JP2011067090A - Permanent magnet motor and permanent magnet linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor having auxiliary grooves on teeth of a stator core, which reduces cogging torque without changing a shape of a press die or the like even when the width of the auxiliary groove is slightly out of an ideal shape because of variation among lots of core materials or machining errors. <P>SOLUTION: The motor includes a rotor 8 having magnetic poles of a plurality of permanent magnets 6, and a stator 5 formed by laminating stator cores 1 having a plurality of teeth 2 facing the permanent magnets 6. Auxiliary grooves 4 are provided on a part of the plane facing the permanent magnets 6 of the teeth 2. When a ratio of the number of magnet poles of the rotor 8 to the number of slots of the stator 5 is m:n, and a groove width angle of the auxiliary groove 4 where (l×k)f component (k: the least common multiple of m and n, l: an integer of 1 or more, and f: a fundamental wave component) of cogging torque becomes minimum is α, the stator 5 is formed by laminating a first stator core having a groove width angle of the auxiliary groove 4 which is larger than α and a second stator core without auxiliary grooves. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a permanent magnet type motor and a permanent magnet type linear motor that use a permanent magnet for a field, and more particularly to a technique for reducing torque pulsation.

  Permanent magnet type motors using strong magnets have the advantage of being small and capable of generating high torque. However, pulsation torque is generated regardless of whether there is no load or not due to the interaction between the magnetic flux of the permanent magnet and the stator slot. In particular, the pulsating torque at no load is called cogging torque, which causes problems such as positioning accuracy and vibration noise. Conventionally, as a technique for reducing cogging torque, for example, as shown in Japanese Patent Application Laid-Open No. 10-42531 and Japanese Patent Application Laid-Open No. 2002-136001, an auxiliary groove is provided at a tooth tip of a stator, and the auxiliary groove is placed at a predetermined position. A method of arranging a predetermined number is considered.

Japanese Patent Laid-Open No. 10-42531 (FIG. 1) JP 2002-136001 A (FIG. 5)

  However, when the auxiliary groove is provided at an ideal position, the cogging torque can be effectively reduced. However, when the auxiliary groove is deviated from the ideal position, there is a problem that the cogging torque cannot be appropriately reduced. For example, when a stator core is formed by stacking stator iron cores having auxiliary grooves, the auxiliary grooves are formed by press punching or the like. There is a problem that cogging torque is generated due to a difference in magnetic characteristics.

  The present invention has been made to solve the above-described conventional problems. In a motor having auxiliary grooves in the teeth of the stator core, the width of the auxiliary grooves due to variations among lots of core material and processing errors. Provided is a motor capable of reducing the cogging torque without changing the shape of a press die or the like even when it slightly deviates from the ideal shape.

  A permanent magnet type motor according to the present invention includes a stator formed by laminating a rotor having magnetic poles of a plurality of permanent magnets and a stator core having a plurality of teeth facing the permanent magnets. An auxiliary groove is provided in a part of the surface facing the permanent magnet, the ratio of the number of magnetic poles of the rotor to the number of slots of the stator is m: n, and the (l × k) f component of cogging torque When the groove width angle of the auxiliary groove that minimizes (k is the least common multiple of m and n, l is an integer of 1 or more, and f is the fundamental wave component) is α, the stator is the groove of the auxiliary groove. A first stator core having a groove width angle larger than α and a second stator core without the auxiliary groove are laminated, and the first and second stator cores are stacked. When the magnitude of the cogging torque per unit stacking length is τc and τd, respectively, As shown in the above formula, the first and second stator cores are stacked.

  According to the permanent magnet type motor according to the present invention, since the stator cores having different auxiliary grooves including zero are combined and laminated, the difference in iron core materials and the processing of the auxiliary grooves Even when the depth and the angle are shifted and the width of the auxiliary groove is deviated from the optimum width, the cogging torque can be reduced while adjusting the stacking ratio of the stator core.

  In other words, since the cogging torque can be adjusted only by changing the lamination ratio of the stator core, it is only necessary to adjust the number of presses of the press machine for processing the stator core, and there is no need to precisely adjust the expensive press die itself. Thus, a low-cogging torque permanent magnet motor can be provided at low cost.

