Electric motor drive control device and method, and electric motor drive control system

Abstract

To provide a control device for motor drive, the control device enabling the constitution thereof to be simplified, and to provide a control method for motor drive and a control system for motor drive.SOLUTION: A motor drive control device of the present invention is a device controlling a motor driven by output of an inverter circuit, the device comprising: a selection unit 12 selecting one output candidate from among a plurality of output candidates by using a predetermined evaluation function; and an inverter control unit 13 controlling the inverter circuit in such a way as to output the output candidate selected by the selection unit 12. The evaluation function is a function including: a plurality of terms corresponding to control mode, the plurality of terms corresponding to a plurality of control methods differing from each other, respectively; and a plurality of control method corresponding to weighting coefficients. When switching control method, the selection unit 12 sets a control method corresponding to switched weighting coefficient to be superior to control method corresponding to weighting coefficients corresponding to the remaining control methods.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric motor drive control device and an electric motor drive control method for controlling the drive of an electric motor, and also to an electric motor drive control system including the electric motor drive control device. [Background technology]

[0002] Electric motors are used as power sources in various systems, and their drive is controlled appropriately depending on the application of the system. For example, there is speed control, which controls the speed of the electric motor, and thrust control (torque control), which controls the thrust (output torque) of the electric motor. When transitioning between these control methods, it is common to switch the control method itself, and one example of this is the technology disclosed in Patent Document 1.

[0003] The motor control device disclosed in Patent Document 1 is a motor control device that controls a motor equipped with an encoder, and includes: a position command generation unit that generates a position command, which is a command value for when a mechanical load driven by the motor approaches a pressurized object and the final position of the mechanical load should be a certain distance before the pressurized object; a position control unit that outputs a first speed command so that the position of the motor detected by the encoder follows the position command; a pressure command generation unit that generates a pressure command, which is a command value for pressure or force to be applied to the pressurized object; a pressure control unit that outputs a second speed command so that when the mechanical load is pressed against the pressurized object, the pressure or force detected by the mechanical load follows the pressure command; a speed command selection unit that selects one of a creep speed that defines an upper limit of the speed of the motor when the mechanical load contacts the pressurized object, the first speed command, or the second speed command and outputs it as a speed command at which the motor should operate; and a speed control unit that outputs a current command to supply current to the motor so that the speed of the motor follows the speed command output by the speed command selection unit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6113378 Summary of the Invention [Problem to be solved by the invention]

[0005] The motor control device disclosed in Patent Document 1 has a complex configuration because it includes a plurality of control units for a plurality of different control methods.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide an electric motor drive control device and an electric motor drive control method that can simplify the configuration, and an electric motor drive control system that includes the electric motor drive control device. [Means for solving the problem]

[0007] After extensive investigation, the inventors have found that the above object can be achieved by the present invention as described below. That is, an electric motor drive control device according to one aspect of the present invention is a device for controlling an electric motor driven by the output of an inverter circuit, and includes: a selection unit that selects one output candidate from among a plurality of output candidates using a predetermined evaluation function; and an inverter control unit that controls the inverter circuit so as to output the output candidate selected by the selection unit, wherein the evaluation function is a function including a plurality of control method-corresponding terms and a plurality of control method-corresponding weighting coefficients corresponding to a plurality of mutually different control methods, and when switching the control method, the selection unit sets the control method-corresponding weighting coefficient corresponding to the control method after switching to have priority over the control method-corresponding weighting coefficients corresponding to the remaining control methods.

[0008] Such an electric motor drive control device switches the control method by changing the weighting coefficient of the evaluation function corresponding to the control method, thereby simplifying the configuration of the inverter control unit that controls the inverter circuit that drives the electric motor, and therefore simplifying the configuration of the electric motor drive control device.

[0009] In another aspect, in the above-mentioned electric motor drive control device, the selection unit includes a voltage pattern generation unit that generates a plurality of time-series voltage patterns that are different from one another and that can be output by the inverter circuit as the plurality of output candidates; a prediction unit that predicts, for each of the plurality of time-series voltage patterns generated by the voltage pattern generation unit, a value of a predetermined physical quantity related to a control objective in accordance with the control method of the electric motor as a predicted value when the time-series voltage pattern is input to the electric motor; and a voltage pattern selection unit that selects, from the plurality of time-series voltage patterns generated by the voltage pattern generation unit, a time-series voltage pattern that corresponds to a predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor predicted by the prediction unit as the one output candidate. Preferably, the selection unit includes a voltage pattern generation unit that performs a voltage pattern generation process to generate a plurality of time-series voltage patterns that can be output by the inverter circuit, the plurality of voltage patterns being different from one another, as the plurality of output candidates; a prediction unit that performs a prediction process to predict, for each of the plurality of time-series voltage patterns generated by the voltage pattern generation unit, a value of a predetermined physical quantity related to a control purpose in accordance with the control method of the electric motor as a predicted value when the time-series voltage pattern is input to the electric motor; and a prediction unit that performs a prediction process to predict, from the plurality of time-series voltage patterns generated by the voltage pattern generation unit, a value of a predetermined physical quantity related to a control purpose in accordance with the control method of the electric motor as a predicted value. and a voltage pattern selection unit that performs a voltage pattern selection process to select, as the one output candidate, a time-series voltage pattern that corresponds to the predicted value with the highest evaluation based on the evaluation function, wherein the inverter control unit performs an inverter control process to control the inverter circuit so as to output the output candidate selected by the selection unit, and the motor drive control device further comprises a repetition control unit that causes the voltage pattern generation unit, the prediction unit, the voltage pattern selection unit, and the inverter control unit to repeatedly perform the voltage pattern generation process, the prediction process, the voltage pattern selection process, and the inverter control process at a predetermined control period.

[0010] Such a motor drive control device uses so-called model predictive control, which repeats optimization over a finite time, and can therefore avoid or reduce discontinuous changes in behavior of the motor caused by switching weighting coefficients corresponding to the control method.

