JP2015008604A - Interior permanent magnet synchronous dynamo-electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify a structure capable of lowering the cogging torque, in an interior permanent magnet synchronous dynamo-electric machine.SOLUTION: In an interior permanent magnet dynamo-electric machine of concentrated winding having 8 poles and 12 slots, when the mechanical angle formed by both ends 332, 333 of a rotor, constituted of one or more permanent magnet 33, in the stator side circumferential direction of each pole is (a) with reference to the axis of rotation 321 of the rotor, the distance between the middle point 334 of both ends in the stator side circumferential direction and the axis of rotation is A, the width of a bridge provided to couple the rotor outside part and the part between rotor poles, converted to a mechanical angle with reference to the axis of rotation, is λ, and the distance between the boundary 225 of the teeth body and teeth flange and the axis of rotation on the slot side end face of the teeth is B, the mechanical angle b formed by the rotor side end face 223 of the teeth body with reference to the axis of rotation is set to satisfy the following formula.

Description

  The present invention relates to an embedded permanent magnet type synchronous rotating electric machine.

  In the electrification of automobiles, the vehicle motor, which is a key component, is one of the important development items. There are many types of motors. Among them, the concentrated permanent interior permanent magnet synchronous motor (hereinafter also referred to as “IPMSM”) has a relatively small coil end. It is relatively small and generates less heat than other types of motors. Therefore, the concentrated winding IPMSM is advantageous for a small vehicle, particularly a two-wheeled EV based on air cooling.

  On the other hand, the concentrated winding IPMSM has a torque pulsation at no load called cogging torque larger than other types of motors. This point gives an uncomfortable feeling to the operator of the two-wheeled EV that can be moved when there is no load, and causes the merchantability of the two-wheeled EV to decrease.

  Patent document 1 is mentioned as a prior art for suppressing a cogging torque. This document discloses a technique for suppressing cogging torque in a rotating electrical machine.

JP 11-299199 A

  In the prior art, the number of rotor poles and the number of stator slots in the rotating electrical machine are not limited. However, in order to efficiently reduce the cogging torque of the rotating electrical machine, it is necessary to specify the structure of the rotor and the stator after limiting the number of poles and the number of slots.

  The present invention has been made in view of such problems, and an object of the present invention is to specify a structure capable of reducing cogging torque in an embedded permanent magnet type synchronous rotating electric machine having concentrated winding and 8 poles and 12 slots suitable for a two-wheeled EV. .

を満足するように設定されたことを特徴とする。 In order to achieve the above object, an embedded permanent magnet type rotating electrical machine having concentrated winding and 8 poles and 12 slots according to the present invention includes a substantially cylindrical stator and a substantially cylindrical shape and the number of poles provided inside the stator. And the stator has a substantially cylindrical stator core and 12 teeth provided at equal intervals in the circumferential direction on the inner peripheral surface of the stator core, and each of the teeth is an inner part of the stator core. A teeth main body that protrudes radially inward from the circumferential surface; and a teeth flange that protrudes in the circumferential direction from the tip of the teeth main body, between the two adjacent teeth. Each slot is provided and a coil is wound around each tooth in the form of concentrated winding. A mechanical angle (unit: degree) formed by both ends in the circumferential direction of the stator of each pole of the rotor composed of one or a plurality of permanent magnets with respect to the rotation axis of the rotor is defined as a, A distance (unit: millimeter) between the midpoint of both ends in the stator side circumferential direction of each pole of the rotor and the rotation axis of the rotor is A, and in the rotor, adjacent to the rotor outer portion radially outside the permanent magnet. A value (unit: degree) obtained by converting the width of the bridge portion provided so as to connect the rotor pole portion between the two poles to a mechanical angle with respect to the rotation axis of the rotor is λ. When the distance (unit: millimeters) between the boundary between the teeth body and the teeth flange on the slot side end surface of the teeth and the rotation axis of the rotor is B, the rotation axis of the rotor is used as a reference. The tea Eggplant mechanical angle of the rotor side end face of the body (in degrees) b is,

It is set to satisfy the above.

