CN115349222A

CN115349222A - Drive control system

Info

Publication number: CN115349222A
Application number: CN202180025461.2A
Authority: CN
Inventors: 大谷正幸
Original assignee: Nidec Shimpo Corp
Current assignee: Nidec Shimpo Corp
Priority date: 2020-03-30
Filing date: 2021-03-26
Publication date: 2022-11-15
Also published as: JPWO2021200631A1; WO2021200631A1

Abstract

The drive control system includes a motor, a reduction gear, and a control unit. The motor has: a stator having an excitation coil; and a rotor having a magnetic member that rotates about a rotation axis with respect to the stator. The reduction gear device has a gear mechanism to which a lubricating material is added, and is capable of increasing the rotational power output from the motor according to the reduction ratio. The control unit can perform PID control of the driving of the motor by changing an integral gain according to the temperature of the lubricant.

Description

Drive control system

Technical Field

The present invention relates to a drive control system.

Background

The conventional drive control system includes: a motor; a speed reducer connected to the motor; and a control unit for controlling the motor. The reduction gear has a gear mechanism capable of increasing the rotational power output from the motor according to a reduction ratio. (see, for example, japanese patent laid-open publication No. 2018-035885).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-035885

Disclosure of Invention

Problems to be solved by the invention

However, in the drive control system as described above, the viscosity of the lubricating material fluctuates in accordance with a change in the temperature of the lubricating material added to the gear mechanism. This causes variation in the responsiveness of the motor connected to the reduction gear. Therefore, when the motor is feedback-controlled so as to approach the target speed, there is a problem that the rotational speed overshoots the target speed, and the rotational speed cannot follow the target speed.

The invention aims to provide a drive control system capable of improving the stability of feedback control.

Means for solving the problems

An exemplary drive control system of the present invention includes a motor, a reduction gear, and a control unit. The motor has: a stator having an excitation coil; and a rotor having a magnetic member that rotates about a rotation axis with respect to the stator. The reduction gear device has a gear mechanism to which a lubricating material is added, and is capable of increasing the rotational power output from the motor according to the reduction ratio. The control unit performs feedback control of driving of the motor. The control unit can perform PID control by changing the integral gain according to the temperature of the lubricant.

Effects of the invention

According to the exemplary invention, a drive control system capable of improving the stability of feedback control can be provided.

Drawings

Fig. 1 is a sectional view of a drive device included in a drive control system according to embodiment 1 of the present invention.

Fig. 2 is a block diagram showing a drive control system according to embodiment 1 of the present invention.

Fig. 3 is a block diagram showing a drive control system according to embodiment 2 of the present invention.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, a direction parallel to the rotation axis of the motor is referred to as an "axial direction", a direction perpendicular to the rotation axis of the motor is referred to as a "radial direction", and a direction along an arc centered on the rotation axis of the motor is referred to as a "circumferential direction". In the present application, the shapes and positional relationships of the respective parts will be described with the axial direction as the vertical direction and the reduction gear side as the upper side with respect to the motor. The vertical direction is a name used for explanation only, and does not limit the actual positional relationship and direction.

In the present application, the "parallel direction" also includes a substantially parallel direction. In the present application, the term "vertical direction" also includes a substantially vertical direction.

< embodiment 1 >

< 1. Structure of driving device

A driving device according to an exemplary embodiment of the present invention will be described. Fig. 1 is a vertical sectional view of a drive device 30 included in a drive control system 1 according to embodiment 1 of the present invention.

The drive device 30 has a motor 10 and a reduction gear 20. The driving device 30 decelerates the rotational power of the motor 10 by the reduction device 20 and outputs the decelerated power. The driving device 30 can be used as a power source for driving a joint of a robot, for example. The motor 10 and the reduction gear 20 are axially aligned and integrally formed.

< 2. Structure of motor

The motor 10 is of an axial gap type and is flat in shape having a radial dimension larger than an axial dimension. This enables the drive device 30 to be downsized in the axial direction. The motor 10 includes a rotor 11, a stator 12, a bearing portion 13, and a motor housing 14. The rotor 11, the stator 12, and the bearing 13 are housed in a motor case 14.

The stator 12 includes a laminated steel plate portion 121, a base portion 122, and an excitation coil (not shown). The laminated steel plate portion 121 is formed by laminating a plurality of annular magnetic bodies. The outer peripheral portion of the laminated steel plate portion 121 is fixed to the motor case 14. The base portion 122 is cylindrical, and the outer peripheral portion of the base portion 122 is fixed to the inner peripheral portion of the laminated steel plate portion 121. The bearing portion 13 is held by an inner peripheral portion of the base portion 122. The excitation coil (not shown) is formed by winding a conductive wire, and the magnetic core extends parallel to the rotation axis C.

The rotor 11 includes a shaft 111,

disk portions

112a and 112b, and

magnetic members

113a and 113b. The shaft 111 is formed in a cylindrical shape extending in the axial direction. The shaft 111 is rotatably held by the bearing portion 13.

The

disk portions

112a and 112b are disk-shaped and coaxially fixed to the shaft 111. The disk portion 112a is disposed axially above the laminated steel plate portion 121, and the disk portion 112b is disposed axially below the laminated steel plate portion 121. The upper surface of the circular plate portion 112a is connected to a cam 21 of the reduction gear 20, which will be described later, and the rotational power of the rotor 11 is output to the cam 21.

The magnetic member 113a is fixed to the lower surface of the disk portion 112a, and the magnetic member 113b is fixed to the upper surface of the disk portion 112 b. Thereby, the exciting coil (not shown) and the

magnetic members

113a and 113b are arranged in the axial direction. The

magnetic members

113a and 113b are fixed to the entire circumferences of the

disk portions

112a and 112b, and N poles and S poles are alternately arranged along the circumferential direction.

The circuit board 123 is disposed between the stator 12 and the disk portion 112 b. A temperature detection portion 123a and a position detection sensor 123b are mounted on the circuit board 123. The temperature detection unit 123a is disposed near the lower end of the excitation coil (not shown) 122. That is, the temperature detection unit 123a is disposed facing the excitation coil. Thus, the temperature detection unit 123a can detect the temperature of the exciting coil with high accuracy. The position detection sensor 123b detects the rotational position of the rotor 11, and may be any of a mechanical type, a magnetic type, an optical type, and an electromagnetic induction type, for example.

< 3. Structure of reduction gear

The reduction gear unit 20 is a so-called wave gear unit, and includes a cam 21, an externally toothed gear 22, an internally toothed gear 23, an output member 24, a flexible bearing 25, and a gear housing 26. The reduction gear unit 20 is formed of a wave gear, and thus the drive unit 30 can be downsized in the axial direction. The cam 21 is an annular member having an elliptical outer shape. An external gear 22 is disposed radially outward of the cam 21, and an internal gear 23 is disposed radially outward of the external gear 22. The cam 21, the external gear 22, the internal gear 23, and the flexible bearing 25 are housed in a gear housing 26. The outer peripheral portion of the internal gear 23 is fixed to the inner peripheral portion of the gear housing 26. The gear housing 26 is coupled to the motor housing 14 in the axial direction.

The external gear 22 is formed in a flexible cup shape, and an opening surface of the external gear 22 is arranged axially downward. The output member 24 is fixed to the upper portion of the external gear 22.

The flexible bearing 25 is disposed between the cam 21 and the external gear 22. The flexible bearing 25 is disposed such that the inner race is fixed to the cam 21 and the flexible outer race is in contact with the external gear 22. The external gear 22 is deformed in an ellipsoidal manner while shifting the position of the major axis in the circumferential direction as the cam 21 rotates.

Since the number of teeth of the external gear 22 is different from that of the internal teeth of the internal gear 23, the external gear 33 rotates relative to the internal gear 23 by the difference in the number of teeth every time the meshing position rotates by 1 revolution. Thereby, the rotational power of the cam 21 is decelerated and transmitted to the external gear 22. The rotational power increased by the reduction gear 20 is output via the output member 24.

Further, a lubricant is added to the gear mechanism including the external gear 22 and the internal gear 23, and the gear mechanism rotates smoothly. As the lubricant, oil, grease, or the like is used. That is, the reduction gear unit 20 has a gear mechanism to which a lubricating material is added, and the reduction gear unit 20 can increase the rotational power output from the motor 10 according to the reduction ratio.

< 4. Feedback control >

Fig. 2 is a block diagram showing the drive control system 1. The drive control system 1 includes a motor 10, a reduction gear 20, and a control unit 100 that performs PID control of driving of the motor 10. The control unit 100 includes a CPU, a ROM, and a RAM, and the control unit 100 is connected to the temperature detection unit 123a and the position detection sensor 123b. For example, the control unit 100 is constituted by a computer provided in a device including the drive device 30, and the entire device including the drive device 30 functions as the drive control system 1.

The control unit 100 includes a rotation speed detection unit 110, a target speed setting unit 120, a subtraction unit 125, a PID control unit 130, a lubricant temperature detection unit 140, a gain variable unit 150, and a drive circuit unit 160.

The rotation speed detecting unit 110 sequentially detects the pulse signals output from the position detecting sensor 123b, and calculates the rotation speed of the motor 10 from the detection cycle.

Upon receiving a command to output a predetermined rotational power to the output member 24, the target speed setting unit 120 outputs a target speed for outputting the predetermined rotational power to the subtracting unit 125.

Subtracting unit 125 calculates a difference between the target speed output from target speed setting unit 120 and the detected speed output from rotational speed detecting unit 110, and outputs the difference to PID control unit 130.

PID control unit 130 includes a proportional unit 131, a differential unit 132, an integral unit 133, and an addition unit 134. The proportional unit 131 outputs a signal obtained by multiplying the difference between the detected speed and the target speed by a proportional gain Kp to the addition unit 134. The differentiating section 132 outputs a signal obtained by differentiating the difference between the detected speed and the target speed and multiplying the result by a differential gain Kd to the adding section 134. The integrating unit 133 integrates the difference between the detected speed and the target speed and outputs a signal obtained by multiplying the integrated gain Ki to the adding unit 134.

The adding unit 134 adds the signals output from the proportional unit 131, the differentiating unit 132, and the integrating unit 133. The signal added by the adding unit 134 is a signal for matching the actual rotation speed of the motor 10 detected by the rotation speed detecting unit 110 with the target speed, and is output to the drive circuit unit 160. In the present embodiment, the rotation speed of the motor 10 can be made to coincide with the target speed without the differentiating operation. Therefore, the differential gain Kd can be set to zero at all times. Thus, the PID control unit 130 can easily generate a signal for matching the rotation speed of the motor 10 with the target speed.

The drive circuit unit 160 performs energization and interruption in the forward and reverse directions to the three-phase field coils of the motor 10 in accordance with a signal input from the PID control unit 130. Thereby, the rotor 11 is rotationally driven by the electromagnetic action of the stator 12 and the rotor 11. In addition, the feedback control always controls the rotation speed of the motor 10 to be equal to the target speed. The rotational power is output to the reduction gear unit 20 by the rotation of the shaft 111, and the rotational power reduced in accordance with the reduction ratio of the wave gear mechanism is output via the output member 24.

The lubricant temperature detecting unit 140 derives the temperature of the lubricant of the reduction gear transmission 20 from the temperature near the exciting coil detected by the temperature detecting unit 123 a. The temperature of the field coil and the temperature of the lubricant increase in conjunction with the increase in the rotation speed of the rotor 11. Therefore, the temperature of the lubricant can be derived by detecting the temperature of the exciting coil. That is, the control unit 100 derives the temperature of the lubricant based on the temperature detected by the temperature detection unit 123 a. Thus, the temperature of the lubricant can be accurately derived with a simple configuration.

The gain variable unit 150 can change the integral gain Ki according to the temperature of the lubricant derived by the lubricant temperature detection unit 140. The responsiveness of the motor 10 connected to the reduction gear unit 20 varies depending on the viscosity of the lubricating material added to the gear mechanism. In addition, the viscosity of the lubricant is linked to the temperature of the lubricant. Therefore, by setting the optimum integral gain Ki for the temperature of the lubricant in the reduction gear unit 20, the responsiveness of the motor 10 can be stabilized. In addition, an optimum integral gain Ki with respect to the temperature of the lubricant is stored in advance. The optimum integral gain Ki can be expressed by a linear function, a higher-order function, or a discretized table with respect to the temperature of the lubricant.

In the feedback control, the gain variable portion 150 sets the integral gain Ki to be small as the temperature of the lubricant increases. Thereby, it is possible to avoid that the viscosity of the lubricating material is lowered and the responsiveness of the motor 10 becomes excessively sensitive. On the other hand, the gain variable section 150 sets the integral gain Ki to be larger as the temperature of the lubricant decreases. This can prevent the viscosity of the lubricant from increasing and the responsiveness of the motor 10 from being deteriorated. Therefore, it is possible to prevent the viscosity from changing due to the temperature of the lubricating material being high or low, resulting in the responsiveness of the motor 10 becoming excessively sensitive or blunted. That is, the control unit 100 can change the integral gain Ki according to the temperature of the lubricant to perform PID control of the driving of the motor 10. This can provide the drive control system 1 capable of improving the stability of the feedback control.

In the feedback control, the gain variable portion 150 may be constantly changed with respect to the temperature of the lubricant of the reduction gear unit 20, or may be changed at predetermined temperature intervals. Further, the change may be started after the motor 10 is started and the temperature of the lubricant exceeds a predetermined value.

< embodiment 2 >

Next, embodiment 2 of the present invention will be explained. Fig. 3 is a block diagram showing the drive control system 1 of embodiment 2. For convenience of explanation, the same reference numerals are given to the same parts as those in embodiment 1 shown in fig. 1 and 2. Embodiment 2 is different from embodiment 1 in that the integral gain Ki can be changed according to the magnetic force of the magnetic member. The other portions are the same as those of embodiment 1.

The magnetic force detector 170 derives the magnetic force of the

magnetic members

113a and 113b from the temperature near the exciting coil detected by the temperature detector 123 a. The magnetic force of the

magnetic members

113a and 113b decreases in conjunction with the temperature increase of the

magnetic members

113a and 113b. Therefore, by detecting the temperature near the exciting coil, the magnetic force of the

magnetic members

113a and 113b can be derived with high accuracy.

The gain varying unit 150 can vary the integral gain Ki in accordance with the temperature of the lubricant derived by the lubricant temperature detecting unit 140 and the magnetic force of the

magnetic members

113a and 113b derived by the magnetic force detecting unit 170. That is, the control unit 100 can derive the magnetic forces of the

magnetic members

113a and 113b from the temperature detected by the temperature detection unit 123a, and can change the integral gain Ki based on the derived magnetic forces of the

magnetic members

113a and 113b and the temperature of the lubricant derived based on the temperature detected by the temperature detection unit 123a to perform PID control of the driving of the motor 10. This can further improve the stability of the feedback control.

< 4. Other >)

The above embodiments are merely illustrative of the present invention. The configuration of the embodiment may be appropriately modified within a range not exceeding the technical idea of the present invention. In addition, the embodiments may be implemented in combination within a possible range.

In the present embodiment, a combination of the axial gap motor 10 and the reduction gear unit 20 having the wave gear structure has been described as an example, but the present invention is not limited thereto. The motor 10 may also be of the radial gap type. The reduction gear unit 20 may be constituted by another gear mechanism such as a planetary gear.

Further, although PID control unit 130 is configured by proportional unit 131, differential unit 132, and integrating unit 133, it may be configured by only proportional unit 131 and integrating unit 133.

The temperature detection unit 123a is disposed inside the motor case 14, but may be disposed outside the motor case 14. The temperature detector 123a may be disposed outside the gear housing 26 to detect the temperature of the lubricant. The temperature detector 123a may be disposed inside the gear housing 26 to directly detect the temperature of the lubricant.

In the present embodiment, the feedback control is performed based on the rotation speed of the motor 10, but the feedback control may be performed based on the rotation speed of the output member 24 side of the reduction gear unit 20. In addition, feedback control may be performed by position control and torque control in addition to speed control.

In the present embodiment, the entire device including the driving device 30 functions as the drive control system 1. However, the control unit 100 may be provided separately from the apparatus including the driving device 30. For example, the control unit 100 may be constituted by a computer or the like that collectively controls a factory, and controls the driving device 30 based on a signal transmitted from the outside of the device including the driving device 30. Further, the control unit 100 may be provided integrally with the drive device 30, and the drive device 30 itself may function as the drive control system 1.

Industrial applicability

The present invention is applicable to, for example, a robot that drives a joint or the like using a drive device having a drive control system as a power source, and an electric vehicle that uses a drive device having a drive control system as a power source.

Description of the reference symbols

1: a drive control system; 10: a motor; 11: a rotor; 12: a stator; 13: a bearing portion; 14: a motor housing; 20: a reduction gear; 21: a cam; 22: an external gear; 23: an internal gear; 24: an output member; 25: a flexible bearing; 26: a gear housing; 30: a drive device; 100: a control unit; 110: a rotation speed detection unit; 111: a shaft; 112a, 112b: a circular plate portion; 113a, 113b: a magnetic member; 120: a target speed setting unit; 121: a laminated steel plate portion; 122: a base part; 123: a circuit board; 123a: a temperature detection unit; 123b: a position detection sensor; 125: a subtraction unit; 130: a PID control unit; 131: a proportional part; 132: a micro-fraction; 133: an integrating part; 134: an addition unit; 140: a lubricant temperature detection unit; 150: a gain variable section; 160: a drive circuit unit; 170: a magnetic force detection unit; c: an axis of rotation.

Claims

1. A drive control system having:

a motor including a stator having a field coil and a rotor having a magnetic member that rotates about a rotation axis with respect to the stator;

a reduction gear having a gear mechanism to which a lubricating material is added, the reduction gear being capable of increasing the rotational power output from the motor according to a reduction ratio; and

a control section capable of PID-controlling the driving of the motor by changing an integral gain according to the temperature of the lubricant.

2. The drive control system of claim 1,

the differential gain of the PID control is always zero.

3. The drive control system according to claim 1 or 2,

the drive control system further has a temperature detection portion that detects a temperature of the excitation coil,

the control unit derives the temperature of the lubricant from the temperature detected by the temperature detection unit.

4. The drive control system of claim 3,

the temperature detection unit is disposed facing the excitation coil.

5. The drive control system according to claim 3 or 4,

the control unit derives the magnetic force of the magnetic member from the temperature detected by the temperature detection unit, and performs PID control of the driving of the motor by changing an integral gain from the derived magnetic force of the magnetic member and the temperature of the lubricant derived from the temperature detected by the temperature detection unit.

6. The drive control system according to any one of claims 1 to 5,

the gear mechanism is composed of a wave gear.

7. The drive control system according to any one of claims 1 to 6,

the motor is of an axial gap type in which field coils and the magnetic members are arranged in an axial direction.