Control device, control method, and control system

Abstract

The embodiment of the invention provides a control device, a control method and a control system, which can suppress control instability caused by changes of a control object due to external factors. A control device according to an embodiment controls an object to be controlled, and includes a first controller, a second controller, a detector, and a corrector. The first controller generates a second command value by inputting a first measurement value measured by a control object and a first command value which is a target value of the first measurement value. The second controller generates, as a third command value, a target value to be supplied to the control object, using a second measurement value measured by the control object and the second command value as inputs. The detector detects a change in the second measurement value caused by an external factor of the control object and changes the control mode. The corrector generates a second correction value according to the control mode and corrects the second controller.

Description

[0001] Reference to related applications

[0002] This application claims the priority of Japanese Patent Application No. 2023-149460 (filing date: September 14, 2023) as a basic application. The present application incorporates the entire contents of the basic application by reference. Technical Field

[0003] Embodiments of the present invention relate to a control device, a control method, and a control system. Background Art

[0004] It is generally known that a plurality of controllers are used to control a control object such as a motor. An input to one of the plurality of controllers includes a command value output by another controller.

[0005] However, when a change occurs in the controlled object due to external factors such as a change in load torque, a command value of one controller and a command value of the other controller become opposite commands, and there is a concern that control may become unstable. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a control device, a control method and a control system which can suppress control instability caused by changes of a control object caused by external factors.

[0007] The control device of this embodiment is a control device for controlling a control object, and includes a first controller, a second controller, a detector, and a corrector. The first controller takes a first measurement value measured by the control object and a first instruction value as a target value of the first measurement value as input, and generates a second instruction value. The second controller takes a second measurement value measured by the control object and the second instruction value as input, and generates a target value supplied to the control object as a third instruction value. The detector detects a change in the second measurement value of the control object caused by an external factor and changes the control mode. The corrector generates a second correction value according to the control mode and corrects the second controller.

[0008] The control method of the present embodiment is a control method for controlling a control object, comprising: a first control step, taking a first measurement value measured by the control object and a first instruction value as a target value of the first measurement value as input to generate a second instruction value; a second control step, taking a second measurement value measured by the control object and the second instruction value as input to generate a target value supplied to the control object as a third instruction value; a detection step, detecting a change in the second measurement value of the control object caused by an external factor and changing a control mode; and a correction step, generating a second correction value according to the control mode and correcting the third instruction value.

[0009] The control system of the present embodiment is a control system including a DC motor and a control device for controlling the DC motor, the control device including: a first controller, which takes as input a first measurement value, i.e., a rotation speed measured by the DC motor, and a first instruction value as a target value of the first measurement value, and generates as a second instruction value a target value of current; a second controller, which takes as input a second measurement value, i.e., a current value measured by the DC motor, and the second instruction value, and generates as a third instruction value a target value of voltage supplied to the DC motor; a detector, which detects changes in the second measurement value of the DC motor caused by external factors and changes a control mode; and a corrector, which generates a second correction value according to the control mode and corrects the second controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a diagram schematically showing an example of a control system according to an embodiment.

[0011] Figure 2 This is a block diagram showing a configuration example of a control device.

[0012] Figure 3 This is a diagram schematically showing the input and output relationship of signals of each structure of the control device.

[0013] Figure 4 It is a diagram schematically showing the detection operation of the detector.

[0014] Figure 5 FIG. 1 is a diagram schematically illustrating control instability of the second PI controller when load fluctuation occurs.

[0015] Figure 6 It is a timing chart showing an operation example in a control cycle of the control device.

[0016] Figure 7 It is a block diagram showing a configuration example of a control device according to a comparative example.

[0017] Figure 8 It is a diagram showing time-series changes of various signals of the control device of the present embodiment.

[0018] Fig. 9 It is a diagram showing time-series changes of various signals of the control device of the comparative example.

[0019] Fig.10 It is a diagram showing a structural example of a control object.

[0020] Fig.11 It is a diagram showing a circuit configuration example of the control system 1 .

[0021] Fig.12This is a diagram showing an example in which a controller and a driver board are configured as a microcomputer mounting board.

[0022] Fig.13 This is a flowchart showing a processing example of the control device.

[0023] Description of Reference Numerals

[0024] 1: control system; 20: control device; 30: control object; 200: detector; 202: corrector; 204: first PI controller; 206: second PI controller; 301: motor; tor: load torque. DETAILED DESCRIPTION

[0025] Hereinafter, the control device, control method and control system of the embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, the embodiment shown below is an example of the embodiment of the present invention, and the present invention is not limited to these embodiments for interpretation. In addition, in the drawings referred to in the present embodiment, for the same part or the part having the same function, the same reference numeral or similar reference numeral is sometimes marked and its repeated description is omitted. In addition, there are cases where the dimensional ratio of the drawings is different from the actual ratio for the convenience of description and the case where a part of the structure is omitted from the drawings.

[0026] Figure 1 1 is a diagram schematically showing an example of a control system according to an embodiment. The control system 1 includes, for example, a processing device 10, a control device 20, and a control object 30. The control system 1 is a system for driving the control object 30. The control object 30 of one embodiment is, for example, a DC motor, but is not limited thereto. A detailed configuration example of the control object 30 will be described later using Fig.10 In addition, in this embodiment, a sensor for measuring the state of a DC motor, an inverter for driving a DC motor, etc. are sometimes referred to as a DC motor (see Fig.10 ).

[0027] The processing device 10 is, for example, a computer. The processing device 10 sends an instruction value such as a speed instruction value ωref for driving the controlled object 30 to the control device 20. The speed instruction value ωref is an instruction value of the rotation speed (rotation speed) of the motor. The processing device 10, for example, has an input / output interface for exchanging data with a user, and the processing device 10 generates an instruction value for driving the controlled object 30 based on the value input by the user, and outputs it to the control device 20. When the controlled object 30 is a DC motor, the instruction value is, for example, the speed instruction value ωref. In addition, the processing device 10 may also be a computer for automatically driving the controlled object 30 appropriately, in which case the processing device 10 outputs an appropriate instruction value set in the processing device 10 to the control device 20.

