JP5248751B2 - Slotless permanent magnet type rotating electrical machine - Google Patents

Description

  The present invention relates to a slotless permanent magnet type rotating electrical machine.

  Conventionally, mainly for the purpose of thinning the stator core, a rotor in which an even number of permanent magnets are arranged at equal intervals on the surface of the rotor core so as to have different polarities, and a gap so as to face the rotor In a smooth armature type three-phase brushless motor comprising a stator iron core arranged through a plurality of coils of non-overlapping concentrated winding arranged on the stator iron core, the number of coils is 6n, and a permanent magnet There are some which have a high performance by setting the number of poles to 10n (n is a natural number) and improving the short coefficient (for example, see Patent Document 1).

  Further, in a permanent magnet type motor having a stator in which a winding and an iron core are arranged and a rotor in which a permanent magnet constituting a plurality of magnetic poles is arranged, the winding is constituted by a coil having a plurality of concentrated winding air cores. When the iron core includes teeth inserted into the air core of the coil, and the arrangement angle width of the coil is θc and the angle width of the teeth (that is, the inner circumferential angle width of the coil) is β × θc, 0 <Β ≦ 0.5, and when the outer radius of the coil is ro, the inner radius of the coil is ri, and the tip radius of the teeth is rt, (θc × ri × π / 180) / (ro− ri) ≧ 4 (provided that ri ≦ rt ≦ ro) (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-234989 JP 2004-187344 A

  However, according to the conventional technique described in Patent Document 1, since the ratio of the number of coils to the number of permanent magnet poles is set to 6:10, the number of components is increased as compared with the case of normal 3: 4. For this reason, particularly in a small-sized motor that is mass-produced, there is a problem that the number of manufacturing steps increases due to an increase in the number of parts, resulting in an increase in cost.

  In addition, according to the conventional technique described in Patent Document 2, in order to improve both the rated torque and the maximum torque, fine teeth are used, and furthermore, the angular width of the teeth (that is, the inner peripheral angular width of the coil). ) Is optimized. However, if minute teeth are provided in the stator core, cogging torque and torque ripple are increased. For this reason, there has been a problem that vibration noise is generated and the motor cannot be used in a precision machine or the like.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a small slotless permanent magnet type rotating electric machine that reduces cogging torque and torque ripple and copper loss.

In order to solve the above-described problems and achieve the object, the present invention provides a cylindrical stator core having an axial length Lf (≈ rotating electric machine total length L) , and a coil on an inner peripheral surface of the stator core. Three coils arranged at equal intervals in the circumferential direction with an arrangement angle width of 120 °, and having an axial length of approximately Lc (≈ stator core length Lf ≈ rotating electric machine total length L) , coil outer circumferential angle width θγ, coil A coil concentratedly wound in a track shape with an inner circumferential angle width θτ, a cylindrical rotor core, and four magnetic poles are arranged on the rotor core so that the polarities are alternately different in the circumferential direction, and the axial length Lm (≈ rotating electric machine total length L) In a slotless permanent magnet type rotating electric machine provided with a permanent magnet formed with an outer diameter D, the coil inner peripheral pitch τ (= θτ / 120 °) is set to 0 <coil inner peripheral The pitch τ ≦ 0.33 + 0.47 D / L.

  According to the present invention, 0 <coil inner peripheral pitch τ ≦ 0.33 + 0.47 D / L, so that the cogging torque and the torque ripple are reduced, and the slotless permanent magnet type rotation with high efficiency and miniaturization is achieved. There is an effect that an electric machine can be obtained.

