JP2004064968A - Compound three-phase stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost stepping motor of high resolution, low rotational distortion, and low vibrations. <P>SOLUTION: Stator magnet poles made up of 6k pieces magnetic materials are arranged in its radial direction, wound with 3k phase windings. Two or more pieces of teeth are provided at the end of the magnet poles. An HB stepping motor is structured with two pieces of rotors having Nr pieces of rotor pole teeth in equal pitch on the circumference of the rotors displaced to each other by 1/2 pitch clamping a permanent magnet magnetized in the axial direction. A permanent magnet motor is structured with a cylindrical magnet that is magnetized into two or more pairs Nr of N and S poles alternately in equal pitch in its circumferential direction. This motor is a dynamo electric machine that includes the stepping motor in which the relation of Nr = (k/2) (12n±5)[where n is an integer of 1 or larger, and k is an even number of 2 or larger] is satisfied. <P>COPYRIGHT: (C)2004,JPO

Description

従って、更にステップ角を小さくするには（１）式より、相数Ｐを大きくする。
Ｐ＝２である２相が広く使用されているが、３相や５相も分解能の高いものには使用されている。
そこで、更に分解能の高い６相式を安価なモータ構造と安価なドライバーにての実現を行う。
６相ドライバーは３相ドライバー２個を活用するようにする。
一方、　ステップ角θｓは、固定子主極数を６ｋ個とした図１、図２の構造のステッピングモータの場合には　以下の様にも現せる。