[0028] The control device 20 is a control device that controls the control object 30, generates a command value required to drive the control object 30, and outputs it to the control object 30. When the control object 30 is a DC motor, the control device 20 generates, for example, a voltage command value Vref and outputs it to the control object 30. The voltage command value Vref is a target value of the voltage supplied to the control object 30.

[0029] In addition, the control device 20 receives the measured value obtained from the actual operation of the control object 30 from the control object 30 or its peripheral module. When the control object 30 is a DC motor, for example, the current measured value I and the speed measured value ω are input to the control device 20. In this way, the control device 20 generates a voltage command value Vref based on the received speed command value ωref, the current measured value I, and the speed measured value ω, and outputs it to the control object 30 so that the control object 30 is driven according to the command value from the processing device 10. In addition, the speed measured value ω of the present embodiment corresponds to the first measured value, the speed command value ωref corresponds to the first command value, the current measured value I corresponds to the second measured value, the current command value Iref described later corresponds to the second command value, and the voltage command value Vref corresponds to the third command value.

[0030] Here, use Figure 2 , Figure 3 A detailed configuration example of the control device 20 will be described. Figure 2 2 is a block diagram showing a configuration example of the control device 20. Figure 2 As shown, the control device 20 has a detector 200 , a corrector 202 , a first PI controller 204 , and a second PI controller 206 . Figure 3 2 is a diagram schematically showing the input-output relationship of the signals of the computing unit of each structure of the control device 20. The control of the control object 30 performed by the control device 20 is, for example, feedback control that repeats a predetermined control cycle t. t represents the time sequence of the control cycle of the feedback control. For example, if t is 1, it means the first cycle, t is 2, it means the second cycle, and t is 3, it means the third cycle.

[0031] The control device 20 is a control device that controls the control object 30 and is a device that can control the control object 30 while suppressing the influence of load fluctuation (disturbance) caused by external factors. The control device 20 has a plurality of control modes according to the state of the control object 30.

[0032] The plurality of control modes are, for example, at least one of a first mode (normal mode) and a second mode (correction mode). For example, the normal mode is a control mode in which a load change of the control object 30 caused by an external factor is within a prescribed range, and the correction mode is a control mode in which a load change of the control object 30 caused by an external factor is outside the prescribed range.

[0033] The detector 200 detects the change of the current measurement value I of the control object 30 caused by the disturbance and changes the control mode. That is, the detector 200 has an arithmetic unit and a storage element, and outputs a mode signal signal corresponding to the state of the control object 30. In addition, when the load change exceeds the prescribed range, the detector 200 outputs the mode signal signal indicating the correction mode. On the other hand, when the load change is within the prescribed range, the detector 200 outputs the mode signal signal indicating the normal mode. That is, when the current control cycle is the normal mode and the current measurement value I changes regardless of the change of the current command value Iref, the detector 200 changes the current control cycle from the normal mode to the correction mode.

[0034] In addition, the detector 200 generates an estimated value of the current measurement value I in the current control cycle based on the transition of the current measurement value I and the current command value Iref in the past control cycle, and changes the current control cycle from the normal mode to the correction mode when the difference between the current measurement value I and the estimated value is greater than the threshold value. In addition, the detector 200 may estimate the range of the current measurement value I in the current control cycle based on the transition of the current measurement value I and the current command value Iref in the past control cycle, and change the current control cycle from the normal mode to the correction mode when the current measurement value I is outside the range.

[0035] In addition, the detector 200 changes the current control cycle from the calibration mode to the normal mode when the current control cycle is in the calibration mode and the difference between the speed measurement value ω and the speed command value ωref is reversed. In addition, the detector 200 may also change the current control cycle from the calibration mode to the normal mode when the current control cycle is in the calibration mode and the absolute value of the difference between the speed measurement value ω and the speed command value ωref is less than a specified value.

[0036] The detector 200 outputs false (=1) as the mode signal signal in the normal mode, and outputs true (=2) as the mode signal signal in the correction mode. That is, the detector 200 outputs the mode signal signal to the corrector 202, the first PI controller 204, and the second PI controller 206. The details of the detector 200 will be described later.

[0037] The corrector 202 has a computing unit and a storage element, generates a first correction value Ic1 according to the control mode, and corrects the first PI controller 204. In addition, the corrector 202 generates a second correction value Ic2 according to the control mode, and corrects the second PI controller 206. The corrector 202 outputs the current measurement value I to the second PI controller 206 when in the normal mode, and outputs the second correction value Ic2 to the second PI controller 206 when in the correction mode.

[0038] More specifically, when the current control cycle is changed from the normal mode to the correction mode, the corrector 202 holds and outputs the current measurement value I measured during the control cycle immediately before the current control cycle as the second correction value Ic2. In addition, when the current control cycle is changed from the normal mode to the correction mode, the corrector 202 may hold and output the current measurement value I during the period when the change is below the specified value in the past multiple control cycles as the second correction value Ic2. For example, the corrector 202 may hold the current measurement value I of the past multiple N cycles, and hold and output the value before the current measurement value I changes significantly, or the value of the average value of the current measurement value I that satisfies the same condition as the second correction value Ic2. Moreover, when the corrector 202 is changed from the correction mode to the normal mode, the first correction value Ic1 based on the current measurement value I of the current control cycle is output to the first PI controller 204.

[0039] In more detail, when the corrector 202 changes from the correction mode to the normal mode based on the mode signal signal of the detector 200, the corrector 202 outputs the correction value Ic1 shown in the formula (3) described later as the first correction value to the first PI controller 204. In addition, the corrector 202 can store the current measurement value I(t) in a time series. In the correction mode, the corrector 202 outputs the current measurement value Ic2 as a fixed value to the second PI controller 206 as the second correction value. Here, the current measurement value Ic2 is, for example, the current measurement value I(t-1) immediately before the load change occurs. For example, it is the current measurement value I(t-1) in the normal mode immediately before the change from the normal mode to the correction mode.

