KR20160029167A - Step motor assembly and method for controlling the same - Google Patents

Abstract

According to an embodiment of the present invention, provided is a step motor assembly comprising: a first step motor and a second step motor. The first step motor includes a first stator, and a first rotor which is relatively rotated with respect to the first stator. The second step motor includes a second stator which is coupled to the first rotor, and a second rotor which is relatively rotated with respect to the second stator. The minimum step angle of the step motor assembly is a difference between the step angle of the first step motor and the step angle of the second step motor.

Description

A step motor assembly and a method of controlling the step motor assembly

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor and a step motor control method, and more particularly, to a step motor assembly including a plurality of step motors having a high resolution and a control method of the step motor assembly.

A stepper motor is a motor that rotates at a certain angle by a pulse-shaped input voltage. The stepper motor is continuously rotated by a series of input pulse sequences. Today, stepping motors are widely used in a variety of devices that perform linear or rotary motion.

Fig. 1 shows a conventional step motor in a basic form. Fig. 1a schematically shows a plane of a step motor, and Fig. 1b schematically shows a side cross-section. This general step motor includes the stator 1, the rotor 2, and the shaft 3 integrally coupled to the rotor. The stator 1 is fixedly coupled to the housings 7 and 8 of the step motor and the shaft 3 integrated with the rotor 2 is connected to the housing 7 And 8, respectively.

The stator 1 is formed of, for example, an electromagnet in which a coil is wound on an iron core, and the rotor 2 is made of a permanent magnet. When a pulse is applied to the coil wound around the stator 1, a magnetic force is generated, and the magnetic force is repeated to pull the N pole or the S pole of the rotor 2, thereby rotating the rotor 2. [

The step motor determines the resolution according to the physical structure of the stator and the rotor constituting the step motor, and the rotation angle, that is, the step angle, which is rotated by one pulse input is determined according to the resolution. Generally, a stepper motor with a high resolution is required for precise device control. However, a stepper motor with a high resolution has a disadvantage in cost, and has a limitation in increasing resolution.

U.S. Patent No. 4,897,588 (published January 30, 1990)

According to an embodiment of the present invention, there is provided a step motor assembly having a high resolution in a simple configuration.

According to an embodiment of the present invention, there is provided a step motor assembly capable of rotating within a minimum pulse input time up to a target rotation angle input to a step motor assembly, and a control method thereof.

According to an embodiment of the present invention, there is provided a step motor assembly including a first step motor and a second step motor, wherein the first step motor includes: a first stator; And a first rotor rotating relative to the first stator, the second step motor including a second stator coupled to the first rotor; And a second rotor rotating relative to the second stator, wherein a minimum step angle of the step motor assembly is a difference between a step angle of the first step motor and a step angle of the second step motor A step motor assembly is provided.

According to an embodiment of the present invention, there is provided a stator comprising a first stator having a first stator and a first rotor rotatable relative to the first stator, a second stator coupled to the first rotor, A method for controlling a step motor assembly including a second step motor having a second rotor rotating relative to a stator, the method comprising the steps of: Decomposing into a combination of minimum step angles; Comparing the number of rotations with a minimum step angle of the step motor assembly to a preset reference value; And calculating a pulse value to be applied to each of the first step motor and the second step motor according to the comparison result.

According to an embodiment of the present invention, a step motor assembly having a high resolution can be provided by serially connecting two step motors with relatively low resolution.

According to an embodiment of the present invention, the step motor driving time can be shortened by rotating within the smallest pulse input time possible up to the target rotation angle input to the step motor assembly.

1A and 1B are diagrams for explaining a conventional step motor,
2 is a view for explaining a step motor assembly according to an embodiment of the present invention;
3 is a view for explaining the operation of the step motor assembly according to an embodiment of the present invention;
4 is a flowchart illustrating a method of controlling a step motor assembly according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being "above" (or "below", "right", or "left") another element, ) Or it may mean that a third component may be interposed therebetween. Further, in the drawings, the thickness of the components is exaggerated for an effective description of the technical content.

Also, in this specification, expressions such as 'upper', 'lower (lower)', 'left', 'right', 'front', 'rear' And it is a relative expression used for convenience of explanation based on the drawings when describing the present invention with reference to the respective drawings.

Where the terms first, second, etc. are used herein to describe components, these components should not be limited by such terms. These terms have only been used to distinguish one component from another. The embodiments described and exemplified herein also include their complementary embodiments.

In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms "comprise" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other elements.

Hereinafter, the present invention will be described in detail with reference to the drawings. In describing the specific embodiments below, various specific details have been set forth in order to explain the invention in greater detail and to assist in understanding it. However, it will be appreciated by those skilled in the art that the present invention may be understood by those skilled in the art without departing from such specific details. In some cases, it should be mentioned in advance that it is common knowledge in describing an invention that parts not significantly related to the invention are not described in order to avoid confusion in explaining the present invention.

FIG. 2 is a view for explaining a step motor assembly according to an embodiment of the present invention, and shows an exemplary sectional view of a step motor assembly.

Referring to the drawings, a step motor assembly 100 according to an embodiment includes a first step motor 10 and a second step motor 20. The first stepping motor 10 includes a stator 11 attached to the housings 17 and 18 and a rotor 12 that rotates relative to the stator 11. In one embodiment, the rotor 12 is configured to rotate integrally with the shaft 13, and the shaft 13 is connected to the housings 17, 18 of the first stepping motor 10 by means of connecting means such as a bearing 14. [ As shown in Fig.

The second stepping motor 20 includes a stator 21 attached to the housings 27 and 28 and a rotor 22 that rotates relative to the stator 21. In one embodiment, the rotor 22 is configured to rotate integrally with the shaft 23, and the shaft 23 is connected to the housings 27, 28 of the second stepping motor 20 by means of connecting means such as a bearing 24. [ (Not shown). The shaft 23 protrudes outside the housing 27 of the second stepping motor 20 and a load is connected to the shaft 23, An assembly may be used to drive the load.

In a preferred embodiment, the stator 21 of the second stepping motor 20 is formed to rotate integrally with the rotor 12 of the first stepping motor 10. The shaft 13 of the first stepping motor 10 is coupled to the housing 28 of the second stepping motor 20 so that the shaft 13 and the housings 27 and 28 are integrally rotatable The rotor 12 of the first stepping motor 10 and the stator 21 of the second stepping motor 20 can rotate integrally.

In one embodiment, the stator 11, 21 of each of the first step motor 10 and the second step motor 20 is implemented as an electromagnet and each of the rotors 12, 22, which is a corresponding member of the electromagnet, Lt; / RTI > Alternatively, the stator 11, 12 of each of the first step motor 10 and the second step motor 20 may be implemented as permanent magnets and the rotors 12, 22 may be implemented as electromagnets.

Each of the first step motor 10 and the second step motor 20 has a different step angle (an angle at which the step motor rotates by one pulse). The resolutions of the first stepping motor 10 and the second stepping motor 20 are different. In addition, the first step motor 10 and the second step motor 20 receive the pulse values different from each other at the same time, and the rotors 12 and 22 can rotate, May rotate in the same rotation direction or in opposite directions. This will be described later with reference to Figs. 3 and 4 below.

3 is a view for explaining the operation of the step motor assembly according to an embodiment of the present invention.

Referring to the drawings, a step motor assembly according to an embodiment includes a first step motor 10, a second step motor 20, and a driving unit 30. The first step motor 10 and the second step motor 20 shown in FIG. 3 are the same as or similar to the first and second step motors 10 and 20 shown in FIG.

In the embodiment of FIG. 3, the step motor assembly further includes a drive 30. The driving unit 30 is a functional unit for driving the step motor assembly. In one embodiment, the driving unit 30 may include a pulse generating unit 31 and a control unit 33.

The pulse generating unit 31 applies pulse values for driving the first and second step motors 10 and 20 of the step motor assembly to the step motors 10 and 20, respectively. In one embodiment, the stator 11, 21 of each of the first and second stepping motors 10, 20 is implemented as an electromagnet, and accordingly, the pulse generating section 31 is provided with each of the stator 11, It is possible to drive the respective rotors 12 and 22 of the first and second stepping motors by applying different pulse springs.

The electrical connections of the pulse generator 31 and the stators 11 and 21 to the stator 11 and 21 in order to apply the pulse wave generated by the pulse generator 31 can be implemented in various ways according to the embodiment have. Since the stator 11 of the first stepping motor 10 is fixed without rotation, it is possible to connect electric wires from the pulse generating section 31 to the stator 11. [ The stator 21 of the second stepping motor 20 rotates with respect to the first stepping motor 10. Therefore, in the embodiment in which the rotation range of the second stepping motor 20 is limited, it is possible to directly connect the electric wire to the rotor 21 in the pulse generating section 31. If the rotation range of the stepping motor 20 is large A through hole is formed in the shaft 13 of the first stepping motor 10 and a flexible wire is passed through the shaft 13 and connected to the stator 21 of the second step motor 20, And the electrical connection with the stator 21 can be ensured by using a slip ring.

In one embodiment, the pulse generator 31 may be implemented as a switching circuit composed of a plurality of semiconductor transistors, for example, and may control the gate of each transistor to generate a desired desired spherical pulse wave, Can be applied to the stator (11, 21).

At this time, a control signal for controlling the gates of the respective transistors can be applied from the control section 33. That is, the control unit 33 controls the generation and the form of the pulse wave to be applied to the first and second stepping motors 10 and 20. For example, when the target rotation angle at which the shaft 23 of the second step motor 20 of the step motor assembly is to be rotated relative to the housings 17, 18 of the first stepping motor 10 is input, The first and second stepping motors 33 and 33 respectively determine the rotation angles at which the shafts 13 and 23 should rotate, And controls the pulse generating section 31 so that the pulse wave of the pulse generating section 31 can be applied.

In general, the "resolution" of a stepper motor means how many pulses must be input for one revolution of the rotor (ie, shaft) of the stepper motor, and "step / rev." Or "pulse / rev.". The "step angle" of each step motor is the angle at which the rotor (ie, the shaft) rotates by one input pulse. When the rotation angle is expressed in degrees (step angle) ) Is established.

The step motor assembly 100 may be rotated by applying pulses to the first step motor 10 and the second step motor 20 of the step motor assembly 100 according to an embodiment of the present invention at the same time, The minimum value of the rotational angles among the rotational angles is hereinafter referred to as "minimum step angle ". In this case, the minimum step angle is an angle at which the output shaft of the step motor assembly 100, that is, the shaft 23 of the second step motor 20, is rotated with respect to the step motor assembly 100 device itself, Is the angle at which the shaft (23) rotates relative to the housings (17, 18) or the stator (11) of the step motor (10).

In one embodiment, the first stepping motor 10 and the second stepping motor 20 have different resolutions from each other. Preferably, the resolution ("R1") of the first stepping motor 10 and the resolution ("R2") of the second stepping motor 20 have a similar value. For example, when R2 is greater than R1, it is preferable to select the first stepper motor and the second stepper motor so that R2 is not more than 10 times greater than R1 in one embodiment. In another embodiment, the first stepper motor and the second stepper motor may be selected such that R1 has a value between 0.8 * R2 and R2, preferably between 0.9 * R2 and R2.

Assuming that the step angle of the first stepping motor 10 is "A" and the step angle of the second stepping motor 20 is "B" in the embodiment, A = 360 / R1 and B = 360 / do.

Preferably, when the minimum step angle of the step motor assembly 100 is assumed to be "S ", the present invention is characterized in that the difference in resolution (or step angle) between the first step motor 10 and the second step motor 20 The following equation is established.

[Equation 1]

S = | A-B |

That is, the minimum step angle of the step motor assembly 100 is equal to the difference between the step angle of the first step motor 10 and the step angle of the second step motor 20 constituting the step motor assembly.

For example, the step motor assembly 100 according to an embodiment may include a first step motor 10 having a resolution R1 of 180 steps / rev. And a second step motor 10 having a resolution R2 of 200 steps / rev. And a step motor 20. That is, the step motor assembly 100 is constructed of a two-step motor having resolutions of 180 and 200, which are similar to each other. In this case, the entire assembly including the first and second step motors, that is, the step motor assembly 100 The minimum step angle (S) is as follows.

S = | A-B | = 360/180 - 360/200 = 20-18 = 2 (°)

On the other hand, when the resolution of the step motor assembly 100 is assumed to be "Ra ", Ra is expressed as follows.

&Quot; (2) "

Ra = 360 / S = (R1 * R2) / (R2-R1)

That is, the resolution Ra of the step motor assembly 100 is proportional to the product of the resolution R1 of the first stepping motor and the resolution R2 of the second stepping motor, and the resolution of the first stepping motor, Is inversely proportional to the difference in resolution (R2-R1).

An example of the control algorithm of the step motor assembly 100 according to one embodiment will now be described. It is assumed that the step angle A of the first stepping motor 10 of the assembly 100 is 1 占 and the step angle B of the second stepping motor 20 is 0.9 占. That is, the resolution R1 of the first stepping motor 10 is 360 steps / rev. And the resolution R2 of the second stepping motor 20 is 400 steps / rev.

It is assumed that the step motor assembly 100 having such a configuration is rotated 17.8 degrees in the clockwise direction, for example. That is, in this case, the target rotation angle of the stub motor assembly 100 is 17.8 degrees, and the shaft 23 of the second step motor is fixed to the stator 11 (or the housings 17, 18) It should rotate by the angle of rotation.

In the above example, the minimum step angle S of the step motor assembly 100 is 0.1 占 There are two methods of rotating the shaft 23 by the target rotation angle.

First, the first step motor 10 having a large step angle among the first and second step motors is rotated clockwise by 17 DEG, and further rotated clockwise 8 times with the minimum step angle S of the step motor assembly 100 And rotating by the target rotation angle, and

Second, the first stepping motor 10 is rotated clockwise by 18 degrees and then counterclockwise by the minimum step angle S of the stepping motor assembly 100 to rotate by the target rotation angle.

If the first method is used, the target rotation angle is expressed as follows.

17.8 = 17 * A + 8 * (A-B) = 25 * A-8 * B

That is, in this case, 25 pulses are applied to the first stepping motor 10 so that the shaft 13 of the first stepping motor 10 rotates clockwise, and at the same time, the shaft 23 of the second stepping motor 20 It is possible to rotate by the target rotation angle by applying eight pulses to the second step motor 20 so as to rotate in the counterclockwise direction.

If the second method is used, the target rotation angle is expressed as follows.

17.8 = 18 * A-2 * (A-B) = 16 * A + 2 * B

That is, in the case of the second method, 16 pulses are applied to the first stepping motor 10 so as to rotate clockwise, and two pulses are applied to the second stepping motor 20 so as to rotate clockwise, can do. Compared with the first method, since the number of pulses applied to the step motor by the second method is small, the step motor assembly 100 can be driven more quickly by the second method.

As can be seen from the above example, both of the above-described methods can be used to rotate the target rotation angle. However, in the first method, it is necessary to apply at least 25 pulses in order to rotate the target rotation angle. In the second method, It is more effective to use the second method in this case. Either the target rotation angle and the minimum step angle of the assembly 100 may be more efficient.

Hereinafter, the control method of the step motor assembly 100 in a case where the target rotation angle and the minimum step angle of the assembly are not specified by generalizing the above-described example will be described with reference to FIG.

4 is a flowchart illustrating a method of controlling a step motor assembly according to an embodiment of the present invention. For the sake of explanation, the step angle and resolution of the step motor assembly 100 will be expressed as follows.

A: Step angle of the first step motor

B: Step angle of the second step motor (assuming A > B)

S: Minimum step angle of the step motor assembly (S = A - B)

In the above configuration, it is assumed that the target rotation angle of the step motor assembly 100 is inputted to the control unit 33 at a predetermined value. At this time, it is assumed that the target rotation angle has an arbitrary angle within the resolution of the step motor assembly 100.

If the target rotation angle is "X ", the control unit 33 compares the target rotation angle X in step S110 of FIG. 4 with the step angle of the step motor of large step angle Step angle is disassembled. This can be expressed as follows.

X = x1 * A + x2 * S

The control unit 33 calculates the number of rotations x1 by the first stepping motor 10 and the number of rotations x2 by the minimum step angle of the assembly 100 when the target rotation angle is given. Here, "x1" is the number of times the step angle is rotated by the stepper motor, i.e., the pulse value to be applied to the stepper motor, and "x2" At this time, the value of x1 is selected as the largest possible value within the range not exceeding the target rotation angle only by the rotation of the shaft 13 of the first stepping motor 10, and then the shaft 13 is rotated by x1 * A The number of rotations (x2) of the minimum step angle based on the remaining angle from the position rotated by the angle to the target rotation angle can be calculated.

Thereafter, in step S120, the control unit 33 compares the number of rotations (x2) with the minimum step angle of the step motor assembly 100 to a preset reference value. In one embodiment, this reference value can be determined according to the number of times at least the step angle should be rotated at the minimum step angle to rotate by the step angle of the step motor (i.e., the first step motor 10). In one embodiment, the reference value may be 1/2 of the number of times the step angle should be rotated by the minimum step angle to rotate by the step angle of the step motor of which the step angle is large. In other words, the expression is expressed as follows.

Reference value = <A/2S>

Here, the symbol "&gt;" is the rounding value of the value in parenthesis "&gt;" as a rounding function, A is the step angle of the step motor having the large step angle (first step motor), and S is the minimum step angle.

In an alternative embodiment, the reference value may be [A / 2S], where "[]" is the decreasing function.

Next, in step S130, the control unit 33 controls the first step motor 10 and the second step motor 20 according to the comparison result between the number of rotations (x2) at the minimum step angle and the reference value The pulse value is calculated.

In one embodiment, if the number of rotations (x2) to be rotated at the minimum step angle is equal to or less than a reference value (e.g., < A / 2S>), the target rotation angle X is expressed as follows.

X = x1 * A + x2 * S

  = x1 * A + x2 * (A-B)

  = (x1 + x2) * A - x2 * B

That is, in this case, when the first stepping motor 10 rotates in the "(x1 + x2)" target direction and the second stepping motor 20 rotates "x2" The control unit 33 sends a control signal to the pulse generating unit 31 to generate a pulse of "(x1 + x2)" to rotate in the target direction with respect to the first stepping motor 10, Quot; x2 "pulses to rotate in the opposite direction to the target with respect to the two-step motor 20. [

If the number of rotations (x2) to be rotated by the minimum step angle is larger than the reference value (e.g., < A / 2S >), the target rotation angle X is expressed as follows.

X = (x1 + 1) * A- (A / S-x2) * S

  = (x1 + 1) * A- {A / (A-B) -x2} * (A-

  = {x1 + x2-B / (A-B)} * A + {A /

That is, in this case, the first stepping motor 10 rotates in the target direction "{x1 + x2-B / (AB)}" and the second stepping motor 20 also rotates in the target direction "{A / the control unit 33 sends a control signal to the pulse generating unit 31 to rotate the first stepping motor 10 in the target direction To generate a "{A / (AB) -x2}" pulse for generating a {x1 + x2-B / (AB)} conferring pulse for the second stepping motor 20 do.