[0011] In another aspect, the above-mentioned electric motor drive control device further includes a predetermined tool that moves using the electric motor as a power source, and a position measurement unit that measures the position of a predetermined location on the tool, wherein the plurality of control methods include a first control method that performs control based on a position deviation of the tool or a speed deviation of the electric motor based on the position deviation, and a second control method that performs control based on a torque deviation of the electric motor or a current deviation of the electric motor based on the torque deviation, and the selection unit switches between the first control method and the second control method based on a first comparison result of the position deviation and a predetermined first deviation threshold value with respect to a target position and a second comparison result of the torque deviation or the current deviation and a predetermined second deviation threshold value.

[0012] Such an electric motor drive control device can cause a tool powered by an electric motor to perform, for example, a pasting operation using a first control method, and can cause it to perform, for example, a pushing operation using a second control method, and when switching between these pasting and pushing operations, it can avoid or reduce discontinuous changes in behavior of the electric motor caused by switching the weighting coefficient corresponding to the control method.

[0013] In another aspect, in the above-mentioned motor drive control device, when switching the control method, the selection unit continuously changes the plurality of control method-corresponding weighting coefficients over time, thereby setting the control method-corresponding weighting coefficient corresponding to the control method after switching to be more dominant than the control method-corresponding weighting coefficients corresponding to the remaining control methods.

[0014] When switching the control method, such an electric motor drive control device continuously changes the weighting coefficients corresponding to the plurality of control methods in accordance with time, thereby realizing a smooth transition of the control method.

[0015] Another aspect of the present invention provides an electric motor drive control method for controlling an electric motor driven by the output of an inverter circuit, the method comprising: a selection step for selecting one output candidate from a plurality of output candidates using a predetermined evaluation function; and an inverter control step for controlling the inverter circuit so as to output the output candidate selected in the selection step, wherein the evaluation function is a function including a plurality of control method corresponding terms and a plurality of control method corresponding weighting coefficients corresponding to a plurality of mutually different control methods, and wherein, when switching the control method, the selection step sets the control method corresponding weighting coefficient corresponding to the control method after the switch to have priority over the control method corresponding weighting coefficients corresponding to the remaining control methods.

[0016] Such a motor drive control method switches the control method by changing the weighting coefficient of the evaluation function corresponding to the control method, thereby simplifying the configuration of the inverter control unit that controls the inverter circuit that drives the motor, and therefore simplifying the configuration of the motor drive control device that controls the motor driven by the output of the inverter circuit.

[0017] In another aspect, in the above-mentioned electric motor drive control method, the selection step includes a voltage pattern generation step of generating a plurality of time-series voltage patterns that can be output by the inverter circuit, the time-series voltage patterns being different from one another, as the plurality of output candidates; a prediction step of predicting, for each of the plurality of time-series voltage patterns generated in the voltage pattern generation step, a value of a predetermined physical quantity related to a control objective in accordance with the control method of the electric motor as a predicted value when the time-series voltage pattern is input to the electric motor; and a voltage pattern selection step of selecting, from the plurality of time-series voltage patterns generated in the voltage pattern generation step, a time-series voltage pattern that corresponds to a predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor predicted in the prediction step, as the one output candidate.

[0018] Such a motor drive control method uses so-called model predictive control, which repeats optimization over a finite time, and therefore can avoid or reduce discontinuous changes in behavior of the motor caused by switching weighting coefficients corresponding to the control method.

[0019] In another aspect, the above-mentioned electric motor drive control method further includes a predetermined tool that moves using the electric motor as a power source, and a position measurement unit that measures the position of a predetermined location on the tool, wherein the plurality of control methods include a first control method that performs control based on a position deviation of the tool or a speed deviation of the electric motor based on the position deviation, and a second control method that performs control based on a torque deviation of the electric motor or a current deviation of the electric motor based on the torque deviation, and the selection unit switches between the first control method and the second control method based on a first comparison result of the position deviation and a predetermined first deviation threshold value with respect to a target position and a second comparison result of the torque deviation or the current deviation and a predetermined second deviation threshold value.

[0020] Such an electric motor drive control method can cause a tool powered by an electric motor to perform, for example, a pasting operation using a first control method, and to perform, for example, a pushing operation using a second control method, and when switching between these pasting and pushing operations, it is possible to avoid or reduce discontinuous changes in behavior of the electric motor caused by switching the weighting coefficient corresponding to the control method.

[0021] In another aspect, in the above-mentioned electric motor drive control method, the selection step, when switching the control method, continuously changes the plurality of control method-corresponding weighting coefficients over time, thereby setting the control method-corresponding weighting coefficient corresponding to the control method after switching to be more dominant than the control method-corresponding weighting coefficients corresponding to the remaining control methods.

[0022] In this motor drive control method, when switching the control method, the weighting coefficients corresponding to the plurality of control methods are changed continuously with time, so that a smooth transition of the control method can be realized.

[0023] Another aspect of the present invention provides an electric motor drive control system comprising an electric motor, an inverter circuit for driving the electric motor, and an electric motor drive control unit for controlling the electric motor by controlling the inverter circuit, wherein the electric motor drive control unit is any one of the electric motor drive control devices described above.

