sectional shapes have the same polar pitch angle τp (FIG. 2), so L5 and L6 are the same, but the two types of cross-sectional shapes have different shapes of the grooves 120 (air gaps). Specifically, as shown in FIG. 11, in the two adjacent cross-sectional shapes, the inner wall slope b1 of the groove portion 120 continuing to the edge portion of the flat portion c of the outermost peripheral portion of the q-axis core 46 and the bridge portion ( 61, 62) differ from each other in the size of the angle formed by the outer wall surface a1 and the size of the angle formed by the similar inner wall slope b2 and the outer wall surface a2. Therefore, the two types of cross-sectional shapes have different distribution states of the q-axis magnetic flux, so that the phases of the torque pulsations of the reluctance torque are different. This reduces the torque ripple of the reluctance torque.

As shown in FIG. 11, the short sides of the rectangular cross section of the permanent magnet 70 in the circumferential direction and the outer wall surfaces a1 and a2 of the first and second bridge portions 61 and 62 are arranged in parallel in the radial direction. . Further, as shown in FIG. 11, the groove portion 120 has a substantially V-shaped cross section. Therefore, the angle between a1 and b1 and the angle between a2 and b2 are both acute angles. As a result, reluctance torque with less pulsation can be obtained without enlarging the q-axis core 46 .

In the first embodiment, both ends of the d-axis core protrude from the positions of the first bridge portion 61 and the second bridge portion 62 toward the q-axis core 46 in the circumferential direction. The magnetic flux from to the stator spreads in the circumferential direction at each magnetic pole. Therefore, variations in the magnetic flux density at the d-axis core end portion 42 in the circumferential direction of the d-axis core 41 are alleviated. Furthermore, by canceling out the pulsating components between the magnetic poles having different cross-sectional shapes, the cogging torque can be reduced and the no-load induced electromotive force can be converted into a sine wave. When the no-load induced electromotive force is sinusoidal, it is possible to reduce the harmonic loss caused by the structure of the rotating electrical machine such as the slot combination, and improve the efficiency of the rotating electrical machine.

Although the description is omitted in each cross-sectional view, in the first embodiment, magnetic gaps are provided between the circumferential ends of the permanent magnet 70 and the first and second bridge portions 61 and 62. . This also reduces the cogging torque. Note that the magnetic gap portion may be a space portion, or may be a portion filled with a non-magnetic material such as resin.

As described above, according to the rotary electric machine of the first embodiment, torque pulsation can be reduced in a wide operating range from low load to high load.

Embodiment 2 FIG. 12 shows a schematic configuration of a rotary electric machine drive system that is Embodiment 2 of the present invention.

In the second embodiment, the rotating electric machine of the first embodiment is applied as the rotating electric machine 1 in FIG. 12 .

In the rotating electrical machine drive system 200 of FIG. 12, electric power for driving the rotating electrical machine 1 is supplied from a power source 210 via a power conversion device 220 including an inverter, a converter, and the like. In this case, the power conversion device 220 can control the output of the rotating electrical machine 1 according to the load 230 driven by the rotating electrical machine 1 .

In the rotary electric machine according to the conventional technology and the comparative example (Figs. 8 and 9), even if the torque pulsation can be reduced at a certain operating point, the torque pulsation cannot be reduced at other operating points. There is concern that torque pulsation may occur. When torque pulsation occurs, generally in torque control, control is performed to flow a current that cancels out the torque pulsation. Torque pulsation is generated as a high-order pulsation component, so a highly responsive power conversion device 220 is required in order to follow the torque pulsation, which increases the cost of the power conversion device 220 . In addition, since a harmonic current is injected to suppress torque ripple, switching loss in the power conversion device 220 and harmonic loss occurring in the rotary electric machine 1 increase, leading to a decrease in system efficiency. Even in speed control, when the moment of inertia of the rotor is small, torque pulsation leads to speed fluctuations, so as in torque control, a highly responsive power conversion device 220 is required and system efficiency is reduced.

On the other hand, in the second embodiment, since the rotating electric machine of the first embodiment is applied, the rotating electric machine 1 can reduce the torque pulsation in a wide operating range. It can suppress pulsation. Therefore, the high-response power conversion device 220 becomes unnecessary in both the torque control and the speed control. In addition, the switching loss in the power conversion device 220 and the harmonic loss generated in the rotating electrical machine 1 can be reduced, so the system efficiency of the rotating electrical machine drive system 200 is improved. Also, in the case of position control, there is no decrease in controllability due to torque pulsation, and highly accurate position control is possible for various loads. Also, vibration and noise caused by torque pulsation can be reduced.