[0040] The first PI controller 204 is a controller capable of performing feedback control based on PID control. The first PI controller 204 receives as input the rotation speed measured by the control object 30, i.e., the speed measurement value ω(t) (first measurement value) and the target value of the speed measurement value ω(t), i.e., the speed command value ωref(t) (first command value), and generates the target value of the current as the current command value Iref(t) (second command value). More specifically, the first PI controller 204 performs PID control according to equations (1) and (2) based on the speed command value ωref(t) and the speed measurement value ω(t) in the normal mode, and outputs the current command value Iref(t). Equation (2) is an error term between the speed command value ωref(t) and the speed measurement value ω(t). The first PI controller 204 has an operator and a storage element. K1 and K2 are constants. The storage element stores, for example, measurement values, operation values, coefficients, etc. required for the operation of equations (1) to (2). In addition, the first PI controller 204 of the present embodiment corresponds to the first controller.

[0041] [Formula 1]

[0042]

[0043] [Formula 2]

[0044] e1(t)=ωref(t)-ω(t) (2)

[0045] Furthermore, the first PI controller 204 stores the mode signal signal, and replaces the integral value of the equation (1) with the first correction value Ic1 according to the equation (3) when switching from the correction mode to the normal mode.

[0046] [Formula 3]

[0047] Ic1=I(t) / K2 (3)

[0048] In addition, in the present embodiment, the first correction value Ic1 is calculated by the corrector 202, but the present invention is not limited to this. The first PI controller 204 may perform the calculation based on the mode signal signal.

[0049] In this way, the first PI controller 204 generates the current command value Iref(t) of the current control cycle t based on the current difference value e1(t) between the speed measurement value ω(t) and the speed command value ωref(t) in the current control cycle t and the integrated value obtained by integrating the past difference value e1(τ) between the speed measurement value ω(τ) (τ is a value less than t) and the speed command value ωref(τ) in the past control cycle. In addition, when the first PI controller 204 changes from the correction mode to the normal mode, it generates the current command value Iref(t) based on the current difference value e1(t) and the first correction value Ic1.

[0050] The second PI controller 206 is a controller capable of performing feedback control based on PID control. The second PI controller 206 receives the current value measured by the control object 30, that is, the current measurement value I(t) (second measurement value) and the current command value Iref(t) (second command value) as input, and generates a target value of the voltage supplied to the control object 30 as the voltage command value Vref(t) (third command value).

[0051] More specifically, when the current control cycle t is in the normal mode, the second PI controller 206 performs PID control according to equations (4) and (5) based on the current command value Iref(t) and the current measured value I(t) and outputs the voltage command value Vref(t). The second PI controller 206 has an operator and a storage element. K3 and K4 are constants. The storage element stores, for example, measured values, calculated values, coefficients, etc. required for the calculation of equations (4) to (6). In addition, the second PI controller 206 of the present embodiment corresponds to the second controller.

[0052] [Formula 4]

[0053]

[0054] [Formula 5]

[0055] e2(t)=Iref(t)-I(t) (5)

[0056] In the correction mode, e2(t) according to equation (6) is used instead of equation (5). That is, when the current control cycle t is in the correction mode, the second PI controller 206 uses the second correction value Ic2 and the current command value Iref(t) as inputs to generate the voltage command value Vref(t). That is, when in the correction mode, the second correction value Ic2 as a fixed value is used instead of the current measurement value I(t). In this way, the influence of the change of the current measurement value I(t) caused by the load change can be suppressed. As described above, the second correction value Ic2 is, for example, the current measurement value I(t-1) immediately before the load change occurs, and is supplied by the corrector 202, but is not limited to this. For example, the second PI controller 206 can also be generated based on the mode signal signal.

[0057] [Formula 6]

[0058] e2(t)=Iref(t)-Ic2 (6)

[0059] Here, refer to Figure 2 , Figure 3 and use Figure 4 The following describes in detail an operation example of the detector 200 . Figure 4 2 is a diagram schematically showing the detection operation of the detector 200. The vertical axis represents the current and the horizontal axis represents the time. Figure 4 As shown, the detector 200 stores the current measurement value I and the current command value Iref in time series, for example. The detector 200 detects the load variation by using the correlation between the current measurement value I that varies in time series and the load of the control object 30 that varies in time series, for example.

[0060] As shown in the circuit equations (7) and (8) of the DC motor, the change (disturbance) of the load torque caused by external factors is in the same direction as the increase or decrease of the current. Here, V is the supply voltage to the DC motor, k_t is the torque constant, T is the load torque, k_e is the back electromotive force constant, and N is the speed of the DC motor.

[0061] [Formula 7]

[0062] V=k_e×N+RI (7)

[0063] [Formula 8]

[0064] T=k_t×I (8)

[0065] The detector 200 uses the characteristics of the circuit equations (7) and (8) to calculate the measurement range Eb(t) in normal times (when there is no load change) using the data of the current measurement values ​​I(t-n) to I(t-1) and the current command values ​​Iref(t-n) to I(t-1) in the current control cycle before t, for example. n is a natural number greater than 2. In this way, the detector 200 estimates the measurement range Eb(t) of the next current measurement value I(t) based on the changes in the current command values ​​Iref(t-n) to I(t-1) and the measurement values ​​I(t-n) to I(t-1).

[0066] When the current measurement value I(t) is within the measurement range Eb(t), the detector 200 outputs a mode signal signal indicating a normal mode. On the other hand, when the current measurement value Iu(t) or Id(t) is outside the measurement range Eb(t), the detector 200 outputs a mode signal signal indicating a correction mode. In addition, the method for generating the measurement range Eb(t) is an example and is not limited to this. For example, an estimated value of the current measurement value I(t) in the current control cycle t may be generated based on the change of the current command value Iref(t-n)~I(t-1) and the measurement value I(t-n)~I(t-1), and when the difference between the current measurement value I(t) and the estimated value is greater than a threshold value, the current control cycle is changed from the normal mode to the correction mode.

