JP2003070192A - Rotating machine using built-in permanent magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotating machine using a built-in permanent magnets, which can reduce cogging torque without skewing the stator teeth of the rotat ing machine which has a fractional slot stator. SOLUTION: This device has a stator 100 which has stator windings of plural phases and a stator core 10 where a plurality of slots 10a are formed in the circumferential direction to wind stator windings, a rotor 200 which has a rotor core 15 where a plurality of permanent magnets 17a and 17b are arranged and built in the circumferential direction facing the stator core 10 at a fixed interval. A plurality of slots 10a formed on the stator core 10 are fractional slots. When the slot pitch of the slots 10a is τs , the number of poles of the stator 100 is p, the opening width of the slot 10a in the circumferential direction is Lop, and the inside diameter of the stator 100 is Ds, assuming N is a natural number and θ(mechanical angle) is the width in the circumferential direction of the surface of the outer circumference of the permanent magnets 17a and 17b, θ is nearly equal to [(360/p)-τs ×n±(Lop×360)/(π×Ds)}].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet-embedded rotating machine configured by embedding a plurality of permanent magnets in the circumferential direction of a rotor.

[0002]

2. Description of the Related Art In a permanent magnet-embedded rotary machine constructed by embedding a plurality of permanent magnets in the circumferential direction of a rotor, one method for reducing cogging torque (torque fluctuation when no current is applied) is as follows. It has been conventionally proposed to skew the teeth of the stator by one slot (or half slot) in the axial direction.

However, if the teeth of the stator are skewed, the winding is difficult to perform during winding and workability is deteriorated, which is a problem. For this reason, a method for reducing the cogging torque without skewing the teeth of the stator is desired.

In order to solve such a problem, for example, in Japanese Patent Laid-Open No. 11-299199, the width of the permanent magnet is set to an optimum value to reduce the cogging torque without skewing the teeth of the stator. A method has been proposed. FIG. 10 illustrates a conventional method of reducing the cogging torque by setting the width of the permanent magnet disclosed in JP-A No. 11-299199 to an optimum value.
FIG. 4 is a quarter sectional view in the circumferential direction of a permanent magnet embedded rotary machine having eight poles and 48 slots of phases.

In this prior art, the angle θ1 (formed by the circumferential width of the outer circumferential surface of the stator side of the plurality of permanent magnets 117 built in the rotor iron core 115 of the rotor 400 and the axial center of the rotor 400 ( Where mechanical slot angle is τs (mechanical angle) of the stator core 110 of the stator 300 and P is the number of poles,

[0006]

[Equation 4]

Set to. As a result, for example, 3 phase 8
It is possible to obtain the circumferential width θ (mechanical angle) of the permanent magnet that minimizes the cogging torque of the rotating machine having 48 poles, that is, an integer slot in which the number of slots for each pole and each phase is 2.

[0008]

However, the width θ of the permanent magnet disclosed in the above-mentioned Japanese Patent Laid-Open No. 11-299199.
The formula for obtaining is not applicable to a rotating machine having a so-called fractional slot stator in which the number of slots for each pole and each phase is not an integer. That is, an appropriate value cannot be obtained for a rotating machine having a stator with a fractional slot. The fractional slot stator is used for the purpose of reducing torque ripple, for example.

The present invention has been made in order to solve the above problems, and even in a rotating machine having a stator with a fractional slot, the cogging torque can be reduced without skewing the teeth of the stator. The purpose is to obtain an embedded rotating machine.