[0024] This makes it possible to provide an electric motor drive control system including any one of the above-mentioned electric motor drive control devices. Because such an electric motor drive control system includes any one of the above-mentioned electric motor drive control devices, the configuration can be simplified. [Effects of the Invention]

[0025] The electric motor drive control device and the electric motor drive control method according to the present invention can simplify the configuration, and the present invention can provide an electric motor drive control system including the electric motor drive control device. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a block diagram showing a configuration of an electric motor drive control system according to an embodiment; [Figure 2] FIG. 2 is a block diagram showing a configuration of an MPC control unit in the electric motor drive control system. [Figure 3] FIG. 2 is a circuit diagram showing a configuration of an inverter circuit in the electric motor drive control system. [Figure 4] 10 is a vector diagram showing a voltage that can be output by the inverter circuit. [Figure 5] 4A and 4B are diagrams for explaining an example of a time-series voltage pattern that can be output by the inverter circuit. [Figure 6] 3 is a diagram for explaining an application example of the electric motor drive control system. FIG. [Figure 7] 4 is a flowchart showing an operation of the electric motor drive control system. [Figure 8] 8 is a flowchart showing a process related to a weighting coefficient corresponding to a control method in the application example in the flowchart shown in FIG. 7. [Figure 9] FIG. 8 is a flowchart showing a process relating to a control method corresponding weighting coefficient (processing of the second modified embodiment) in the flowchart shown in FIG. 7 as a second modified embodiment. [Figure 10]10 is a graph showing changes in control method corresponding weighting coefficients in a second modified embodiment. [Figure 11] FIG. 10 is a diagram showing a simulation result as an example. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, components with the same reference numerals in each drawing indicate the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

[0028] Fig. 1 is a block diagram showing the configuration of an electric motor drive control system according to an embodiment. Fig. 2 is a block diagram showing the configuration of an MPC control unit in the electric motor drive control system. Fig. 3 is a circuit diagram showing the configuration of an inverter circuit in the electric motor drive control system. Fig. 4 is a vector diagram showing voltages that can be output by the inverter circuit. Fig. 5 is a diagram for explaining an example of a time-series voltage pattern that can be output by the inverter circuit. Fig. 6 is a diagram for explaining an application example of the electric motor drive control system. Fig. 6A shows the configuration of a pressing device to which the electric motor drive control system is applied, and Fig. 6B shows a time chart of each control method.

[0029] The electric motor drive control system according to the embodiment drives and controls an electric motor, and includes an electric motor drive control device that controls the electric motor driven by the output of an inverter circuit. In this embodiment, the electric motor drive control system S drives and controls the electric motor by vector control using model predictive control. As shown in FIG. 1, the electric motor drive control system S includes, for example, an electric motor M, an inverter circuit IV, a PWM modulator PW, a two-phase to three-phase conversion unit CV1, a model predictive control unit MC, a three-phase to two-phase conversion unit CV2, a current measurement unit CS, and a speed measurement unit VS. The electric motor drive control system S is applied to, for example, a pressing device D shown in FIG. 6, and further includes a proportional control unit PC, a subtraction unit SU, and a position measurement unit PS.

[0030] The electric motor M is connected to the inverter circuit IV and is driven by the AC output of the inverter circuit IV. For example, the electric motor M is a synchronous motor driven by three-phase AC current of U-phase, V-phase, and W-phase output from the inverter circuit IV, and more specifically, in this embodiment, it is a permanent magnet synchronous motor (PMSM). More specifically, in this embodiment, the electric motor M is a linear PMSM, but it may also be a rotary PMSM. However, the electric motor M is not limited to this and may be another type of motor, such as an induction motor (IM) or a switched reluctance motor (SRM).

[0031] In one application example shown in FIG. 6 , an electric motor drive control system S controls an electric motor (here, a linear PMSM) M of a pressing device D as an example of the electric motor M. The pressing device D includes an electric motor M, a pressing tool TL powered by the electric motor M, and a position measurement unit PS that measures the position of a predetermined location (e.g., the tip) of the pressing tool TL. The electric motor M includes a stator ST and a mover RT that moves linearly in a direction extending and retracting relative to the stator ST through electromagnetic interaction. The pressing tool TL is, for example, a cylindrical member and is connected to the mover RT by a plate-shaped connecting support member HS that connects and supports the pressing tool TL to the mover RT of the electric motor M. The tip of the pressing tool TL moves toward and away from the workpiece WK as the mover RT moves via the connecting support member HS. As the mover RT moves toward the workpiece WK, the tip of the pressing tool TL approaches, abuts, and is pressed into the workpiece WK. The position measurement unit PS is, for example, a linear encoder that detects the position (amount of projection) of the mover RT relative to the stator ST, and measures the position of the tip from the detected position of the mover RT and the dimension (length) of the mover RT in the projection / retraction direction. The position measurement unit PS outputs the measured position of the tip to the subtraction unit SU. Note that the position measurement unit PS is not limited to such a linear encoder, and may be any other device as long as it can measure the position of the tip of the pressing tool TL.