Embodiment 3 FIG. 13 shows a schematic configuration of an electric vehicle that is Embodiment 3 of the present invention.

In the third embodiment, the rotating electric machines of the first embodiment are applied as the rotating electric machines 351 and 352 in FIG. 13 .

As shown in FIG. 13 , an electric vehicle 300 is equipped with an engine 360 , rotating electric machines 351 and 352 , and a battery 380 .

When driving the rotating electrical machines 351 and 352 , the battery 380 supplies DC power to the power conversion device 370 (inverter device) for driving the rotating electrical machines 351 and 352 . The power conversion device 370 converts the DC power from the battery 380 into AC power and supplies the AC power to the rotating electric machines 351 and 352, respectively.

During regenerative running, the rotating electric machines 351 and 352 generate AC power according to the kinetic energy of the vehicle and supply it to the power conversion device 370 . The power conversion device 370 converts the AC power from the rotary electric machines 351 and 352 into DC power and supplies the DC power to the battery 380 .

Rotational torque generated by engine 360 and rotating electric machines 351 and 352 is transmitted to wheels 310 via transmission 340 , differential gear 330 and axle 320 .

In general, automobiles are required to have a wide driving range, such as high torque at low speeds when starting on a slope, low torque at high speeds on highways, and medium torque at medium speeds when driving on streets. Torque pulsation is reduced in the rotary electric machines 351 and 352 in such a wide operating range. Therefore, the noise and vibration caused by the torque pulsation of the rotary electric machines 351 and 352 can be reduced in a wide operating range, so the ride comfort of the electric vehicle 300 is improved.

In addition, by reducing the torque pulsation of rotating electric machines 351 and 352, the mechanical impact applied to transmission 340 and differential gear 330 can be mitigated. Therefore, it is possible to improve the safety and extend the life of the electric vehicle 300 . In addition, harmonic current injection for reducing torque pulsation becomes unnecessary, and the system efficiency of electric vehicle 300 is improved, so that the cruising distance of electric vehicle 300 can be extended.

Even in an electric vehicle that does not include the engine 360 and is driven only by the power of the rotating electric machine, by applying the rotating electric machine of the first embodiment, the same effect as that of the third embodiment can be obtained.

FIG. 14 shows a schematic configuration of an electric railway vehicle that is Embodiment 4 of the present invention.

In the fourth embodiment, the rotating electric machine of the first embodiment is applied as the rotating electric machine 1 in FIG. 14 .

As shown in FIG. 14 , the electric railway vehicle 400 includes a bogie 440 including gears 410 , wheels 420 , axles 430 and the rotating electric machine 1 . Rotating electric machine 1 drives wheels 420 connected to axles 430 via gears 410 . The rotating electric machine 1 is driven by a power conversion device (not shown). In addition, in the present embodiment 4, the cart 440 has two rotating electrical machines 1 mounted thereon, but the present invention is not limited to this, and one or three or more may be mounted.

In general, railroad vehicles are required to have torque characteristics in a wide speed range from start to maximum speed, and also to have a wide torque range depending on the load factor. Torque pulsation is reduced in the rotary electric machine 1 in such a wide operating range. Therefore, the noise and vibration caused by the torque pulsation of the rotating electric machine 1 can always be reduced regardless of the occupancy rate, so the ride comfort of the electric railway vehicle 400 is improved. Moreover, since the torque pulsation of the rotary electric machine 1 is reduced, the mechanical impact applied to the gear 410 is alleviated. Therefore, it is possible to improve the safety and extend the life of the electric railway vehicle 400 . In addition, harmonic current injection for reducing torque pulsation becomes unnecessary, and the system efficiency of electric railway vehicle 400 is improved.

It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

For example, the electric vehicle is not limited to the above-described electric vehicle or electric railway vehicle, and may be other electric vehicles that require reduction of torque pulsation. Also, the electric railway vehicle may take in power from an overhead wire, or may take in power from a battery mounted on the vehicle.