It is sectional drawing of the permanent magnet type motor by Embodiment 1 of this invention. It is a figure which expands and shows the stator core of the permanent magnet type motor by Embodiment 1 of this invention. It is a perspective view which shows a part of stator core of the permanent magnet type motor by Embodiment 1 of this invention. It is a figure which shows the relationship between the dummy slot angle and cogging torque 6f component by Embodiment 1 of this invention. It is a figure which shows the other lamination | stacking state of the stator core by Embodiment 1 of this invention. It is a figure which shows the lamination | stacking state of the stator core by Embodiment 2 of this invention. It is a figure which shows the relationship between the dummy slot angle and cogging torque 6f component by Embodiment 2 of this invention. It is a conceptual diagram which shows the structure of the axial direction of the stator and rotor of a permanent magnet type motor by Embodiment 4 of this invention. It is a conceptual diagram which shows the structure of the axial direction of the stator and rotor of a permanent magnet type motor by Embodiment 5 of this invention. It is a conceptual diagram which shows the structure of the other stator and rotor axial direction of the permanent magnet type motor by Embodiment 5 of this invention. It is a perspective view which shows a part of stator core of the permanent magnet type motor by Embodiment 6 of this invention. It is a figure which shows the relationship between the cogging torque 6f component by 12th Embodiment of this invention, the 12f component, and a dummy slot angle. It is sectional drawing of the permanent magnet type motor by Embodiment 7 of this invention. It is a figure showing the cogging torque of an IPM motor and an SPM motor. It is a figure which shows the magnitude | size of the cogging torque 12f component of an IPM motor and a SPM motor. It is a figure which shows the adjustment method of the cogging torque of the permanent magnet type motor by Embodiment 8 of this invention. It is a figure which expands and shows the stator core of the permanent magnet type motor by other embodiment of this invention. It is a schematic perspective view which shows the linear motor by other embodiment of this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
1 is a cross-sectional view of a permanent magnet type motor according to Embodiment 1 of the present invention. FIG. 2 is an enlarged view of the stator core shown in FIG.

  In the figure, a permanent magnet type motor 10 includes a stator 5 formed by laminating a stator core 1 and a rotor 8 having a permanent magnet 6 as a magnetic pole. A plurality of teeth 2 and winding slots 3 (windings are not shown) are formed on the inner peripheral side of the stator core 1. An auxiliary groove 4 is provided at a position facing the tip of the teeth 2 of the stator core 1, that is, the permanent magnet 6. Reference numeral 3a denotes a slot opening.

  On the other hand, the rotor 8 includes a permanent magnet 6 and a rotating shaft 7. The permanent magnet 6 constitutes the magnetic pole of the rotor 8, and magnets having different polarities are alternately arranged at equal intervals.

  In the present embodiment, it is assumed that the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P. As shown in FIG. 2, two auxiliary grooves 4 are provided at the tip of the teeth 2 of the stator core 1 at a position equally divided into three by the mechanical angle θ in the circumferential direction from the center of the slot opening 3 a. . Furthermore, as shown in FIG. 3, a plurality of stator cores 1 having different groove widths (dummy slot angles) of the auxiliary grooves 4 are stacked in the axial direction to form the stator 5.

  Here, the cogging torque is obtained by considering the magnetomotive force component of the permanent magnet 6 and the variation component of the permeance of the stator teeth 2, thereby minimizing the number of poles of the rotor 8 and the number of stator slots per rotation of the rotor 8. It is known to have a pulsation of the common multiple. In other words, assuming that the phenomenon that occurs in one electrical angle period, that is, in units of two poles, is the fundamental wave f, when the number of magnetic poles of the rotor 8 is 2P and the number of slots of the stator 5 is 3P, the cogging torque of the 6f component becomes a problem. There are many cases. Therefore, it is considered to reduce this by using auxiliary grooves (dummy slots), which will be described below.

  As shown in FIG. 2, when the circumferential groove width (hereinafter referred to as a dummy slot angle) of the auxiliary groove 4 is represented by α and the mechanical angle of the slot opening is represented by β, the dummy slot angle α and the cogging torque 6f component The relationship is as shown in FIG. In FIG. 4, the magnitude of the cogging torque 6f component is minimized at a predetermined dummy slot angle α1. Conventionally, the motor is designed with the dummy slot angle α1 at which the cogging torque is minimized as the ideal auxiliary groove 4 groove width. However, in actuality, the auxiliary groove 4 with the dummy slot angle α1 (α1 is substantially equal to the slot opening angle β) is affected by magnetic saturation and a minute shape error, so that it is difficult to stably manufacture in an ideal state. It is.