  ADVANTAGE OF THE INVENTION According to this invention, the structure which can reduce a cogging torque can be identified in the embedded permanent magnet type | mold synchronous rotary electric machine of the concentrated winding suitable for two-wheeled EV and 8 poles and 12 slots.

It is a top view which shows one form of an embedded permanent magnet type | mold synchronous motor. It is explanatory drawing which shows a mode that the teeth front-end | tip part of the synchronous motor shown in FIG. 1, and the outer peripheral part of the rotor core were expanded. It is explanatory drawing of the parameter which specifies the structure of a synchronous motor. Is effective pole width and the parameter b or graph showing relationships between the estimated value b _calc. It is explanatory drawing which shows the result of having analyzed the flow of the magnetic flux in a synchronous motor. It is explanatory drawing which shows the result of having analyzed the flow of the magnetic flux in another synchronous motor. It is explanatory drawing which shows the result of having analyzed the flow of the magnetic flux in another synchronous motor. It is explanatory drawing which shows another form.

[First embodiment]
With reference to FIG. 1, one form of the synchronous motor 1 is demonstrated. The synchronous motor 1 includes a substantially cylindrical stator 2 and a substantially columnar rotor 3 provided inside the stator 2. A gap 4 is provided between the stator 2 and the rotor 3.

  The stator 2 includes a substantially cylindrical stator core 21 and twelve teeth 22 provided at equal intervals in the circumferential direction so as to protrude radially inward from the inner circumferential surface of the stator core 21. Slots 23 are respectively provided between the two adjacent teeth 22. A coil 24 is wound around each tooth 22 in the form of concentrated winding.

  The rotor 3 includes a substantially cylindrical rotor core 31 and a rotating shaft 32. Eight permanent magnets 33, each constituting a pole of the rotor 3, are embedded in the outer peripheral portion of the rotor core 31 at equal intervals in the circumferential direction. That is, the number of poles of the synchronous motor 1 is 8. Each permanent magnet 33 has a rectangular parallelepiped shape, and is magnetized so that a magnetic flux in the radial direction is generated when embedded in the rotor core 31.

  As described above, the synchronous motor 1 is an interior permanent magnet synchronous motor (IPMSM) having concentrated winding and 8 poles and 12 slots. FIG. 2 shows an example of a state in which the tip end portion of the tooth 22 of the synchronous motor 1 and the outer peripheral portion of the rotor core 31 are enlarged and the generated magnetic flux.

  Each tooth 22 includes a teeth main body 221 that protrudes radially inward from the inner peripheral surface of the stator core 21, and a teeth flange 222 that protrudes in the circumferential direction from the tip of the teeth main body 221.

  Eight magnet embedded holes 311 are provided in the outer peripheral portion of the rotor core 31 at equal intervals in the circumferential direction. The permanent magnet 33 is embedded in the magnet embedded hole 311. In the rotor core 31, the rotor outer portion 312, which is radially outside the permanent magnet 33 embedded in the magnet embedding hole 311, and the rotor pole portion 313 between the two adjacent poles respectively constituted by the permanent magnet 33. A bridge portion 314 is provided to connect the two. The width in the vertical direction with respect to the connecting direction of the bridge portion 314 is indicated by a symbol W.

  In such a synchronous motor 1, the magnetic flux generated from the stator side end surface 331 of a certain permanent magnet 33 includes magnetic fluxes J 1 and J 2 that flow into the teeth 22 through the rotor outer side 312 and the gap 4, and the rotor outer side 312. And a magnetic flux J3 that passes through the bridge portion 314 and is short-circuited in the rotor core 31. Among such magnetic fluxes, cogging torque is generated due to magnetic fluxes J1 and J2 having circumferential components in the gap 4. On the other hand, since the magnetic flux J3 is short-circuited in the rotor core 31, it does not contribute to the generation of cogging torque. In the teeth 22 into which the magnetic fluxes J1 and J2 flow, magnetic saturation occurs in the teeth flange 222, which is a smaller portion than the teeth main body 221.