[0032] Returning to FIG. 1 , the PWM modulator PW is a circuit that outputs a rectangular wave with a variable pulse width, and the inverter circuit IV is a circuit that converts DC power to AC power. In this embodiment, the PWM modulator PW and the inverter circuit IV constitute a so-called three-phase PWM inverter motor driver that drives an electric motor with three-phase AC power. The PWM modulator PW and the inverter circuit IV are connected to a model predictive controller MC via a two-phase to three-phase converter CV1 and convert DC power from a predetermined DC power source Vdc into AC power with a predetermined frequency under the control of the model predictive controller MC. More specifically, the PWM modulator PW is a circuit that outputs a rectangular wave with a frequency and pulse width under the control of the model predictive controller MC as a control signal (IV control signal) to the inverter circuit IV, as described below. The inverter circuit IV is connected to the PWM modulator PW and converts DC power from the DC power source Vdc into AC power with a predetermined frequency under the control of the IV control signal from the PWM modulator PW. As shown in FIG. 3, the inverter circuit IV includes three pairs of switching elements Tr1, Tr4, Tr2, Tr5, Tr3, and Tr6 connected in parallel, each pair consisting of two switching elements connected in series. More specifically, the inverter circuit IV includes six switching elements Tr1 to Tr6. These first to sixth switching elements Tr1 to Tr6 are power semiconductor elements having an on / off switching function, such as insulated gate bipolar transistors (IGBTs). One terminal (e.g., each collector terminal) of each of the first to third switching elements Tr1 to Tr3 is connected to one terminal of a DC power supply Vdc. The other terminal (e.g., emitter terminal) of the first switching element Tr1 is connected to one terminal (e.g., each collector terminal) of the fourth switching element Tr4. The other terminal (e.g., emitter terminal) of the second switching element Tr2 is connected to one terminal (e.g., each collector terminal) of the fifth switching element Tr5. The other terminal (e.g., emitter terminal) of the third switching element Tr3 is connected to one terminal (e.g., each collector terminal) of the sixth switching element Tr6. The other terminals (e.g., each emitter terminal) of the fourth to sixth switching elements Tr4 to Tr6 are each connected to the other terminal of the DC power supply Vdc.Each control terminal (e.g., gate terminal) of the first through sixth switching elements Tr1-Tr6, to which an IV control signal for turning the switching elements Tr on and off is input, is connected to a PWM modulator PW. Each of the first through sixth switching elements Tr1-Tr6 has a diode D1-D6 connected between its one terminal and its other terminal, with its anode terminal connected to the other terminal. A first connection point connecting the first switching element Tr1 and the fourth switching element Tr4 outputs, for example, a U-phase AC current and is connected to an input terminal connecting the U-phase of the motor M. A second connection point connecting the second switching element Tr2 and the fifth switching element Tr5 outputs, for example, a V-phase AC current and is connected to an input terminal connecting the V-phase of the motor M. A third connection point connecting the third switching element Tr3 and the sixth switching element Tr6 outputs, for example, a W-phase AC current and is connected to an input terminal connecting the W-phase of the motor M. In this configuration, the inverter circuit IV is a so-called two-level three-phase inverter circuit, and one of the switching elements Tr1, Tr2, Tr3 in each set and the other of the switching elements Tr4, Tr5, Tr6 are controlled in accordance with an IV control signal from the PWM modulator PW so as to have mutually opposite switching modes (when one is on, the other is off, and when one is off, the other is on), and converts the DC power of the DC power supply Vdc to output three-phase AC current of U phase, V phase, and W phase to the electric motor M.

[0033] The current measurement unit CS is connected to the three-phase to two-phase conversion unit CV2, measures the currents flowing from the inverter circuit IV to the motor M (in this embodiment, the U-phase current, the V-phase current, and the W-phase current), and outputs each measurement result to the three-phase to two-phase conversion unit CV2. The current measurement unit CS is configured to include, for example, an AC ammeter.

[0034] The speed measurement unit VS is connected to each of the 2-phase to 3-phase conversion unit CV1, the 3-phase to 2-phase conversion unit CV2, and the model predictive control unit MC, and is a device that measures the speed of the mover RT of the electric motor M and outputs the measured speed to each of the 2-phase to 3-phase conversion unit CV1, the 3-phase to 2-phase conversion unit CV2, and the model predictive control unit MC. The speed measurement unit VS determines the speed by time-differentiating the measurement result of the position measurement unit PS. The speed measurement unit VS is not limited to this and may have other configurations, such as a laser Doppler type speed sensor.

[0035] If the electric motor M is a rotary PMSM, a rotation angle measurement unit (not shown) is used instead of the speed measurement unit VS, and the rotation angle measurement unit outputs the rotation angle to the model predictive control unit MC via a rotation speed processing unit (not shown). The rotation angle measurement unit is connected to the two-phase to three-phase conversion unit CV1, the three-phase to two-phase conversion unit CV2, and the rotation speed processing unit, respectively, and is a device that measures the magnetic pole position of the electric motor M in terms of angle and outputs the measurement results (rotation angle, electrical angle (= mechanical angle / number of pole pairs of the electric motor M)) to the two-phase to three-phase conversion unit CV1, the three-phase to two-phase conversion unit CV2, and the rotation speed processing unit, respectively. The rotation angle measurement unit is configured with, for example, a rotary encoder (pulse generator), a Hall IC, etc. In the case of a sensorless system, the rotation angle measurement unit may calculate the rotation angle of the electric motor M from the current and voltage using a model of the electric motor M. The rotational speed processing unit is connected to the model predictive control unit MC, and calculates the rotational speed of the electric motor M from the measurement result (rotation angle) input from the rotational angle measurement unit, and outputs the calculated rotational speed to the model predictive control unit MC. For example, the rotational speed can be calculated by time-differentiating the rotational angle measured by the rotational angle measurement unit and multiplying the result by the reciprocal of the number p of pole pairs of the electric motor M.

[0036] The two-phase to three-phase converter CV1 is connected to the model predictive controller MC and the PWM modulator PWM, and calculates the target voltage v based on the measurement result (speed) input from the speed measurement unit VS and the voltage pattern determined by the model predictive controller MC as described below. d * , v q * From this, the target voltage vd * , v q * The control circuit 10 calculates a control signal (PWM control signal) for controlling the PWM modulator PW so that the target U-phase current, V-phase current, and W-phase current corresponding to the above are output from the inverter circuit IV, and outputs this PWM control signal to the PWM modulator PW.

[0037] The three-phase to two-phase converter CV2 is connected to the model predictive controller MC, and converts the excitation current (d-axis current) i d and torque current (q-axis current) i q and calculate the d-axis current i d and q-axis current i q is output to the model prediction control unit MC.

[0038] The model predictive control unit MC controls the drive of the electric motor M via the PWM modulator PW and the inverter circuit IV by vector control using model predictive control. More specifically, the model predictive control unit MC includes, for example, a control unit 11, a selection unit 12, and an inverter control unit 13, as shown in FIG.

[0039] The control unit 11 controls each part of the electric motor drive control system S in accordance with the function of each part, and controls the electric motor drive control system S as a whole.

[0040] The selection unit 12 selects one output candidate from among a plurality of output candidates using a predetermined evaluation function. The inverter control unit 13 controls the inverter circuit IV so as to output the output candidate selected by the selection unit 12. The evaluation function is a function including a plurality of control method corresponding terms and a plurality of control method corresponding weighting coefficients corresponding to a plurality of different control methods. For example, the evaluation function is a polynomial obtained by multiplying, for each of the plurality of control methods, the control method corresponding term corresponding to the control method by the control method corresponding weighting coefficient and linearly combining the multiplication results. When switching the control method, the selection unit 12 sets the control method corresponding weighting coefficient corresponding to the control method after switching to be more dominant than the control method corresponding weighting coefficients corresponding to the remaining control methods.