1 rotating electric machine 5 frame 10 stator 20 stator core 21 stator winding 22 stator slot 25 stator teeth 30 rotor 40 rotor core 41 d-axis core 42 d-axis core end 46 q-axis core 47 q-axis core End portion 50 Magnet insertion hole 61 First bridge portion 62 Second bridge portion 63 Bridge portion 70 Permanent magnets 81, 82 Connection portion 90 Shaft 100 Gap 110 Inner core 120 Grooves 131, 132, 133, 134 Cross-sectional shape 150 Leakage magnetic flux 160 q-axis magnetic flux 200 rotary electric machine drive system 210 power source 220 power converter 230 load 300 electric vehicle 310 wheel 320 axle 330 differential gear 340 transmission 351, 352 rotary electric machine 360 engine 370 power converter 380 battery 400 electric railcar 410 gear 420 Wheel 430 Axle 440 Bogie

Claims (14)

a stator;
a rotor comprising a rotor core facing the stator;
In a rotating electrical machine comprising
The rotor core has a V-shaped magnet insertion hole, a d-axis core arranged on the outer circumference side of the magnet insertion hole, and an inner circumference arranged on the inner circumference side of the magnet insertion hole. a side core and a q-axis core circumferentially adjacent to the d-axis core;
A permanent magnet is inserted into the magnet insertion hole,
The d-axis core is connected to the inner core by a bridge portion,
The rotor core has a plurality of types of cross-sectional shapes for one pole pitch angle τp,
The d-axis core is connected to the inner peripheral core by a first bridge portion adjacent to one of both ends of the magnet insertion hole and a second bridge portion adjacent to the other of the both ends,
A distance L1 between an end portion of the d-axis core on the first bridge portion side and the center of the magnetic pole is larger than a distance L2 between a connecting portion between the first bridge portion and the d-axis core and the center of the magnetic pole. ,
The distance L3 between the second bridge portion side end of the d-axis core and the magnetic pole center is longer than the distance L4 between the connection portion between the second bridge portion and the d-axis core and the magnetic pole center. A rotary electric machine characterized by being large . In the rotary electric machine according to claim 1,
The rotary electric machine , wherein the plurality of types of cross-sectional shapes are arranged in the circumferential direction of the rotor, in the rotation axis direction, or in both the circumferential direction and the rotation axis direction. In the rotary electric machine according to claim 1,
The d-axis core has an overhanging portion extending in the circumferential direction from the connecting portion between the first bridge portion and the d-axis core and the connecting portion between the second bridge portion and the d-axis core. Rotating electric machine. In the rotary electric machine according to claim 1 ,
The difference between the maximum value and the minimum value of the circumferential open angle τd from the end of the d-axis core on the first bridge side to the end on the second bridge side in the plurality of types of cross-sectional shapes , which is smaller than the slot pitch angle τs of the stator . In the rotary electric machine according to claim 1 ,
A rotary electric machine , wherein a groove is positioned between the d-axis core and the q-axis core . In the rotary electric machine according to claim 5 ,
A rotary electric machine , wherein the groove is substantially V-shaped . In the rotary electric machine according to claim 1 ,
the L1, the L2, the L3, and the L4;
a distance L5 between the end portion of the d-axis core on the first bridge portion side and the radially outermost peripheral portion of the q-axis core;
a distance L6 between the end portion of the d-axis core on the second bridge portion side and the radially outermost peripheral portion of the q-axis core;
a distance L7 from the rotation axis center of the radial outermost peripheral portion of the q-axis core on the first bridge portion side;
a distance L8 from the rotation axis center of the radial outermost peripheral portion of the q-axis core on the second bridge portion side;
A rotary electric machine, wherein one of a distance L9 between an outer peripheral surface of the d-axis core and an outer peripheral surface of the permanent magnet on the magnetic pole center is different in the plurality of types of cross-sectional shapes. In the rotary electric machine according to claim 7 ,
A rotary electric machine , wherein any one of L1 to L4 is different in the plurality of types of cross-sectional shapes . In the rotary electric machine according to claim 7 ,
A rotary electric machine , wherein any one of L5 to L8 is different in the plurality of types of cross-sectional shapes . In the rotary electric machine according to claim 7 ,
The rotary electric machine , wherein the L9 is different in the plurality of types of cross-sectional shapes . In the rotary electric machine according to claim 5 ,
A rotary electric machine, comprising: a bridge portion that connects the d-axis core and the q-axis core and closes an opening of the groove portion . A rotary electric machine drive system comprising a rotary electric machine that drives a load and a power conversion device that drives the rotary electric machine,
A rotary electric machine drive system, wherein the rotary electric machine is the rotary electric machine according to claim 1 . a rotating electrical machine, a battery, and a power conversion device that converts DC power of the battery into AC power and supplies the AC power to the rotating electrical machine, wherein torque of the rotating electrical machine is transferred to wheels via a transmission. In an electric vehicle transmitted to
An electric vehicle, wherein the rotating electric machine is the rotating electric machine according to claim 1 . a rotating electric machine;
a wheel driven by the rotating electric machine via a gear;
In an electric rail vehicle comprising a bogie having
An electric railway vehicle, wherein the rotating electric machine is the rotating electric machine according to claim 1 .

Images