JP2016092974A - Rotor structure of ipm motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide torque higher than conventional one by setting arrangement of magnets in a rotor yoke on predetermined positions.SOLUTION: A rotor structure of an IPM motor includes a rotor yoke (1) fitted to a rotary shaft (2) and composed of a magnetic material and even magnets arranged in the rotor yoke (1) along a radial direction. In the respective magnets (3), a pair of magnets (3) constitute one pair-pole (30) and the pair-pole (30), when being observed from an axial direction, is arranged like a V-shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rotor structure of an IPM motor, and in particular, among magnets provided in a rotor, a pair of magnets constitutes a single pole that is one pole, and as a V-shaped arrangement, a higher torque than conventional is provided. It relates to a new improvement to be obtained.

The name of the literature is not particularly shown as a conventional rotor structure of the motor, but as a first conventional configuration, as shown in FIGS. 4 to 6, the rotor 10 provided on the rotary shaft 2 has a structure. A plurality of segment magnets 3 are attached to the circumference of the rotor yoke 1 via a spacer 4 on the circumference.
Further, as a second conventional example, as shown in FIGS. 7 to 9, a ring magnet 3A is fitted on the outer periphery of the rotor yoke 1 of the rotor 10 fitted to the rotary shaft 2, and this ring magnet 3A has a predetermined angle. N poles and S poles are magnetized at intervals.

  The rotor 10 having the first and second conventional configurations shown in FIGS. 4 and 7 belongs to a so-called well-known SPM (Surfacial Permanent Magnet) structure. As a structure other than the SPM structure, FIG. 11, for example, a well-known IPM (Internal Permanent Magnet) structure disclosed in Patent Document 1 is used, and a plurality of magnets 3 are embedded in a rotor yoke 1 held by a rotating shaft 2. One magnet 3 forms an N pole or S pole as one magnetic pole. The rotor 10 is rotatably disposed inside the stator 11.

JP 2013-106388 A

Since the conventional rotor structure of the motor is configured as described above, the following problems exist.
That is, in the structure in which the segment magnet is attached to the rotor surface, it is necessary to take measures to prevent scattering of the magnet, and for this reason, the gap becomes wide, so it is difficult to obtain a large torque constant for the same magnet volume. It was. In addition, when a method such as wire cutting is used as a method of shaping the shape of the magnet, the amount of usable magnets that can be taken out from a rectangular magnet member of the same volume will be reduced, so that it can be used for the usable magnets. There was a disadvantage that the price was high.
On the other hand, in the case of a ring magnet, since it is not necessary to take measures to prevent scattering of the magnet, the gap can be narrowed, but there is a demerit that the cost and the manufacturing cost of the magnet alone are high and the cost is high.

In general, in the calculation of torque characteristics without considering saturation of the yoke (stator and rotor), the torque constant of the motor is the gap permeance [Lm / (Lm + Lg) where Lm: magnet thickness (in the magnetic path) It is known that it is proportional to the length of the magnet (Lg: gap length (the length of the gap in the magnetic path))] and the surface area of the magnet (the cross-sectional area of the magnetic path). The surface area is
2 × π × Rr × lm / Np (where Rr: outer radius of rotor, lm: axial thickness of rotor (product thickness), Np: number of poles)]
It is structurally impossible to make it larger.

  Further, in the conventional configuration shown in FIG. 10 and FIG. 11, the magnet arrangement structure similar to the configuration of the present invention is shown, but only one magnet constitutes one magnetic pole, It is not intended to increase the torque as in the present invention, but by adjusting the circumferential width of the protrusion 12 formed to protrude from the outer periphery of the rotor yoke 1, the teeth 13 of the stator 11 and In this configuration, the cogging torque is adjusted by adjusting the degree of magnetic coupling, which is different from the configuration for increasing the torque as in the present invention.

  The present invention has been made to solve the above-described problems, and in particular, among each magnet provided in the rotor, a pair of one pole, which is one pole, constitutes a V-shaped arrangement, An object of the present invention is to provide a rotor structure of an IPM motor that can obtain a higher torque than before.

  A rotor structure of an IPM motor according to the present invention includes a rotor yoke made of a magnetic material provided on a rotating shaft, and an even number of magnets provided in the rotor yoke along a radial direction at predetermined angular intervals, Each magnet constitutes a pair of poles, which is one pole, and the pair of poles is arranged in a V shape when viewed from the axial direction. It is the structure formed with the magnetic material.