（１），（２）より　一般的には（３）式を得る。

（３）で　ｋ＝２　として、次式を得る。

即ち、１２主極構造では、（４）式を満たすようにすればよい。
本発明は回転子がＨＢ型のみでなく、極対数Ｎｒで円筒磁石の外周にＮ極Ｓ極交互に磁化した回転子をＨＢ型と同じ固定子に組み合わせたタイプの６相機にも適用できる。
（４）式で、ｎ＝１０として、Ｎｒ＝１２５　とすると、θｓ＝３０°／１２５＝０．２４°が実現できる。
【０００６】
（４）式でｎ＝４として、Ｎｒ＝５３となる。これをアウターロータとして、固定子側に永久磁石を設けた構造とし、手段２の構成でｋ＝２とすると、１２主極の固定子構造で、図３が正面図、図４が側面断面図で構成された回転電機となる。図１で固定子１２主極は、１８０°離れた２個のａで１相即ちａ相を形成し、他も同様にｂ、ｃ、ｄ、ｅ、ｆ相が形成されている。そして、ａ，ｂ、ｃ相で１個の３相を、ｄ、ｅ、ｆ相で残りの３相を形成する。そして各主極は、ａ，ｄ，ｂ，ｅ，ｃ，ｆ　の順に配置されている。
固定子はｋ＝２の場合は、図１の場合も、図３の場合も、完全対称な１２主極となるので、固定子を珪素鋼板から、順送り抜き型で打ち抜き積層する際に、９０°づつ回転させながら、積層が可能となる。珪素鋼板は圧延されたロール状に巻かれたフープ材料であるので、圧延方向に磁気異方性が存在する。またロールの幅の左右で厚みが異なる傾向がある。これらの磁気異方性や厚み偏差を９０°回転積層することで、キャンセルできるので、セテッピングモータのようなエヤギャップの小さなモータでは磁気やギャップの偏りの影響を大きく受けるので、９０°回転積層は非常に有効な手段となる。
本願の図面番号は、図１、２と同じ部品名は同じ番号が付けてある。図４で１が磁性体よりなる２個の固定子であり、８なる軸方向に２極に磁化した永久磁石８を２個の固定子で同位置にて挟み１２個のスロットを通してコイル３を巻線してある。７は磁性体よりなる回転子でその内周に等ピッチでＮｒ個の歯を有している。この歯数Ｎｒは（４）式を満足するようにすればよい。
７は２個、７Ａと７Ｂとして歯ピッチの１／２、周方向にずらせて固着し、１の外周でエヤギャップを保って回転自在に設ける。固定子主極の小歯ピッチは回転子歯ピッチと同じか、コギングトルクを減らす等の目的で多少変えてもも良い。尚、８の形状は１の中心の中心穴を有する円盤状部分と略同じか、更に放射状の主極部をも含んだ形状であっても良い。即ち８にいのスロット部があれば、２個の１と８を含めて各主極にコイル３を巻けることになる。また永久磁石を固定子側に設ける利点は次の様である。永久磁石の軸と垂直方向の面積を回転子に永久磁石を設けるより、大きく出来る。特にアウターロータ型ではその差が大きい。すると永久磁石のコイルとの鎖交磁束を大きくでき、特に低速時のトルクを増加出来るので、またアウターロータではＮｒを大きくとれるので、分解能も高くなり、ダイレクトドライブに最適となる。またモータの中心部に穴を設けた中空穴モータではその穴径を大きく出来る。
【０００７】
図５は手段３の構成説明図であり、また２個の既成の３相駆動回路Ｄ，Ｄ´を用いて本発明の複合３相回路を実現するブロック図である。即ちＰ，Ｐ´に交互にトリガーパルスを入力する。モータ部は手段１または２において、ｋ＝２として、各相のコイルの巻き終わりの内３相分同志を短絡したダブルスター結線でもよいが、または、３相を形成する各相のコイルの巻き終わりと次相の巻始めを順次結合した所謂デルタ結線とし、それを２セット設けた図５に示したようなダブルデルタ結線とした複合３相ステッピングモータとする。ダブルデルタ方式は循環電流が流れ易く、ダンピング効果が期待出来、低振動化に有利となる。また各相のコイル抵抗が略並列に内部でつながれるので、低インピーダンスコイルとなり、高速にスターより有利となる。
【０００８】
図６は本発明の回転原理を説明する図である。（４）式でｎ＝１でＮｒ＝７の場合で示す。説明図を簡単にするために、各主極の小歯数は１とする。Ｓｔが固定子、Ｒｔが回転子である。１相づつ励磁した場合であるが、回転子歯ピッチ即ちＮ極とＮ極間ピッチの１／１２づつステップ移動することが分かる。また励磁順、１）、２）、３）、、、、、において、必ず、次の相の励磁極性は現相の極性と逆極性となりながら、駆動されることが分かる。これは回転子を２個の軸受け間で偶力を発生させる所謂サイドプル現象である不平衡電磁力を２相または４相励磁低減時に低減させ、低振動化にする効果を有する。
【０００９】
図７はｋ＝２の１２主極の場合で本発明の複合３相デルタ結線図である。即ち図５のモータ部のブロック図の具体的な構成を示したものである。図８は同様に１２主極で別の本発明の複合３相スター結線図を示したものである。図７でコイル端子のａとｄ，ｂとｅ，ｃとｆを各々並列または直列に接続し、入力を３端子とすると、３相ステッッピングモータとして動作する。即ちステップ角が複合３相駆動時の２倍となるので高速駆動に適することになる。図８の場合でも同様である。
【００１０】
図９は本発明の複合３相ステッピングモータの４相励磁の電圧または電流シーケンス図を示す。図６では１相励磁の場合を示したが、実際は４相励磁または各相正弦波状の電流となるような、マイクロステップ駆動を行い、低振動で、出力を大きく取り出すようにするのが望ましい。
例えば、図９と図８を対比させてみると、２個の同相はお互いに異極に磁化され、また１２主極の励磁順で隣接主極は異極性に磁化されることを特徴としていることが分かる。
【００１１】
【発明の効果】
１）．回転子に永久磁石を用いた簡単な構造により安価で高分解能、低振動なインナーロータ型またはアウターロータ型複合３相ステッピングモータが実現する。
２）．対称１２主極固定子なので９０°回転積層方式で珪素鋼板を積層出来、低コギングトルクで振動となる。
３）．永久磁石を固定子側に設けた構造のアウターロータ式本発明は鎖交磁束を大きくでき、低速大トルク、また高分解能となり、ダイレクトドライブ駆動に有利。中空穴モータにも適する。
４）．次相を逆極性に励磁するので、２相または４相励磁時、不平衡電磁力を低減し、低振動に有利となる。
５）．特に３相ダブルデルタ結線とすることで、ダンパー効果を有し、また低インピーダンス化から高速性も期待できる。
６）．既成の３相駆動回路を２個で駆動出来るのでドライバーも安価となる。
７）．低速駆動には複合３相機、高速駆動には３相機とコイル結線のみで、変えることが出来る。
【図面の簡単な説明】
【図１】第一の本発明の正面構造図
【図２】第一の本発明の側面構造図
【図３】別の本発明の正面構造図
【図４】別の本発明の側面構造図
【図５】本発明の駆動ブロック図
【図６】本発明の回転原理説明図
【図７】本発明のコイル結線図
【図８】別の本発明のコイル結線図
【図９】本発明の励磁シーケンス図
【符号の説明】
１　　　　　　　：固定子ハウジング、
２　　　　　　　：固定子鉄心、
３　　　　　　　：コイル、
４　　　　　　　：ブラケット、
５　　　　　　　：軸受け、
６　　　　　　　：軸、
７　　　　　　　：回転子、
８　　　　　　　：永久磁石、[0001]
[Industrial applications]
The present invention relates to a rotating electric machine including a stepping motor used for OA equipment and the like.