Therefore, in the present embodiment, the relationship between the dummy slot angle α and the cogging torque is analyzed in consideration of the phase, not just the absolute value. As a result, the cogging torque has been found that the phase of the 6f component changes before and after the dummy slot angle α1, as shown in FIG. And consider actively using this relationship. That is, when the magnitudes per unit stacking length of the cogging torque of the stator core A with the dummy slot angle α3 and the stator core B with the dummy slot angle α2 are τ _a and τ _b , respectively, The stator cores A and B are laminated in inverse proportion to the magnitude of the cogging torque as shown in FIG.

  As a result, the phase of the cogging torque before and after the dummy slot angle α1 is canceled, and the magnitude of the cogging torque 6f component can be reduced. As shown in FIG. 3, the stator cores A and B can be stacked in a combination of A1: B1: A2 (A1, A2 are stator core A, B1 is stator core B). As shown in FIG. 5, there is a method of laminating at a ratio of A1: B2: A2: B3 (A1 and A2 are stator cores A, and B1 and B2 are stator cores B). That is, any combination may be used as long as the lamination ratio of the stator cores A and B in the entire axial direction satisfies the formula (1).

As described above, according to the present embodiment, the ratio of the number of magnetic poles of the rotor 8 to the number of slots of the stator 5 is 2: 3, and the 6f component (f is the fundamental wave component) of the cogging torque is minimized. When the groove width angle of the auxiliary groove 4 is α1, the stator core B having an angle α2 where the groove width angle of the auxiliary groove 4 is smaller than α1, and the stator having an angle α3 where the groove width angle of the auxiliary groove 4 is larger than α1. The iron core A is laminated. For this reason, even when the optimum angle of the auxiliary groove is different from the ideal value due to the convenience of the iron core material and the mold accuracy, only τ _a and τ _b change. Therefore, the stator cores A and B shown by the equation (1) By adjusting the stacking ratio, the cogging torque can be reduced.

  In the above embodiment, attention is focused on the cogging torque 6f component, but the cogging torque 12f component can also be reduced by the same method.

Embodiment 2. FIG.
In the first embodiment, the stator core A in which the groove width angle (dummy slot angle) of the auxiliary groove is larger than the ideal angle α1 and the stator core B smaller than the ideal angle α1 are combined and laminated. In the embodiment, a description will be given of a structure in which a stator core C in which the groove width angle (dummy slot angle) of the auxiliary groove is larger than the ideal angle α1 and a stator core D in which the dummy slot angle is zero, that is, no auxiliary groove is combined. .

  FIG. 6 is a view showing a laminated state of the stator core according to the second embodiment of the present invention. In the present embodiment, as in the first embodiment, it is assumed that the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P. Two auxiliary grooves 4 are provided at the tip of one tooth 2 at a position equally divided into three by the mechanical angle θ in the circumferential direction from the center of the slot opening 3a. Then, as shown in FIG. 6, the stator core C in which the groove width angle (dummy slot angle) of the auxiliary groove is larger than the ideal angle α1 and the stator core D in which the dummy slot angle is zero, that is, no auxiliary groove is laminated. Thus, the stator 5 is formed.

Here, as shown in FIG. 7, since the phase of the 6f component changes before and after the dummy slot angle α1 and the sign of the cogging torque can be reversed, the groove width angle (dummy slot angle) of the auxiliary groove is When the magnitude of the cogging torque per unit stacking length of the stator core C having α4 larger than the ideal angle α1 and the stator core D having zero dummy slot angle, that is, no auxiliary groove, as τ _c and τ _d , respectively, As shown in Equation (2), the stator cores C and D are stacked in inverse proportion to the magnitude of the cogging torque.

  As a result, the phase of the cogging torque before and after the dummy slot angle α1 is canceled, and the magnitude of the cogging torque 6f component can be reduced. As shown in FIG. 6, the stator cores C and D may be stacked in combination with other layers such as C1: D1: C2 (C1 and C2 are stator cores C and D1 is stator cores D). As long as the ratio of the number of stator cores C and D in the entire stacking direction satisfies the formula (2), they may be combined in any way.

