JP2012175752A - Synchronous rotary electric machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synchronous rotary electric machine which can have torque larger than torque generated through mutual action between a rotating magnetic field of a stator and magnetic flux of permanent magnets of a rotor in synchronous operation.SOLUTION: A synchronous rotary electric machine 11 includes a rotor 13 having a plurality of permanent magnets 19 arranged so that adjacent permanent magnets have alternately different magnetic poles, and a stator winding is a concentrated winding. The rotor 13 has bar conductors 20a arranged on inner-diameter sides of the permanent magnets 19 and at positions corresponding to gaps between permanent magnets 19 so as to always perform synchronous operation over the entire rotation area. The synchronous rotary electric machine 11 is characterized in that the number (q) of slots of each pole and each phase represented as q=Z/(2Zm) is a fractional slot smaller than 1/2, where Zis the number of slots, Zis the number of pole pairs, and (m) is the number of phases.

Description

  The present invention relates to a synchronous rotating electric machine, and more particularly to a synchronous rotating electric machine in which a permanent magnet is provided on a rotor (rotor).

  In a synchronous motor having a permanent magnet in the rotor, the rotor rotates at a synchronous speed with the rotating magnetic field by the interaction between the rotating magnetic field of the stator winding provided in the stator and the magnetic flux of the permanent magnet of the rotor. When the inductance of the stator winding of each phase changes according to the rotational position of the rotor, and when the inductance of the stator winding increases with the rotation of the rotor, an excitation current is supplied to the stator winding, Torque (positive torque) that rotates the rotor in the rotation direction is generated. On the other hand, if an excitation current is supplied to the stator winding when the inductance of the stator winding decreases with the rotation of the rotor, torque (negative torque) that rotates the rotor in the direction opposite to the rotation direction is generated. . And the supply timing of the exciting current to the stator winding of each phase is controlled corresponding to the position of the rotor (see, for example, Patent Document 1).

  Further, as a permanent magnet type rotating electrical machine, there is one in which a rotor is provided with a conductor that forms a starting winding in addition to a permanent magnet (see, for example, Patent Document 2). As shown in FIG. 7, the rotating electrical machine disclosed in Patent Document 2 has a plurality of first permanent magnets 52 in the rotor 51 and the same polarity as the first permanent magnets 52 between the first permanent magnets 52. A field pole composed of a second permanent magnet 54 arranged so that the distance from the stator 53 to the back surface as viewed from the stator 53 is smaller than that of the first permanent magnet 52 is provided. A conductor 55 constituting a starting winding is provided between the field poles and on the back side of the second permanent magnet 54. In the permanent magnet type synchronous electric machine provided with the start winding, the synchronous control is performed after being started by the asynchronous control.

Japanese Patent Laid-Open No. 2000-278989 JP-A-57-145556

  The rotating electrical machine is desired to be downsized, and if the torque can be increased with the same power consumption, the rotating electrical machine can be easily downsized. However, in the configuration in which the rotor is rotated only by the interaction between the rotating magnetic field of the stator and the magnetic flux of the permanent magnet of the rotor as in Patent Document 1, power consumption increases in order to increase the torque.

  On the other hand, in Patent Document 2, by providing the start winding, the torque at the start, which is an asynchronous operation, is increased. However, the conductor 55 constituting the starting winding is for obtaining the starting torque, and no consideration is given to the torque increase during the synchronous operation.

  The present invention has been made in view of the above-described problems, and its object is to increase the torque from the torque generated by the interaction between the rotating magnetic field of the stator and the magnetic flux of the permanent magnet of the rotor in the entire rotation region. An object of the present invention is to provide a synchronous rotating electrical machine that can perform the above.

  In order to achieve the above object, the invention according to claim 1 is a synchronous rotating electric machine including a rotor having a plurality of permanent magnets arranged such that magnetic poles of adjacent permanent magnets are alternately different from each other. The stator winding is a concentrated winding, and a secondary conductor is disposed on the rotor on the inner diameter side or between the permanent magnets.

