JPH10322997A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To operate a brushless motor at a high speed, equal to or above a specified number of revolutions by forming an armature coil from a single conductor, and serially connecting a single conductor positioned in a required pole or phase at a coil end. SOLUTION: The present invention relates to a brushless motor, which is driven at a high speed of 4000 rpm or above by a flip-flop inverter and delivers a favorable performance. In case of 8-pole and 6-phase, a coil in each phase of an armature coil 22 is formed into a wave shape. To move a rotor 10 to the right, the phases of the armature coil 22 are connected, respectively, so that traveling waves in the same direction are produced. In addition, a circular or an elliptic closed or open slot is formed in the stator core, and a single insulated conductor is inserted into the slot to be connected to the armature coil 22. As a result, leakage flux within the slot can be reduced, and further the skin effect at the cross section of the conductor within the slot can be effectively reduced, especially during high-frequency driving. Thus, highly efficient operation is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor driven by a variable frequency power supply such as an inverter.
The present invention relates to a brushless motor driven at a high speed of 0 rpm or more and capable of exhibiting good performance.

[0002]

2. Description of the Related Art DC motors have been used for railways for many years, but brushes and commutators are indispensable, so maintenance and maintenance costs are increased, and the merits corresponding to their good performance are diminished. It is getting. In addition, since there is a possibility that flashover or the like may occur on the commutator surface, it is not suitable for high-speed rotation, and it is difficult to manufacture a device that can withstand a high armature voltage, and as a result, it becomes expensive. Had drawbacks. In recent years, the emergence of a VVVF (variable voltage frequency) inverter has made it possible to utilize an induction motor having a cage rotor adapted only to the need of constant speed operation, thereby greatly reducing maintenance costs and speed control. Taking advantage of simplicity, its range of applications is expanding rapidly. However, an induction motor using a VVVF inverter has disadvantages such as a small starting torque, a difficulty in smooth rotation because it is not a perfect sine wave current, and an increase in loss due to a harmonic current. I have.

[0003]

An induction motor essentially generates a torque proportional to the rotor slip and has an almost constant speed operating characteristic, but cannot operate at a synchronous speed determined by the number of poles and the frequency. . Therefore, a variable frequency power supply such as an inverter is required to perform speed control. However, since the output of the inverter or the like is a distorted wave current including many harmonics other than the fundamental wave, a significant loss of the efficiency and output torque is caused by generation of a harmonic loss or a reverse phase torque. Further, there is a problem that high-speed rotation drive at a synchronous speed determined by a commercial frequency is impossible or the like. On the other hand, a DC motor that switches a DC current to a rectangular wave current by a commutator and a brush inside the motor does not essentially have the above-described drawbacks of the induction motor, but in addition to high efficiency operation and high starting torque, It is easy to control speed and torque. In the transportation sector where it is inevitable to reduce the size and weight of the equipment, it is extremely important to increase the rotation speed of the motor and reduce the size and weight of the motor. Fortunately, one of the inventors of the present invention is a flip-flop type linear motor (Matsui, Matsuoka: Prototype of permanent magnet field type linear motor car;
Utilizing the experience of the development of 870 pages), a brushless motor having a permanent magnet rotor suitable for high-speed rotation using a flip-flop type inverter instead of a commutator and a brush has been conceived. The present invention is to provide a brushless motor which can reduce extremely complicated work and a lot of man-hours for inserting and shaping a winding into a slot in the conventional manufacturing of a motor, and also capable of greatly reducing the manufacturing cost. It is in.