[0002]
[Prior art]
1). The three-phase permanent magnet type stepping motor has a lower vibration than the two-phase type, and the number of transistors is eight compared to eight in the two-phase type. However, there is a problem that the resolution is insufficient for a so-called direct drive motor that does not use a speed reducer. That is, as the number of rotor pole pairs is increased, the positioning accuracy and rotation unevenness at low speed are improved. However, even with a resolution of about 100 pole pairs, for example, in the case of rotation unevenness, it becomes worse at a low speed of about 100 rpm or less. There was a problem that it could not be used for the required transfer drum of a copying machine.
2). Japanese Patent Application No. 07-072458 discloses a prior art which solves the above-mentioned lack of resolution. This is a method in which two three-phase coils are prepared on a stator having a 12-pole structure, and the resolution is doubled as double three phases, so that good rotation unevenness can be obtained even at low speed.
3). However, these prior art systems have a problem that the stator core cannot be rotated and laminated by 90 ° after the stator core is punched from a silicon steel plate because the twelve main poles are not equally spaced at the tooth pitch and are not perfectly symmetrical. Was. If the 12 main poles are perfectly symmetric, by laminating 90 °, the directionality of the rolling direction of the silicon steel sheet can be canceled to improve the magnetic balance, the gap magnetic flux density approaches the sine wave, and harmonics can be reduced, Further, the thickness unevenness after lamination is uniform, so that the air gap can be uniform. There were the above problems.
[0003]
[Problems to be solved by the invention]
It is an object of the present invention to improve and solve the above-mentioned conventional techniques 1), 2) and 3).
[0004]
[Means for Solving the Problems]
"Means 1"
A stator magnetic pole made of 6k magnetic materials is arranged in a radial direction, a 3k-phase winding is wound, and a plurality of teeth are provided at their ends, and the circumference of the rotor is inserted through a gap. An HB type stepping motor having two or more Nr rotor pole teeth at the same pitch and having a permanent magnet magnetized in the axial direction shifted by ピ ッ チ pitch, or a cylindrical magnet circle In a permanent magnet type motor magnetized in a plurality of pole pairs Nr at equal pitch alternately in the circumferential direction with N poles and S poles, a stepping motor characterized by the relationship of Nr = (k / 2) (12n ± 5) is included. Rotating electric machine.
Here, n is an integer of 1 or more, and k is an even number of 2 or more. Incidentally, this means can be naturally applied to an inner rotor type motor and an outer rotor type motor.
"Means 2"