[0067] More simply, for example, the value obtained by adding the difference Id between the current measurement value I(t-1) and the current measurement value I(t-2) to the current measurement value I(t-1) is set as In(t). Then, with In(t) as the center point, the ± range obtained by multiplying the difference Id by a predetermined coefficient Keb may be set as the measurement range Eb(t).

[0068] In addition, for example, if the deviation between the speed command value ωref(t) and the speed measurement value ω(t) caused by the load change is suppressed, the detector 200 changes the correction mode to the normal mode. The detector 200 changes the correction mode to the normal mode when the difference value between the speed command value ωref(t) and the speed measurement value ω(t) is reversed relative to the control cycle (t-1). Alternatively, the detector 200 may change the correction mode to the normal mode when the absolute value of the difference between the speed command value ωref(t) and the speed measurement value ω(t) is within a specified value. In addition, the detector 200 may change the control mode at the moment when it is found that there is a sign of a reversal in the magnitude relationship between the speed command value ωref(t) and the speed measurement value ω(t) using a method such as a slope based on differentiation of the speed measurement value ω(t) or a prediction based on machine learning.

[0069] Here, the control instability suppressed by the output of the corrector 202 is described. First, the stability of the control brought about by using the first correction value Ic1 is described. For example, when the load increases, the speed measurement value ω(t) decreases, so during the period from the correction mode to the switching to the normal mode, the current command value Iref(t) shows an increasing trend in order to increase the speed measurement value ω(t) that has decreased due to the increase in load to the speed command value ωref(t). That is, the integral term of equation (1) shows a tendency to increase the current command value Iref(t). On the other hand, immediately before switching from the correction mode to the normal mode, the absolute value of the difference between the speed command value ωref(t) and the speed measurement value ω(t) is within a specified value and stabilized. In this state, if the integral term of equation (1) is maintained, the current command value Iref(t) will further increase.

[0070] Therefore, when the first PI controller 204 switches from the correction mode to the normal mode, the integral term of the formula (1) is replaced by the first correction value Ic1 according to the formula (3). That is, when the correction mode is switched to the normal mode, the current command value Iref(t) output by the first PI controller 204 becomes the formula (9). That is, the error term shown in the formula (2) is added to the current measurement value I(t) when the normal mode is switched. It can be seen that the current command value Iref(t) is output in order to suppress the difference between the speed command value ωref(t) and the speed measurement value ω(t) and maintain a state close to the current measurement value I(t). Therefore, even if the normal mode is switched, the absolute value of the difference between the speed command value ωref(t) and the speed measurement value ω(t) can be maintained within the specified value.

[0071] [Formula 9]

[0072] Iref(t)=K1×(ωref(t)-ω(t))+I(t) (9)

[0073] Next, refer to Figure 5 The stability of control achieved by using the second correction value IC2 will be described. Figure 5 2 is a diagram schematically illustrating the control instability of the second PI controller 206 when a load change occurs. Figure 5 As shown, when load fluctuation occurs due to external factors, for example, due to transient phenomena, the magnitude relationship between the current command value Iref(t) and the current measurement value I(t) may become unstable.

[0074] For example, when the load of the controlled object 30 increases, Iref(t)>I(t) should be satisfied in order to increase the voltage, and when the load of the controlled object 30 decreases, Iref(t)<I(t) should be satisfied in order to decrease the voltage. However, when the load changes, the magnitude relationship becomes unstable, so when the load increases, Iref(t)<I(t) may be satisfied. In this case, the controlled object 30 is controlled in the opposite direction to the original speed, and the speed further decreases, and the time to return to the original speed is extended.

[0075] On the other hand, when the load of the controlled object 30 decreases, Iref(t)>I(t) may occur. In this case, the controlled object 30 is controlled in the opposite way to the original speed, the speed further increases, and the time to return to the original speed increases.

[0076] Therefore, when the correction mode is changed, the corrector 202 outputs the current measurement value Ic2 of the fixed value as the second correction value to the second PI controller 206 as shown in formula (6). As described above, the corrector 202 is, for example, the current measurement value I(t-1) immediately before the load change occurs, and the current measurement value I(t-1) and the current command value Iref(t-1) have close values.

[0077] On the other hand, when the load increases, the current command value Iref(t) of the first PI controller 204 increases in order to restore the speed, and is therefore greater than the current measurement value I(t-1) as the second correction value, and the voltage command value Vref(t) increases. In addition, when the load decreases, the current command value Iref(t) of the first PI controller 204 decreases in order to restore the speed when the load decreases, and is therefore smaller than the current measurement value I(t-1) as the second correction value, and the voltage command value Vref(t) decreases. In this way, by setting the second correction value Ic2 to, for example, the current measurement value I(t-1) immediately before the load change occurs, the control object 30 is prevented from being controlled in the opposite direction to the original state.

[0078] Here, refer to Figure 2 , Figure 3 and use Figure 6 An operation example in the control cycle t of the control device 20 of the present embodiment will be described. Figure 6 1 is a timing diagram showing an example of operation in the control cycle t of the control device 20. The period of time t1 to t10 corresponds to one control cycle. Here, the example in which the corrector 202 outputs IC2(t) or the current measurement value I(t) as the second correction value to the second PI controller 206 is used for explanation. In addition, the example in which the internal storage element of the module can always store the input signal as long as the control device 20 is operating is used for explanation. Therefore, in the following, when the signal is represented by a high level, data can be input from the internal storage element of the module.

