Stator structure of a rotating machine

Abstract

This invention provides a stator structure for a rotating machine that can suppress cogging torque. [Solution] The stator structure 1 of the rotating machine, as shown in Figures 1 and 2, is a stator structure of a rotating machine having a permanent magnet field rotor and a stator 2 on which windings 3 are concentrated, wherein the stator 2 has a plurality of teeth 21 and is equally divided in the circumferential direction. The number of divisions of the stator 2 is a number that excludes 1 from the divisors of the number of teeth, the greatest common divisor of the number of magnetic poles and the number of teeth, and integer multiples of the greatest common divisor.

Description

Technical Field

[0001] The present invention relates to a stator structure of a rotating machine.

Background Art

[0002] Conventionally, as a fixed core of a motor, a split fixed core in which a plurality of segments each having a plurality of salient poles are arranged in a substantially annular shape has been proposed (see, for example, Patent Document 1). In the split fixed core of the motor described in Patent Document 1, the boundary positions of the segments are set so that the amount of magnetic flux passing through the segment boundaries during energization is substantially the same, thereby suppressing the imbalance of the magnetic attraction force acting between the segments.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the fixed core is divided as in the split fixed core described in Patent Document 1, there may be errors in the dimensions of each segment and relative misalignment when assembling the segments, and it may be difficult to ensure the roundness of the core after assembly. When the roundness of the core decreases, cogging torque is likely to occur, and suppression of cogging torque has been desired.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a stator structure of a rotating machine capable of suppressing cogging torque.

Means for Solving the Problems

[0006] To solve the above problems, the stator structure of a rotating machine according to the present invention is a stator structure of a rotating machine having a permanent magnet field rotor and a stator with concentrated windings, wherein the stator has a plurality of teeth and is equally divided in the circumferential direction, and the number of divisions of the stator is a number that excludes 1 from the divisors of the number of teeth, the greatest common divisor of the number of magnetic poles and the number of teeth, and integer multiples of the greatest common divisor.

[0007] According to this embodiment, even if the roundness of the stator decreases due to manufacturing errors or the like, it is possible to suppress cogging torque with the same number of components as the number of magnetic poles (for example, the 8th order component in the case of 8 magnetic poles).

[0008] The number of divisions of the stator may be a number that excludes 1 from the divisors of the number of teeth, the common divisor of the number of magnetic poles and the number of teeth, and integer multiples of the common divisor. According to this embodiment, the cogging torque of the same number of components as the number of magnetic poles can be further suppressed. [Effects of the Invention]

[0009] The stator structure of the rotating machine according to the present invention can suppress cogging torque. [Brief explanation of the drawing]

[0010] [Figure 1] This is a plan view showing the stator and windings of the stator structure of a rotating machine according to an embodiment of the present invention. [Figure 2] This is a plan view showing the stator of a stator structure of a rotating machine according to an embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will now be described with reference to the drawings. The stator structure 1 of a rotating machine according to an embodiment of the present invention is a stator structure of a rotating machine having a permanent magnet field rotor and a stator 2 on which windings 3 are concentrated, as shown in Figures 1 and 2, wherein the stator 2 has a plurality of teeth 21 and is equally divided in the circumferential direction. The number of divisions of the stator 2 is a number that excludes 1 from the divisors of the number of teeth, the greatest common divisor of the number of magnetic poles and the number of teeth, and integer multiples of the greatest common divisor.

[0012] Here, Figure 1 is a plan view showing the stator 2 and winding 3 of the stator structure 1 of a rotating machine according to an embodiment of the present invention, and Figure 2 is a plan view showing the stator 2.

[0013] The stator structure 1 of the rotating machine according to the embodiment of the present invention is a stator structure for an inner rotor type and permanent magnet type brushless DC motor. In an outer rotor type motor, a number of divisions like that of the stator 2 described below may be adopted. Furthermore, the rotating machine is not limited to a motor, but may also be a generator.

[0014] The stator 2 is a segmented fixed iron core composed of multiple (three in this embodiment) core members 2A to 2C. Each of the core members 2A to 2C is formed in an arc shape with a central angle of 120° and is press-fitted into a housing or the like to form a ring shape that constitutes a magnetic circuit.

[0015] Each of the core members 2A to 2C has four teeth 21, and the total number of teeth in the stator 2 is 12. A winding 3 is provided for each tooth 21 by concentrated winding. In other words, the number of teeth is equal to the number of slots on which the winding 3 is provided.

[0016] The windings 3 provided on each tooth 21 are connected as U-phase, V-phase, or W-phase. In this embodiment, in a counterclockwise direction, one U-phase winding 3u, one V-phase winding 3v, and one W-phase winding 3w are arranged in this order. Since each core member 2A to 2C has 4 teeth, each core member 2A to 2C is provided with two windings 3 of one phase and one winding 3 of another phase. The windings 3 may be connected in a delta configuration or a star configuration.

[0017] In the stator structure 1 of the rotating machine, the permanent magnet field rotor has 8 magnetic poles (4 magnetic pole pairs). The greatest common divisor of the number of magnetic poles (8) and the number of teeth (12) is 4, which becomes the period of the in-phase coil.

[0018] As described above, stator 2 is equally divided in the circumferential direction, and the number of divisions (i.e., the number of core members 2A to 2C) is 3. Note that "equal division" means that the central angles of the divided core members 2A to 2C are equal to each other. When the stator is equally divided, the candidate number of divisions is the divisors of the number of teeth, excluding 1. In the case of a number of teeth of 12, the candidate numbers of divisions are 2, 3, 4, 6, and 12.

[0019] Furthermore, the common divisors of the number of poles 8 and the number of teeth 12 are 2 and 4, and their greatest common divisor is 4. Of the above candidate numbers for partitioning, 2 and 4 are common divisors of the number of poles 8 and the number of teeth 12, and 6 and 12 are integer multiples of the common divisors of the number of poles 8 and the number of teeth 12. Therefore, if we remove 2 and 4, which are common divisors of the number of poles 8 and the number of teeth 12, and their integer multiples, from the above candidate numbers for partitioning, only partitioning number 3 remains. Note that the greatest common divisor is included in the common divisors, so if we remove the common divisors of the number of poles 8 and the number of teeth 12, and their integer multiples, from the candidate numbers for partitioning, the greatest common divisor and its integer multiples will also be removed.

[0020] The three core members 2A to 2C are designed such that the outer peripheral portions and the tips of the teeth 21 are arranged along predetermined circles, respectively. In the core members 2A to 2C, errors in dimensions in the radial direction and the circumferential direction may occur due to manufacturing errors. Further, when the three core members 2A to 2C are assembled and integrated into a housing or the like, a deviation from the original mounting position or the like may occur. Due to these manufacturing errors, the positions of the teeth 21 and the windings 3 may deviate from the designed positions, and such a deviation from the design value is simply referred to as "position deviation" hereinafter. Note that such position deviation includes position deviation toward the inner diameter side and position deviation toward the outer diameter side.

[0021] Each of the teeth 21 is provided with a winding 3 of the U-phase, V-phase or W-phase. However, when position deviation occurs in a plurality of teeth 21 (particularly when position deviation occurs on the same side), the cogging torque generated varies depending on the phase combination of the windings 3 provided on the teeth 21 in which the position deviation has occurred.

[0022] Further, when the waveform of the cogging torque generated due to the position deviation is analyzed by Fourier transform or the like, it is confirmed that the influence of the component of the same order as the number of poles (the 8th order in the present embodiment) is large.

[0023] At this time, when the number of divided parts of the core is 4, which is the greatest common divisor of the number of poles 8 and the number of teeth 12, and the period of the in-phase coil coincides with the number of divided parts, the cogging torque of the 8th order component as described above tends to increase.

[0024] As described above, according to the stator structure 1 according to the embodiment of the present invention, the number of divided parts 3 of the stator 2 is a number excluding 1, the greatest common divisor 4 of the number of poles 8 and the number of teeth 12, and the integer multiples 4 and 12 of this greatest common divisor among the divisors 1, 2, 3, 4, 6, 12 of the number of teeth 12. Even when the roundness of the stator 2 is reduced due to manufacturing errors or the like, the cogging torque of the component having the same number as the number of poles can be suppressed.

[0025] Furthermore, since the number of divisions of stator 2, 3, is a number that excludes 1 from the divisors of the number of teeth (1, 2, 3, 4, 6, 12), the common divisors of the number of magnetic poles (8) and the number of teeth (12) (2, 4, 6, 12), and the integer multiples of these common divisors (2, 4, 6, 12), the cogging torque with the same number of components as the number of magnetic poles can be further suppressed.

[0026] Furthermore, the present invention is not limited to the embodiments described above, and includes other configurations that can achieve the objectives of the present invention, including modifications such as those shown below. For example, in the above embodiments of the present invention, the number of divisions of stator 2 is set to 3, which is a number excluding 1 from the divisors of the number of teeth 12 (1, 2, 3, 4, 6, 12), the common divisors of the number of magnetic poles 8 and the number of teeth 12 (2, 4), and integer multiples of these common divisors (2, 4, 6). However, the number of divisions of the stator may be a number excluding 1 from the divisors of the number of teeth, the greatest common divisor of the number of magnetic poles and the number of teeth, and integer multiples of this greatest common divisor. That is, under the conditions of 12 teeth and 8 magnetic poles, a 2-division or 6-division may be adopted, excluding the greatest common divisor 4 and its integer multiple 12. If there are multiple candidate numbers of divisions, an appropriate one may be adopted considering the winding space factor and the yield of the materials used in the stator.

[0027] Furthermore, although the above embodiments of the present invention illustrate the conditions of 12 teeth and 8 magnetic poles, the number of teeth and magnetic poles are not limited to these conditions and can be appropriately selected. From the viewpoint of accuracy of rotation control, the number of magnetic poles is preferably 8 or more, and from the viewpoint of ease of manufacture, the number of magnetic poles is preferably 28 or less, more preferably 20 or less, and even more preferably 16 or less. Similarly, the number of teeth is preferably 9 or more, preferably 24 or less, and more preferably 18 or less.

[0028] Table 1 shows specific examples of the preferred number of teeth and number of magnetic poles as described above.

[0029] [Table 1]

[0030] Conditions 1 to 5 shown in Table 1 are most preferred, conditions 6 to 8 are next preferred, and condition 9 is the next preferred.

[0031] Furthermore, the arrangement of the U, V, and W phases in the winding in the circumferential direction is not particularly limited. That is, as in the embodiment described above, there may be one U phase, one V phase, and one W phase, or multiple U phases may be arranged in a clockwise or counterclockwise direction, followed by the same number of V phases, and then the same number of W phases. For example, in conditions 2, 4, 8, and 9 above, there may be two U phases, followed by two V phases, and then two W phases, or in conditions 5 and 6 above, there may be three U phases, followed by three V phases, and then three W phases.

[0032] Although embodiments of the present invention have been described above, the present invention is not limited to the stator structure of a rotating machine according to the above embodiments, but includes all embodiments included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention. [Explanation of Symbols]

[0033] 1... Stator structure of a rotating machine, 2... Stator, 21... Teeth

Claims

1. A stator structure for a rotating machine having a permanent magnet field rotor and a stator with concentrated windings, The stator has multiple teeth and is equally divided in the circumferential direction, The stator structure of a rotating machine is characterized in that the number of divisions of the stator is a number that excludes 1 from the divisors of the number of teeth, the greatest common divisor of the number of magnetic poles and the number of teeth, and integer multiples of the greatest common divisor.

2. The stator structure of a rotating machine according to claim 1, characterized in that the number of divisions of the stator is a number that excludes 1 from the divisors of the number of teeth, the common divisor of the number of magnetic poles and the number of teeth, and integer multiples of said common divisor.

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