Since the rotor structure of the IPM motor according to the present invention is configured as described above, the following effects can be obtained.
That is, a rotor yoke made of a magnetic material provided on a rotating shaft, and an even number of magnets provided in the rotor yoke along a radial direction at a predetermined angular interval, each magnet being a pair of the magnets A pair of poles, which are one pole, is configured, and when the pair of poles is viewed from the axial direction, a high torque constant and a low price can be realized by being configured in a V shape.
In addition, since the rotating shaft is formed of a non-magnetic material, a magnetic flux that does not contribute to torque is generated on the magnet shaft side and does not contribute to torque. However, the magnetic flux rotating in the rotor is reduced as much as possible. Can do. Further, since the rotor yoke can be directly provided on the rotating shaft, the assembly of the rotor is facilitated.

It is a top view which shows the rotor structure of the IPM motor by this invention. It is a magnetic flux diagram of the rotor structure of FIG. It is explanatory drawing which shows the magnetic flux density of the rotor structure of FIG. It is a top view which shows the 1st conventional structure of the rotor structure of the conventional IPM motor. FIG. 5 is a magnetic flux diagram of the rotor structure of FIG. 4. It is explanatory drawing which shows the magnetic flux density of the rotor structure of FIG. It is a top view which shows the 2nd conventional structure of the rotor structure of the conventional IPM motor. FIG. 8 is a magnetic flux diagram of the rotor structure of FIG. 7. It is explanatory drawing which shows the magnetic flux density of the rotor structure of FIG. It is a top view which shows the rotor structure of the conventional IPM motor. It is sectional drawing of FIG. It is a diagram which shows the torque constant of a conventional structure and this invention structure. It is a diagram which shows the induced voltage waveform of a conventional structure and this invention structure.

  In the rotor structure of the IPM motor according to the present invention, among the magnets provided in the rotor, a pair of magnets constitutes a single pole, which is one pole, and a V-shaped arrangement provides higher torque than before. It is.

Hereinafter, preferred embodiments of a rotor structure of an IPM motor according to the present invention will be described with reference to the drawings.
In addition, the same code | symbol is attached | subjected and demonstrated to a part the same as that of a prior art example, or an equivalent part.
In FIG. 1, what is indicated by reference numeral 1 is a cylindrical rotor yoke fitted on the outer periphery of a rotating shaft 2 made of a nonmagnetic material such as austenitic stainless steel. A plurality of grooves 20 are formed in the radial direction at angular intervals.

Each groove 20 is formed in a longitudinal shape along the axial direction of the rotor yoke 1, and a magnet 3 having a longitudinal plate shape is inserted and fixed in each groove 20.
The length Lma of each magnet 3 along the radial direction of the rotor yoke 1 is equal to the radial thickness of the rotor yoke 1.

A rotor 10 is formed by the rotor yoke 1, the magnet 3 and the rotating shaft 2. Each of the magnets 3 is embedded in the configuration of FIG. 1, but one pole is formed by a pair of magnets 3 directly adjacent to each other. The pair of electrodes 30 is formed.
That is, by forming the N pole or the S pole by the pair of poles 30, in the case of the configuration of the rotor 10 of FIG. 1, five pairs of poles are formed by the five pairs of poles 30. In FIG. 2, the magnetic flux density is shown in FIG.

  The pair of magnets 3 constituting the pair of poles 30 are configured to have a V-shape in the plan view or the side view seen from the axial direction of FIG.

A stator 11 having a plurality of projecting magnetic poles 13 projecting inward at predetermined angular intervals is provided outside the rotor 10, and a stator winding 11A is wound around each projecting magnetic pole 13. .
The rotor yoke 1 of the rotor 10 and the outer ends of the magnets 3 are rotatably provided with respect to the inner ends of the projecting magnetic poles 13 through a slight gap G.

Next, the gap permeance and the surface area of the magnet 3 (the cross-sectional area of the magnetic path) of the IPM motor according to the present invention have the relationship described in the above paragraph 0006,
Lmb / (Lmb + Lg) [where Lmb: length in the direction perpendicular to the radial direction of the magnet = length parallel to the magnetic path, Lg: gap length (gap length in the magnetic path)]
Lma × lm [where Lma: length in the radial direction of the magnet = length perpendicular to the magnetic path, lm: axial thickness of the rotor (stack thickness)]
Given in.