[0004]

In consideration of the essential advantages of a DC motor that can perform high-efficiency operation and has excellent controllability and start-up torque, it is possible to take advantage of the advantages of a DC motor and to use a motor without a commutator and brush. Development is expected to dramatically expand the scope of its application. FIG. 1 shows the configuration of an armature coil of a high-speed flip-flop type motor (hereinafter abbreviated as FFM). The development view of the armature coil and the stator of the FFM shown in FIG. 1 is a case of eight poles and six phases, and the coils of each phase of the armature coil 22 are formed in a wave shape. Further, for example, to move the rotor 10 in the right direction in the drawing, the armature coil 22 is connected to each phase so that a traveling wave in the same direction is generated. Furthermore,
The armature coil 22 is formed by providing a circular or elliptical closed slot or open slot in the stator core, and inserting a single-wire insulated conductor into this slot. By adopting such a mode, the leakage magnetic flux in the slot, that is, the leakage reactance, can be reduced, and the skin effect in the cross section of the conductor in the slot particularly at the time of high-frequency driving can be effectively reduced, and high-efficiency operation can be performed. . A substantially constant torque characteristic can be obtained by selecting the magnetic pole width Mw of the permanent magnet as the field from the pitch width (Cw) and the number of phases (N) of the armature coil in the range shown in the following equation. Can be. Cw × (N−1) / (N) ≦ Mw ≦ Cw By further transforming the above equation, when the number of magnetized poles of the rotor is P, the magnetic pole arc angle θ is 360 × (N−1) / (N × P) ≦ θ ≦ 360 × N /
(N × P). Selecting the magnetic pole width Mw or the magnetic pole arc angle θ of the permanent magnet in the range calculated from the above equation has the effect of averaging the magnetic flux distribution between the poles in a sinusoidal manner. It can also be used for improvement. This shows a remarkable effect in reducing the armature reaction during the load operation of the FFM. Hereinafter, the details of the present invention will be described.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a stator of an FFM according to the present invention is shown in FIGS. FIG. 2 is a side view as seen from the end bracket side, and the right half shows details of the coil end portion excluding the end bracket. On the other hand, FIG.
It is a front view of the coil end part of the stator of FIG. As can be easily understood from both figures, the armature coil 22 housed in the stator has a structural characteristic of one slot and one conductor, and the single conductor 21 is disposed in the slot 26 and has The single conductor 21 of each phase has a structure in which the single conductor 21 is connected by a crossover conductor 23. From the technical idea of the present invention, it is easily understood that the single conductor 21 can be constituted by a cage structure or the like in which a bar-shaped conductor or a slot is coated with an insulating film or the like and then the conductor is die-cast. FIG.
2 shows a configuration of an FM rotor. A permanent magnet 18 is fixed to a magnetic member 16 via a nonmagnetic member 14 on a shaft 12. FIG. 5 shows an example of the structure of the arc segment-shaped permanent magnet 18. The rotor 10 has eight poles, and the magnetic pole arc angle θ of the permanent magnet is selected to be 37.5 degrees. The permanent magnet 18 may be fixed by using an adhesive such as a resin, but may be fixed by a high-tension reinforcing fiber such as CFRP. In addition, when bonding permanent magnets, it is effective to strengthen the fixing of the central part of the permanent magnet and weaken the end part or make it free, as a method of relaxing the stress due to thermal strain due to temperature rise as well as centrifugal stress. It is. FIG. 6 is a wiring diagram in which the FFM according to the present invention is connected to a flip-flop type inverter (for example, when the number of magnetic poles of the rotor is P = 4 and the number of phases of the armature coil is N = 3). A rectangular wave alternating current by the flip-flop type inverter 35 is supplied to the armature coil 22 on the stator side, and the current flowing through the armature coil is changed according to a change in the relative position between the armature coil and the permanent magnet on the rotor side. By flowing the current, the rotor can be driven in accordance with the current flow velocity. First, the commercial power supply 31 is changed to a DC voltage by the converter 33. The converter 33 has a phase control circuit 38.
Means for controlling the direct current. Next, the output of the converter 33 is a flip-flop type inverter 35.
And is converted into a rectangular wave current. At this time, the flip-flop type inverter 35 operates the commutation control circuit 39 to which the signal of the position detection sensor 37 of the permanent magnet of the rotor is inputted.
It is a configuration controlled by. FIG. 7 shows the FFM of the present invention.
In the case where is driven by a flip-flop type inverter. To make the explanation easier to understand,
One phase was shown. In FIG. 9A, the converter 33 at the left end is subjected to constant current control in a thyristor bridge configuration, and its output is applied to one phase 35 of a flip-flop type inverter. As shown in the figure, a current control element such as a thyristor, a diode and a capacitor are connected.Unlike a normal inverter operation, it is not a function of simply converting DC to AC, but rather a direction of DC current by a switch operation by a thyristor. Just switch. When the thyristors TH1 and TH2 are turned on,
A current flows in the direction shown in the figure, and acts on magnetic flux from the S pole of the permanent magnet 18 to cause the electromagnetic force to move the armature coil 22 to the right. (B) shows T from thyristors TH1 and TH3.
This is a commutation period to H2 and TH4. At this time, the permanent magnet 1
Reference numeral 8 denotes a timing at which the potential changes from the south pole to the north pole. (C) is the reverse of the case of (a), in which thyristors TH2 and TH4 are on and thyristors TH1 and TH3 are off. As can be seen from the above description, by providing a constant current forward / inverting device on the primary side of the flip-flop inverter, it is possible to control the commutation speed of the flip-flop inverter, and the motor is controlled over the entire area from start to stop. The rotation of can be controlled.

As an example of manufacturing an FFM, P = 8 and N = 6
In the following, the design data will be described. The FFM magnet rotor is composed of eight arc segment-shaped permanent magnets and a rotor with a shaft. The rotor with shaft is shaft 1 (diameter 30mm, length 360mm, material is S4
5C), a cylindrical non-magnetic member 2 (outer diameter: 139.7 mm,
Inner diameter 30.3mm, length 160mm, material is SUS30
4) and a cylindrical magnetic member 3 (outside diameter: 189.7 mm, inside diameter: 140 mm, length: 160 mm, material is S10C). FIG. 5 shows a cross-sectional shape of the eight permanent magnets 4 arranged on the surface of the shaft-equipped rotor. One permanent magnet 4 is an arc segment-shaped permanent magnet (width 61.0-6).
8.0 mm, thickness 10.0 mm, length 160 mm, permanent magnet: Nd-Fe-B system maximum energy product 35 MGOe)
It is. The angle of the pitch width (Cw) of the armature coil is 45
Degree (360 / P), the magnetic pole arc angle of the permanent magnet is 37.5 degrees [45 × (N-1)] as shown in FIG.
/ N]. FIG. 2 shows a stator on which armature coils are provided. FIG. 2 is a front view of the stator, and FIG. 3 is a side view of the stator. The stator is a cylindrical magnetic member (outer diameter 274.0 m
m, inner diameter 214.0 mm, length 160 mm, material is silicon steel plate for motor), and N × P = 4 in which armature coils are arranged.
It has eight slots 26. Slot 6 has a diameter of 8.0
mm and a length of 160 mm, the center of which is located 5.0 mm from the inner peripheral surface of the stator 5 facing the rotor. Also,
Forty-eight slots 6 are provided at every angle 7.5 [360 / (N ×
P)] in the stator 5. Forty-eight single-wire insulated conductors (conductor diameter: 6.0 mm) are inserted into the forty-eight slots 6, and the ends of the in-phase insulated conductors are connected by plate-shaped conductors by the method shown in FIGS. As a condition of the shape of the plate-shaped conductor, a cross-sectional area of 28 mm ² or more is required. A motor according to the present invention comprising the above-described stator shown in FIG. 2 and the magnet rotor shown in FIG. 4 is connected to a flip-flop type inverter (number of armature coil phases N = 6, armature coil voltage V = 3).
(60 V, commutation frequency f = 800 Hz), and the test evaluation was performed. As a result, the number of rotations of the motor was 5,750 rpm. As shown in FIGS. 4 and 5, a plurality of arc segment-shaped permanent magnets may be arranged on the outer periphery of the cylindrical iron core to form a rotor. However, it goes without saying that the effects of the present invention can be sufficiently obtained with a ring-shaped magnet. . Further, the arc segment-shaped permanent magnet may be arranged inside the iron core instead of the outer periphery. By arranging the permanent magnet inside the rotor, the reliability as a rotor for high-speed rotation is further improved. According to the purpose, ring-shaped permanent magnets or arc-segmented permanent magnets can be alternately magnetized to multiple N-poles and S-poles to provide a magnetic field for the rotor. In the case of high-speed rotation, durability can be expected to be improved by using ceramic balls instead of steel balls for the balls of the bearing for bearings.