  In view of such a cogging torque generation factor, the present inventor has intensively studied. As a result, the present inventor cannot effectively reduce the cogging torque by finding the relationship between the circumferential width of the stator side end surface 331 of the permanent magnet 33 and the circumferential width of the teeth body 221. The knowledge that there is not. And this inventor made several trial manufactures of the synchronous motor 1, and measured the cogging torque of each prototype.

  Parameters for specifying the structure of the prototype synchronous motor 1 are shown in FIG. As shown in FIG. 3A, the parameter a is a mechanical angle formed by one end 332 and the other end 333 in the circumferential direction of the stator side end surface 331 of the permanent magnet 33 with respect to the axis 321 of the rotating shaft 32. (Unit: degree). The parameter A is the distance (unit: millimeter) between the midpoint 334 and the axial center 321 between the one end 332 and the other end 333 in the circumferential direction of the stator side end surface 331 of the permanent magnet 33.

  As shown in FIG. 3B, the parameter b is a mechanical angle (unit: degree) of the rotor-side end surface 223 of the teeth body 221 with respect to the axis 321. The parameter B is a distance (unit: millimeter) between the boundary 225 between the tooth main body 221 and the tooth flange 222 on the slot side end surface 224 of the tooth 22 and the axis 321.

  Furthermore, a value (unit: degree) obtained by converting the width W of the bridge portion 314 shown in FIG. 2 into a mechanical angle with the axis 321 as a reference is set as a parameter λ.

The inventor made a prototype of the synchronous motor 1 by selecting a plurality of combinations of the values of the parameters a, λ, and b. At this time, the parameters A and B have common values. Specifically, parameter A is 51.4 and parameter B is 57.2. Then, the cogging torque of each prototype was measured. The results obtained thereby are shown in Table 1.

  Table 1 shows the relationship between the combinations of the values of the parameter a and the parameter λ and the value of the parameter b when the measured value of the cogging torque is minimized for each combination. The effective pole width is a calculated value of a-2λ. As shown in FIG. 2, the effective pole width is 2 in the vicinity of both ends in the circumferential direction of the permanent magnet 33 among the magnetic fluxes J1 to J3 generated from the stator side end surface 331 of one permanent magnet 33 constituting each pole. This is a value in view of the point that the magnetic flux J3 directed to the bridge portion 314 does not contribute to the cogging torque.

  In Table 1, λ = 1.1 is a conversion value when the width W of the bridge portion 314 is 1 millimeter. Further, λ = 0.6 is a converted value when the width W of the bridge portion 314 is 0.5 millimeter.

ただし、式（１）の「２／３」という数値は、極数８とスロット数１２との比である。表１にはさらに、パラメータｂの値とその試算値ｂ_ｃａｌｃとの誤差ｂ−ｂ_ｃａｌｃの値も示している。 Similarly, Table 1 also shows a trial calculation value b _calc of the parameter b using the effective pole width a-2λ in order to find the relationship between the parameter a and the parameter b. The present inventor performed a trial calculation of the parameter b using the following equation.

However, the numerical value “2/3” in the equation (1) is a ratio of the number of poles 8 to the number of slots 12. Table 1 also shows the value of the error b−b _calc between the value of the parameter b and the estimated value b _calc thereof.

FIG. 4 is a graph showing the relationship between the effective width a-2λ of Table 1 and the parameter b and the estimated value b _calc thereof. Reference numeral G1 shows the relationship between the effective pole width and the parameter b, reference numeral G2 shows the relationship between the effective pole width and the estimated value b _calc.

  Based on the above, the present inventors have further studied. According to Table 1 and FIG. 4, the absolute value of the error is 0.6 or less for the prototypes S2 to S9. The effective polar width a-2λ of these prototypes S2 to S9 is larger than 23 and smaller than 31. On the other hand, the prototypes S1 and S10 have a relatively large error, which exceeds 1.0. In addition, the effective pole width a-2λ of the prototype S1 is less than 23, and the effective pole width a-2λ of the prototype S10 is more than 31.