[0079] like Figure 6As shown, from top to bottom, the speed command value ωref(t-1), the current command value Iref(t-1), the speed measurement value ω(t), the current measurement value I(t), the detector 200, the mode signal signal, the corrector 202, the first correction value IC1(t), the second correction value IC2(t), the speed command value ωref(t), the first PI controller 204, the current command value Iref(t), the second PI controller 206, and the voltage command value Vref(t) are shown. The high-level signal indicates the validity of each signal and module, and the low-level signal indicates the invalidity of each signal and module. The horizontal axis is time. The so-called validity of the signal means that the signal is input to the operator of each module, or the signal is output from the operator of each module. In addition, the so-called validity of the module means the period of the operation of the operator of the module. In addition, the input to the operator in the following description is either the input of data stored in the internal elements of the module in time series, or the input from outside the module.

[0080] First, during the period from t1 to t2, the speed command value ωref(t-1), the current command value Iref(t-1), the speed measurement value ω(t), and the current measurement value I(t) are input to the computing unit of the detector 200. If the mode signal signal(t-1) is the normal mode, and the current measurement value I(t) enters the measurement range Eb(t) calculated in the calculation cycle (t-1) (refer to Figure 4 ), the detector 200 outputs a mode signal signal (t) indicating the normal mode. On the other hand, if the mode signal signal (t-1) is the normal mode and the current measurement value I (t) does not enter the measurement range Eb (t) (refer to Figure 4 ), the detector 200 outputs a mode signal signal(t) indicating the calibration mode.

[0081] In addition, the detector 200's operator outputs a mode signal signal (t) indicating a normal mode when the mode signal signal (t-1) is in the correction mode and the absolute value of the difference between the speed measurement value ω (t) and the speed measurement value ω (t-1) is within a prescribed value. On the other hand, the detector 200 outputs a mode signal signal (t) indicating a correction mode when the mode signal signal (t-1) is in the correction mode and the absolute value of the difference between the speed measurement value ω (t) and the speed measurement value ω (t-1) is not within a prescribed value. Furthermore, the detector 200's operator calculates the measurement range Eb (t+1) during time t1 to t4.

[0082] During the period from time t3 to time t4, the current measurement value I(t) and the mode signal signal(t) are input to the calculation unit of the corrector 202. When the mode signal signal(t-1) is in the correction mode and the mode signal signal(t) is in the normal mode, the calculation unit of the corrector 202 outputs the first correction value Ic1(t)=current measurement value I(t) / k2 as shown in formula (3).

[0083] In addition, the calculation unit of the corrector 202 outputs the second correction value Ic2(t) when the mode signal signal(t) is in the correction mode. The second correction value Ic2(t) is fixed to the current measurement value Ic2 when the mode signal signal is changed from the normal mode to the correction mode. On the other hand, the calculation unit of the corrector 202 outputs the current measurement value I(t) when the mode signal signal(t) is in the normal mode.

[0084] During the period from time t5 to t6, the speed command value ωref(t), the speed measurement value ω(t) and the mode signal signal(t) are input to the operator of the first PI controller 204. When the mode signal signal(t-1) is in the correction mode and the mode signal signal(t) is in the normal mode, the operator of the first PI controller 204 outputs the current command value Iref(t) according to formula (9). On the other hand, in other cases, the operator of the first PI controller 204 outputs the current command value Iref(t) according to formula (1).

[0085] During the period from time t7 to t8, the current command value Iref(t) and the second correction value Ic2(t) or the current measurement value I(t) are input to the operator of the second PI controller 206. When the mode signal signal(t) is the normal mode, the current measurement value I(t) is input to the operator of the second PI controller 206, and the voltage command value Vref(t) according to equations (4) and (5) is output. On the other hand, when the mode signal signal(t) is the correction mode, the second correction value Ic2(t) is input to the operator of the second PI controller 206, and the voltage command value Vref(t) according to equations (4) and (6) is output. In this way, the control device 20 performs operations in the order of the detector 200, the corrector 202, the first PI controller 204, and the second PI controller 206 over time. As a result, the operations of the first PI controller 204 and the second PI controller 206 can be corrected by the correction values ​​IC1 and IC2 generated by the corrector 202 according to the change of the control mode in the current control cycle t by the detector 200.

[0086] Figure 7 2 is a block diagram showing a configuration example of a control device 20a of a comparative example. Figure 7 As shown, the control device 20a includes a first PI controller 204a and a second PI controller 206a. The control device 20a of the comparative example is different from the control device 20 of the present embodiment in that it does not include the detector 200 and the corrector 202. The first PI controller 204a and the second PI controller 206a of the comparative example perform the same control operation as the case where the first PI controller 204 and the second PI controller 206 of the present embodiment are operated in the normal mode.

[0087] Figure 8 1 is a diagram showing time-series changes of various signals of the control device 20 according to the present embodiment. Figure 8 The vertical axis of (a) represents the load torque tor of the controlled object 30 . Figure 8 The vertical axis of (b) represents the speed measurement value ω and the speed command value ωref. Figure 8 The vertical axis of (c) represents the current measurement value I and the current command value Iref. Figure 8 The vertical axis of (d) represents the voltage command value Vref.

[0088] In the control device 20 of this embodiment, as Figure 8 As shown in (a), during the period between time T1 and T2, the load torque tor of the control object 30 increases due to external factors. With the increase of the load torque tor, as shown in Figure 8 As shown in (b), the speed measurement value ω(T) decreases. On the other hand, since the speed command value ωref(T) is larger than the speed measurement value ω(T), the current command value Iref(T) increases.

[0089] like Figure 8 As shown in (c), the detector 200 outputs the mode signal signal indicating the correction mode at the time T2 when the current measurement value I(T) is outside the measurement range Eb(T). Thus, the corrector 202 outputs the current measurement value I(T1) at the time T1 as the second correction value Ic2 to the second PI controller 206.

[0090] like Figure 8 As shown in (d) of FIG. 1 , since the current command value Iref(T) becomes larger than the second correction value Ic2 at time T1, the voltage command value Vref output by the second PI controller 206 also increases. Figure 8 As shown in (b), at time T3, the speed ω starts to increase.