[0010]

A permanent magnet embedded rotary machine according to the present invention has a plurality of stator windings of a plurality of phases and a plurality of slots formed in the circumferential direction for winding the stator windings. A stator having a stator core and a rotor having a rotor core in which a plurality of permanent magnets are arranged in the circumferential direction and face each other with a predetermined gap in the stator core In the permanent magnet embedded rotating machine in which the plurality of slots provided are fractional slots, the slot pitch of the slots is τ
s, the number of poles of the stator is p, and the circumferential opening width of the slot is Lo
where p is the inner diameter of the stator and n is a natural number, the circumferential width θ (mechanical angle) of the outer peripheral surface of the permanent magnet is

[0011]

[Equation 5]

[0012]

Also, the permanent magnet embedded rotary machine according to the present invention comprises a stator winding having a plurality of phases and a stator core having a plurality of slots formed in the circumferential direction for winding the stator winding. A stator having a rotor and a rotor having a rotor core in which a plurality of permanent magnets are arranged in a circumferential direction and face each other with a predetermined gap in the stator core; In a permanent magnet embedded type rotating machine in which the slots are fractional slots, when the slot pitch of the slots is τs, the number of poles of the stator is p, the circumferential opening width of the slot is Lop, and the inner diameter of the stator is Ds, Circumferential width θ of the outer peripheral surface of the magnet
(Mechanical angle)

[0014]

[Equation 6]

It is assumed that

Further, the permanent magnet embedded rotary machine according to the present invention comprises a stator winding of three phases and a stator core having 36 slots formed in the circumferential direction for winding the stator winding. A stator having eight poles and a rotor having a rotor core that is opposed to the stator core with a predetermined gap and has a plurality of permanent magnets arranged in the circumferential direction and provided therein are provided. In the permanent magnet embedded rotary machine, the circumferential width θ of the outer peripheral surface of the permanent magnet
(Mechanical angle)

[0017]

[Equation 7]

It is assumed that

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 is a quarter sectional view in the circumferential direction showing a first embodiment of a permanent magnet embedded rotary machine of the present invention. Since the stator 100 of the permanent magnet embedded type rotating machine shown in FIG. 1 has three phases and eight poles and 36 slots as described below, the number of slots for each pole and each phase is 1.5,
The number of slots for each pole and each phase is a non-integer so-called fractional slot. Note that this configuration is used as an example for description, and the present invention is not limited to the 3-phase 8-pole 36-slot.

In FIG. 1, the stator 100 is manufactured by punching out steel plates and stacking the steel plates.
The stator core 10 in which a is formed at equal intervals in the circumferential direction is manufactured by winding a three-phase winding (not shown) between each slot 10a.

On the other hand, the rotor 200 has a cylindrical rotor core 15 made by punching steel plates and laminating the steel plates, and the rotor core 15 is provided so as to penetrate through the rotor core 15 in the axial direction. The permanent magnets 17a, 17 are provided in the permanent magnet insertion holes 15a.
b is inserted and manufactured. The permanent magnets 17a and 17b may be magnetized before being inserted, or may be magnetized after being inserted. A minute gap 14 is formed as a rotation gap between the stator 100 and the rotor 200.

The present invention limits the size and shape of the permanent magnets 17a and 17b in the circumferential direction. In the permanent magnet embedded rotary machine of the present embodiment, the slot pitch of the slots 10a is τs, and the stator. When the number of poles of 100 is p, the circumferential opening width of the slot 10a is Lop, and the inner diameter of the stator 100 is Ds, n is a natural number and the permanent magnet 17
The circumferential width θ (mechanical angle) of the outer peripheral surfaces of a and 17b is

[0023]

[Equation 8]

It is said that. θ and τs are angles and the unit is degrees or deg. Ds and Lop are lengths and the unit is mm. By setting the width of the permanent magnets in such a relationship, it is possible to obtain a permanent magnet embedded rotary machine with low cogging torque. In the equation, ≅ represents a range of about ± 1 degree.

A detailed description will be given below with reference to the drawings. The cogging torque is a torque pulsation when there is no energization, and is caused by the stator slot 10a. In order to investigate the cogging torque in detail, an analysis was performed using the linear motor shown in FIG. 2 as a model. The model of this linear motor is composed of a stator 24 having a stator core 21 having only one slot 20 and a rotor 25 having a rotor core 23 having a permanent magnet 22 built therein. A void 26 is formed between the child 25 and the child 25.