  Conventionally, there is a permanent magnet type synchronous rotating electrical machine having a secondary conductor, but the secondary conductor is provided to obtain a starting torque, and at the time of starting, the operation is started by asynchronous control, and then the operation is shifted to the synchronous operation. . On the other hand, when the rotating electrical machine of the present invention is always operated with synchronous control from the start, a part of the harmonic component of the spatial magnetomotive force distribution acts on the secondary conductor even during the synchronous operation other than the start. A positive induction torque is generated from the secondary conductor with respect to the rotation direction of the rotor. And since a stator winding is concentrated winding, there are many harmonic components compared with distributed winding. Therefore, the torque can be increased from the torque generated by the interaction between the rotating magnetic field of the stator and the magnetic flux of the permanent magnet of the rotor in the entire rotation region.

  According to a second aspect of the present invention, in the first aspect of the present invention, the rotating electrical machine performs a synchronous operation in the entire rotation region. Therefore, the torque can be increased from the torque generated by the interaction between the rotating magnetic field of the stator and the magnetic flux of the permanent magnet of the rotor in the entire rotation region.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein q = Z ₁ / (2Z ₂ m) where Z _{1 is} the number of slots, Z _{2 is} the number of pole pairs, and m is the number of phases. The number of slots per phase per pole represented by is a fractional slot smaller than 1/2. In the fractional slot, by combining the number of poles with the number of slots, a combination with a large least common multiple of the number of poles and the number of slots can be realized. Moreover, even if the teeth corresponding to the stator windings of the same phase are disposed, the coping torque and the torque ripple can be reduced without skew even if the teeth are arranged differently from the permanent magnets of the rotor.

  A fourth aspect of the present invention is the three-phase AC electric machine according to the third aspect, wherein the number of slots is 24 and the number of magnetic poles is 28. Therefore, torque can be increased in a generally used three-phase rotating electrical machine.

  ADVANTAGE OF THE INVENTION According to this invention, the synchronous rotary electric machine which can aim at a torque up from the torque which generate | occur | produces by the interaction of the rotating magnetic field of a stator and the magnetic flux of the permanent magnet of a rotor in a full rotation area | region can be provided.

(A) is a schematic cross section of a synchronous rotary electric motor, (b) is the elements on larger scale of (a). The perspective view of a secondary conductor. The block diagram which shows the control structure of a synchronous rotary electric motor. The schematic diagram which shows the definition of a magnetomotive force coordinate. The figure which shows U-phase single layer winding magnetomotive force distribution. The figure which shows the electric current which flows into a secondary conductor. Sectional drawing of a prior art.

Hereinafter, an embodiment in which the present invention is embodied in a three-phase synchronous rotating motor will be described with reference to FIGS.
As shown in FIG. 1A, the synchronous rotary electric motor 11 includes a cylindrical stator (stator) 12 and a rotor 13 arranged inside the stator 12. The stator 12 is provided with slots 15 at equal intervals so that a plurality of teeth 14 are equally spaced inside. In this embodiment, 24 teeth 14 and 24 slots 15 are provided. A U-phase winding 16u, a V-phase winding 16v, and a W-phase winding 16w as stator windings are wound around the teeth 14 in a concentrated manner. The U-phase winding 16u, the V-phase winding 16v, and the W-phase winding 16w are arranged in the order of the U-phase, V-phase, and W-phase in the clockwise direction in FIG. The windings of the windings wound around the teeth 14 are wound in a single layer winding so that the winding directions of the teeth 14 are alternately opposite to each other. That is, when current is supplied to each of the U-phase winding 16u, the V-phase winding 16v, and the W-phase winding 16w, the direction of the magnetomotive force of the teeth 14 around which the in-phase winding is wound is alternately opposite. It is wound like so.