Here, the maximum value of Lmb decreases as the number of rotor poles increases, but the maximum value of Lma is given by (rotor outer radius−axis radius) and does not depend on the number of rotor poles. . Accordingly, in a motor having a large outer diameter of the rotor and a large number of poles, it is possible to greatly exceed the surface area of the magnet that can be achieved by SPM.
Of the gap permeance and the magnet surface area, which are parameters proportional to the torque constant, the gap permeance does not increase in proportion to the thickness of the magnet 30 (if the thickness increases to some extent compared to the gap, Even if the amount of magnet is increased (Lmb is increased), the gap permeance does not increase so much), the surface area of the magnet 30 is proportionally increased when the radial length Lma of the magnet 30 is increased. The constant also increases. Therefore, taking this Lma as long as possible increases the torque constant of the motor.
Therefore, in the magnet arrangement according to the present invention, since one pole is composed of the pair of magnets 30 formed by the pair of magnets 30 and arranged in a V shape, the magnet surface area in the magnetic path cross section is reduced. The structure that can be the largest.

In the case of an IPM motor, a magnetic flux that does not contribute to torque is generated in the rotor 10 mainly on the shaft side of the magnet 30, but in order to reduce the magnetic flux that rotates in the rotor 10 as much as possible, in the present invention, The rotating shaft 2 is made of a nonmagnetic material (for example, austenitic stainless steel). When using a magnetic material for the rotating shaft 2, although not shown, a method of providing an air hole or the like on the inner end side of the rotor yoke 1 for reducing the magnetic flux rotating in the rotor 10 as much as possible is also conceivable.
As described above, in a relatively large motor having a long distance from the outer diameter of the rotor 10 to the rotating shaft 2 and a motor having a large number of poles, the IPM having the rotor structure according to the present invention can achieve the highest torque constant. it can.

Next, in order to compare the superiority and inferiority of the torque constant due to the arrangement of the magnet 30 in the rotor structure of the IPM motor according to the present invention, the three motors of SPM (segment magnet), SPM (ring magnet) and IPM (structure of the present invention) are compared. The shape of the stator 11 is the same, and the volume of the magnet 30 is also the same.
The theoretical induced voltage waveforms of these three motors are shown in FIG.
FIG. 12 shows a comparison result of torque constants of the three motors obtained from the induced voltage waveform shown in FIG.
Each figure mentioned above is the analysis result (theoretical value which a motor shape has) calculated | required by the finite element method.
As shown by this result, the IPM motor according to the present invention has about 39% of the SPM segment magnet motor and about the SPM ring magnet even though it has the same magnet volume as the other SPM motor. It was revealed that the torque constant was as large as 26 [%].
Therefore, also from the characteristic comparison results of FIGS. 12 and 13, the IPM motor having the rotor structure according to the present invention has the highest torque constant among the above three motors, and the lowest price from the shape of the magnet. Is.

The gist of the rotor structure of the IPM motor according to the present invention is as follows.
That is, it has a rotor yoke 1 made of a magnetic material provided on the rotary shaft 2 and an even number of magnets 3 provided in the rotor yoke 1 along a radial direction at a predetermined angular interval. The pair of magnets 3 constitutes a pair of poles 30 that are one pole, and the pair of poles 30 are arranged in a V shape when viewed from the axial direction. It is the structure formed with the nonmagnetic material.

  In the rotor structure of the IPM motor according to the present invention, among the magnets provided in the rotor, a pair of magnets forms a single pole, which is one pole, and as a V-shaped arrangement, a higher torque than before can be obtained. it can.

DESCRIPTION OF SYMBOLS 1 Rotor yoke 2 Rotating shaft 3 Magnet 10 Rotor 11 Stator 11A Stator winding 13 Protruding magnetic pole 20 Groove 30 Single pole G Gap

Claims (2)

A rotor yoke (1) made of a magnetic material provided on the rotating shaft (2), and an even number of magnets (3) provided in the rotor yoke (1) along the radial direction at predetermined angular intervals. ,
Each of the magnets (3) is a pair of magnets (3) that constitutes one pole (30) as one pole, and the pair of poles (30) are arranged in a V shape when viewed from the axial direction. A rotor structure for an IPM motor, characterized in that   The rotor structure of an IPM motor according to claim 1, wherein the rotating shaft (2) is made of a nonmagnetic material.

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