JPH0332345A - Rotor/stator structure of ac variable reluctance servomotor - Google Patents

Abstract

PURPOSE:To maximize torque generating section by setting the tooth width of rotor and that of stator salient pole to a value obtained by dividing the circumference of a circle having a radius equal to the distance between the center of rotation of the rotor and the tooth face of the rotor salient pole by a value two times of the tooth number of the rotor salient pole. CONSTITUTION:The circumference of a circle having radius equal to the distance between the center of rotation of a rotor 1 and the tooth faces 1a-1d of rotor salient pole is divided by a value two times of the number of tooth of the rotor salient pole. Thus obtained value is employed as the tooth width of rotor and stator salient poles. Consequently, the distances between the tooth widths of the rotor salient pole and respective rotor salient pole teeth are identical. When exciting current is fed to the exciting windings of rotor salient pole teeth A, A', C, C', the rotor 1 rotates counter clockwise. During rotation, the area of the salient pole teeth A, A' of the stator 2 facing with the salient pole teeth 1a, 1c of the rotor 1 and the area of the salient pole teeth C, C' of the stator 2 facing with the salient pole teeth 1b, 1c of the rotor 1 increase and vary continuously thus producing torque continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of the rotor and stator ultimate teeth in variable reluctance type AC servo motors.

Conventional technology A variable reluctance type AC servo motor has a rotor formed into an ultimate structure by stratifying iron plates, which is rotatably held inside a stator by a motor shaft, and an excitation current is supplied to the excitation winding of the stator. This is a motor that excites the ultimate tooth of the stator, and uses the magnetic attraction force generated on the ultimate tooth of the stator to attract the ultimate tooth of the rotor and generate a rotational force, thereby driving the rotor to rotate.

Compared to a permanent magnet synchronous motor, this motor does not use a magnet in the rotor, so it has the advantage of being simple in structure and inexpensive to manufacture.

Problems to be Solved by the Invention In the above-mentioned variable reluctance type AC servo motor, there was no clear design theory regarding the ultimate tooth width of the rotor and stator.

Therefore, in the past, the ultimate tooth widths of the rotor and stator were arbitrarily set, making it impossible to extract sufficient torque from the motor.

Therefore, an object of the present invention is to provide a rotor-stator structure for a variable reluctance type AC servo motor that maximizes the torque generation section.

Means for Solving the Problems The present invention provides a method in which the circumference of a circle whose radius is the distance from the rotation center of the rotor to the rotor's ultimate tooth surface is divided by twice the rotor's ultimate number of teeth,
By setting these values as the rotor ultimate tooth width and stator ultimate tooth width, the above problem was solved.

The working magnetic permeance P is generally expressed by the following equation (1).

P=μOxS/Lg −=(1) Furthermore, μ
O: Vacuum permeability, S: ultimate opposing area of rotor and stator, Lg gap (distance between rotor ultimate tooth and stator ultimate tooth).

When the magnetic flux φ at a constant current I (constant coercive force H) is determined using the above magnetic permeance P, the following equation (2) is obtained.

φ-P-n-■ ・・・・・・(2)
Note that n is the number of turns of the excitation winding of the stator ultimate tooth.

Moreover, the magnetic energy E is expressed by the following equation (3).

E-n・φ-1=P-nl-nl=43) According to the principle of virtual work, when the excitation current 1 is constant and the gap Lg is constant, the l・lux τ generated in the motor is as follows (4) It is shown by the formula.

τ= d e / dθ (n I) 2 ”μo/Lg)” dS/dθ...
(4) From equation (4) above, it can be seen that for variable reluctance type A and C servo motors, the change in the opposing area (dS/dθ) between the ultimate teeth of the rotor and stator generates the torque τ. I understand.

Therefore, the ultimate tooth widths of the rotor and stator should be set so that the change (d, S/dθ) in the opposing area of the ultimate teeth of the rotor and stator always exists at any 1"11 rotation position of the rotor.

In the present invention, the distance from the rotation center of the rotor to the rotor's ultimate tooth surface is the '1' diameter (the radius of the rotor's ultimate tooth), and the circumference is divided by twice the rotor's ultimate number of teeth, and this value is Since the ultimate tooth width and the stator ultimate tooth width are set as the ultimate tooth width, the opposing areas of the ultimate teeth of the rotor and the stator change almost continuously as the rotor rotates. That is, the change in the facing area (d
S/dθ) always exists, and from equation (4) it is possible to always generate torque.

For example, if the ultimate tooth widths of the rotor and stator are different, there will be a situation where no change in the opposing area (dS/dθ) occurs.
If the ultimate tooth widths of the rotor and the stator are the same, and the ultimate width of the rotor and the width between the two are the same, a change in the ultimate facing area of the rotor and the stator will always occur.

Embodiment FIG. 1 is an overview of an embodiment of the present invention and a transition diagram when the rotor is rotated counterclockwise.

In the figure, 1 is a rotor, and 2 is a stator. In this embodiment, the rotor has four poles (four pole pairs), and the stator has six poles.