Thereafter, in step S140, the pulse generating unit 31 applies the pulse values generated in the above step S130 to the first and second step motors 10 and 20 to the respective stators 11 and 21 . At this time, for example, a pulse value may be applied to the stator 11 and then a pulse value may be applied to the stator 21. Preferably, the stator 11 of the first step motor and the stator 21 of the second step motor It is preferable to reduce the operation time of the entire step motor assembly 100 by applying pulse values at the same time.

Various modifications and variations of the present invention are possible in light of the above teachings. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be determined by the scope of the appended claims, as well as the appended claims.

10, 20: Step motor
11, 21: stator
12, 22: rotor
13, 23: Shaft
17, 18, 27, 28: housing
30:
31:
33:
100: Step motor assembly

Claims (12)

A step motor assembly having a first step motor and a second step motor,
The first stepping motor includes:
A first stator; And
And a first rotor rotating relative to the first stator,
The second stepping motor includes:
A second stator coupled to the first rotor; And
And a second rotor rotating relative to the second stator,
Wherein a minimum step angle of the step motor assembly is a difference between a step angle of the first step motor and a step angle of the second step motor. The method according to claim 1,
Wherein the resolution of the step motor assembly is proportional to the product of the resolution of the first step motor and the resolution of the second step motor. 3. The method of claim 2,
Wherein the resolution of the step motor assembly is inversely proportional to the difference between the resolution of the first step motor and the resolution of the second step motor. The method according to claim 1,
Wherein the step motor assembly further includes a driving unit for driving the first step motor and the second step motor, respectively. The method according to claim 1,
Wherein the first stator and the second stator are electromagnets and the first rotor and the second rotor are permanent magnets. A first stator having a first stator and a first rotor rotating relative to the first stator, a second stator coupled to the first rotor, and a second stator coupled to the second stator, A method for controlling a step motor assembly including a second step motor having a rotor and a drive unit for controlling the driving of the first step motor and the second step motor,
Disassembling the target rotational angle of the step motor assembly into a combination of a step angle of the first step motor and a minimum step angle of the step motor assembly;
Comparing the number of rotations of the driving unit with a minimum step angle of the step motor assembly to a preset reference value; And
And the driving unit calculating a pulse value to be applied to each of the first step motor and the second step motor according to the comparison result. The method according to claim 6,
Wherein a minimum step angle of the step motor assembly is a difference between a step angle of the first step motor and a step angle of the second step motor. The method according to claim 6,
Wherein the reference value is A / 2S, where A is the step angle of the first stepper motor and S is the minimum step angle of the step motor assembly. The method according to claim 6,
After the step of calculating a pulse value to be applied to each of the first and second step motors, the driving unit applies a pulse value to each of the first and second step motors according to the calculated pulse value; &Lt; / RTI &gt; 10. The method of claim 9,
In the step of decomposing the target rotational angle, the target rotational angle X is expressed by the following equation,
X = x1 * A + x2 * S
Wherein A is a step angle of the first stepping motor, x1 is a number of times of rotation by the first stepping motor, S is a minimum step angle of the stepping motor assembly, and x2 is a number of times of rotation by a minimum step angle of the stepping motor assembly How to. 11. The method of claim 10,
Wherein the step of applying a pulse to each of the first and second step motors comprises:
(X1 + x2) is applied to the first stepper motor and the second stepper motor is rotated in the direction opposite to the rotating direction of the first stepper motor when the number of times (x2) is smaller than the reference value lt; RTI ID = 0.0 &gt; x2. &lt; / RTI &gt; 11. The method of claim 10,
Wherein the step of applying a pulse to each of the first and second step motors comprises:
(AB) -x2 (AB) is applied to the second stepper motor when the pulse value (x2) is larger than the reference value by applying a pulse value of {x1 + x2- }, Wherein B is the step angle of the second stepping motor.

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