  Embodiments of a slotless permanent magnet type rotating electrical machine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment FIG. 1 is a cross-sectional view of an embodiment of a slotless permanent magnet type rotating electrical machine according to the present invention, FIG. 2 is a perspective view of a stator core, and FIG. FIG. 4 is a perspective view of a stator to which a coil is attached, FIG. 5 is a perspective view of a rotor, and FIG. 6 is a coil inner peripheral pitch τ and a coil outer periphery. FIG. 7 is a simulation result showing the relationship between the pitch γ and the copper loss, FIG. 7 is a simulation result showing the relationship between the coil inner peripheral pitch τ and the copper loss ratio, and FIG. 8 shows the slotless permanent magnet type rotating electrical machine. FIG. 9 is a simulation result showing the relationship between the ratio of the total length to the rotor outer diameter (L / D) and the maximum allowable coil inner circumferential pitch W. FIG. 9 shows the coil inner circumferential pitch when L / D is 1.5. Simulation results showing the relationship between τ and copper loss ratio. FIG. 10 is a simulation result showing the relationship between the coil inner circumferential pitch τ and the copper loss ratio when L / D is 2.2, and FIG. 11 is a graph when L / D is 4.1. FIG. 12 is a simulation result showing the relationship between the coil inner peripheral pitch τ and the copper loss ratio, and FIG. 12 shows a simulation result showing the relationship between the coil inner peripheral pitch τ and the copper loss ratio when L / D is 6.1. FIG. 13 is a simulation result showing the relationship between the coil inner circumferential pitch τ and the copper loss ratio when L / D is 9.3, and FIG. 14 is a graph showing L / D and the optimum coil inner circumferential pitch. It is a simulation result which shows the relationship with (tau).

  As shown in FIG. 1, the slotless permanent magnet type rotating electrical machine 100 of the embodiment is concentratedly wound around a cylindrical stator core 21 and a non-magnetic bobbin (or air core) 24, and the stator core. The polarities of the three coils 23, the cylindrical rotor core 31, and the rotor core 31 that are affixed at equal intervals in the circumferential direction on the inner circumferential surface of the 21 are alternately different in the circumferential direction. And a four-pole permanent magnet 32 such as a radial anisotropic ring magnet, a polar anisotropic ring magnet, or a segment magnet arranged in a cylindrical shape. The stator core 21 and the coil 23 constitute the stator 20, and the rotor core 31 and the permanent magnet 32 constitute the rotor 30.

As shown in FIG. 1, the rotor 30 (permanent magnet 32) is formed with an outer diameter D. In this specification, it is defined as 360 ° / the number of coils M = coil arrangement angle width θc (in this embodiment, θc = 120 °). Assuming that the angle width of the outer periphery of the coil concentratedly wound on the non-magnetic bobbin 24 is θγ, the angle width of the inner periphery of the coil is θτ, the coil outer periphery pitch γ and the coil inner periphery pitch τ are
Coil outer peripheral pitch γ = θγ / θc = θγ × number of coils M / 360 ° (Equation 1)
Coil inner pitch τ = θτ / θc = θτ × number of coils M / 360 ° (Equation 2)
It is defined as

As shown in FIG. 2, the stator core 21 is formed to have a length of the core length (axial length) Lf. Further, as shown in FIG. 3, the coil 23 is formed in a track-shaped concentrated winding coil having an overall coil length (axial length) Lc, a coil linear portion length L1, and a coil end portion length L2. Is expressed by the following relational expression (Expression 3).
Total coil length Lc = L1 + 2 × L2 (Equation 3)
The coil end length L2 is
Coil end length L2 ≒ πD (θγ-θτ) / 720 ° (Equation 4)
It is a value estimated by.

  In this embodiment, in order to maximize the torque output and reduce the size of the motor, as shown in FIGS. 4 and 5, the stator core length Lf≈coil total length Lc≈magnet length Lm = rotating electric machine total length L. So that each is formed. Due to structural restrictions, etc., there may be cases where the total coil length Lc≈the magnet length Lm cannot be achieved. In this case, generally, if Lm / Lc> 0.9, the torque output will be maximized. Can do.

  Next, simulation results will be described with reference to FIGS. FIG. 6 shows the magnitude of the copper loss when the coil outer peripheral pitch γ and the coil inner peripheral pitch τ of the slotless permanent magnet type rotating electrical machine 100 of the embodiment shown in FIG. 1 are changed by simulation. . The simulation condition is set such that the total length L of the slotless permanent magnet type rotating electrical machine 100 / the outer diameter of the rotor D = 9.3.

  As shown in FIG. 6, in order to reduce (optimize) the copper loss, the coil outer peripheral pitch γ is preferably closer to 1.0, and the copper loss is minimized when the coil inner peripheral pitch τ is about 0.2. ing. In order to set the coil outer peripheral pitch γ to 1.0, the gap between the adjacent coils must be zero, which is difficult to manufacture and has a high possibility of causing problems in insulation. Therefore, in the present embodiment, considering the manufacturability, the optimum value of other parameters was examined with the coil outer peripheral pitch γ being about 0.9.