[0041] More specifically, the selection unit 12 functionally includes a voltage pattern generation unit 121, a prediction unit 122, and a voltage pattern selection unit 123.

[0042] The voltage pattern generation unit 121 generates a plurality of time-series voltage patterns that can be output by the inverter circuit IV, each of which is different from the other, as the plurality of output candidates. That is, the voltage pattern generation unit 121 performs a voltage pattern generation process to generate a plurality of time-series voltage patterns that can be output by the inverter circuit IV, each of which is different from the other. In this embodiment, the inverter circuit IV is a two-level three-phase inverter as described above, and therefore generates two output candidates as shown in FIG. 4 according to the switching modes of the first to sixth switching elements Tr1 to Tr6. 3= 8 different voltages can be output. Voltage vector V0 is the case when the first through third switching elements Tr1-Tr3 are off, the fourth through sixth switching elements Tr4-Tr6 are on, and no power is supplied to the motor M (V0 = (0, 0, 0)). Voltage vector V7 is the case when the first through third switching elements Tr1-Tr3 are on, the fourth through sixth switching elements Tr4-Tr6 are off, and no power is supplied to the motor M (V7 = (0, 0, 0)). The time-series voltage pattern is determined by the prediction horizon, which is the number of control periods to be predicted, and the control horizon, which is the number of control periods over which the voltage, which is the control input, is variable. For this reason, the model predictive control unit MC is preset with appropriate values ​​for the prediction horizon and the control horizon in accordance with the specifications of the model predictive control, and the voltage pattern generation unit 121 generates a plurality of different time-series voltage patterns according to the voltages (eight in the above example) that can be output by the inverter circuit IV, the values ​​for the prediction horizon, and the values ​​for the control horizon. p is 2 and the control horizon N c All the time-series voltage patterns that can be output by the inverter circuit IV when is 1 are shown in a tree diagram. In Figure 5, for the voltage in the current Nth control, p Since is 2, the voltage in the next (N+1)th control and the voltage in the next (N+2)th control are predicted, and the control horizon N cis 1, all time-series voltage patterns that can be output by the inverter circuit IV are branched from the voltage in the current Nth control to eight voltages V0 to V8 in the next (N+1)th control, and in the next (N+2)th control, each voltage V0 to V8 is maintained at that voltage, resulting in eight sets of time-series voltage patterns. As another example, if the prediction horizon is 2 and the control horizon is 2, the prediction horizon is 2 for the voltage in the current Nth control, so the voltage in the next (N+1)th control and the voltage in the further next (N+2)th control are predicted, and since the control horizon is 2, all time-series voltage patterns that can be output by the inverter circuit IV are branched into eight voltages V0 to V8 in each of the (N+1)th control and the (N+2)th control, resulting in 64 sets of time-series voltage patterns.

[0043] The prediction unit 122 predicts, for each of the multiple time-series voltage patterns generated by the voltage pattern generation unit 121, the value of a predetermined physical quantity related to a control objective in accordance with the control method of the electric motor M as a predicted value when the time-series voltage pattern is input to the electric motor M. That is, the prediction unit 122 performs a prediction process of predicting, for each of the multiple time-series voltage patterns generated by the voltage pattern generation unit 121, the value of a predetermined physical quantity related to a control objective in accordance with the control method of the electric motor M as a predicted value when the time-series voltage pattern is input to the electric motor M. 1 and 6, the control methods in this embodiment include a first control method (position control, speed control) that performs control based on a position deviation of the pressing tool TL or a speed deviation of the electric motor M based on the position deviation, and a second control method (torque control, current control) that performs control based on a torque deviation of the electric motor M or a current deviation of the electric motor M based on the torque deviation. When switching between the first control method and the second control method, the control method weighting coefficient corresponding to the control method after switching is set to have priority over the control method weighting coefficient corresponding to the remaining control method. This allows for a transition of the control method (control mode) (from one control method to the other).

[0044] More specifically, in this embodiment, since position control and torque control are performed, the predetermined physical quantities related to the control objective according to the control method for the electric motor M are the speed and the current. Therefore, the prediction unit 122 predicts the d-axis current i d (k), q-axis current i q (k), velocity v m (k) and d-axis voltage v d From (k), by using the following equation 1, the d-axis current i d P (k+1) and calculate the d-axis current i d (k), q-axis current i q (k), velocity v m (k) and q-axis voltage v q From (k), by using the following equation 2, the q-axis current i q P (k+1) is predicted. The predicted d-axis current i d P (k+1) and q-axis current i q P (k+1), the prediction unit 122 calculates the torque F in the (k+1)th control by using the following equation 3. e P (k+1) and use the following equation 4 to calculate the velocity v in the (k+1)th control. m P Predict (k+1).

[0045]

number

[0046]

number

[0047]

number

[0048]

number

[0049] where i d P (k) is the predicted value of the d-axis current in the kth control, and i q P (k) is the predicted value of the q-axis current in the kth control, and F e P (k) is the predicted value of the torque in the kth control, and v m P (k) is the predicted value of the velocity in the kth control. T s is the control period (sampling interval). R is the winding resistance of the motor M, p is the number of pole pairs in the motor M, Ψ is the flux linkage of the permanent magnet in the motor M, M is the mass of the mover RT in the motor M, D is the kinetic friction resistance of the mover RT in the motor M, and τ is the magnetic pole pitch (distance between magnetic poles) in the motor M. L d is the d-axis inductance, and L q is the q-axis inductance. In this embodiment, since the motor M is a permanent magnet synchronous motor, the following equation 5 is obtained. Note that in the case of the kth control, (k) represents the measured value, and (k+1), (k+2), (k+3), ... represent predicted values.