A permanent magnet magnetized in the axial direction is sandwiched between two stators each having 6k stator magnetic poles arranged radially outward from the substantially annular magnetic body, and the two stators are sandwiched. A coil is wound over the magnetic poles, and a 3k-phase winding having the same phase formed by k coils is wound, and a plurality of teeth are provided at the tips thereof. In an abduction type motor in which two annular magnetic members having Nr rotor pole teeth at equal pitches on the circumference are concentrically fastened with a shift of 1/2 the tooth pitch, Nr = (k / 2) ( 12n ± 5), a rotating electric machine including a stepping motor.
Here, n is an integer of 1 or more, and k is an even number of 2 or more.
"Means 3"
In the means 1 or 2, when k = 2, a double star connection in which three phases of the winding ends of the coils of each phase are short-circuited, or a winding end of each phase coil forming the three phases and a winding start of the next phase. A rotating electric machine including a stepping motor, which is a so-called delta connection in which two sets are provided, and a double delta connection in which two sets are provided.
"Means 4"
In any one of the means 1 to 3, a composite three-phase rotating electric machine is characterized in that at k = 2, the next phase is excited to have a polarity opposite to that of the current phase in order to reduce unbalanced electromagnetic force.
"Means 5"
In the means 1 or 2, a stepping motor which can be driven even as a three-phase machine by connecting k complex three-phase windings of the 6k stator main poles in parallel or in series inside or outside the motor. Including rotating electric machines. Here, n is an integer of 1 or more, and k is an integer of 2 or more.
[0005]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. One embodiment of the first invention is shown in FIGS. 1 and 2 are provided with k = 2 in order to realize the means 1.
1 is a front view, and FIG. 2 is a side sectional view. Reference numeral 1 denotes a stator housing, and 2 denotes a stator core, which is provided with 6k main poles, and has a plurality of teeth at a portion facing the rotor at a tip end thereof. The coils 3 are provided at their main poles. FIG. 1 is a diagram of the number of twelve main poles when k = 2, but shows three main poles 2a, 2d, and 2b at intervals of 30 °, and coils 3a, 3d, and 3b wound around them. FIG. The brackets 4 are fixed to both sides of 1, and the rotor shaft 6 is supported by the bearing 5. Numeral 6 designates two magnetic members so as to sandwich a permanent magnet 8 magnetized in the axial direction by rotating two rotors 7 having a large number of Nr teeth on the outer periphery thereof at a pitch 1/2 of the tooth pitch. The rotor 7 is fastened. This is a so-called hybrid (abbreviated as HB) type rotor.
In general, a rotating electric machine, particularly a stepping motor, has low rotation unevenness at high speed and poor rotation unevenness at low speed. However, when the step angle is reduced and the so-called resolution is improved, the rotation unevenness is improved even at a low speed.
1 and 2, the step angle can be reduced. However, when the Nr is increased, the tooth width is reduced, and the tooth width is limited to about the rotor plate thickness.
Generally, the step angle θs is expressed by the following equation, where P is the number of phases.