  The rotor 13 includes a rotor core 17 in which a plurality of (for example, several tens) disk-shaped electromagnetic steel plates are stacked, and a rotor shaft (rotating shaft) 18 inserted through the center of the rotor core 17. The rotor 13 is rotatably supported by a bearing of a housing (not shown) via a rotor shaft 18 with the outer peripheral surface of the rotor core 17 spaced apart from the teeth 14. In the rotor core 17, holes (flux barriers) are formed in each virtual region obtained by equally dividing the rotor core 17 in the circumferential direction (28 divisions in this embodiment), and the permanent core is formed in a flat plate shape having a substantially rectangular cross section in each hole. A magnet 19 is attached. Each permanent magnet 19 is magnetized such that the magnetization direction (magnetization direction) is the thickness direction. The adjacent permanent magnets 19 are provided so that the outer peripheral side of the rotor 13 has different poles, that is, the N poles and S poles of the adjacent permanent magnets 19 are alternately directed to the stator 12 side. In the synchronous rotary electric motor 11 of this embodiment, the stator 12 has 24 slots and the rotor 13 has 28 magnetic poles. In FIG. 1A, a symbol N or S indicating which of the N pole and S pole of the permanent magnet 19 faces the stator 12 side is attached to the inner side in the radial direction of the permanent magnet 19 (illustration of the symbols). Are omitted).

  Therefore, the synchronous rotary electric motor 11 of this embodiment has a fraction smaller than ½ when the number of slots q per pole per phase expressed by the following equation is calculated, and the synchronous rotary electric motor 11 has a concentrated winding fraction slot embedded magnet synchronization. Become a motor.

q = Z ₁ / (2Z ₂ m)
However, _{Z 1} is the number of slots, _{Z 2} is pole pair (the number of magnetic poles 1/2), m is the number of phases. The synchronous rotary motor 11 has a slot number Z ₁ of 24, a pole pair number Z ₂ of 14 (28/2), and a phase number of 3, so that q = 24 / (2 × 14 × 3) = 2/7 is a fraction. Become a slot.

  Further, the rotor core 17 is provided with a bar conductor 20a as a secondary conductor penetrating the rotor core 17 at a position facing the center of the adjacent permanent magnet 19 closer to the rotor shaft 18 than each permanent magnet 19. As shown in FIG. 2, both end portions of each bar conductor 20a are connected to an end ring 20b, respectively, and a cage-shaped secondary conductor 20 as a whole is fixed to the rotor 13 so as to be integrally rotatable.

  Next, the operation when the synchronous rotary electric motor 11 configured as described above is applied to a traveling motor mounted on a vehicle will be described. As shown in FIG. 3, the control device 21 of the synchronous rotary motor 11 converts the DC power of the battery 22 as a DC power source into three-phase AC by the inverter 23, and each phase (U phase, V) of the synchronous rotary motor 11. The inverter 23 is controlled so as to supply an alternating current to be supplied to the windings 16u, 16v, 16w of the phase (phase W). The current supplied to each phase is detected by the current sensor 24, and the detection signal is input to the control device 21. The synchronous rotating motor 11 is provided with a position sensor 25 as position detecting means for detecting the position of the rotor 13 (the position of the magnetic pole), and the detection signal is input to the control device 21. For the position sensor 25, for example, a resolver or a rotary encoder is used.

  The control device 21 includes a CPU 26 and a memory 27, and the amount of alternating current to be supplied to the windings 16u, 16v, 16w of each phase so as to achieve the target vehicle speed based on the data such as the accelerator depression angle and the detection signal of the position sensor 25. And the frequency is calculated and the inverter 23 is controlled so that the alternating current is supplied to the windings 16u, 16v, and 16w of each phase. The control device 21 performs the synchronous control based on the position information of the rotor 13 by the position sensor 25 so as to always perform the synchronous operation in the entire rotation region from the low rotation region (low speed region) to the high rotation region (high speed region). To control the drive of the synchronous rotating motor 11.

  When an alternating current having a predetermined frequency is supplied to the U-phase winding 16u, V-phase winding 16v, and W-phase winding 16w of the stator 12, a rotating magnetic field is generated in the stator 12, and the rotating magnetic field acts on the rotor 13. . Then, the rotor 13 rotates in synchronization with the rotating magnetic field by the magnetic attractive force and the repulsive force between the rotating magnetic field and the magnetic flux of the permanent magnet 19.