  As described above, according to the present embodiment, the ratio of the number of magnetic poles of the rotor 8 to the number of slots of the stator 5 is 2: 3, and the 6f component (f is the fundamental wave component) of the cogging torque is minimized. When the groove width angle of the auxiliary groove 4 is α1, the stator core C having an angle α4 where the groove width angle of the auxiliary groove 4 is larger than α1 and the stator core D having a zero groove width angle of the auxiliary groove 4 are Laminated.

  In this way, when a stator core with or without auxiliary grooves is mixed and created, the presence or absence of auxiliary grooves can be obtained by retracting the punch part of the press mold for forming the auxiliary grooves with a cam device etc. The stator iron core can be made relatively easily. In addition, since the auxiliary groove is arranged at an ideal position by the conventional method, a minute cogging torque is caused by the problem of variation in the shape of the auxiliary groove due to accuracy error of press dies, etc., and the difference in magnetic characteristics of the iron core material. However, in the case of this embodiment, the cogging torque is adjusted by changing the lamination ratio of the stator cores C and D even if a machining error or a difference in magnetic characteristics of the iron core occurs. Since it is possible, there is an effect that it is possible to provide a low cogging motor that is excellent in mass productivity by reducing the number of mold steps.

  In the above embodiment, attention is focused on the cogging torque 6f component, but the cogging torque 12f component can also be reduced by the same method.

Embodiment 3 FIG.
In the first and second embodiments, it is assumed that the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P. However, the number of magnetic poles of the rotor is 4P (P Is an integer greater than or equal to 1), the same applies even when the number of slots of the stator 5 is 3P.

  That is, in the present embodiment, the number of magnetic poles of the rotor 8 is 4P (P is an integer of 1 or more), the number of slots of the stator 5 is 3P, and the tip of the teeth 2 of the stator core 1 is Two auxiliary grooves 4 are provided at a position equally divided by a mechanical angle θ in the circumferential direction from the center of the slot opening 3a. Further, a plurality of stator cores 1 having different groove widths (dummy slot angles) of the auxiliary grooves 4 are stacked in the axial direction to form the stator 5.

  Here, the cogging torque is known to have a pulsation of the least common multiple of the number of poles of the rotor and the number of stator slots per rotation of the rotor 8, and is generated in one cycle of electrical angle, that is, in units of two poles. If the phenomenon is the fundamental wave f, when the number of magnetic poles of the rotor 8 is 4P and the number of slots of the stator 5 is 3P, the cogging torque of the 12f component often becomes a problem. In the cogging torque, the phase of the 12f component changes before and after the ideal dummy slot angle, and the sign of the sign can be reversed, as described in the above embodiment.

  Therefore, in the present embodiment, as described in the first embodiment, the stator core having a groove width angle smaller than the ideal angle and the groove width angle of the auxiliary groove 4 larger than the ideal angle. Laminate an angle stator core. Further, as described in the second embodiment, the stator core having the auxiliary groove 4 whose groove width angle is larger than the ideal angle and the stator core whose auxiliary groove 4 has the zero groove width angle are stacked. As a result, the phase of the cogging torque before and after the ideal angle of the dummy slot is canceled, and the magnitude of the cogging torque 12f component can be reduced.

  Here, attention is focused on the cogging torque 12f component, but the cogging torque 24f component can also be reduced by the same method.

Embodiment 4 FIG.
FIG. 8 is a conceptual diagram showing an axial configuration of a stator and a rotor of a permanent magnet type motor according to Embodiment 4 of the present invention.

  In the present embodiment, similarly to the first embodiment, it is assumed that the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P. Two auxiliary grooves 4 are provided at the tip of the tooth 2 at a position equally divided into three by the mechanical angle θ in the circumferential direction from the center of the slot opening 3a.

  Further, as shown in FIG. 8, a stage skew rotor is used that reduces the cogging torque by dividing the permanent magnet 6, which is the magnetic pole of the rotor 8, in the axial direction and shifting it in the circumferential direction. The step skew angle (the skew angle of the permanent magnet shifted in the axial direction) is set so that one of the cogging torque 6f component or the 12f component is minimized.

  In the present embodiment, the stator core A satisfying the formula (3) and the other of the cogging torque 6f or 12f component within the step range of each permanent magnet divided in the axial direction are minimized. B is laminated in the axial direction.