  Based on Table 1 and FIG. 4, the error of 0.6 or less in the prototypes S2 to S9 is due to the material characteristics of the stator 2 and the rotor 3 and the error factors when the synchronous motor 1 is manufactured and assembled. The present inventor determined that

  Furthermore, the inventor analyzed the flow of magnetic flux in the prototypes S1, S5, and S10. The analysis results are shown in FIGS. In addition, the cogging torque (unit: N · m) in the prototypes S1, S5, and S10 was 0.07, 0.05, and 0.18, respectively.

  FIG. 5 shows the analysis result of the prototype S1. The arrow line Y in the figure indicates the flow of magnetic flux. According to the figure, a magnetic flux K11 is generated from the permanent magnet 33-11 toward the teeth body 221-11. Further, a magnetic flux K12 is generated from the teeth body 221-12 toward the permanent magnet 33-12. The magnetic fluxes K11 and K12 cancel each other. On the other hand, in the teeth main body 221-13 and the gap 4 around the teeth, a magnetic flux K13 having a component in a substantially circumferential direction as well as a substantially radial direction is generated. As a result, the cogging torque becomes relatively large. .

  FIG. 6 shows the analysis result of the magnetic flux of the prototype S5. According to the figure, a magnetic flux K21 is generated from the teeth body 221-21 toward the permanent magnet 33-21. Moreover, the magnetic flux K22 has arisen so that it may go to the permanent magnet 33-21 from the teeth main body 221-22. The magnetic fluxes K21 and K22 cancel each other. Further, a magnetic flux K23 having a substantially radial vector that does not contribute to cogging torque is generated from the permanent magnet 33-22 toward the teeth body 221-23.

  As described above, in the prototype S5, the magnetic fluxes K21 and K22 that are divided into the two tooth bodies to cancel the magnet torque and the magnetic flux K23 having a radial vector that does not contribute to the cogging torque exist in a balanced manner. Cogging torque can be suppressed.

  FIG. 7 shows the analysis result of the magnetic flux of the prototype S10. According to the figure, a magnetic flux K31 having a substantially radial vector that does not contribute to the cogging torque is generated from the teeth body 221-31 toward the permanent magnet 33-31. On the other hand, magnetic fluxes K32 and K33 are generated from the permanent magnets 33-32 toward the tooth bodies 221-32 and 221-33, respectively. Since the balance between these two magnetic fluxes is poor, the two magnetic fluxes cannot be offset. As a result, the cogging torque becomes relatively large.

Based on Table 1 and FIGS. 4 to 7 as described above, the present inventor found an expression representing the relationship between the parameter a and the parameter b as follows.

  By setting the parameter b so as to satisfy Expression (2), the cogging torque in the synchronous motor 1 can be reduced. Further, since the parameters a and b are determined by the mechanical angle, the expression (2) can be applied to the synchronous motor 1 having an arbitrary size.

[Other forms]
In the embodiment described so far, each pole of the rotor 3 is constituted by one permanent magnet 33. However, the present invention is not limited to this, and the formula (2) can also be used when each pole is constituted by a plurality of permanent magnets.

  For example, as shown in FIG. 8, each pole can be constituted by two permanent magnets 33-51 and 33-52. These two permanent magnets are embedded so as to have a V shape in plan view. In FIG. 8, only one pole with the rotor 3 is shown, and the other seven poles are not shown.

  Of the circumferential ends of the stator side end faces of the permanent magnets 33-51 and 33-52 constituting one pole, the circumferential ends near the adjacent poles are denoted by reference numerals 332-51 and 333-52. Yes. These circumferential ends 332-51 and 333-52 are the stator side circumferential ends of the rotor poles.