  The fractional slot motor includes a large number of rotating magnetic fields in addition to the synchronous rotating magnetic field component, and the asynchronous rotating magnetic field component acts on the bar conductor 20a inserted in the rotor core 17 to generate an induction torque, and there is no bar conductor 20a. Compared to the torque, the torque is increased in the entire rotation range.

  Hereinafter, the reason why the bar conductor 20a generates a positive torque in the same direction as the rotation direction will be described. The spatial magnetomotive force distribution is formed by synthesizing the spatial magnetomotive force distributions of the U phase, the V phase, and the W phase. The magnetomotive force F induced in one slot is defined as F = NI, where N is the number of turns of the winding and I is the armature current. The coordinate definition of the space magnetomotive force distribution generated in the stator 12 is defined as shown in FIG. 4, and the single layer magnetomotive force distribution of the U-phase winding is shown in FIG. 5 according to the definition. From FIG. 5, the U-phase magnetomotive force distribution in the 24-slot single layer winding is as follows.

フーリエ級数展開は一般的に次式で与えられる。

The Fourier series expansion is generally given by

係数ａ_ｎ，ｂ_ｎは次式で示される。

The coefficients a _n and b _n are expressed by the following equations.

したがって、以上の条件からＵ相の起磁力分布Ｆ_Ｕ（θ_ｍ）は次式で表すことができる。θ_ｍは機械角。

Therefore, from the above conditions, the magnetomotive force distribution F _U (θ _m ) of the U phase can be expressed by the following equation. θ _m is the mechanical angle.

このとき、ｎ＝４ｋ−２（ｋ＝１，２，３…）である。Ｖ相、Ｗ相の起磁力分布はＵ相の起磁力分布の位相を±２π／３ずらすことによって得られる。したがって、Ｖ相、Ｗ相の起磁力分布Ｆ_Ｖ（θ_ｍ）、Ｆ_Ｗ（θ_ｍ）は次式で表される。

At this time, n = 4k−2 (k = 1, 2, 3,...). The magnetomotive force distribution of the V phase and the W phase is obtained by shifting the phase of the magnetomotive force distribution of the U phase by ± 2π / 3. Therefore, the magnetomotive force distributions F _V (θ _m ) and F _W (θ _m ) of the V phase and the W phase are expressed by the following equations.

このとき、Ｉ_Ｕ，Ｉ_Ｖ，Ｉ_Ｗは次式で表される。

At this time, I _U , I _V , and I _W are expressed by the following equations.

βは電流位相角、ω_Ｓは電源角速度であり、ω_ｒｔ＝１４θ_ｍで表される。Ｆ_Ｕ（θ_ｍ）、Ｆ_Ｖ（θ_ｍ）、Ｆ_Ｗ（θ_ｍ）にそれぞれ各相電流を代入し、足し合わせて合成することによってｋごとの空間起磁力成分Ｆ_ｋ（θ_ｍ）は次式で表される。

β is a current phase angle, ω _S is a power source angular velocity, and is expressed by ω _r t = 14θ _m . By substituting each phase current for F _U (θ _m ), F _V (θ _m ), and F _W (θ _m ), and adding them together, the spatial magnetomotive force component F _k (θ _m ) for each _k is It is expressed by the following formula.

このとき、Ｆ_ｋは起磁力の振幅、ｓ_ｋはすべりとする。また、ｔを自然数としてδ_ｋはｋ＝３ｔのとき＋、ｋ＝３ｔ−２のとき−の符号を表し、ｋ＝３ｔ−１のときＦ_ｋ（θ_ｍ）は零になる。起磁力の振幅を定数と変数に分離し、Ｆ_ｋ＝ＡＮＩとする。但し、Ａを起磁力振幅係数とする。ｋに対するすべりｓ_ｋと起磁力振幅係数Ａとの関係を表１に示す。

At this time, F _k is an amplitude of the magnetomotive force, and s _k is a slip. Further, δ _k represents a sign of + when k = 3t and − when k = 3t−2, where t is a natural number, and F _k (θ _m ) becomes zero when k = 3t−1. The amplitude of the magnetomotive force is separated into a constant and a variable, and F _k = ANI is set. However, A is a magnetomotive force amplitude coefficient. Table 1 shows the relationship between the slip s _k and the magnetomotive force amplitude coefficient A with respect to _k .