  The details of the method of stacking the stator cores A and B are the same as those described in the first embodiment. Further, the stator core stacking method described in the second embodiment can be similarly applied.

  As described above, according to the present embodiment, the magnetic poles of the rotor 8 are skewed in multiple stages in the axial direction, and the angle of the stage skew is set to an angle at which one of the cogging torque 6f component or 12f component is minimized. Since the lamination of the stator cores is set so that the other of the 6f component or the 12f component of the cogging torque is minimized within the above steps, the reduction of both the 6f component and the 12f component of the cogging torque can be reduced by the step skew. Because of the independent design elements of the relative angle and the stacking ratio of the stator core with and without auxiliary grooves, each can be adjusted independently, and the effect of facilitating adjustment and design for reducing cogging torque is obtained. It is done.

  The present invention can be similarly applied to a permanent magnet motor in which the number of magnetic poles of the rotor is 4P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P.

  Furthermore, this embodiment is generalized as follows. That is, the ratio of the number of magnetic poles of the rotor 8 to the number of slots of the stator 5 is m: n, and the magnetic poles of the rotor 8 are skewed by multiple stages in the axial direction, and the angle of the stage skew is the kf component of the cogging torque. Alternatively, 2 kf components (k is the least common multiple of m and n, and f is the fundamental wave component) are set to an angle at which one of them becomes the minimum, and the stack of stator cores has a cogging torque kf component or 2 kf component in the above stage. The other is set to be the minimum. As a result, the kf component or the 2 kf component of the cogging torque can be simultaneously reduced.

Embodiment 5 FIG.
FIG. 9 is a conceptual diagram showing the axial configuration of the stator and rotor of a permanent magnet type motor according to Embodiment 5 of the present invention.

  In the present embodiment, similarly to the first embodiment, it is assumed that the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P. Two auxiliary grooves 4 are provided at the tip of the tooth 2 at a position equally divided into three by the mechanical angle θ in the circumferential direction from the center of the slot opening 3a.

  Further, as shown in FIG. 9, an oblique skew rotor that reduces cogging torque by skewing the permanent magnet 6 that is the magnetic pole of the rotor 8 obliquely in the axial direction is used. The angle of the skew is set so that one of the frequency components of the cogging torque 6f component or the 12f component is minimized.

  In this case, the stator core is symmetrical with respect to the axial center so that the other of the frequency components of the cogging torque 6f component or the 12f component is minimized, and as in the first and second embodiments. The stator 5 is formed by laminating by various methods.

  As shown in FIG. 10, in the case of the rotor 8 having a plurality of oblique skews in the axial direction, the cogging torque is obtained by combining the stator cores so as to be symmetrical with respect to the axial center within the same oblique skew. Can also be reduced.

  As described above, according to the present embodiment, the magnetic poles of the rotor 8 are obliquely skewed in the axial direction, and the angle of the oblique skew is set to an angle that minimizes one of the cogging torque 6f component or 12f component. In addition, since the lamination of the stator cores is symmetric with respect to the axial center and is set so that the other of the 6f component or the 12f component of the cogging torque is minimized, both the 6f component and the 12f component of the cogging torque are provided. Is made up of independent design elements such as the skew angle and the lamination ratio of the stator cores with and without auxiliary grooves, each of which can be adjusted independently, making adjustment and design to reduce cogging torque easy The effect of becoming can be achieved.

  The present invention can be similarly applied to a permanent magnet motor in which the number of magnetic poles of the rotor is 4P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P.

  Furthermore, this embodiment is generalized as follows. That is, the ratio of the number of magnetic poles of the rotor 8 to the number of slots of the stator 5 is m: n, and the magnetic poles of the rotor 8 are obliquely skewed in the axial direction, and the angle of the oblique skew is the kf component of the cogging torque. Alternatively, the angle is such that one of the 2 kf components (k is the least common multiple of m and n, and f is the fundamental wave component) is the minimum, and the stack of the stator cores 1 is symmetric with respect to the axial center of the skew skew and It is characterized in that it is set so that the other of the kf component or the 2 kf component of the cogging torque is minimized. As a result, the kf component or the 2 kf component of the cogging torque can be simultaneously reduced.

Embodiment 6 FIG.
FIG. 11 is a perspective view showing a part of a stator core of a permanent magnet type motor according to Embodiment 6 of the present invention.