  In this case, the parameter a is a mechanical angle (unit: degree) formed by the stator side circumferential ends 332-51 and 333-52 of the rotor pole with respect to the axis 321 of the rotating shaft 32. The parameter A is the distance (unit: millimeter) between the center point 334-51 and the axial center 321 of the stator side circumferential ends 332-51 and 333-52 of the rotor pole. Further, bridge portions (not shown) are provided in the vicinity of both ends 332-51 and 333-52 in the stator side circumferential direction of the poles. By determining the parameters a and A in this way, the effective pole width a-2λ can be calculated for each pole. Therefore, even when each pole is composed of a plurality of permanent magnets, the formula (2) can be used. it can.

  When returning to the case where each pole is constituted by one permanent magnet as shown in FIG. 3, the parameter a is constituted by one permanent magnet 33 based on the axis 321 of the rotating shaft 32. It can also be said to be a mechanical angle (unit: degree) formed by the stator side circumferential ends 332 and 333 of the rotor poles.

  In addition, in order to further reduce the cogging torque, as shown in FIG. 2, a so-called petal-shaped rotor core in which the rotor outer portion 312 of the rotor core 31 bulges toward the stator 2 may be used. Moreover, the front-end | tip part of the teeth collar part 222 can also be made into an acute angle shape. Further, a permanent magnet with skew magnetization may be used.

  Further, the expression (2) is not limited to the embedded permanent magnet type synchronous motor 1, but can be applied to an embedded permanent magnet type rotating electrical machine including an embedded permanent magnet type synchronous generator.

  In the above, specific embodiments of the structure of the embedded permanent magnet type rotating electrical machine have been specifically described. However, the present invention is not limited to such an embodiment, and all changes and modifications apparent to those skilled in the art are included in the technical scope of the present invention.

1 Synchronous motor 2 Stator 3 Rotor 4 Gap

21 Stator core 22 Teeth 23 Slot 24 Coil

221 Teeth body 222 Teeth collar 223 Rotor side end surface 224 Slot side end surface 225 Boundary

31 Rotor core 32 Rotating shaft 33 Permanent magnet

311 Magnet embedded hole 312 Rotor outer peripheral portion 313 Rotor pole portion 314 Bridge portion 321 Axle 331 Stator side end surface 332 Circumferential end 333 Circumferential other end 334 Midpoint

G1, G2 Graphs J1 to J3 Magnetic flux K11 to K13 Magnetic flux K21 to K23 Magnetic flux K31 to K33 Magnetic flux S1 to S10 Prototype W Bridge width

Claims (1)

A substantially cylindrical stator and a substantially columnar and eight-pole rotor provided inside the stator, wherein the stator has a substantially cylindrical stator core and an inner circumferential surface of the stator core at equal intervals in the circumferential direction. And 12 teeth, each tooth projecting radially inward from the inner peripheral surface of the stator core, and projecting from the tip of the teeth body in the circumferential direction. Teeth are provided, and slots are provided between the two adjacent teeth, respectively, and concentrated windings in which coils are wound around each tooth in the form of concentrated winding and embedded in 8 poles and 12 slots. In a permanent magnet type rotating electrical machine,
The mechanical angle (unit: degree) formed by the stator side circumferential ends of each pole of the rotor composed of one or a plurality of permanent magnets with respect to the rotation axis of the rotor is a,
The distance (unit: millimeter) between the midpoint of both ends in the circumferential direction of the stator of each pole of the rotor and the rotational axis of the rotor is A,
In the rotor, a width of a bridge portion provided so as to connect a rotor outer portion radially outside the permanent magnet and a rotor pole portion between two adjacent poles is set to a rotation axis of the rotor. A value (unit: degree) converted to a mechanical angle based on λ is λ,
When the distance (unit: millimeters) between the boundary between the teeth main body and the teeth flange portion on the slot side end surface of the teeth and the rotation axis of the rotor is B,
The mechanical angle (unit: degree) b formed by the rotor side end surface of the teeth body, with respect to the rotation axis of the rotor,

Embedded permanent magnet type rotating electrical machine, characterized in that it is set to satisfy

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