The analysis is performed as follows. That is, the rotor 25 with the built-in permanent magnet 22 advances in the right direction in FIG. 2 as indicated by an arrow A in the figure, and requires 20 steps to reach the right end of the permanent magnet 22 to the left end of the slot 20. It takes 20 steps and the right end of the permanent magnet 22 is slot 2
The right edge of 0 is reached. Then, the thrust of each step generated during the movement is measured. In the model, the width of the permanent magnet 22 is so large that it does not affect the analysis.
It is said that it is possible to consider only the influence of the right edge of.

The results of the above analysis are shown in FIG. From FIG. 3, the thrust gradually increases from step 20 when the right end of the permanent magnet 22 reaches the left end of the slot 20.
It can be seen that the right end of 2 reaches the right end of the slot 20 and becomes maximum at 40 steps. On the contrary, when the permanent magnet 22 exits the slot 20 (not shown), the thrust is maximum when the left end of the permanent magnet 22 reaches the left end of the slot 20 (the same value as when entering the slot 20 described above, and the reference numeral is the same). (Opposite), the thrust gradually decreases, and becomes 0 when the left end of the permanent magnet 22 reaches the right end of the slot 20.

The thrust in this analysis can be considered as the cogging torque of the permanent magnet embedded rotary machine. From these facts, when the width of the permanent magnet 17a is appropriately controlled in the rotating machine, the position where the cogging torque when the permanent magnet 17a enters the slot 10a becomes the maximum and the cogging torque when the permanent magnet 17a exits the slot 10a. It is possible to reduce the cogging torque by adjusting the phase of the position where the maximum value is obtained, and it is possible to obtain a permanent magnet embedded rotary machine with a low cogging torque.

In obtaining a permanent magnet embedded rotary machine having a low cogging torque by such a method, in the case of a fractional slot, it is impossible to match the phase with the permanent magnet 17a having one pole, so that the permanent magnet for two poles is used. The magnets 17a and 17b are used to match the phases.

When these matters are applied to a permanent magnet embedded type rotary machine having a fractional slot of three phases, eight poles and 36 slots, FIG.
As shown in. That is, the permanent magnet 1 on the right side of FIG.
When the right end of 7a is located at the right end of slot 10a1,
The left end of the permanent magnet 17b on the left side of FIG. 4 is the slot 10a2.
Place it so that it is the left edge of. On the contrary, when the right end of the right permanent magnet 17a is located at the left end of the slot 10a1, the left end of the left permanent magnet 17b may be located at the right end of the slot 10a2.

When the above is expressed by an equation, the slot 10a
Where s is the slot pitch, p is the number of poles of the stator 100, Lop is the circumferential opening width of the slot 10a, and Ds is the inner diameter of the stator 100, where n is a natural number and the permanent magnet 1
The circumferential width θ (mechanical angle) of the outer peripheral surfaces of 7a and 17b is

[0032]

[Equation 9]

It follows that In addition, in order to explain each variable, it is illustrated in FIG.

Next, the verification using the finite element method will be performed. 3 phase 8 pole 36 slot, slot opening width is 3m
The cogging torque was analyzed by changing the width θ of the permanent magnet with a permanent magnet embedded type rotating machine having a m and a stator inner diameter of 134 mm. The result is shown in FIG. When the width of the permanent magnet is reduced, the amount of magnetic flux is reduced, so that the value of cogging torque is reduced, and there are some areas where the value becomes smaller. Applying to equation (1), θ = 7.5, 12.5,
17.5, 22.5, 27.5, 32.5,
It becomes 37.5 and 42.5, and it turns out that the calculation result of Formula (1) and the analysis result of FIG. 6 are equal.

Here, Japanese Patent Laid-Open No. 11-
The equation for finding the width θ1 of the permanent magnet disclosed in Japanese Patent No. 299199 and the equation (1) for finding the width θ of the permanent magnet according to the present embodiment will be compared.