表１より空間起磁力分布がｋ＝４のとき、すべりが０となり、回転磁界に対しロータが静止していることから、同期磁界として作用していることが確認できる。ｋ＝４以外の空間起磁力分布は、回転速度に対し回転速度の１４θ_ｍと比較したときのすべりを導出して、すべりが０より大きく１未満であれば回転方向に対し正のトルクが出ると考えられる。その上で表１よりｋ＝１のときすべりが６／７であり、正の誘導トルクが期待される。

From Table 1, when the spatial magnetomotive force distribution is k = 4, the slip is 0, and the rotor is stationary with respect to the rotating magnetic field, so that it can be confirmed that it acts as a synchronous magnetic field. k = 4 spatial magnetomotive force distribution of the other is to derive a slip when compared to 14Shita _m rotational speed relative to the rotational speed, positive torque exits with respect to the rotation direction if greater than 1 than slip 0 it is conceivable that. Furthermore, from Table 1, when k = 1, the slip is 6/7, and a positive induction torque is expected.

  The increase in the maximum torque with and without the bar conductor 20a was verified by a three-dimensional finite element method analysis (3D-FEM). As a result, the maximum torque when the bar conductor 20a is present is 1.07 when the maximum torque when the bar conductor 20a is absent is 1. For comparison, when only the hole for inserting the bar conductor 20a was formed and air was used without inserting the bar conductor 20a, the maximum torque was 1.01, and the maximum torque was 1.01. That is, it was confirmed that the torque was increased by providing the bar conductor 20a.

  In addition, when a sinusoidal current is passed as the armature current, the current flowing through the bar conductor 20a, as shown in FIG. 6, contributes to positive torque when the power supply cycle (one cycle is 360 °) is used as a reference. It was confirmed that it was the same as 420 °, which is the period calculated from one slip.

According to this embodiment, the following effects can be obtained.
(1) The synchronous rotating motor 11 includes a rotor 13 having a plurality of permanent magnets 19 arranged so that the magnetic poles of adjacent permanent magnets are alternately different, and includes a U-phase winding 16u, a V-phase winding 16v, and W. The phase winding 16w is a concentrated winding, and a secondary conductor (bar conductor 20a) is disposed on the rotor 13 on the inner diameter side of the permanent magnet 19 provided at regular intervals. Therefore, by always performing synchronous operation in the entire rotation region, it is possible to increase the torque from the torque generated by the interaction between the rotating magnetic field of the stator 12 and the magnetic flux of the permanent magnet 19 of the rotor 13 in the entire rotation region. it can.

(2) The synchronous rotating motor 11 has the number of slots q per phase represented by q = Z ₁ / (2Z ₂ m) where Z ₁ is the number of slots, Z _{2 is} the number of pole pairs, and m is the number of phases. Is a fractional slot smaller than 1/2. Therefore, a combination with a large least common multiple of the number of poles and the number of slots can be realized by bringing the number of poles and the number of slots close to each other. Further, even if the teeth 14 correspond to the stator windings having the same phase, the teeth 14 are arranged in different degrees of opposition to the permanent magnets 19 of the rotor 13 so that cogging torque and torque ripple can be reduced without skew. .

  (3) The synchronous rotating motor 11 is a three-phase AC electric machine having 24 slots and 28 magnetic poles. Therefore, torque can be increased in a generally used three-phase rotating electrical machine.

  (4) Each winding 16u, 16v, 16w is wound around each tooth 14 by single layer winding. Therefore, a positive induction torque is more likely to be generated by the bar conductor 20a than in the case of winding with two-layer winding.

  (5) The synchronous rotary electric motor 11 includes a position sensor 25 that detects the position of the rotor 13, and the control device 21 performs synchronous control in the entire rotation region based on the position information of the rotor 13 detected by the position sensor 25. The synchronous rotary motor 11 is driven and controlled. Therefore, the control by the CPU 26 is simplified as compared with the case where the synchronous control is performed without providing the position sensor 25.

  (6) The synchronous rotating motor 11 is applied to a traveling motor mounted on a vehicle. Although the travel motor is desired to be downsized, the synchronous rotating motor 11 contributes to downsizing because the torque is increased in the entire rotation region. Moreover, since the position sensor 25 is generally provided in the traveling motor, the cost does not increase even if the position sensor 25 is provided.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The synchronous rotating motor 11 is a three-phase motor having a fractional slot other than 24 and 28, and the number of slots of the stator 12 is 24 and the magnetic pole of the rotor 13 is not limited to 28. May be. However, in the case of a three-phase motor having a fractional slot, depending on the combination of the number of slots and the magnetic pole, the induction torque due to the harmonic component acting on the bar conductor 20a does not become a positive torque but a negative torque (the direction opposite to the rotation direction of the rotor 13). In the design, it is necessary to calculate the slip with respect to k using the formula of the space magnetomotive force component F _k (θ _m ) and to adopt a combination in which a positive induction torque is expected.

The synchronous rotary motor 11 is not limited to a fractional slot.
The synchronous rotary motor 11 is not limited to the embedded magnet type, and may be a surface magnet type.
○ The stator winding may be a two-layer winding.

The bar conductor 20 a may be provided on the inner diameter side of the permanent magnet 19 at a position facing the permanent magnet 19, or may be provided between the permanent magnets 19 on the same circumference as the permanent magnet 19.
The bar conductor 20a is not the same as the number of the permanent magnets 19, that is, the number of poles, but may be a natural number times the number of poles. For example, two magnets may be provided between the permanent magnets 19, or one magnet may be provided between the permanent magnets 19 and one on the inner diameter side of the permanent magnet 19.

  The synchronous rotary motor 11 is a sensorless type motor in which the position sensor 25 for detecting the position of the rotor 13 is not provided. For example, the rotor speed and the magnetic pole position are calculated from the current and the voltage, and the vector control is performed based thereon. It may be an electric motor.

The synchronous rotary electric motor 11 may be an outer rotor type electric motor in which the rotor is provided outside the stator.
○ It may be applied to a generator instead of an electric motor.

  A relationship between the state of the armature current in which the current flowing through the bar conductor 20a contains a large amount of harmonic components that generate a positive induction torque and the rotational speed of the rotor 13 is obtained in advance by testing. The control device 21 may perform synchronous control based on the data.

The following technical idea (invention) can be understood from the embodiment.
(1) In the invention according to any one of claims 1 to 3, the stator winding is wound by a single layer winding.

  (2) In the invention according to any one of claims 1 to 3 and the technical idea (1), the synchronous rotating electrical machine is provided with a sensor for detecting the position of the rotor, and is detected by the sensor. Synchronous operation is performed based on the obtained position information.

  DESCRIPTION OF SYMBOLS 13 ... Rotor, 16u ... U phase winding as stator winding, 16v ... V phase winding similarly, 16w ... W phase winding similarly, 19 ... Permanent magnet, 20a ... Bar conductor as a secondary conductor.

Claims (4)

A synchronous rotating electrical machine including a rotor having a plurality of permanent magnets arranged so that magnetic poles of adjacent permanent magnets are alternately different from each other,
A synchronous rotating electrical machine characterized in that a stator winding is a concentrated winding, and a secondary conductor is disposed on the rotor on the inner diameter side or between the permanent magnets.   The synchronous rotating electric machine according to claim 1, wherein synchronous operation is performed in the entire rotation region. When the number of slots is Z ₁ , the number of pole pairs is Z ₂ , and the number of phases is m, the number of slots per phase per pole represented by q = Z ₁ / (2Z ₂ m) is a fractional slot smaller than 1/2. The synchronous rotating electrical machine according to claim 1 or 2.   The synchronous rotating electric machine according to claim 3, wherein the synchronous rotating electric machine is a three-phase AC electric machine having 24 slots and 28 magnetic poles.

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