[0050]

number

[0051] F^ in Equation 4 l (k) is the load torque in the kth control. In Equation 4, ^ is written above F, but for convenience of notation, ^ is written after F here. Load torque F^ lIn (k), the electric motor drive control system S further includes a torque sensor for detecting torque, and currently, in the case of the kth control, the measured value measured by the torque sensor may be used. However, if it is difficult to arrange the torque sensor, for example, the load torque F^ can be calculated by the following equation 6. l (k) is estimated.

[0052]

number

[0053] In the above example, in the current k-th control, the dq-axis current [i dq (k+1), i dq (k+2)] and velocity [v m (k+1), v m (k+2)] is predicted, and each of the eight voltage patterns is determined.

[0054] The voltage pattern selection unit 123 selects, as the one output candidate, a time-series voltage pattern corresponding to the predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor M predicted by the prediction unit 122, from among the multiple time-series voltage patterns generated by the voltage pattern generation unit 121. That is, the voltage pattern selection unit 123 performs a voltage pattern selection process of selecting, as the one output candidate, a time-series voltage pattern corresponding to the predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor M predicted by the prediction unit 122, from among the multiple time-series voltage patterns generated by the voltage pattern generation unit 121.

[0055] As described above, the evaluation function is a function including a plurality of control method corresponding terms corresponding to a plurality of mutually different control methods and a plurality of control method corresponding weighting coefficients. As described above, the plurality of control methods are position control and torque control in this embodiment. Therefore, the plurality of control method corresponding terms are a position error, here, the first term g of the velocity error based on the position error. s (k), and the torque deviation of the electric motor M, that is, the second term of the current deviation, g c(k). The second term g c (k) is the second q term of the current deviation of the q-axis current g cq (k) and the second d term of the current deviation of the d-axis current g cd (k). In this embodiment, the first term g s (k), 2q term g cq (k) and Section 2dg cd (k) When the weighting coefficients corresponding to each control method are a, b, and c, the evaluation function is expressed by a linear combination of these as shown in the following equation 7-1, and the first term g, (k), the second term g cq (k) and Section 2dg cd (k) is expressed by the following equations 7-2, 7-3, and 7-4, respectively.

[0056]

number

[0057] In the case of a permanent magnet synchronous motor, in order to prevent unnecessary power supply, the d-axis current i that does not contribute to torque generation is d Since it is important to keep g at 0, the second d term g cd (k) is defined as in equation 7-4 above.

[0058] v m * (k) is the target speed in the kth control, and may be input to the model predictive control unit MC from the outside, but in this embodiment, it is input to the model predictive control unit MC from the proportional control unit PC.

[0059] More specifically, the subtraction unit SU is connected to the position measurement unit PS and the proportional control unit PC, and calculates the target position X of the tip of the pressing tool TL in the k-th control, which is input from the outside. m * (k) indicates the position X of the tip of the pressing tool TL in the kth control input from the position measurement unit PS. m (k) is subtracted, and the result of the subtraction (=X m * (k)-X m(k), the position deviation of the pressing tool TL) is output to the proportional control unit PC. The proportional control unit PC performs proportional control by multiplying the subtraction result input from the subtraction unit SU by a predetermined gain, and calculates the target speed v in the k-th control. m * The voltage pattern selector 123 generates the target speed v (k) input from the proportional controller PC and outputs it to the model predictive controller MC. m * (k), and the velocity v input from the velocity measurement unit VS m (k) is used to find the first term g in the above equation 7-2. s (k) is calculated. Note that the velocity V of the mover RT m When the velocity of the tip of the pressing tool TL is proportional to the velocity of the tip of the pressing tool TL, the velocity measurement unit VS is omitted and the position X of the tip of the pressing tool TL measured by the position measurement unit PS is m By differentiating with respect to time, the velocity V of the mover RT is m may be sought and used.

[0060] i q * (k) is the target q-axis current in the k-th control, and may be input to the model predictive control unit MC from the outside. In this embodiment, the voltage pattern selection unit 123 of the model predictive control unit MC calculates the target torque F in the k-th control by the following equation 8: e * (k) shows the target q-axis current i in the kth control. q * That is, in this embodiment, the model predictive control unit MC receives the target torque F e * Then, the voltage pattern selection unit 123 selects the target q-axis current i q * (k), and the q-axis current i input from the 3-2 phase conversion unit CV2 q By using (k), the second q term g in the above equation 7-3 cq Find (k).

[0061]

number

[0062] The voltage pattern selection unit 123 selects the d-axis current i d By using (k), the second d term g in the above equation 7-4 cd Find (k).

[0063] When switching the control method, the voltage pattern selection unit 123 sets the weighting coefficient corresponding to the control method after switching to be more important than the weighting coefficient corresponding to the remaining control method. In the example shown in FIGS. 1 and 6, in the case of the first control method in which control is performed based on the position error of the pressing tool TL or the speed error of the linear permanent magnet motor RM based on the position error, the first term g s (k) is the weighting coefficient a for the control method, cq (k) and Section 2dg cd (k) In the case of a second control method in which the weighting coefficients b and c corresponding to each control method are set to have priority and are controlled based on the torque deviation of the linear permanent magnet motor RM or the current deviation of the motor based on the torque deviation, the 2q term g cq (k) and Section 2dg cd (k) The weighting coefficients b and c for each control method are calculated by the first term g s (k) is set to have priority over the control method corresponding weight coefficient a. More specifically, the voltage pattern selection unit 123 switches between the first control method and the second control method based on a first comparison result of the position deviation and a predetermined first deviation threshold value that is appropriately set in advance for the target position, and a second comparison result of the torque deviation or the current deviation and a predetermined second deviation threshold value that is appropriately set in advance. More specifically, as shown in FIG. 6B, for example, the first control method is set to an enableable position X m_sw is set as the first deviation threshold value, and the target position X m * is set appropriately in advance for position X m is valid position X m_sw and the absolute value of the q-axis current deviation |i q* -i q | is the second deviation threshold △i q If it is less than (X m_sw <X m and |i q * -i q |<△i q are both satisfied), the voltage pattern selection unit 123 selects the second q term g cq (k) and paragraph 2d g cd (k) Set the weighting coefficients b and c corresponding to each control method to b0 and c0, and set the first term g s (k) Set the weighting coefficient a corresponding to the control method to 0 (a=0, b=b0, c=c0, b0, c0>0). This results in the second q term g cq (k) and paragraph 2d g cd (k) The weighting coefficients b0 and c0 corresponding to each control method are the first term g s The weighting coefficient corresponding to the control method (k) is set to be more significant than 0, and the motor M is controlled by the second control method (torque control). On the other hand, in the remaining case (X m_sw <X m and |i q * -i q |<△i q does not hold), the voltage pattern selection unit 123 selects the first term g s (k) is set to a0 as the weighting coefficient a for the control method, and the second q term g cq (k) and paragraph 2d g cd (k) Set the weighting coefficients b and c corresponding to each control method to 0 and c0 (a=a0, b=0, c=c0, a0, c0>0). This results in the first term g s The weighting coefficient a0 for the control method in (k) is the 2q term g cq (k) and paragraph 2d g cd (k) The weighting coefficients corresponding to each control method are set to be more significant than 0 and c0, and the motor M is controlled by the first control method (position control).