[0007]

As described above in detail, the motor according to the present invention driven by the alternating current of the rectangular wave by the flip-flop type inverter does not have a commutator and a brush in principle. The difference between the motor according to the present invention and the DC motor is the presence or absence of a commutator and a brush. In the motor according to the present invention having no commutator and no brush, there is no occurrence of commutation spark due to abnormal commutation voltage. Further, since there is no problem of abrasion of the commutator and the brush, the present invention facilitates the design of a large motor. Furthermore, in the case of high-speed rotation, the waveform coil is adopted as the armature coil, so there is no need to insert and shape windings into the slot as in the conventional case, and the structure is extremely simple, making coil production and motor assembly easy. Become. Sunahachi,
The brushless motor according to the present invention can be easily mass-produced beyond the concept of a conventional motor, and can be expected to greatly improve durability and reliability. Further, it is possible to significantly reduce the size and weight.

[Brief description of the drawings]

FIG. 1 is a development view of an armature coil and a rotor according to the present invention.

FIG. 2 is a side view of the brushless motor according to the present invention.

FIG. 3 is a front view of the brushless motor according to the present invention.

FIG. 4 is a magnet rotor of a brushless motor according to the present invention.

FIG. 5 shows a permanent magnet of a magnet rotor according to the invention.

FIG. 6 is a connection diagram of a flip-flop type inverter and a brushless motor.

FIG. 7 is an operation explanatory diagram of a flip-flop inverter.

[Explanation of symbols]

10 rotor, 12 shaft, 14 non-magnetic member, 1
6 magnetic members, 18 permanent magnets, 21 single conductors, 22
Armature coil, 23 transition conductor, 24 stator core,
25 conductor end, 26 slot, 31 power supply, 33
Converter, 35 flip-flop type inverter, 3
7 position detection sensor, 38 phase control circuit, 39 commutation control circuit, 42 bearing, 44 end bracket, 46 yoke

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiko Kuriyama 5200 Mikajiri, Kumagaya City, Saitama Prefecture Inside the Kumagaya Plant of Hitachi Metals Co., Ltd. (72) Inventor Ichizo Matsui 1-17-4 Sotokanda, Chiyoda-ku, Tokyo Magnet Transport System Development Co., Ltd.

Claims (4)

[Claims] 1. A brushless motor in which an armature coil is arranged in a slot provided in a stator and a permanent magnet is fixed to a rotor, wherein the armature coil is formed of a single conductor, and has a coil end portion. A brushless motor characterized in that the single conductors located at required poles or phases are connected in series and are operated at a high speed of 4000 rpm. 2. The armature coil according to claim 1, wherein a conductor cross section of the armature coil has a substantially circular or elliptical shape. When the number of slots per pole is less than 6, the slot is a closed slot. A brushless motor. 3. The method according to claim 1, wherein
When the number of magnetized poles of the rotor is P, the magnetic pole arc angle θ of the permanent magnet is set to 360 × (N−1) / (N × P) ≦ θ ≦ 3.
A brushless motor characterized by 60 × N / (N × P). . 4. A brushless motor in which an armature coil is arranged in a slot provided in a stator and a permanent magnet is fixed to a rotor, wherein the armature coil is formed of a single conductor and has a coil end portion. A brushless motor, wherein the single conductors located at required poles or phases are connected in series and driven at high speed by a flip-flop type inverter.