The rotor 1- is fixed to a rotatable motor shaft and held by a rotation bearing. The rotor 1 has four ultimate teeth 1
a to 1d, and the tooth width of the four rotor single-pole teeth 1a to 1d is set to the distance from the rotation center of the rotor 1 to the circumferential surface of the ultimate teeth 1a to 1d, that is, the ultimate radius of the rotor. The circumference is divided into 8 equal parts (-2X rotor ultimate teeth). As a result, each of the rotor ultimate tooth widths 1a to 1d and the distance between each rotor ultimate tooth (width of the trough) are the same.

Stator 2 has the ultimate tooth A of the A phase, /M and the ultimate tooth B of the B phase,
B-1C phase has ultimate teeth C and C-, each stator ultimate tooth faces each stator ultimate tooth with a minute gap, and each ultimate tooth A, A, -, B, B of stator 2.
The tooth widths of -, C, and C- are configured to have the same dimensions as the ultimate tooth width of the rotor 1.

Although not shown in FIG. 1, excitation windings are wound around each ultimate tooth of the stator 2, and have an A-phase and a B-phase.

The C-phase out-of-phase excitation current flows through the excitation winding, and the stator bipolar teeth A, A-, B, B", C, C-
are sequentially magnetized to attract the rotor's first pole teeth 1-a to 1-b, and the rotor 1 is rotated by this magnetic attraction force.

As shown in FIG. 1(a), the state where the ultimate teeth A, A'' of the A phase of the stator 2 and the valley of the rotor 1- is opposed to each other is defined as an electrical angle of 0 degrees, and now the A-phase and C-phase The steta ultimate tooth A,,'M
, C, C-, when an excitation current is passed through the excitation windings of the rotor 1, the ultimate tooth 1. a and 1c are attracted to the ultimate teeth Δ and A- of the stator, respectively, and ultimate teeth 1b and ld of the rotor are attracted to the ultimate tooth CC' of the stator, and the rotor 1 is moved in the direction of the arrow shown, that is, counterclockwise in the figure. 1 (b),
Next, it will rotate as shown in FIG. 1(c). Note that FIG. 1(b) shows the state when the electrical angle is rotated by 30.0 degrees, and FIG. 1(C) shows the state when the electrical angle is rotated by 60.0 degrees. During this rotation, the ultimate tooth of rotor 1 ], a, lc and stator 2
The opposing area of the ultimate teeth A, A- and the ultimate 1'J of the rotor 1
], b, , 1-d and the ultimate teeth c, c' of the stator 2 are constantly increasing and changing in their opposing areas, which means that torque is constantly being generated.

Next, from the state of Fig. 1 (C), the ultimate tooth A of the stator 2 is
, If the excitation current is applied only to the excitation winding A-, the rotor 1
The ultimate teeth 1a, Ic of the stator 2 are attracted to the ultimate teeth A, A- of the stator 2, and the rotor 1 has an electrical angle of 90.
0 degrees), then Fig. 1(e) (electrical angle 1-20.0
degrees).

The ultimate tooth A of the stator 2 from the state shown in FIG. 1(e).

When excitation current is applied to the excitation windings A'', B, B-, the ultimate teeth 1a, 1-c and ld, 1b of the rotor ↓ become the ultimate teeth A, A', B, of the stator 2, respectively.
! 3-, the rotor 1 is rotated through the state shown in FIG. 1(f) (electrical angle 150.0 degrees) to the state of the 11th station (g) (electrical angle 180.0 degrees).

Thereafter, if current is applied only to the excitation windings of the ultimate teeth B and B- of the stator, the rotor 1- will further rotate counterclockwise, and as mentioned above, the excitation windings of the ultimate teeth of the stator 2 If the excitation current is applied while switching sequentially to , the rotor 1 will rotate in the counterclockwise direction. The same applies when the rotor 1 is moved clockwise, for example, as shown in FIG. 1(a).
In the state of , the ultimate tooth A of stator 2, , ! M, B,
When B- is magnetized by an exciting current, the rotor 1 rotates clockwise.

It should be noted that the excitation method is not limited to the above-mentioned 1-2 phase excitation force type, and it goes without saying that other excitation methods may be used.

As described above, the rotor 1 rotates, but in Figs.
As is clear from (g), the opposing area between the ultimate tooth of the rotor 1 and the excited ultimate tooth of the stator is always changing no matter what rotational position the rotorbo is at, and as a result, the variable reluctance type A , C servo motor always generates torque.

Effects of the Invention In the present invention, the ultimate tooth widths of the rotor and stator are designed such that no matter what rotational position the rotor is in, the opposing area between the ultimate teeth of the rotor and the ultimate teeth of the stator always changes as the rotor rotates. Therefore, the torque generation section can be maximized.

[Brief explanation of drawings]

FIGS. 1(a) to 1(g) are an overview of a variable reluctance type AC servo motor according to an embodiment of the present invention, and a diagram showing changes when the rotor is rotated counterclockwise. 1... Rotor, 2... Stator, 1a to 1d... Ultimate tooth of rotor, A, A', B, B", C, C"... Ultimate tooth of stator.

Claims (1)

[Claims] For variable reluctance type AC servo motors, divide the circumference whose radius is the distance from the rotor's center of rotation to the rotor's ultimate tooth surface by twice the rotor's ultimate number of teeth, and calculate this value as the rotor's ultimate tooth width and stator's ultimate tooth width. A rotor-stator structure of a variable reluctance type AC servo motor characterized by: