KR101173302B1 - Apparatus for measuring force of motor - Google Patents

Abstract

Disclosed is a force measuring apparatus of a motor that can more easily measure the force generated by the eccentricity of the rotor during rotational driving of the motor. The force measuring apparatus of the motor according to the present invention includes a motor including a rotor and a stator, a magnetic bearing provided on one side of the rotor to support the rotor, and a cogging force and the eccentricity of the rotor generated while the rotor is rotating. And a control unit for providing a compensation current for compensating for the force of the eccentric force caused by the eccentric force to the magnetic bearing so that the rotor maintains a designated position, and using the compensation current to determine the eccentric force due to the cogging force and the eccentricity of the rotor. Measure the force. According to such a configuration, the bearing, the calculation of the force, and the acquisition of data are all solved in one device including the magnetic bearing, so that the force generated during the driving of the motor can be more easily measured.

Description

Force measuring device for motors {APPARATUS FOR MEASURING FORCE OF MOTOR}

The present invention relates to a device for measuring the force of the motor, and more particularly to a force measuring device of the motor for more easily measuring the force generated by the eccentricity of the rotor during the rotational drive of the motor.

In general, a motor has a pulling force between a magnet attached to a rotating shaft and an iron core core disposed on a stator. Due to the presence of this pulling force, the axis of rotation of the motor is rotated eccentrically, not at the center of the stator. If this eccentricity does not occur and the rotational axis of the motor is driven by being accurately positioned at the center of the stator, only cogging force will be generated between the rotational axis and the stator. In practice, however, it is impossible to position the axis of rotation exactly in the center of the stator without this eccentricity.

Even if the axis of rotation is located at the center of the stator, eccentricity occurs because the core core of the stator cannot be machined into a 360 degree symmetrical shape. If the force causing the eccentricity can be divided by the force in the X-axis direction and the force in the Y-axis direction, it can be predicted how much the rotational center will perform the swing motion. Therefore, the degree of eccentricity in designing a system such as an index table, a grinder, and other machine tools that includes a rotating body is the subject of research. Through this, the system can be designed to predict and minimize the rotation of the motor. have.

On the other hand, in order to experimentally measure such eccentricity, a contact bearing is mounted on a rotating shaft of a motor, and a load cell is connected to the bearing to fix the eccentricity on the stage. It was.

However, in the case of finely adjusting the eccentricity with the stage, it is necessary to work while checking whether the eccentricity has actually occurred as much as desired through an external sensor, and a separate data acquisition device is also required to receive the result of the load cell and the sensor output. Another inconvenience is that a separate load cell is required.

Therefore, there is a need for a study of a reliable device that can measure the force and cogging force generated by the eccentricity of the rotating shaft while the motor is driven more accurately and simply without the provision of additional devices.

The present invention has been made in view of the above problems, and does not include a separate measuring device called a load cell, and provides an eccentric force through a method of providing a compensation current for compensating a force generated by the eccentricity of the rotor when the motor is driven. An object of the present invention is to provide a force measuring device of a motor capable of measuring the force of eccentric force and cogging force.

Another object of the present invention is to provide a force measuring apparatus of a motor which can be adjusted so that the eccentricity of the rotor occurs as desired without a stage.

Still another object of the present invention is to provide a force measuring device of a motor capable of performing a bearing role, a force calculation, and data acquisition at a time by mounting a magnetic bearing.

F_x : 코깅력과 편심력의 합력에 대한 X축 성분
K_i : 자기베어링의 전류강성
i_x : X축 방향으로 자기베어링에 제공되는 보상전류
K_a : 자기베어링의 변위강성
x : X축 방향으로 로터의 중심이 편향 이동된 변위량
<수학식 2>

F_y : 코깅력과 편심력의 합력에 대한 Y축 성분
K_i : 자기베어링의 전류강성
i_y : Y축 방향으로 자기베어링에 제공되는 보상전류
K_a : 자기베어링의 변위강성
y : Y축 방향으로 로터의 중심이 편향 이동된 변위량.

또한, 상기 자기베어링은 상기 로터의 축을 중심으로 두 자석이 서로 마주보도록 적어도 1쌍으로 구비되는 것을 특징으로 한다.
또한, 상기 마주보는 자석 중 한쪽 자석을 기준으로 N극과 S극을 잇는 선이 상기 로터의 축방향과 평행하여 상기 자석에 의한 자속이 상기 로터의 축을 따라 흐르는 것을 특징으로 한다.
또한, 상기 마주보는 자석 중 한쪽 자석을 기준으로 N극과 S극을 잇는 선이 상기 로터의 축방향과 수직하여 상기 자석에 의한 자속이 상기 로터의 반경방향으로 발생하는 것을 특징으로 한다.
또한, 상기 자기베어링은 상기 로터의 축방향과 수직한 단면이 십자 모양을 형성하도록 X축과 Y축 방향으로 2쌍이 구비된 것을 특징으로 한다.
또한, 상기 갭센서는 상기 로터의 X축 방향과 Y축 방향으로의 이동 변위를 각각 측정할 수 있도록 상기 X축 방향과 Y축 방향을 따라 한 개씩 적어도 두 개가 구비되는 것을 특징으로 한다.Force measuring apparatus of the motor according to an embodiment of the present invention for achieving the above object is a motor including a rotor and a stator; A magnetic bearing provided at one side of the rotor to support the rotor; A control unit for providing the magnetic bearing with a compensating current for compensating for the combined force of the cogging force generated during the rotation of the rotor and the eccentric force due to the eccentricity of the rotor to maintain the rotor at a designated position; And a gap sensor on one side of the rotor, the gap sensor capable of measuring a displacement amount according to the positional movement of the rotor, wherein the controller is configured to calculate an X-axis component of the coercive force and the eccentric force. It calculates through 1, and the Y-axis component is characterized by calculating through the following equation (2).
&Quot; (1) &quot;

F _x : X-axis component of the coercive force and the eccentric force
K _i : Current stiffness of magnetic bearing
i _x : Compensation current provided to the magnetic bearing in the X axis direction
K _a : displacement stiffness of magnetic bearing
x: displacement amount in which the center of the rotor is deflected in the X axis direction
&Quot; (2) &quot;

F _y : Y-axis component of the coercive force and the eccentric force
K _i : Current stiffness of magnetic bearing
i _y : Compensation current provided to the magnetic bearing in the Y-axis direction
K _a : displacement stiffness of magnetic bearing
y: displacement that deflected the center of rotor in the Y-axis direction.

In addition, the magnetic bearing is characterized in that provided in at least one pair so that the two magnets facing each other around the axis of the rotor.
In addition, a line connecting the N pole and the S pole with respect to one of the opposing magnets is parallel to the axial direction of the rotor, characterized in that the magnetic flux by the magnet flows along the axis of the rotor.
In addition, a line connecting the N pole and the S pole with respect to one of the opposing magnets is perpendicular to the axial direction of the rotor, characterized in that the magnetic flux generated by the magnet in the radial direction of the rotor.
In addition, the magnetic bearing is characterized in that the pair is provided in the X-axis and Y-axis direction so that the cross section perpendicular to the axial direction of the rotor to form a cross shape.
In addition, the gap sensor is characterized in that at least two are provided one by one along the X-axis and Y-axis direction so that the displacement of the rotor in the X-axis direction and the Y-axis direction, respectively.

delete

delete

delete

delete

According to the present invention having the configuration as described above, first, a compensation current for compensating for the force generated by the eccentricity of the rotor during driving of the motor is provided, without having to provide a separate measuring device called a load cell and the motor from the compensation current. The cogging force of the cogging force and the eccentric force of the calculation is calculated, it can reduce the inconvenience caused during the installation of the load cell or the error during the installation process.

Second, it is possible to give the rotor as much eccentricity as desired by setting the target position value of the rotor without the stage, thereby increasing the work efficiency.

Third, the magnetic bearing is mounted, and the compensation current amount and the displacement of the rotor can be known by the feedback system. Therefore, the device is simplified because there is no need for a separate data acquisition device as well as a load cell.

1 is a view schematically showing a force measuring device of a motor according to the present invention;
Figure 2 is a view according to the arrangement of the magnetic bearing of the force measuring device of the motor of Figure 1,
3 is a view schematically showing the arrangement of a gap sensor of the force measuring device of the motor of FIG. 1, and
4 is a view for explaining the generation of the force generated during the rotational drive of the motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The force measuring device 1 of the motor according to an embodiment of the present invention is a device for measuring a force acting on the motor by using a magnetic bearing. In general, when the rotating shaft of the motor is surrounded by the stator to rotate the cogging force (eccentric force) due to the cogging force (eccentric force) and the eccentricity of the rotating shaft acts in order to more effectively measure the force of the motor according to the present invention (1) Presented. The force measuring device 1 of the motor includes a motor 10, a magnetic bearing 100, and a controller 200.

1 is shown for more detailed description. 1 is a view schematically showing a force measuring device 1 of a motor according to the present invention.

The motor 10 preferably includes a rotor 11 to which a magnet is attached and rotates and a stator 12 fixed to a state where the iron core core is attached to cause rotation of the rotor 11. The rotor 11 preferably includes a rotor shaft connected integrally.

The magnetic bearing 100 is provided on one side of the rotor 11 to support the rotor 11. That is, the magnetic bearing 100 is preferably mounted on the rotor shaft connected integrally with the rotor 11. The magnetic bearing 100 includes a magnet 110 and a coil 120.

The magnetic bearings 100 are preferably provided in at least one pair so that the two magnets are disposed to face each other about the axis of the rotor 11. Therefore, in general, two pairs are preferably arranged such that the magnetic bearing 100 is arranged in a cross shape when viewed in a cross section cut perpendicular to the axial direction of the rotor 11, but is not limited thereto.

On the other hand, the magnetic bearing 100 is preferably disposed on the axis of the rotor 11 extending in both directions with respect to the position where the rotor 11 and the stator 12 are coupled. Thus, when measuring the force while supporting from both sides, it is possible to measure the force of the cogging force and eccentric force generated in the motor 10 more accurately and stably.

The controller 200 is connected to the magnetic bearing 100 to adjust the amount of current supplied to the coil 120 provided in the magnetic bearing 100. That is, in more detail, the control unit 200 supplies a current to the coil 120 through feedback control. In such a way that the rotor 11 maintains the designated position when the motor 10 is driven through the feedback control, the control unit 200 magnetically compensates the compensating current to compensate for the cogging force and the eccentric force generated when the motor is driven. It is provided to the coil 120 of (100).

The amount of compensation current provided while the feedback control is performed is obtained by the controller 200. When the amount of compensation current is obtained, the sum of the cogging force and the eccentric force can be calculated from the compensation current. This calculation is also made in the controller 200. The detailed force calculation process is described later.

According to an embodiment, the force measuring device 1 of the motor according to the present invention further includes a gap sensor 300. The gap sensor 300 is provided at one side of the rotor 11 to measure the displacement of the rotor 11 when the rotor 11 rotates.

The gap sensor 300 is connected to the control unit 200 to transmit the displacement information of the rotor 11 to the control unit 200. Therefore, the controller 200 supplies current to the magnetic bearing 100, receives the position information of the rotor from the gap sensor 300, and then adjusts the amount of current so that the rotor can be placed at the target position. ), Feedback control is provided. This feedback system allows the user to adjust the position of the rotating rotor 11 at will.

On the other hand, in order to explain in more detail the arrangement of the magnetic bearing 100 is shown in FIG. 2 is a view showing a cross section according to the arrangement of the magnetic bearing 100.

Referring to (a) of FIG. 2, for example, the magnetic bearings 100 are disposed to face each other, and a line connecting the N pole and the S pole with respect to one of the magnets 110 facing each other is connected to the rotor ( The magnetic bearing 100 may be arranged to be parallel to the axial direction of 11). In this case, the magnetic flux by the magnet 110 flows along the axis of the rotor 11.

Unlike this, referring to FIG. 2 (b), the magnetic bearings are formed such that a line connecting the N pole and the S pole with respect to one of the magnets 110 facing each other is perpendicular to the axial direction of the rotor 11. 100) may be disposed. In this case, magnetic flux generated by the magnet 110 is generated in the radial direction of the rotor 11.

In the present invention, the arrangement form of the magnetic bearing 100 is not limited, and various arrangement forms of the magnetic bearing 100 may be possible if necessary.

On the other hand, the gap sensor 300, in order to accurately measure the planar movement displacement in the direction perpendicular to the axial direction of the rotor 11, so as to measure the movement displacement in the X-axis direction and the Y-axis direction, respectively At least two are preferably provided along each axial direction. That is, as shown in FIG. 3, two gap sensors 300 may be provided at one side of the rotor 11 along the X-axis direction and the Y-axis direction. Therefore, the displacement x of the rotor 11 in the X-axis direction and the displacement y of the rotor 11 in the Y-axis direction are measured, and the measured value is transmitted to the controller 200 so that the controller 200 measures the measured value. Using x and y, feedback control and force can be calculated. A more detailed calculation process will be described later.

In order to more accurately and stably measure the displacement of the rotor 11, the gap sensor 300 is an axis of the rotor 11 extending in both directions about the position at which the rotor 11 and the stator 12 are coupled. May be arranged respectively. In addition, the gap sensor 300 may be disposed between the rotor 11 and the stator 12 or may be integrally formed with the magnetic bearing 100.

The operation of the force measuring device 1 of the motor according to the present invention having the configuration as described above will be described with reference to FIGS.

When the motor 10 is driven, the rotor 11 rotates inside the stator 12. At this time, as shown in (a) of FIG. 4, if the rotational center of the rotor 11 is positioned to exactly match the center of the stator 12, it is generated by the change of the magnetoresistance between the rotor 11 and the stator 12. Only cogging force is present. In practice, however, the center of the rotor 11 and the center of the stator 12 cannot be coincided with each other. As shown in FIG. 4B, as the rotor 11 rotates, an eccentricity is generated and such eccentricity occurs. As a result, an eccentric force is generated between the rotor 11 and the stator 12. Therefore, as a result, when the motor 10 is driven, cogging force and eccentric force are generated between the rotor 11 and the stator 12.

The force of the cogging force and the eccentric force can be divided into the force of the X-axis component and the force of the Y-axis component, as shown in FIG. The force depends on the degree of eccentricity, ie the position of the center of the rotor 11.

In order to measure the force of the cogging force and the eccentric force according to the position of the center of the rotor 11, first, the position of the center of the rotor 11 to be measured is determined. The position of the center of the rotor 11 determined as described above is input to the control unit 200, and in the control unit 200, current is transferred to the coil 120 of the magnetic bearing 100 to move the center of the rotor 11 to the input position. To feed.

In this case, as shown in FIG. 2, the magnetic bearing 100 is illustrated as having two pairs along the respective axial directions such that the rotor 11 can move in the X-axis direction and the Y-axis direction by magnetic force. Therefore, the center of the rotor 11 may move in a planar manner by supplying the X-axis current supplied to the magnetic bearing provided in the X-axis direction and the Y-axis current supplied to the magnetic bearing provided in the Y-axis direction, respectively.

On the other hand, as shown in Figure 3, the gap sensor 300 is provided along the X-axis direction and the Y-axis direction, respectively, how much the displacement of the center of the rotor 11, the displacement information can be obtained in each axial direction have. Such displacement information is transmitted to the controller 200.

The control unit 200 receiving displacement information from the gap sensor 300 compares the position of the center of the rotor 11 that the user first inputs and then adjusts the amount of current supplied to the coil 120. Provide feedback control. Through such feedback control, the center of the rotor 11 reaches the position designated by the user.

When the center of the rotor 11 reaches the position designated by the user, an eccentric force is generated between the rotor 11 and the stator 12 along with the cogging force and the combined force is the X-axis component and the Y-axis component. Can be divided. On the other hand, in order for the rotor 11 to rotate while maintaining the center of the rotor 11 at a specified position, a compensating current must be continuously supplied to compensate for the coercive force of the cogging force and the eccentric force. The coercive force of the cogging force and the eccentric force applied to the motor 10 in the state where the center of (11) is eccentric can be obtained. The combined force is preferably divided into X component and Y component and calculated and measured respectively. The calculation of this force is made in the control unit 200. The formula for the force is shown in the following formula.

delete

Where F _x And F _y Are the X- and Y-axis components of the cogging force and the eccentric force, respectively, and i _x And i _y Are the currents supplied to the magnetic bearings 100 provided in the X-axis direction and the Y-axis direction, respectively, and x and y represent the rotor 11 in the X-axis direction and the Y-axis direction, respectively, as shown in FIG. The center represents the displacement amount deflected.

In addition, K _i is the current stiffness of the magnetic bearing, and K _a is the displacement stiffness of the magnetic bearing, which is obtained numerically or experimentally according to the shape of the magnetic bearing.

As a result, the user may move the center of the rotor 11 to a desired target position through the gap sensor 300, the magnetic bearing 100, and the controller 200, and may give an eccentricity as desired. The amount of eccentricity can also be finely adjusted by controlling the current in the controller 200. Therefore, the cogging force and the eccentric force generated according to the eccentricity of the rotor 11 of the motor 10 can be experimentally determined by dividing the force in the X-axis direction and the force in the Y-axis direction.

So F _x If we find and F _y , we can predict that the rotational motion of the axis of rotation will be inconsistent with the rotational axis as long as the bearing rigidity and damping are known.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

1: power measuring device of motor 10: motor
11: rotor 12: stator
100: magnetic bearing 110: magnet
120: coil 200: control unit
300: gap sensor

Claims (8)

A motor including a rotor and a stator;
A magnetic bearing provided at one side of the rotor to support the rotor; And
A control unit for providing the magnetic bearing with a compensating current for compensating for the combined force of the cogging force generated during the rotation of the rotor and the eccentric force due to the eccentricity of the rotor to maintain the rotor at a designated position; And
And a gap sensor on one side of the rotor, the gap sensor capable of measuring a displacement amount according to the positional movement of the rotor.
The control unit calculates the X-axis component for the coercive force and the eccentric force of the force through Equation 1, and calculates the Y-axis component through the equation (2).
&Quot; (1) &quot;

F _x : X-axis component of the coercive force and the eccentric force
K _i : Current stiffness of magnetic bearing
i _x : Compensation current provided to the magnetic bearing in the X axis direction
K _a : displacement stiffness of magnetic bearing
x: Displacement amount in which the center of the rotor is deflected in the X axis direction
&Quot; (2) &quot;

F _y : Y-axis component of the coercive force and the eccentric force
K _i : Current stiffness of magnetic bearing
i _y : Compensation current provided to the magnetic bearing in the Y-axis direction
K _a : displacement stiffness of magnetic bearing
y: displacement that deflected the center of rotor in the Y-axis direction.
delete The method of claim 1,
The magnetic bearing is a force measuring device of a motor, characterized in that provided with at least one pair of two magnets facing each other about the axis of the rotor. The method of claim 3,
And a line connecting the N pole and the S pole with respect to one of the opposing magnets is parallel to the axial direction of the rotor, so that magnetic flux by the magnet flows along the axis of the rotor. The method of claim 3,
The force measuring device of the motor, characterized in that the line connecting the N pole and the S pole with respect to one of the opposing magnets is perpendicular to the axial direction of the rotor, the magnetic flux generated by the magnet in the radial direction of the rotor . The method of claim 3,
The magnetic bearing is a force measuring device of the motor, characterized in that the pair is provided in the X-axis and Y-axis direction so that the cross section perpendicular to the axial direction of the rotor to form a cross shape. delete The method of claim 1,
At least two gap sensors are provided one by one along the X and Y axis directions to measure the displacement of the rotor in the X and Y axis directions, respectively. .

Images