In the case of a fractional slot permanent magnet embedded rotary machine with 8 poles and 36 slots as an example, the mechanical angle of the slot opening width is 2.5 degrees, and 16 / p is 2 degrees, and the last term on the right side of both is The values are almost the same. Since the number of slots is 36, τs = 10 degrees, and using the formula (1) of the present embodiment, the permanent magnet width θ becomes θ = 45−10n + 2.5, that is, 42.5 degrees, 37. 5 degrees, 32.
5 degrees, 27.5 degrees, 22.5 degrees, 17.5 degrees, 1
It becomes 2.5 degrees, 7.5 degrees, and 2.5 degrees.

On the other hand, using the formula of Japanese Patent Application Laid-Open No. 11-299199, the width θ of the permanent magnet is θ1 = 10n + 2, so 42 °, 32 °, 22 °, 12 °,
It will be twice. When these calculation results are compared with the analysis results shown in FIG. 6, all the values that minimize the cogging torque are shown when the formula (1) of the present embodiment is used. It can be seen that the formula of -299199 gazette does not satisfy all the conditions for minimizing the cogging torque.

That is, the formula of Japanese Patent Laid-Open No. 11-299199 represents the value that minimizes the cogging torque in the case of integer slots, but it can express all the values that minimize the cogging torque when applied to fractional slots. It turns out that not.

From the above, in the permanent magnet embedded type rotating machine of this embodiment, a plurality of slots 10a are formed in the circumferential direction for winding the stator windings of a plurality of phases and the stator windings. A rotor 100 having a fixed stator core 10 and a rotor core 1 in which a plurality of permanent magnets 17a and 17b are arranged in the circumferential direction so as to face the stator core 10 with a predetermined gap and are housed therein.
In the permanent magnet embedded type rotating machine including the rotor 200 having 5 and the plurality of slots 10a formed in the stator core 10 are fractional slots, the slot pitch of the slots 10a is τs, and the number of poles of the stator 100 is P, slot 1
The circumferential opening width of 0a is Lop, and the inner diameter of the stator 100 is D
Let s be a natural number and permanent magnets 17a, 1
The circumferential width θ (mechanical angle) of the outer peripheral surface of 7b

[0040]

[Equation 10]

It is assumed that Therefore, even in a rotating machine having a stator with a fractional slot, the cogging torque can be reduced without skewing the teeth of the stator core 10.

For the sake of explanation, the permanent magnets 17a. 17
Although b has a trapezoidal cross section, a similar effect can be obtained with a trapezoid with an inverted cross section or a rectangular cross section as long as the magnet width of the outer peripheral surface on the stator side satisfies the condition. Further, the permanent magnet may be slightly skewed to the extent of manufacturing error.

Embodiment 2. With respect to the width θ of the permanent magnet represented by the equation (1) of the first embodiment, the cogging torque can be reduced even if n is a natural number. However, the smaller n is, the larger the torque of the rotating machine becomes.
When n = 1, the width θ of the permanent magnet is

[0044]

[Equation 11]

The torque characteristic can be made better by using the above method, as compared with the case other than n = 1.

For example, FIG. 7 shows an example where n = 1. Also n
= 2 is shown in FIG. Both of the rotating machines in both figures have a small cogging torque, but the torque when energized is 1
It is clear that the larger the width of 7a and 17b is, the larger the width of 7a and 17b is, and the permanent magnet embedded rotary machine of FIG. 8 is superior to the permanent magnet embedded rotary machine of FIG. Other configurations are similar to those of the first embodiment.

From the above, in the permanent magnet embedded rotary machine of the present embodiment, a plurality of slots 10a are formed in the circumferential direction for winding the stator windings of a plurality of phases and the stator windings. A rotor 100 having a fixed stator core 10 and a rotor core 1 in which a plurality of permanent magnets 17a and 17b are arranged in the circumferential direction so as to face the stator core 10 with a predetermined gap and are housed therein.
In the permanent magnet embedded type rotating machine including the rotor 200 having 5 and the plurality of slots 10a formed in the stator core 10 are fractional slots, the slot pitch of the slots 10a is τs, and the number of poles of the stator 100 is P, slot 1
The circumferential opening width of 0a is Lop, and the inner diameter of the stator 100 is D
where s is the circumferential width θ (mechanical angle) of the outer peripheral surfaces of the permanent magnets 17a and 17b,

[0048]

[Equation 12]

It is assumed that Therefore, it is possible to obtain a more excellent rotating machine having a large torque when energized.