Therefore, in order to further reduce the step angle, the number of phases P is increased according to the equation (1).
Two phases where P = 2 are widely used, but three phases and five phases are also used for those having high resolution.
Therefore, a six-phase system with higher resolution is realized with an inexpensive motor structure and an inexpensive driver.
Six-phase drivers will utilize two three-phase drivers.
On the other hand, the step angle θs can be expressed as follows in the case of the stepping motor having the structure shown in FIGS. 1 and 2 in which the number of stator main poles is 6k.

More generally, Equation (3) is obtained from (1) and (2).

The following equation is obtained by setting k = 2 in (3).

That is, in the case of a 12-pole structure, the expression (4) may be satisfied.
The present invention is applicable not only to the HB type rotor, but also to a six-phase machine in which a rotor in which the number of pole pairs is Nr and the N pole and the S pole are alternately magnetized on the outer periphery of a cylindrical magnet is combined with the same stator as the HB type.
In the equation (4), when n = 10 and Nr = 125, θs = 30 ° / 125 = 0.24 ° can be realized.
[0006]
In the equation (4), Nr = 53, where n = 4. Assuming that this is an outer rotor and a structure in which a permanent magnet is provided on the stator side, and k = 2 in the configuration of the means 2, a stator structure having 12 main poles, FIG. 3 is a front view, and FIG. The rotating electric machine is composed of In FIG. 1, the main pole of the stator 12 forms one phase, that is, the a phase by two a's separated by 180 °, and similarly forms the b, c, d, e, and f phases. The a, b, and c phases form one three phase, and the d, e, and f phases form the remaining three phases. Each main pole is arranged in the order of a, d, b, e, c, f.
When k = 2, the stator has 12 main poles that are completely symmetric in both FIG. 1 and FIG. 3. Therefore, when the stator is punched and laminated from a silicon steel plate using a progressive punching die, 90 Stacking is possible while rotating by degrees. Since the silicon steel sheet is a hoop material wound into a rolled roll, there is magnetic anisotropy in the rolling direction. Also, the thickness tends to be different between the left and right sides of the roll width. These magnetic anisotropies and thickness deviations can be canceled by laminating them by 90 °, so that a motor with a small air gap such as a stepping motor is greatly affected by magnetism and the bias of the gap. It is a very effective means.
In the drawing numbers of the present application, the same component names as those in FIGS. In FIG. 4, reference numeral 1 denotes two stators made of a magnetic material, and a permanent magnet 8 magnetized to two poles in an axial direction of 8 is sandwiched by two stators at the same position, and a coil 3 is passed through 12 slots. It is wound. Numeral 7 is a rotor made of a magnetic material and has Nr teeth at an equal pitch on the inner periphery thereof. The number of teeth Nr may satisfy the expression (4).
7 are fixed to each other as 7A and 7B by being shifted in the circumferential direction by 1/2 of the tooth pitch, and rotatably provided around the outer periphery of 1 while maintaining an air gap. The small tooth pitch of the stator main pole may be the same as the rotor tooth pitch or slightly changed for the purpose of reducing cogging torque. The shape of 8 may be substantially the same as the disk-shaped portion having the center hole of 1 or may be a shape including a radial main pole portion. That is, if there are eight slots, the coil 3 can be wound around each main pole including two 1 and 8. The advantage of providing the permanent magnet on the stator side is as follows. The area in the direction perpendicular to the axis of the permanent magnet can be made larger than providing a permanent magnet on the rotor. In particular, the difference is large in the outer rotor type. Then, the linkage magnetic flux with the coil of the permanent magnet can be increased, and especially the torque at low speed can be increased, and Nr can be increased in the outer rotor, so that the resolution is also improved, which is optimal for direct drive. In the case of a hollow hole motor having a hole at the center of the motor, the hole diameter can be increased.
[0007]
FIG. 5 is an explanatory view of the configuration of the means 3, and is a block diagram for realizing the composite three-phase circuit of the present invention using two existing three-phase drive circuits D and D '. That is, a trigger pulse is input to P and P 'alternately. In the means 1 or 2, the motor unit may be a double star connection in which k = 2, k = 2, and three phases are short-circuited at the end of winding of each phase coil, or the winding of each phase coil forming three phases may be used. A so-called delta connection in which the end and the beginning of the winding of the next phase are sequentially connected, and a double delta connection as shown in FIG. In the double delta system, a circulating current flows easily, a damping effect can be expected, and this is advantageous for reducing vibration. In addition, since the coil resistances of the respective phases are internally connected substantially in parallel, a low-impedance coil is provided, which is more advantageous than a star at a high speed.
[0008]
FIG. 6 is a diagram for explaining the rotation principle of the present invention. Equation (4) shows the case where n = 1 and Nr = 7. In order to simplify the illustration, the number of small teeth of each main pole is assumed to be one. St is a stator, and Rt is a rotor. It can be seen that, although the excitation is performed one phase at a time, the rotor moves in steps of 1/12 of the rotor tooth pitch, ie, the pitch between the N poles. In addition, it can be seen that in the excitation order, 1), 2), 3),..., The drive is always performed while the excitation polarity of the next phase is opposite to the polarity of the current phase. This has the effect of reducing the unbalanced electromagnetic force, which is a so-called side-pull phenomenon that generates a couple between the two bearings of the rotor when the two-phase or four-phase excitation is reduced, thereby lowering the vibration.
[0009]
FIG. 7 is a composite three-phase delta connection diagram of the present invention in the case of 12 main poles where k = 2. That is, the specific configuration of the block diagram of the motor unit in FIG. 5 is shown. FIG. 8 also shows another composite three-phase star connection diagram of the present invention with 12 main poles. In FIG. 7, when the coil terminals a and d, b and e, and c and f are connected in parallel or in series, respectively, and the input is made into three terminals, the motor operates as a three-phase stepping motor. That is, the step angle is twice as large as that in the composite three-phase driving, so that it is suitable for high speed driving. The same applies to the case of FIG.
[0010]
FIG. 9 shows a voltage or current sequence diagram of four-phase excitation of the composite three-phase stepping motor of the present invention. FIG. 6 shows the case of one-phase excitation. However, it is preferable to actually perform four-step excitation or micro-step driving so as to generate a sinusoidal current in each phase, to obtain a large output with low vibration.
For example, comparing FIGS. 9 and 8, two in-phases are magnetized with different polarities, and the adjacent main poles are magnetized with different polarities in the order of the 12 main poles. You can see that.
[0011]
【The invention's effect】
1). An inexpensive, high-resolution, low-vibration inner-rotor or outer-rotor composite three-phase stepping motor is realized with a simple structure using a permanent magnet for the rotor.
2). Since it is a symmetrical 12-pole stator, silicon steel plates can be laminated by a 90 ° rotation lamination method, and vibration is generated with low cogging torque.
3). The outer rotor type having a structure in which a permanent magnet is provided on the stator side The present invention can increase the interlinkage magnetic flux, has a low speed and a large torque, and has a high resolution, which is advantageous for direct drive driving. Also suitable for hollow hole motors.
4). Since the next phase is excited to the opposite polarity, unbalanced electromagnetic force is reduced during two-phase or four-phase excitation, which is advantageous for low vibration.
5). In particular, the three-phase double delta connection has a damper effect, and can be expected to have high speed due to low impedance.
6). Since two existing three-phase driving circuits can be driven by two, the driver is also inexpensive.
7). The combination can be changed only by the combination of the three-phase machine and the coil connection for the low-speed drive and the composite three-phase machine for the low-speed drive.
[Brief description of the drawings]
FIG. 1 is a front structural view of a first present invention. FIG. 2 is a side structural view of a first present invention. FIG. 3 is a front structural view of another present invention. FIG. FIG. 5 is a drive block diagram of the present invention. FIG. 6 is an explanatory view of a rotation principle of the present invention. FIG. 7 is a coil connection diagram of the present invention. FIG. 8 is a coil connection diagram of another present invention. Excitation sequence diagram [Description of symbols]
1: Stator housing,
2: Stator core
3: coil,
4: Bracket,
5: Bearing,
6: axis,
7: Rotor,
8: permanent magnet,