[0091] At time T4 when the speed measurement value ω increases and the magnitude relationship with the speed command value ωref reverses, the detector 200 outputs a mode signal signal indicating the normal mode. The corrector 202 outputs the first correction value Ic1 (see equation (3)) to the first PI controller 204 at time T4. The first PI controller 204 replaces the integral value with the first correction value Ic1 (see equation (9)) and performs control in the normal mode. Similarly, the second PI controller 206 switches to the normal mode control at time T4. Thus, as Figure 8 As shown in (c), the current command value Iref(T) and the current measurement value I(T) gradually approach and stabilize. Figure 8 As shown in (b), from time T4 onwards, the minute vibration of the speed measurement value ω(T) converges with the passage of time, gradually approaches the speed command value ωref(T) and stabilizes.

[0092] Fig. 9 1 is a diagram showing time-series changes of various signals of the control device 20a of the comparative example. The horizontal axis represents time. Fig. 9 The vertical axis of (e) represents the load torque tor of the controlled object 30 . Fig. 9 The vertical axis of (f) represents the speed measurement value ω and the speed command value ωref. Fig. 9 The vertical axis of (g) represents the current measurement value I and the current command value Iref. Fig. 9 The vertical axis of (h) represents the voltage command value Vref.

[0093] Relative to Figure 8 In the comparative example, Fig. 9 As shown in (e) of FIG. 1 , the load of the control object 30 increases during the period T1a to T5a. As the load increases, Fig. 9 As shown in (f), the speed measurement value ω(Ta) decreases. On the other hand, since the speed command value ωref is larger than the speed measurement value ω, the current command value Iref(Ta) increases.

[0094] On the other hand, in the comparative example, Fig. 9 As shown in (g), since the normal mode remains unchanged even when a load change occurs, even if the load increases after time T1a, the current measurement value I(Ta) may be larger than the current command value Iref(Ta). Fig. 9 As shown in (h), the speed ω is decreasing, but the voltage command value Vref (Ta) is also decreasing. Fig. 9 As shown in (f), the speed measurement value ω is further reduced. On the other hand, in the control device 20 of the present embodiment, when a load variation occurs, as described above, the second PI controller 206 uses the second correction value Ic2, so that the instability of control is suppressed.

[0095] Again Fig. 9 As shown in (g), the current command value Iref(T6a) which continues to increase becomes larger than the current measurement value I(T6a). Fig. 9 As shown in (h), at time T6a, the voltage command value Vref (Ta) turns to increase. Fig. 9 As shown in (f), the speed measurement value ω starts to increase after time T6a.

[0096] like Fig. 9 As shown in (f), at time T7a, the magnitude relationship between the speed measurement value ω(T7a) and the speed command value ωref(T7a) is reversed. Fig. 9 As shown in (g), the first PI controller 204 maintains the current command value Iref(Ta) larger than the current measurement value I(Ta) until T8a due to the influence of the integral term (refer to equation (1)). Fig. 9 As shown in (f), this time, the speed measurement value ω(Ta) exceeds the speed command value ωref(Ta). In this way, in the comparative example, the speed measurement value ω repeatedly vibrates, resulting in a long time until it converges to the speed command value ωref. On the other hand, in the control device 20 of the present embodiment, the first PI controller 204 replaces the integral value of the integral term with the first correction value as described above (refer to formula (3)), so that the small vibration of the speed measurement value ω(T) converges (refer to formula (9)), gradually approaches the speed command value ωref(T) and stabilizes.

[0097] Fig.10 is a diagram showing an example of a structure of a control object. Fig.10 As shown, the control object 30 includes, for example, a motor 301, a position sensor 302, a coordinate conversion unit 303, a PWM converter 304, an inverter 305, a current sensor 306, and an A / D converter 307. For example, in a permanent magnet synchronous motor 301 (hereinafter referred to as motor 301) as a brushless DC motor, a position sensor 302 for detecting the rotation position of the rotor is installed. The position sensor 302 detects and outputs an electrical angle θ and a rotation speed ω as a speed measurement value. In addition, a load torque tor is connected to the motor as a load.

[0098] The electrical angle θ is input to the coordinate conversion unit 303, and the coordinate conversion unit 303 converts the voltage command value Vref into a three-phase voltage command based on the electrical angle θ, and outputs it to the PWM converter 304. The PWM converter 304 generates a three-phase PWM signal based on the three-phase voltage command Vuvw, and outputs it to the inverter 305 (power converter). Each phase output terminal of the inverter 305 is connected to each phase winding of the motor 301.

[0099] The current of each phase detected by the current sensor 306 is A / D converted via the A / D converter 307 and output to the coordinate conversion unit 303. The coordinate conversion unit 303 outputs the current measurement value I. In addition, the symbol DQ represents a vector represented by the DQ coordinate system, but it is not limited to this and may also be one or more scalar values ​​containing necessary information.

[0100] Fig.11 1 is a diagram showing an example of a circuit structure of a control system 1. The control device 20 and a part of the controlled object 30 are configured as a microprocessor-based controller IC 100 having an MCU (Micro Controller Unit). For example, the control device 20, the coordinate conversion unit 303, the PWM converter 304, and the A / D converter 307 are configured as an MCU (Micro Controller Unit). In addition, the inverter 305 is configured as a drive board D102. In this way, the detector 200, the corrector 202, the first PI controller 204, and the second PI controller 206 of the control device 20 can be integrally configured as an MCU.

[0101] Fig.12 1 is a diagram showing an example of a circuit substrate of a control system 1. For example, it is an example in which a controller IC100 and a driver board D102 are configured as a microcomputer mounting board. The microcomputer mounting board M104 carries the controller IC100 and the driver board D102. In addition, the position sensor 302 and the current sensor 306 are configured as a sensor board B106. The sensor board B106 is configured, for example, by a field effect transistor (FET: Field Effect Transistor) and a high-performance semiconductor power switch (PD: Intelligent Power Device). In this way, the control device 20 and a part of the controlled object 30 can be integrally configured as a circuit substrate.