  FIG. 7 is a simulation result when the coil outer peripheral pitch γ is about 0.9 and the coil inner peripheral pitch τ is a parameter, and the copper loss ratio when L / D is 1.5 to 9.3, respectively. Indicates.

  In order to reduce the size of a general permanent magnet motor with teeth, it is effective to increase the space factor of the winding. By applying the winding to all the places where the winding can be placed, the copper loss can be reduced. The induced voltage can be improved. Therefore, in the present embodiment, simulation is performed using a copper loss ratio with a copper loss as a reference value when the coil inner circumferential pitch τ is zero (when the winding is applied to all places where the winding can be arranged). Was done.

  As shown in FIG. 7, the copper loss ratio decreases as the coil inner peripheral pitch τ is increased from zero, and when the coil inner peripheral pitch τ is greater than a certain coil inner peripheral pitch τ, it is larger than the copper loss ratio when the coil inner peripheral pitch τ is zero. I understand that In the present specification, the coil inner peripheral pitch τ that has a copper loss ratio larger than the copper loss ratio when τ = 0 is referred to as a maximum allowable coil inner peripheral pitch W.

  When the overall length L of the rotating electrical machine is a constant value and the coil inner circumferential pitch τ is zero, the above phenomenon is caused by the fact that the coil end portion length L2 that hardly contributes to torque generation is as shown in (Equation 4) above. However, if the coil inner circumferential pitch τ is made larger than zero, L2 becomes smaller, and the coil linear portion length L1 that contributes to torque generation becomes larger, resulting in improved torque output and reduced copper loss. is there.

  Further, when the coil inner peripheral pitch τ is larger than the maximum allowable coil inner peripheral pitch W, the ampere turn that is considered to contribute to the torque in the cross section of the rotating electrical machine is reduced, thereby reducing the torque output and increasing the copper loss. It is considered to be.

  FIG. 8 shows the relationship between L / D and the maximum permissible coil inner circumferential pitch W. As shown in FIG. 8, the maximum permissible coil inner circumferential pitch τ varies depending on the size of L / D, and decreases as L / D increases. This is because the influence of the coil end is large when L / D is small (equivalent to a thin motor), and the influence of the coil end is small when L / D is large (equivalent to a trunk length motor). It is done.

FIG. 8 shows an approximate expression of the maximum permissible coil inner circumferential pitch W.
Maximum permissible coil inner pitch W = 0.33 + 0.47D / L (Formula 5)
Indicates. The slotless permanent magnet type rotating electric machine 100 reduces the copper loss and increases the coil inner pitch τ by setting the coil inner pitch τ to be equal to or less than “W” in (Equation 5). Efficiency can be improved and downsizing can be achieved.

  Next, the relationship between the coil inner peripheral pitch τ and the copper loss ratio will be examined in detail. 9 to 13 show the relationship between the coil inner peripheral pitch τ and the copper loss ratio when L / D is 1.5 to 9.3, respectively. The copper loss ratio affects the heat generation temperature of the rotating electrical machine, but if the copper loss ratio is a difference of about 5%, the tolerance of individual motors can be tolerated as well as the residual magnetic flux density of the permanent magnet and the coil application angle. Within range.

  Therefore, in the present embodiment, the optimum coil inner circumferential pitch τ in which the copper loss ratio is in the range of the minimum value to the minimum value + 5% is obtained. 9 to 13 show the range of the coil inner peripheral pitch τ (optimum coil inner peripheral pitch τ) in which the copper loss ratio becomes the minimum value to the minimum value + 5%. As shown in FIGS. 9 to 13, the range of the optimum coil inner peripheral pitch τ is different for each value of L / D.

FIG. 14 shows the range of L / D and the coil inner peripheral pitch τ for the copper loss ratio to be the minimum value to the minimum value + 5%. Moreover, in FIG. 14, as an approximate expression of the coil inner peripheral pitch τ,
Coil inner peripheral pitch τ = K = 0.16 + 0.27 D / L ± 50% (Equation 6)
Indicates. As shown in FIG. 14, the range of the coil inner peripheral pitch τ for the copper loss ratio to be the minimum value to the minimum value + 5% can be approximated by the above (formula 6). Therefore, in order to reduce (reduce) the copper loss of the slotless permanent magnet type rotating machine 100, the coil inner circumferential pitch τ may be set to 0.5K to 1.5K.