[0064] The model predictive control unit MC, 2-phase to 3-phase conversion unit CV1, 3-phase to 2-phase conversion unit CV2, subtraction unit SU, and proportional control unit PC can be configured using a microprocessor equipped with a CPU (Central Processing Unit), memory, and its peripheral circuits. The control unit 11, selection unit 12, inverter control unit 13, 2-phase to 3-phase conversion unit CV1, and 3-phase to 2-phase conversion unit CV2 in the model predictive control unit MC are functionally configured in the CPU by executing a predetermined program. The selection unit 12 is functionally configured in the CPU by executing a predetermined program, with a voltage pattern generation unit 121, a prediction unit 122, and a voltage pattern selection unit 123.

[0065] Next, the operation of this embodiment will be described. Fig. 7 is a flowchart showing the operation of the electric motor drive control system. Fig. 8 is a flowchart showing the processing related to the control method corresponding weighting coefficient in the one application example in the flowchart shown in Fig. 7.

[0066] When the power is turned on in such an electric motor drive control system S, the necessary units are initialized and begin operation. Then, for example, by executing a program, the CPU is functionally configured with a model predictive control unit MC, a two-phase to three-phase conversion unit CV1, and a three-phase to two-phase conversion unit CV2; the model predictive control unit MC is functionally configured with a control unit 11, a selection unit 12, and an inverter control unit 13; and the selection unit 12 is functionally configured with a voltage pattern generation unit 121, a prediction unit 122, and a voltage pattern selection unit 123. In the example shown in Fig. 6, the CPU is further functionally configured with a subtraction unit SU and a proportional control unit PC.

[0067] Then, each of the processes S11 to S16 shown in FIG. 7 is repeatedly executed by the control unit 11 at predetermined control intervals until the driving of the electric motor M is stopped.

[0068] 7, first, in this (kth) operation, the current value of each phase measured by the current measurement unit CS is acquired, and the speed value measured by the speed measurement unit VS is acquired (S11). The current measurement unit CS outputs the acquired current value of each phase to the three-phase to two-phase conversion unit CV2, and the speed measurement unit VS outputs the acquired speed to the two-phase to three-phase conversion unit CV1, the three-phase to two-phase conversion unit CV2, and the model predictive control unit MC. Then, in the example shown in FIG. 6, in this process S11, the position measured by the position measurement unit PS is acquired, and the position measurement unit PS outputs the acquired position to the subtraction unit SU.

[0069] Next, the three-phase to two-phase conversion unit CV2 calculates the d-axis current i from the current value and speed of each phase acquired in step S11. d and q-axis current i q and calculate the d-axis current i d and q-axis current i q is output to the model prediction control unit MC (S12).

[0070] Next, the model predictive control unit MC generates multiple time-series voltage patterns that can be output by the inverter circuit IV, each different from the other, using the voltage pattern generation unit 121 of the selection unit 12, depending on the preset prediction horizon value and control horizon value (S13, voltage pattern generation process).

[0071] Next, the model predictive control unit MC uses the predictor 122 of the selector 12 to predict, as a predicted value, the value of a predetermined physical quantity related to the control objective of the electric motor M when the time-series voltage pattern is input to the electric motor M, for each of the multiple time-series voltage patterns generated by the voltage pattern generator 121 in step S13 (S14, prediction process). More specifically, in this embodiment, the predictor 122 calculates the predicted value of the d-axis current i d P The predicted value of the q-axis current i q P The torque F is predicted using the following equation (3): e P The predicted velocity v is calculated using the following equation 4.m P Ask for.

[0072] Next, the model prediction control unit MC selects, by the voltage pattern selection unit 123 of the selection unit 12, from the multiple time-series smoothed voltage patterns generated by the voltage pattern generation unit 121 in process S13, a time-series smoothed voltage pattern corresponding to the predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor M predicted by the prediction unit 1122 in process S14 (S15, voltage pattern selection process).

[0073] In this process S15, first, the subtraction unit SU calculates the target position X m * From the position X obtained by the position measurement unit PS in step S11, m The proportional control unit PC then performs proportional control based on the subtraction result to obtain the target speed v m * is generated and output to the model prediction control unit MC.

[0074] 8, the voltage pattern selection unit 123 first selects the position X acquired by the position measurement unit PS in step S11. m is valid position X m_SW It is determined whether or not the control method corresponding weighting coefficient has been exceeded (S151a). If the result of this determination is that the control method corresponding weighting coefficient has not been exceeded (NO), the voltage pattern selection unit 123 next executes process S154a and terminates the weighting coefficient determination process S151a to S154a for determining the control method corresponding weighting coefficient. On the other hand, if the result of the above determination is that the control method corresponding weighting coefficient has been exceeded (YES), the voltage pattern selection unit 123 next executes process S152a.