[0102] Fig.13 2 is a flowchart showing an example of the processing of the control device 20. Here, the control cycle t is explained by changing to 1, 2, 3, 4, etc. in a time series. It is assumed that t = 1 at the start of control and the control mode is normal (signal is false). As described above, a control cycle is as follows: Figure 6 As shown, it corresponds to the period from t1 to t10.

[0103] First, the speed command value ωref(t-1), the current command value Iref(t-1), the speed measurement value ω(t), the current measurement value I(t), and the mode signal signal(t-1) are input to the operator of the detector 200 (step S100). Next, the detector 200 determines whether the mode signal signal(t-1) of the current control cycle is the normal mode (false) or the correction mode (true) (step S102). In addition, the value of the previous control cycle mode signal signal(t-1) is maintained in the storage element of the detector 200. When the detection process of the current control cycle t starts, the value of the previous control cycle mode signal signal(t-1) represents the mode of the current control cycle. On the other hand, when the detection process of the current control cycle t ends, the value of the control cycle mode signal signal(t) represents the mode of the current control cycle.

[0104] When the detector 200 determines that the mode signal signal(t-1) is in the normal mode (false) ("Yes" in step S102), the detector 200 calculates the range prediction Eb(t) (step S104). Next, the detector 200 determines whether the current measurement value I(t) is within the range prediction Eb(t) (step S106). When the detector 200 determines that it is within the range prediction Eb(t) ("Yes" in step S106), the mode signal signal(t) is set to the normal mode (false), the mode signal signal(t) is input to the operator of the corrector 202 (step S108), and the current measurement value I(t) is output to the second PI controller 206 (step S110).

[0105] The first PI controller 204 uses the speed measurement value ω(t) and the speed command value ωref(t) to calculate the current command value Iref(t) according to equation (1), and outputs it to the second PI controller 206 (step S112). Next, the second PI controller 206 uses the current measurement value I(t) and the current command value Iref(t) to calculate the voltage command value Vref(t) according to equations (4) and (5), and outputs it to the control object 30 (step S114). Next, when the processing device 10 has not completed the control process ("No" in step S116), t is incremented by 1 (step S118), and the control starting from step S100 is repeated. On the other hand, when the processing device 10 has completed the control process ("Yes" in step S116), the control of the control device 20 is completed.

[0106] On the other hand, when the detector 200 determines that it is not within the range prediction Eb(t) ("No" in step S106), it sets the mode signal signal(t) to the correction mode (true), inputs the mode signal signal(t) to the operator of the corrector 202 (step S120), and outputs I(t-1) as the second correction value IC2 to the second PI controller 206 (step S122). The corrector 202 maintains and outputs the second correction value IC2 until the mode signal signal(t) becomes the normal mode (false).

[0107] Next, the first PI controller 204 uses the speed measurement value ω(t) and the speed command value ωref(t) to calculate the current command value Iref(t) according to equation (1), and outputs it to the second PI controller 206 (step S124). Next, the second PI controller 206 uses the second correction value I(t-1) and the current command value Iref(t) to calculate the voltage command value Vref(t) according to equations (4) and (6), and outputs it to the control object 30 (step S126).

[0108] On the other hand, when the detector 200 determines that the mode signal signal(t-1) before the control period is the correction mode (true) ("No" in step S102), the detector 200 calculates the absolute value of the difference between the speed command value ωref(t) and the speed measurement value ω(t) (step S128). Next, the detector 200 determines whether the sign of the difference value is reversed or whether the absolute value of the difference is within a specified value (step S130). For example, it is determined whether the sign of the difference value is reversed or whether the absolute value of the difference is within 5% of the speed command value ωref(t).

[0109] When the detector 200 determines that the value is not within the specified value ("No" in step S130), the mode signal signal (t) is set to the correction mode (true), the mode signal signal (t) is input to the operator of the corrector 202 (step S132), and the second correction value IC2 is output to the second PI controller 206 (step S134). The first PI controller 204 and the second PI controller 206 perform the same operation as step S124 and step S126.

[0110] On the other hand, when the detector 200 determines that the current is within the specified value ("Yes" in step S130), the mode signal signal (t) is set to the normal mode (false), the mode signal signal (t) is input to the operator of the corrector 202 (step S136), and I (t) / k2 is output as the first correction value IC1 to the first PI controller 204 (step S138). In addition, the corrector 202 outputs the current measurement value I (t) to the second PI controller 206 (step S110).

[0111] The first PI controller 204 uses the first correction value IC1, the speed measurement value ω(t) and the speed command value ωref(t) to perform an operation according to equation (9), calculates the current command value Iref(t), and outputs it to the second PI controller 206 (step S140). The second PI controller 206 performs the same operation as step S114.

[0112] As described above, according to the present embodiment, the detector 200 detects the change in the current measurement value I of the controlled object 30 caused by the external factors, thereby changing the control mode to the correction mode, and the corrector 202 supplies the second correction value IC2 for correcting the output of the second PI controller 206 according to the change to the correction mode. Thus, the second PI controller 206 can perform control using the second correction value IC2 instead of control using the current measurement value I when the controlled object 30 changes due to the external factors, and can suppress control instability caused by the change of the controlled object 30 due to the external factors.

[0113] At least a part of the control device 20 described in the above embodiment may be constituted by hardware or software. In the case of being constituted by software, a program for realizing at least a part of the functions of the control device 20 may be stored in a recording medium such as a floppy disk or a CD-ROM, and read by a computer for execution. The recording medium is not limited to a removable recording medium such as a magnetic disk or an optical disk, but may also be a fixed recording medium such as a hard disk unit or a memory.

[0114] In addition, a program that realizes at least a part of the functions of the control device 20 may be distributed via a communication line such as the Internet (including wireless communication). Furthermore, the program may be encrypted or modulated and distributed in a compressed state via a wired line such as the Internet, a wireless line, or stored in a recording medium.