  In the present embodiment, the number of magnetic poles of the rotor 8 is 2P (P is an integer of 1 or more), the number of slots of the stator 5 is 3P, and the slot opening 3a is formed at the tip of the teeth 2 of the stator core 1. Two auxiliary grooves 4 are provided at a position equally divided by a mechanical angle θ in the circumferential direction from the center. Further, two types of stator cores A ″ (dummy slot angle θ 2) and B ″ (dummy slot angle θ 1) having different groove widths (dummy slot angles) of the auxiliary grooves 4 are stacked in the axial direction to form the stator 5. Forming.

  FIG. 12 is a diagram showing the relationship between the cogging torque 6f and 12f components and the dummy slot angle in the present embodiment. In FIG. 12, when the magnitude of the cogging torque 6f component at the dummy slot angles θ1 and θ2 is Y1 and Y2, and the magnitude of the cogging torque 12f component is Z1 and Z2, Y2 = −δ × Y1, Z2 = −δ ×. A stator core B ″ having an auxiliary groove 4 with a dummy slot angle θ1 and a stator core A ″ having an auxiliary groove 4 with a dummy slot angle θ2 such that Z1 (δ is a positive real number) are prepared. Then, by stacking the stator core B ″ having the dummy slot angle θ1 and the stator core A ″ having the dummy slot angle θ2 in the axial direction at a ratio of δ: 1, both the cogging torque 6f component and the 12f component are reduced. be able to.

  When there are two types of cogging torque frequency components of 6f and 12f, in the above embodiment, the rotor 8 is skewed, and the cogging torque is reduced by the lamination ratio of the stator core with the stator core without the auxiliary groove. However, in the present embodiment, the cogging torque having two types of frequency components can be reduced by appropriately selecting the lamination ratio of the stator core and the dummy slot angle as described above. Therefore, it is possible to eliminate the skew, and it is possible to eliminate problems such as magnetization and torque reduction accompanying the execution of the skew.

  The present invention can be similarly applied to a permanent magnet motor in which the number of magnetic poles of the rotor is 4P (P is an integer of 1 or more) and the number of slots of the stator 5 is 3P.

  Furthermore, this embodiment is generalized as follows. That is, the ratio of the number of magnetic poles of the rotor 8 to the number of slots of the stator 5 is m: n, and the groove width angle of the auxiliary groove 4 is the kf component of cogging torque (θ is the minimum of m and n). When the magnitude of the common multiple, f is the fundamental wave component) Y1 and Y2, and the cogging torque 2kf component is Z1 and Z2, Y2 = −δ × Y1, Z2 = −δ × Z1 (δ is a positive real number) ), And the stator core 1 having the dummy slot angle θ1 and the stator core 1 having the dummy slot angle θ2 are δ: 1. It is characterized by being laminated in the axial direction at a ratio of As a result, it is possible to simultaneously reduce both the cogging torque kf component and the 2 kf component without skewing the rotor 8.

Embodiment 7 FIG.
As a method for holding a permanent magnet of a permanent magnet type motor, there are a case of a magnet embedded type (hereinafter referred to as IPM) in which a permanent magnet is inserted into the rotor core, and a type of permanent magnet pasted on the rotor surface (hereinafter referred to as IPM). There are two types of SPM). As shown in FIG. 13, the IPM has a feature that the permanent magnet 6 is held inside the iron core of the rotor 8, so that the mechanical strength is excellent, and an operation of attaching the permanent magnet 6 is unnecessary.

  However, as shown in FIG. 14, the cogging torque of the IPM motor is larger than that of the SPM motor. Further, when the number of magnetic poles of the rotor 8 is 2P (P is an integer equal to or greater than 1) and the number of slots of the stator 5 is 3P, the IPM motor is particularly more cogging torque 12f than the SPM motor as shown in FIG. The component size increases. This is because magnetic flux leaks to the iron cores at both ends of the magnet holding the permanent magnet 6, so that harmonics are contained in the air gap portion with the stator 5 in addition to the fundamental wave.

  However, with a general skew, only a single cogging torque component of 6f component or 12f component can be reduced. Therefore, even if the skew angle is set so as to reduce the cogging torque 6f component, the IPM motor has a larger influence of the 12f component than the SPM motor, and thus has a problem of causing torque pulsation and deteriorating control performance.