Embodiment 3. Due to the saturation of magnetic flux,
A harmonic magnetic flux with an odd number of times the power supply frequency is generated. And
Of these, it has been found that a harmonic of 5 times the power supply frequency is the main cause of torque ripple. This 5 times higher harmonic can be minimized by setting the width of the permanent magnet to θe = 360n / 5, where θe is the width (electrical angle) of the permanent magnet and n is a natural number. FIG. 9 shows a schematic diagram of the relationship between the amplitude of the fifth harmonic and the width of the permanent magnet.

As can be seen from FIG. 9, θe = 72,144
The fifth harmonic is minimized and the torque ripple is minimized. In an 8-pole rotating machine, θ = 18,36.

From the above, in the three-phase eight-pole, 36-slot embedded permanent magnet rotary machine, by setting θ≈37.5 degrees, the cogging torque is small and the torque ripple is small. A rotary machine can be provided. Other configurations are similar to those of the first embodiment.

From the above, the permanent magnet embedded rotary machine according to the present embodiment is provided with 36 slots 10a in the circumferential direction for winding the three-phase stator winding and the stator winding. Stator 100 having a stator core 10 and eight poles
And a rotor 200 having a rotor core 15 facing the stator core 10 with a predetermined gap and having a plurality of permanent magnets 17a and 17b arranged in the circumferential direction and embedded therein. In the rotating machine, the circumferential width θ (mechanical angle) of the outer peripheral surfaces of the permanent magnets 17a and 17b is

[0054]

[Equation 13]

It is assumed that Therefore, it is possible to obtain a better rotating machine having both a cogging torque and a torque ripple.

Needless to say, the structure of the present invention may be applied not only to a permanent magnet embedded type rotating machine but also to a linear motor in which a permanent magnet is embedded. Further, it goes without saying that it may be applied to an outer rotor type rotating machine (where the rotor is arranged outside the stator).

[0057]

The permanent magnet embedded rotary machine according to the present invention includes a stator winding having a plurality of phases and a stator core having a plurality of slots formed in the circumferential direction for winding the stator winding. A stator having a rotor and a rotor having a rotor core in which a plurality of permanent magnets are arranged in a circumferential direction and face each other with a predetermined gap in the stator core; In a permanent magnet embedded type rotating machine in which the slots are fractional slots, when the slot pitch of the slots is τs, the number of poles of the stator is p, the circumferential opening width of the slot is Lop, and the inner diameter of the stator is Ds, n Is a natural number, and the circumferential width θ (mechanical angle) of the outer peripheral surface of the permanent magnet is

[0058]

[Equation 14]

It is assumed that Therefore, even in a rotating machine having a stator with a fractional slot, the cogging torque can be reduced without skewing the teeth of the stator.

Further, the permanent magnet embedded rotary machine according to the present invention comprises a stator winding having a plurality of phases and a stator core having a plurality of slots formed in the circumferential direction for winding the stator winding. A stator having a rotor and a rotor having a rotor core in which a plurality of permanent magnets are arranged in a circumferential direction and face each other with a predetermined gap in the stator core; In a permanent magnet embedded type rotating machine in which the slots are fractional slots, when the slot pitch of the slots is τs, the number of poles of the stator is p, the circumferential opening width of the slot is Lop, and the inner diameter of the stator is Ds, Circumferential width θ of the outer peripheral surface of the magnet
(Mechanical angle)

[0061]

[Equation 15]

It is assumed that Therefore, it is possible to provide a more excellent rotating machine having a large torque when energized.