[0115] Several embodiments have been described above, but these embodiments are only presented as examples and are not intended to limit the scope of the invention. The new devices, methods and programs described in this specification can be implemented in various other ways. In addition, various omissions, substitutions and changes can be made to the devices, methods and programs described in this specification without departing from the scope of the invention.

Claims

1. A control device for controlling a controlled object, characterized in that: have: a first controller, taking as input a first measurement value measured by the control object and a first instruction value as a target value of the first measurement value, and generating a second instruction value; a second controller, taking the second measured value measured by the control object and the second command value as input, and generating a target value to be supplied to the control object as a third command value; a detector for detecting a change in the second measured value of the controlled object caused by an external factor and changing a control mode; as well as A corrector generates a second correction value according to the control mode and corrects the second controller.

2. The control device according to claim 1, characterized in that The control mode includes at least one of a first mode and a second mode, and the control of the control object is a feedback control that repeats a predetermined control cycle. When the current control cycle is in the first mode, the second controller takes the second measured value and the second command value as input to generate the third command value. When a current control cycle is in the second mode, the second controller takes the second correction value and the second instruction value as inputs and generates the third instruction value.

3. The control device according to claim 2, characterized in that The calibrator outputs the second measurement value to the second controller when in the first mode, and outputs the second correction value to the second controller when in the second mode.

4. The control device according to claim 2, characterized in that: The detector changes the current control cycle from the first mode to the second mode when the current control cycle is the first mode and the second measurement value changes regardless of transition of the second command value.

5. The control device according to claim 2, characterized in that: The detector generates an estimated value of the second measurement value in a current control cycle based on changes in the second measurement value and the second instruction value in past control cycles, and changes the current control cycle from the first mode to the second mode when a difference between the second measurement value and the estimated value is greater than a threshold value.

6. The control device according to claim 2, characterized in that: The detector estimates the range of the second measurement value in a current control cycle based on changes in the second measurement value and the second instruction value in past control cycles, and changes the current control cycle from the first mode to the second mode when the second measurement value is outside the range.

7. The control device according to claim 2, characterized in that: The detector changes the current control cycle from the second mode to the first mode when the current control cycle is in the second mode and the difference between the first measurement value and the first command value is reversed.

8. The control device according to claim 2, characterized in that: When the current control cycle is changed from the first mode to the second mode, the corrector holds and outputs the second measurement value measured during a control cycle immediately before the current control cycle as the second correction value.

9. The control device according to claim 2, characterized in that: When the current control cycle is changed from the first mode to the second mode, the corrector stores and outputs the second measurement value during a period in which the variation is less than a predetermined value in a plurality of past control cycles as the second correction value.

10. The control device according to claim 9, characterized in that The first controller generates the second command value of the current control cycle based on a current difference value between the first measurement value and the first command value in the current control cycle and an integrated value obtained by integrating a past difference value between the first measurement value and the first command value in a past control cycle. When the second mode is changed to the first mode, the corrector outputs a first correction value based on the second measurement value of the current control cycle to the first controller. The first controller generates the second instruction value based on the current difference value and the first correction value when the mode is changed from the second mode to the first mode.

11. The control device according to any one of claims 1 to 10, characterized in that: The control object is a DC motor, the first measured value is a rotation speed measured by the DC motor, the second command value is a target value of current, the second measured value is a current value measured by the DC motor, and the third command value is a target value of voltage supplied to the DC motor.

12. A control method for controlling a control object, characterized in that: have: a first control step of generating a second command value by taking as input a first measurement value measured by the control object and a first command value as a target value of the first measurement value; a second control step of taking a second measurement value measured by the control object and the second command value as inputs and generating a target value to be supplied to the control object as a third command value; a detection step of detecting a change in the second measured value of the controlled object caused by an external factor and changing a control mode; as well as The correction step generates a second correction value according to the control mode and corrects the third instruction value.

13. A control system comprising: DC motor; and A control device for controlling the DC motor; The control system is characterized in that The control device comprises: a first controller that receives as input a first measurement value of the rotation speed measured by the DC motor and a first command value that is a target value of the first measurement value, and generates a target value of the current as a second command value; a second controller that receives as input a second measured value of the current measured by the DC motor and the second command value, and generates as a third command value a target value of a voltage supplied to the DC motor; a detector for detecting a change in the second measured value of the DC motor caused by an external factor and changing a control mode; as well as A corrector generates a second correction value according to the control mode and corrects the second controller.

14. The control system according to claim 13, characterized in that: The control mode includes at least one of a first mode and a second mode, and the control of the DC motor is feedback control that repeats a predetermined control cycle. When the current control cycle is in the first mode, the second controller takes the second measured value and the second command value as input to generate the third command value. When a current control cycle is in the second mode, the second controller takes the second correction value and the second instruction value as inputs and generates the third instruction value.

15. The control system according to claim 14, characterized in that: The calibrator outputs the second measurement value to the second controller when in the first mode, and outputs the second correction value to the second controller when in the second mode.

16. The control system according to claim 14, characterized in that: The detector changes the current control cycle from the first mode to the second mode when the current control cycle is the first mode and the second measurement value changes regardless of transition of the second command value.

17. The control system according to claim 14, characterized in that: The detector generates an estimated value of the second measurement value in a current control cycle based on changes in the second measurement value and the second instruction value in past control cycles, and changes the current control cycle from the first mode to the second mode when a difference between the second measurement value and the estimated value is greater than a threshold value.

18. The control system according to claim 14, characterized in that: The detector estimates the range of the second measurement value in a current control cycle based on changes in the second measurement value and the second instruction value in past control cycles, and changes the current control cycle from the first mode to the second mode when the second measurement value is outside the range.

19. The control system according to claim 14, characterized in that: The detector changes the current control cycle from the second mode to the first mode when the current control cycle is in the second mode and the difference between the first measurement value and the first command value is reversed.

20. The control system according to claim 14, characterized in that: When the current control cycle is changed from the first mode to the second mode, the corrector holds and outputs the second measurement value measured during a control cycle immediately before the current control cycle as the second correction value.

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