Drive device and motor control system

Abstract

To provide a drive device capable of appropriately controlling the rotational speed of a motor while increasing the degree of freedom of the installation position of a speed sensor.SOLUTION: A rotation speed calculation unit configured to calculate a rotation speed of an output shaft of a motor based on speed feedback information indicating a rotation speed of a rotation shaft of a mechanical system that rotates in conjunction with rotation of the output shaft of the motor; A drive control unit that receives an input of a speed reference of a rotation speed of an output shaft of the motor and controls the rotation speed of the output shaft of the motor so that the rotation speed of the output shaft of the motor coincides with the speed reference, wherein the rotation speed calculation unit includes a speed feedback corrector that calculates a correction amount for correcting a change amount of the rotation speed due to a mechanical factor of the mechanical system based on the speed feedback information, and a calculator that calculates the rotation speed of the output shaft of the motor based on the speed feedback information and the correction amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a drive device and a motor control system. [Background technology]

[0002] To operate a motor at variable speeds, a drive device using vector control or the like is generally used. To achieve high-precision speed control, a sensor-equipped vector control or the like is used. In sensor-equipped vector control, a speed sensor is attached directly to the rotating shaft of the motor, speed feedback information is input to the drive device, and the voltage applied to the motor is determined based on the speed feedback information and external speed reference information, thereby controlling the motor's rotational speed. In this case, the speed sensor must be attached directly to the rotating shaft of the motor, which poses a challenge in terms of securing installation space.

[0003] Therefore, as another method of vector control, sensorless vector control has been proposed, which performs vector control without using a speed sensor. In sensorless vector control, speed estimates calculated by the drive device are used for control instead of speed feedback information, so a speed sensor is not required.

[0004] As described above, speed sensorless control has been developed, which controls speed without using a speed sensor, but in sensorless control, the speed is estimated based on the current supplied to the motor from the drive device, so there are cases where an accurate speed estimation cannot be performed using the sensorless method due to, for example, changes in the current value caused by external forces, making a speed sensor necessary. In such cases, it is generally necessary to attach a speed sensor directly to the rotating shaft of the motor, but as mentioned above, installation can be difficult due to space constraints.

[0005] Even if it is possible to install a speed sensor on a mechanical shaft that operates in conjunction with the motor, the speed feedback information from that speed sensor may include speed changes due to mechanical factors such as torsion, etc. Therefore, it is difficult to use the speed feedback information from a speed sensor attached to a mechanical shaft as is for controlling the motor speed.

[0006] For this reason, it is desirable that a drive device and a motor control system using the same be able to appropriately control the rotation speed of the motor while increasing the degree of freedom in the installation position of the speed sensor. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-111498 [Patent Document 2] Japanese Patent Publication No. 2022-032344 Summary of the Invention [Problem to be solved by the invention]

[0008] The embodiments of the present invention provide a drive device and a motor control system that can appropriately control the rotation speed of a motor while increasing the degree of freedom in the installation position of a speed sensor. [Means for solving the problem]

[0009] According to an embodiment of the present invention, there is provided a drive device that controls the rotational speed of a motor, comprising: a rotational speed calculation unit that receives input of speed feedback information representing the rotational speed of a rotating shaft of a mechanical system that rotates in conjunction with the rotation of an output shaft of the motor, and calculates the rotational speed of the output shaft of the motor based on the speed feedback information; and a drive control unit that receives input of the rotational speed of the output shaft of the motor from the rotational speed calculation unit and also receives input of a speed reference for the rotational speed of the output shaft of the motor, and controls the rotational speed of the output shaft of the motor so that the rotational speed of the output shaft of the motor coincides with the speed reference, wherein the rotational speed calculation unit has a speed feedback compensator that calculates a correction amount to correct for a change in the rotational speed due to a mechanical factor of the mechanical system, based on the speed feedback information, and a calculator that calculates the rotational speed of the output shaft of the motor based on the speed feedback information and the correction amount. [Effects of the Invention]

[0010] A drive device and a motor control system are provided that can appropriately control the rotation speed of a motor while increasing the degree of freedom in the installation position of a speed sensor. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram schematically illustrating a motor control system and a drive device according to an embodiment. [Figure 2] FIG. 1 is a block diagram schematically illustrating a reference motor control system and a drive device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0013] FIG. 1 is a block diagram schematically illustrating a motor control system and a drive device according to an embodiment. As shown in FIG. 1, the motor control system 2 includes a motor 3, a mechanical system 4, a speed sensor 5, and a drive device 10.

[0014] The motor 3 is, for example, a variable speed motor such as an induction motor. The motor 3 rotates its output shaft by receiving, for example, three-phase AC power from the drive device 10. However, the power supplied to the motor 3 is not limited to AC power, and may be DC power or the like. The motor 3 is not limited to an induction motor or the like, and may be any motor capable of variable speed operation (speed control).

[0015] The mechanical system 4 is driven by the motor 3. The mechanical system 4 is connected to the output shaft of the motor 3, and thereby rotates in conjunction with the rotation of the output shaft of the motor 3. The mechanical system 4 may be any machine that is driven by the motor 3. In other words, the mechanical system 4 may be any machine that has a part that rotates in conjunction with the motor 3.

[0016] The speed sensor 5 is attached to the rotating shaft of the mechanical system 4, which rotates in conjunction with the rotation of the output shaft of the motor 3, and acquires speed feedback information SPF1 representing the rotational speed of the rotating shaft of the mechanical system 4, and inputs the acquired speed feedback information SPF1 to the drive device 10.

[0017] The speed sensor 5 is, for example, a rotary encoder or a resolver. When the speed sensor 5 is a rotary encoder, the speed feedback information SPF1 is a pulse signal corresponding to the rotation speed of the rotating shaft of the mechanical system 4. When the speed sensor 5 is a resolver, the speed feedback information SPF1 is a sinusoidal signal corresponding to the rotation speed of the rotating shaft of the mechanical system 4.

[0018] However, the speed sensor 5 is not limited to the above and may be any sensor capable of measuring the rotational speed of the rotating shaft of the mechanical system 4. The rotational speed of the rotating shaft of the mechanical system 4 measured by the speed sensor 5 does not necessarily have to be the same as the rotational speed of the output shaft of the motor 3. The rotational speed of the rotating shaft of the mechanical system 4 may be different from the rotational speed of the output shaft of the motor 3, for example, by passing through a reducer or a transmission.

[0019] The speed feedback information SPF1 is information (signal) that includes, for example, information on the rotational position (rotational angle) of the rotational shaft of the mechanical system 4, and that enables the rotational speed to be calculated in the drive device 10 based on the change in the rotational position (rotational angle) over time. However, the speed feedback information SPF1 is not limited to the above, and may be any information (signal) that indicates the rotational speed of the rotational shaft of the mechanical system 4.

[0020] The drive device 10 controls the rotation speed of the motor 3. The drive device 10 receives speed feedback information SPF1 from the speed sensor 5, and also receives a speed reference SPR for the rotation speed of the output shaft of the motor 3.

[0021] Based on the speed feedback information SPF1, the drive device 10 calculates the rotation speed SPF2 of the output shaft of the motor 3, and controls the rotation speed of the output shaft of the motor 3 so that the calculated rotation speed SPF2 matches the speed reference SPR. This allows the drive device 10 (motor control system 2) to rotate the output shaft of the motor 3 at a speed according to the speed reference SPR.

[0022] The drive device 10 receives the speed reference SPR as input from an external device such as a higher-level controller by communicating with the external device. The drive device 10 may also receive the speed reference SPR as input from an operation unit that receives operation instructions from an operator or the like. In other words, the speed reference SPR may be manually input to the drive device 10 by operating an operation unit or the like. However, the method of inputting the speed reference SPR to the drive device 10 is not limited to the above, and any method that can appropriately input the speed reference SPR to the drive device 10 may be used. The speed reference SPR may be, for example, a constant value that is preset in the drive device 10.

[0023] The drive device 10 controls the rotation speed of the motor 3, for example, by vector control. The drive device 10 controls the rotation speed of the motor 3, for example, by controlling the frequency of a three-phase AC voltage (three-phase AC current) supplied to the motor 3. However, the method of controlling the rotation speed of the motor 3 by the drive device 10 is not limited to the above, and any method that can appropriately control the rotation speed of the motor 3 may be used.

[0024] The drive device 10 includes a rotational speed calculation unit 12 and a drive control unit 14. The rotational speed calculation unit 12 receives speed feedback information SPF1 as input from the speed sensor 5. The rotational speed calculation unit 12 calculates a rotational speed SPF2 of the output shaft of the motor 3 based on the speed feedback information SPF1, and inputs the calculated rotational speed SPF2 to the drive control unit 14.

[0025] Note that rotation speed calculation unit 12 is not limited to a configuration in which it receives the speed feedback information SPF1 directly from speed sensor 5, and may instead receive the speed feedback information SPF1 from an external device such as a higher-level controller. The configuration in which rotation speed calculation unit 12 receives the speed feedback information SPF1 may be any configuration that is capable of appropriately receiving the speed feedback information SPF1.

[0026] The drive control unit 14 receives the rotation speed SPF2 as an input from the rotation speed calculation unit 12, and also receives the speed reference SPR as an input, and controls the rotation speed of the output shaft of the motor 3 so that the rotation speed SPF2 coincides with the speed reference SPR.

[0027] The drive control unit 14 includes, for example, a subtractor 20, a speed controller 22, and a current controller 24.

[0028] The subtractor 20 calculates the difference between the speed reference SPR and the rotation speed SPF2. The subtractor 20 inputs the calculated difference to the speed controller 22.

[0029] Based on the input difference, the speed controller 22 generates a torque reference for the motor 3 to make the rotation speed SPF2 coincide with the speed reference SPR, and inputs the generated torque reference to the current controller 24.

[0030] The current controller 24 calculates a current reference according to the torque reference and generates a control signal (e.g., a gate signal) for supplying a current of a magnitude according to the current reference to the motor 3. The current controller 24 inputs the generated control signal to a converter that supplies power to the motor 3 and controls the operation of the converter, thereby supplying a current of a magnitude according to the current reference to the motor 3. This makes it possible to control the rotational speed of the output shaft of the motor 3 so that the rotational speed SPF2 coincides with the speed reference SPR.

[0031] The converter that supplies power to the motor 3 may be provided in the motor 3, in the drive device 10, or in the motor control system 2 as a separate device from the motor 3 and the drive device 10.

[0032] The configuration of the drive control unit 14 is not limited to the above, and may be any configuration that is capable of controlling the rotational speed of the output shaft of the motor 3 based on the speed reference SPR and the rotational speed SPF2 so that the rotational speed SPF2 matches the speed reference SPR.

[0033] The rotation speed calculation unit 12 has a speed feedback corrector 30 and a calculator 32. The speed feedback corrector 30 calculates a correction amount SPFE for correcting a change in the rotation speed due to a mechanical factor of the mechanical system 4, based on the speed feedback information SPF1 input from the speed sensor 5. The rotation speed calculation unit 12 inputs the calculated correction amount SPFE to the calculator 32.

[0034] The rotational speed calculation unit 12 further includes, for example, a fast Fourier transformer 34. The fast Fourier transformer 34 performs a fast Fourier transform on the speed feedback information SPF1 and inputs the result of the fast Fourier transform to the speed feedback corrector 30. In other words, the speed feedback information SPF1 may be any information (signal) that represents the rotational speed of the rotating shaft of the mechanical system 4 and that allows frequency analysis by fast Fourier transform to be performed.

[0035] The speed feedback compensator 30 has, for example, information on the results of a natural vibration analysis of the mechanical system 4 that has been performed in advance, and identifies the amount of change in rotation speed due to mechanical factors of the mechanical system 4 by comparing the input fast Fourier transform result with the information on the results of the natural vibration analysis of the mechanical system 4. Then, the speed feedback compensator 30 calculates a correction amount SPFE so as to offset the identified amount of change in rotation speed.

[0036] The velocity feedback corrector 30 updates the correction amount SPFE at a constant period that takes into consideration, for example, the calculation time of the fast Fourier transformer 34 and its own calculation time. In other words, the correction amount SPFE is calculated at a constant period that corresponds to the calculation periods of the fast Fourier transformer 34 and the velocity feedback corrector 30.

[0037] The information on the natural vibration analysis result is, in other words, information on the frequency of vibrations occurring in the mechanical system 4. The speed feedback compensator 30, for example, identifies the Fourier spectrum components of the frequency represented by the information on the natural vibration analysis result as the change in rotation speed due to mechanical factors of the mechanical system 4. The speed feedback compensator 30, for example, calculates the correction amount SPFE by performing an inverse Fourier transform on the identified Fourier spectrum components. This makes it possible to calculate the correction amount SPFE so as to correct, for example, the change in rotation speed due to vibrations of the mechanical system 4.

[0038] The calculator 32 calculates the rotational speed SPF2 of the output shaft of the motor 3 based on the speed feedback information SPF1 input from the speed sensor 5 and the correction amount SPFE input from the speed feedback corrector 30, and inputs the calculated rotational speed SPF2 to the drive control unit 14.

[0039] The calculator 32 corrects the speed feedback information SPF1, for example, by adding a correction amount SPFE to the speed feedback information SPF1 input from the speed sensor 5, and calculates the rotation speed SPF2 of the output shaft of the motor 3 based on the corrected speed feedback information SPF1. As a result, even when the speed feedback information SPF1 is acquired by the speed sensor 5 attached to the rotating shaft of the mechanical system 4, it is possible to correct for changes in the rotation speed due to mechanical factors of the mechanical system 4, such as torsion and vibration, and appropriately acquire the rotation speed SPF2 of the output shaft of the motor 3.

[0040] Furthermore, for example, if the rotational speed of the rotating shaft of the mechanical system 4 is different from the rotational speed of the output shaft of the motor 3, the calculator 32 calculates the rotational speed of the rotating shaft of the mechanical system 4 based on the corrected speed feedback information SPF1, and calculates the rotational speed of the output shaft of the motor 3 from the rotational speed of the rotating shaft of the mechanical system 4 by multiplying the calculated rotational speed of the rotating shaft of the mechanical system 4 by a gear ratio, etc.

[0041] FIG. 2 is a block diagram that schematically illustrates a reference motor control system and a drive device. 2, in the reference motor control system 2a, the speed sensor 5a is directly attached to the rotating shaft of the motor 3. The reference drive device 10a inputs speed feedback information SPF1 input from the speed sensor 5a to the drive control unit 14. In this case, the speed sensor 5a needs to be directly attached to the rotating shaft of the motor 3, which may be difficult to do due to space limitations.

[0042] Furthermore, in sensorless control, which uses a speed estimate calculated by the drive device instead of speed feedback information for control, there are cases where accurate speed estimation cannot be performed in a sensorless manner due to, for example, changes in current value caused by external forces, etc. For example, in an elevator device, when starting to lift a suspended load from a stopped state, in applications where the load is causing the motor 3 to rotate in the opposite direction to its operating direction, speed estimation in a sensorless manner is difficult and a speed sensor may be necessary.

[0043] Even if it is possible to install a speed sensor 5 on the rotating shaft of the mechanical system 4 that operates in conjunction with the motor 3, the speed feedback information of the speed sensor 5 may include speed changes due to mechanical factors such as torsion. Therefore, it is difficult to use the speed feedback information of the speed sensor 5 attached to the rotating shaft of the mechanical system 4 as is for speed control of the motor 3.

[0044] In contrast, in the drive device 10 according to this embodiment, the rotational speed calculation unit 12 includes a speed feedback corrector 30 that calculates a correction amount SPFE for correcting changes in the rotational speed due to mechanical factors of the mechanical system 4 based on the speed feedback information SPF1 input from the speed sensor 5, and a calculator 32 that calculates the rotational speed SPF2 of the output shaft of the motor 3 based on the speed feedback information SPF1 input from the speed sensor 5 and the correction amount SPFE input from the speed feedback corrector 30.

[0045] As a result, in the drive device 10 according to this embodiment, even when speed feedback information SPF1 is acquired by the speed sensor 5 attached to the rotating shaft of the mechanical system 4, it is possible to correct for changes in the rotation speed due to mechanical factors of the mechanical system 4, such as torsion and vibration, and appropriately acquire the rotation speed SPF2 of the output shaft of the motor 3. Then, based on the acquired rotation speed SPF2 of the output shaft of the motor 3, it is possible to appropriately control the rotation speed of the output shaft of the motor 3.

[0046] Therefore, in the drive device 10 according to this embodiment, the rotation speed of the motor 3 can be appropriately controlled while increasing the degree of freedom in the installation position of the speed sensor 5.

[0047] Furthermore, in the drive device 10 according to this embodiment, the rotational speed calculation unit 12 further includes a fast Fourier transformer 34 that performs a fast Fourier transform on the speed feedback information SPF1 and inputs the result of the fast Fourier transform to the speed feedback corrector 30. The speed feedback corrector 30 has information on the results of the natural vibration analysis of the mechanical system 4, and by comparing the input result of the fast Fourier transform with the information on the results of the natural vibration analysis of the mechanical system 4, it identifies the amount of change in the rotational speed due to mechanical factors in the mechanical system 4 and calculates a correction amount SPFE so as to offset the identified amount of change in the rotational speed. This makes it possible to more appropriately calculate the correction amount SPFE.

[0048] The method of calculating the correction amount SPFE by the speed feedback corrector 30 is not limited to the above, and any method may be used that can appropriately calculate the correction amount SPFE for correcting the change in rotation speed due to mechanical factors of the mechanical system 4 based on the speed feedback information SPF1 input from the speed sensor 5.

[0049] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0050] 2, 2a...motor control system, 3...motor, 4...mechanical system, 5, 5a...speed sensor, 10, 10a...drive device, 12...rotational speed calculation unit, 14...drive control unit, 20...subtractor, 22...speed controller, 24...current controller, 30...speed feedback compensator, 32...calculator, 34...fast Fourier transformer

Claims

1. A drive device that controls the rotation speed of a motor, a rotation speed calculation unit that receives an input of speed feedback information representing a rotation speed of a rotation shaft of a mechanical system that rotates in conjunction with the rotation of the output shaft of the motor, and calculates the rotation speed of the output shaft of the motor based on the speed feedback information; a drive control unit that receives an input of the rotation speed of the output shaft of the motor from the rotation speed calculation unit and also receives an input of a speed reference for the rotation speed of the output shaft of the motor, and controls the rotation speed of the output shaft of the motor so that the rotation speed of the output shaft of the motor coincides with the speed reference; Equipped with The rotation speed calculation unit a speed feedback compensator that calculates a correction amount for correcting a change in rotation speed due to a mechanical factor of the mechanical system based on the speed feedback information; a calculator that calculates a rotational speed of an output shaft of the motor based on the speed feedback information and the correction amount; A drive device having the same.

2. the rotational speed calculation unit further includes a fast Fourier transformer that performs a fast Fourier transform on the speed feedback information and inputs a result of the fast Fourier transform to the speed feedback corrector, 2. The drive device according to claim 1, wherein the speed feedback compensator has information on the results of natural vibration analysis of the mechanical system, and by comparing the input result of the fast Fourier transform with the information on the results of natural vibration analysis of the mechanical system, identifies a change in rotation speed due to mechanical factors of the mechanical system, and calculates the correction amount so as to offset the identified change in rotation speed.

3. A motor; a mechanical system that rotates in conjunction with the rotation of the output shaft of the motor; a speed sensor attached to a rotational shaft of the mechanical system and configured to obtain speed feedback information representing a rotational speed of the rotational shaft of the mechanical system; a drive device that controls the rotation speed of the motor; Equipped with The drive device a rotational speed calculation unit that receives the speed feedback information and calculates the rotational speed of the output shaft of the motor based on the speed feedback information; a drive control unit that receives an input of the rotation speed of the output shaft of the motor from the rotation speed calculation unit and also receives an input of a speed reference for the rotation speed of the output shaft of the motor, and controls the rotation speed of the output shaft of the motor so that the rotation speed of the output shaft of the motor coincides with the speed reference; and The rotation speed calculation unit a speed feedback compensator that calculates a correction amount for correcting a change in rotation speed due to a mechanical factor of the mechanical system based on the speed feedback information; a calculator that calculates a rotational speed of an output shaft of the motor based on the speed feedback information and the correction amount; A motor control system having:

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