  14, in the case of a motor having an L / D of 1 or more and less than 3, the coil inner peripheral pitch τ is set to 0.2 to 0.5, and when the L / D is 3 or more, 0.15. If it is set to -0.3, the slotless permanent magnet motor can be reduced in size.

  In the present embodiment, the case of a 4-pole 3-coil concentrated winding motor has been described. However, in a general concentrated winding permanent magnet type rotating electrical machine, the ratio of the number of coils (slots) to the number of magnetic poles is 3n: 3n ± 1. In the case of a rotating electrical machine, copper loss can be reduced (downsized) in the same manner by setting the above-mentioned coil inner circumferential pitch τ.

  As described above, the slotless permanent magnet type rotating electrical machine according to the present invention is useful as a small permanent magnet type rotating electrical machine in which cogging torque and torque ripple are reduced and copper loss is reduced.

It is a cross-sectional view of an embodiment of a slotless permanent magnet type rotating electrical machine according to the present invention. It is a perspective view of a stator core. It is a top view of the coil arrange | positioned at a stator core. It is a perspective view of the stator which stuck the coil. It is a perspective view of a rotor. It is a simulation result which shows the relationship between coil inner periphery pitch (tau), coil outer periphery pitch (gamma), and copper loss. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio. It is a simulation result which shows the relationship between ratio (L / D) of the full length with respect to the rotor outer diameter of a slotless permanent magnet type rotary electric machine, and the maximum permissible coil inner peripheral pitch W. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio when L / D is set to 1.5. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio when L / D is set to 2.2. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio when L / D is 4.1. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio when L / D is set to 6.1. It is a simulation result which shows the relationship between coil inner peripheral pitch (tau) and copper loss ratio when L / D is set to 9.3. It is a simulation result which shows the relationship between L / D and the optimal coil inner peripheral pitch (tau).

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Stator 21 Stator iron core 23 Stator coil 30 Rotor 31 Rotor iron core 32 Permanent magnet 100 Slotless permanent magnet type rotary electric machine D Rotor outer diameter (permanent magnet outer diameter)
Lf Stator core length Lm Magnet length Lc Total coil length L1 Coil straight section length L2 Coil end section length θc Coil arrangement angular width θγ Coil outer peripheral angular width θτ Coil inner peripheral angular width τ Coil inner peripheral pitch γ Coil outer peripheral pitch

Claims (4)

A cylindrical stator core having an axial length Lf (≈ rotating electric machine total length L) ;
Three coils arranged at equal intervals in the circumferential direction with a coil arrangement angle width of 120 ° on the inner peripheral surface of the stator core , and having an axial length Lc (≈stator core length Lf≈rotary electric machine total length L) a coil concentratedly wound in a track shape having a coil outer peripheral angular width θγ and a coil inner peripheral angular width θτ;
A cylindrical rotor core;
Four magnetic poles are arranged on the rotor core so that the polarities are alternately different in the circumferential direction, and the permanent magnet is formed with an axial length Lm (= rotary electric machine total length L) and an outer diameter D;
In slotless permanent magnet type rotating electric machine with
Coil inner pitch τ (= θτ / 120 °)
0 <Inner coil pitch τ ≦ 0.33 + 0.47 D / L
A slotless permanent magnet type rotating electrical machine characterized by the above.   The slotless permanent magnet according to claim 1, wherein 0.5 × (0.16 + 0.27 D / L) ≦ coil inner circumferential pitch τ ≦ 1.5 × (0.16 + 0.27 D / L). Type rotating electric machine.   2. The slotless permanent magnet type rotating electric machine according to claim 1, wherein 1 ≦ L / D <3 and 0.2 ≦ coil inner circumferential pitch τ ≦ 0.5.   2. The slotless permanent magnet type rotating electric machine according to claim 1, wherein 3 ≦ L / D and 0.15 ≦ coil inner peripheral pitch τ ≦ 0.3.

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