Further, the permanent magnet embedded rotary machine according to the present invention comprises a stator winding of three phases and a stator core having 36 slots formed in the circumferential direction for winding the stator winding. A stator having eight poles and a rotor having a rotor core that is opposed to the stator core with a predetermined gap and has a plurality of permanent magnets arranged in the circumferential direction and provided therein are provided. In the permanent magnet embedded rotary machine, the circumferential width θ of the outer peripheral surface of the permanent magnet
(Mechanical angle)

[0064]

[Equation 16]

It is assumed that Therefore, it is possible to provide a more excellent rotating machine that has a small cogging torque and a small torque ripple.

[Brief description of drawings]

FIG. 1 is a ¼ circumferential sectional view showing a first embodiment of a permanent magnet embedded rotary machine of the present invention.

FIG. 2 is a side sectional view of a model of a linear motor for examining cogging torque.

FIG. 3 is a graph showing a result of analysis of a model of a linear motor.

FIG. 4 is a quarter sectional view in the circumferential direction of a rotary machine for explaining phase matching using permanent magnets for two poles in a three-phase eight-pole 36-slot fractional-slot embedded permanent magnet rotary machine. Is.

FIG. 5 is a quarter sectional view in the circumferential direction of the rotating machine in which each variable is entered to explain each variable of the equation (1).

FIG. 6 is a graph showing the results of analysis of cogging torque using the finite element method.

FIG. 7 is a quarter sectional view in the circumferential direction of a rotating machine showing an example when n = 1 in the equation (1).

FIG. 8 is a ¼ circumferential sectional view of the rotating machine showing an example when n = 2 in the equation (1).

FIG. 9 is a graph showing the relationship between the amplitude of the fifth harmonic and the width of the permanent magnet.

FIG. 10: Three-phase 8 for explaining a conventional method of reducing the cogging torque by setting the width of the permanent magnet to an optimum value.
It is a quarter cross-sectional view of a rotating machine having 48 poles.

[Explanation of symbols]

10 stator core, 10a slot, 15 rotor core, 15a permanent magnet insertion hole, 17a, 17b permanent magnet, 100 stator, 200 rotor, τs slot pitch, Lop slot circumferential opening width, Ds stator Inner diameter, θ Circumferential width of permanent magnet (mechanical angle).

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroki Matsubara             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Hidetoshi Teruyama             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 5H002 AA04 AA09 AB07 AE08                 5H621 AA02 GA01 HH01 JK02 JK05                       PP10                 5H622 AA02 CA02 CA07 CB05 PP11                       QB02

Claims (3)

[Claims] 1. A stator having a stator winding of a plurality of phases and a stator core having a plurality of slots formed in a circumferential direction for winding the stator winding, and a predetermined stator core. A rotor having a rotor core in which a plurality of permanent magnets facing each other with a gap are arranged in the circumferential direction and incorporated therein, and the plurality of slots formed in the stator core are fractional slots. In the embedded rotary machine, when the slot pitch of the slots is τs, the number of poles of the stator is p, the circumferential opening width of the slot is Lop, and the inner diameter of the stator is Ds, n is a natural number, and The circumferential width θ (mechanical angle) of the outer peripheral surface of the permanent magnet is given by A permanent magnet embedded rotating machine characterized by the following. 2. A stator having a stator winding of a plurality of phases and a stator core having a plurality of slots formed in a circumferential direction for winding the stator winding, and a predetermined stator core. A rotor having a rotor core in which a plurality of permanent magnets facing each other with a gap are arranged in the circumferential direction and incorporated therein, and the plurality of slots formed in the stator core are fractional slots. In the embedded rotary machine, when the slot pitch of the slots is τs, the number of poles of the stator is p, the circumferential opening width of the slot is Lop, and the inner diameter of the stator is Ds, the outer peripheral surface of the permanent magnet is The circumferential width θ (mechanical angle) of A permanent magnet embedded rotating machine characterized by the following. 3. A stator having a three-phase stator winding and a stator core having 36 slots formed in the circumferential direction for winding the stator winding and having eight poles. A rotor with a rotor core that faces the stator core with a predetermined gap and has a plurality of permanent magnets arranged in the circumferential direction in the rotor. The circumferential width θ (mechanical angle) of the outer peripheral surface of the magnet is given by A permanent magnet embedded rotating machine characterized by the following.