  Therefore, by combining the stator stack structure described in the above embodiment with an IPM rotor (including rotor skew), for example, even when both the two components of the cogging torque 6f component and the 12f component are relatively large, It becomes possible to reduce the two frequency components of the cogging torque.

  As described above, since the IPM motor can suppress deterioration of controllability due to cogging torque, it is possible to obtain an effect that a high-speed magnet holding performance and a small amount of magnet can be obtained.

Embodiment 8 FIG.
FIG. 16 is a diagram showing a cogging torque adjusting method for a permanent magnet type motor according to Embodiment 8 of the present invention. In the cogging torque adjustment method according to the present embodiment, first, the cogging torque per unit thickness in each stator core is measured in advance (step 101), and the amplitude / frequency of each cogging torque frequency component of each stator core is determined. The phase data is accumulated (step 102). Thereafter, as described in the above embodiment, a plurality of stator cores are combined and laminated so that the cogging torque is reduced (step 103), and then the cogging torque is measured (step 104). As a result, if the cogging torque is reduced, the motor is manufactured using the combination of the stator cores as they are (step 105). If the cogging torque is large, phase-frequency analysis is performed (step 106), and then the number of laminated layers in each stator core is adjusted based on the amplitude / phase results of each frequency component measured in advance (step 107). Make a stator core. This is repeated in sequence to produce a stator core for the motor that is below a predetermined cogging torque value.

  As described above, according to the present embodiment, the manufacturing process can be corrected while adjusting the number of laminated stator cores based on the measurement data of the cogging torque of each stator core, thereby preventing a decrease in yield due to deterioration of the cogging torque. be able to.

Other embodiments.
In the above embodiment, an example in which two auxiliary grooves 4 are provided at the tip end portion of the teeth 2 of the stator core 1 at a position that is equally divided into three by the mechanical angle θ in the circumferential direction from the center of the slot opening 3a will be described. However, the number and position of the auxiliary grooves 4 are not limited to this. For example, as shown in FIG. 17, there are three auxiliary groove widths α, γ, α at mechanical angles θ, θ / 2, θ / 2, θ in the circumferential direction from the center of the slot opening 3a. Even if the present invention is applied to the stator core provided with the grooves 4, the same effect can be obtained. Further, the present invention can be similarly applied to the case of the number and positions of the other auxiliary grooves 4.

  The present invention described above can achieve the same effect even when applied to a linear motor using a permanent magnet.

  FIG. 18 is a schematic perspective view showing a linear motor according to another embodiment of the present invention. 18 includes a stator 28 having magnetic poles of a plurality of permanent magnets 26 and a mover 25 formed by laminating an iron core 21 having a plurality of teeth 22 facing the permanent magnets 26. An auxiliary groove 24 is provided on the surface facing the permanent magnet 26, and the groove width is varied depending on the position in the stacking direction of the iron core 28 including zero so that the auxiliary groove 24 reduces cogging torque. .

  In particular, the ratio (P1: P2) of the pitch P1 between the magnetic poles P1 of the permanent magnet 26 and the pitch P2 of the slot 23 between the teeth 22 is m: n, and the (l × k) f component (k is m) of the cogging torque. When the groove width angle of the auxiliary groove 24 at which the least common multiple of n, l is an integer of 1 or more, and f is the fundamental wave component) is the electrical angle α, the groove width angle of the auxiliary groove 24 is the electrical angle α. The smaller iron core 21 and the iron core 21 in which the groove width angle of the auxiliary groove 24 is larger than α in electrical angle are laminated.

  Further, the ratio (P1: P2) of the pitch P1 between the magnetic poles P1 of the permanent magnet 26 and the pitch P2 of the slot 23 between the teeth 22 is m: n, and the (l × k) f component (k is m) of the cogging torque. When the groove width angle of the auxiliary groove 24 that minimizes the least common multiple of n, l is an integer of 1 or more, and f is the fundamental wave component) is α, the iron core 21 without the auxiliary groove 24 and the auxiliary groove 24 It is characterized by being formed by laminating an iron core 21 having a groove width angle greater than α in electrical angle.