Claims (5)

A stator magnetic pole made of 6k magnetic materials is arranged in a radial direction, a 3k-phase winding is wound, and a plurality of teeth are provided at their ends, and the circumference of the rotor is inserted through a gap. An HB type stepping motor having two or more Nr rotor pole teeth at the same pitch and having a permanent magnet magnetized in the axial direction shifted by ピ ッ チ pitch, or a cylindrical magnet circle In a permanent magnet type motor magnetized in a plurality of pole pairs Nr at equal pitch alternately in the circumferential direction with N poles and S poles, a stepping motor characterized by the relationship of Nr = (k / 2) (12n ± 5) is included. Rotating electric machine.
Here, n is an integer of 1 or more, and k is an even number of 2 or more. A permanent magnet magnetized in the axial direction is sandwiched between two stators having 6k stator magnetic poles arranged radially outward from the substantially annular magnetic body, and the two stators are sandwiched. A coil is wound over the magnetic poles, and a 3k-phase winding having the same phase formed by k coils is wound, and a plurality of teeth are provided at the tips thereof. In an abduction type motor in which two annular magnetic members having Nr rotor pole teeth at equal pitches on the circumference are concentrically fastened with a shift of 歯 of the tooth pitch, Nr = (k / 2) ( 12n ± 5), a rotating electric machine including a stepping motor characterized by the following relationship:
Here, n is an integer of 1 or more, and k is an even number of 2 or more. 3. The composite three-phase rotating electric machine including the stepping motor according to claim 1, wherein k = 2, 12 main pole stators of equal pitch are provided, and one of 12 main poles is selected from the end of winding of each phase coil. 4. A double star connection in which three main phases composed of a total of six main poles are short-circuited to each other or a coil of each phase forming the three phases composed of a total of six main poles. A composite three-phase rotating electric machine including a stepping motor, wherein a so-called delta connection in which a winding end and a winding start of a next phase are sequentially connected, and a double delta connection in which two sets are provided.
However, the number of rotor teeth, Nr = 12n ± 5, n is an integer of 1 or more The composite three-phase rotating electric machine including the stepping motor according to claim 1, wherein k = 2, and the next phase is sequentially excited in the opposite polarity to the excitation polarity of the current phase. 5. Phase type rotating electric machine. The composite three-phase rotating electric machine including the stepping motor according to claim 1 or 2, wherein k composite three-phase windings of the 6k stator main poles are connected in parallel or in series inside or outside the motor. A rotating electric machine including a drivable stepping motor as a three-phase machine. Where n is an integer of 1 or more, and k is an integer of 2 or more.

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