  Further, the ratio (P1: P2) of the pitch P1 between the magnetic poles P1 of the permanent magnet 26 and the pitch P2 of the slot 23 between the teeth 22 is m: n, and the groove width angle of the auxiliary groove 24 is an electrical angle of θ1 and θ2. When the magnitude of the cogging torque kf component (k is the least common multiple of m and n and f is the fundamental wave component) is Y1 and Y2, and the magnitude of the cogging torque 2kf component is Z1 and Z2, Y2 = −δ × Y1 , Z2 = −δ × Z1 (δ is a positive real number). The auxiliary groove 24 includes two types of iron cores 21 having a groove width angle of θ1 and θ2, and the groove width angle is θ1. The iron core 22 and the iron core 22 having a groove width angle of θ2 in electrical angle are laminated in the axial direction at a ratio of δ: 1.

  According to such a linear motor, since the iron cores having different auxiliary grooves including the groove width of zero are combined and laminated, the difference in the iron core material, the depth and angle of the auxiliary groove processing Even when the deviation occurs and the width of the auxiliary groove deviates from the optimum width, the cogging torque can be reduced while adjusting the lamination ratio of the stator core.

  In other words, the cogging torque can be adjusted only by changing the lamination ratio of the iron core, so it is only necessary to adjust the number of presses of the press machine for processing the iron core, and it is not necessary to precisely adjust the expensive press mold itself, and the cost is low. A linear motor having a cogging torque can be provided.

  In FIG. 18, the side having the magnetic pole of the permanent magnet 26 is the stator 28 and the side formed by laminating the iron core 21 having the plurality of teeth 22 is the mover 25, but the side having the magnetic pole of the permanent magnet is used. The same can be applied to the case where the movable element and the side formed by stacking the iron cores having a plurality of teeth are used as the stator.

1 stator core, 2 teeth, 3 winding slot, 4 auxiliary groove, 5 stator,
6 permanent magnets, 7 rotating shafts, 8 rotors, 10 permanent magnet type motors.

Claims (5)

A part of a surface of the teeth facing the permanent magnet, the rotor having a magnetic pole of a plurality of permanent magnets and a stator formed by laminating a stator core having a plurality of teeth facing the permanent magnet And the ratio of the number of magnetic poles of the rotor to the number of slots of the stator is m: n, and the (l × k) f component of cogging torque (k is the least common multiple of m and n, where l is an integer equal to or greater than 1 and f is the groove width angle of the auxiliary groove that minimizes the fundamental wave component), the stator has a groove width angle that is greater than α. A first stator core having the second stator core without the auxiliary groove, and a cogging torque of the first and second stator cores per unit stack length Are τc and τd, respectively, as shown in the following equations, A permanent magnet type motor characterized by laminating the stator cores.

The magnetic poles of the rotor are skewed in multiple stages in the axial direction, and the angle of the step skew is set to an angle that minimizes one of the kf component or the 2 kf component of the cogging torque. 2. The permanent magnet motor according to claim 1, wherein the cogging torque is combined so that the other of the kf component and the 2 kf component is minimized in the stage. The magnetic poles of the rotor are obliquely skewed in the axial direction, and the angle of the oblique skew is set to an angle that minimizes one of the kf component or the 2 kf component of the cogging torque, and the stack of the stator cores is 2. The permanent magnet type motor according to claim 1, wherein the permanent magnet type motor is combined so that the other of the kf component and the 2 kf component of the cogging torque is symmetrical with respect to the axial center of the skew skew. 4. The permanent magnet motor according to claim 1, wherein the rotor has a magnet embedded structure in which the permanent magnet is held inside a rotor core. 5. One of the stator or the mover has a plurality of magnetic poles of the permanent magnet, and the other of the stator or the mover is formed by laminating an iron core having a plurality of teeth facing the permanent magnet. An auxiliary groove is provided in a part of the surface facing the permanent magnet, and the ratio of the pitch between the magnetic poles of the plurality of permanent magnets to the pitch of the slots between the plurality of teeth is m: n, and the cogging torque When the groove width angle of the auxiliary groove that minimizes (l × k) f component (k is the least common multiple of m and n, l is an integer of 1 or more, and f is a fundamental wave component) is α as an electrical angle, The other of the stator and the mover is formed by laminating a first iron core having a groove width angle of the auxiliary groove larger than α in electrical angle and a second iron core without the auxiliary groove. The unit stacking length of the cogging torque of the first and second iron cores τc or size, respectively, if the .tau.d, a permanent magnet type linear motor, which comprises laminating the first and second core as shown in the following formula.

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