[0075] This process S1 5 In 2a, the voltage pattern selection unit 123 selects the absolute value of the q-axis current deviation |i q * -i q | is the second deviation threshold △i qIf the result of this determination is that it is not below (NO), the voltage pattern selection unit 123 next executes process S154a and ends the weighting coefficient determination processes S151a to S154a. On the other hand, if the result of the determination is that it is below (YES), the voltage pattern selection unit 123 next executes process S153a and ends the weighting coefficient determination processes S151a to S154a.

[0076] In this process S153a, the voltage pattern selection unit 123 selects the second q term g cq and 2d term g cd The weighting coefficients b and c corresponding to each control method are set to b0 and c0, and the first term g s The weighting coefficient a corresponding to the control method is set to 0 (a=0, b=b0, c=c0, b0, c0>0).

[0077] In the step S154a, the voltage pattern selection unit 123 selects the first term g s (k) is set to a0 as the weighting coefficient a for the control method, and the second q term g cq (k) and Section 2dg cd (k) Set the weighting coefficients b and c corresponding to each control method to 0 and c0 (a=a0, b=0, c=c0, a0, c0>0).

[0078] Then, the voltage pattern selection unit 123 calculates the first term g in the above equation 7-2. s Calculate the second q term g in the above equation 7-3. cq Calculate the second d term g in the above formula 7-4. cd Find the first term g s , the second q term g cq and 2d term g cd Each of these is multiplied by a, b, and c, respectively, and an evaluation function is generated by linearly combining the results of these multiplications.

[0079] Then, the voltage pattern selection unit 123 executes the voltage pattern selection process by using the generated evaluation function.

[0080] Returning to FIG. 7, the model predictive control unit MC then controls the PWM modulator PW and the inverter circuit IV to drive the motor M based on the time-series voltage pattern selected by the voltage pattern selection unit 123 in process S15 via the inverter control unit 13 (S16, inverter control process).

[0081] In this way, the motor M is controlled and driven by the model predictive control. m is valid position X m_SW and the absolute value of the q-axis current deviation |i q * -i q | is the second deviation threshold △i q The speed control (position control) is performed (position control region) until the speed falls below position X. m is valid position X m_SW and the absolute value of the q-axis current deviation |i q * -i q | is the second deviation threshold △i q When the current is below , torque control (current control) is implemented (thrust control region), and the pushing operation of pushing the pushing tool TL into the workpiece WK is performed. Note that when the pushing tool TL comes into contact with the workpiece WK during speed control, the output thrust increases to maintain the speed, that is, the q-axis current i q rises, and eventually the target q-axis current i q * Therefore, during speed control, the deviation from position X m is valid position X m_SW When the absolute value of the q-axis current deviation |i q * -i q | is the second deviation threshold △i q will fall below.

[0082] In addition, valid position X m_SW is set to a value smaller than the displacement at which the workpiece WK comes into contact, and the target position X m *is preferably set to a value larger than the displacement at which the pressing tool TL comes into contact with the workpiece WK. This ensures that the pressing tool TL is reliably moved until it reaches the workpiece WK, and after contacting the workpiece, it can move to torque control as soon as it approaches the target torque.

[0083] Although the above description has been mainly given of the case where the electric motor M is a linear PMSM, the same description can be given of the case where the electric motor M is a rotary PMSM.

[0084] As described above, the motor drive control system S, motor drive control device, and motor drive control method implemented therein in this embodiment switch control methods by changing the weighting coefficient of the evaluation function corresponding to the control method, so that the configuration of the inverter control unit 13 that controls the inverter circuit IV that drives the motor M can be simplified, and therefore the configuration of the motor drive control system S and the configuration of the motor drive control device can be simplified.

[0085] The above-mentioned motor drive control system S, motor drive control device, and motor drive control method use so-called model predictive control, which repeats optimization over a finite time, and therefore can avoid or reduce discontinuous changes in behavior of the motor M caused by switching the weighting coefficient corresponding to the control method.

[0086] The above-mentioned motor drive control system S, motor drive control device, and motor drive control method can cause a pressing tool TL powered by an electric motor M to perform, for example, a pasting operation using a first control method, and to perform, for example, a pushing operation using a second control method, and when switching between these pasting and pushing operations, it is possible to avoid or reduce discontinuous changes in behavior of the electric motor M caused by switching the weighting coefficient corresponding to the control method.

[0087] According to this embodiment, it is possible to provide an electric motor drive control system S, an electric motor drive control device, and an electric motor drive control method that can simplify the configuration.

[0088] In the above embodiment, the load torque F lAlthough (k) is estimated by the above-mentioned equation 6, a torque sensor (force sensor) for measuring torque may be used in the electric motor drive control system S (first variant). In this case, the target q-axis current i q * For (k), the following equation 9 is used instead of the above equation 8. In this equation 9, in torque control, the target torque F e * and the torque sensor measurement value F e M The torque deviation is calculated by the specified gain K F The torque sensor is provided in the electric motor drive control system S, and the measured value F of the torque sensor is added to the target q-axis current. e M can be fed back.

[0089]

number

[0090] Furthermore, in the above-described embodiment, the control-method-corresponding weighting coefficients are changed discretely when switching control methods. However, they may be changed continuously (gradually) when switching control methods (second modified embodiment). In this case, the selector 12 (selection step) changes the plurality of control-method-corresponding weighting coefficients continuously over time when switching control methods, thereby setting the control-method-corresponding weighting coefficient corresponding to the control method after switching to be more dominant than the control-method-corresponding weighting coefficient corresponding to the remaining control methods. Such an electric motor drive control system S, electric motor drive control device, and electric motor drive control method change the plurality of control-method-corresponding weighting coefficients continuously over time when switching control methods, thereby realizing a smooth transition between control methods.

[0091] Fig. 9 is a flowchart showing the processing related to the control method corresponding weighting coefficient (processing of the second modified embodiment) in the flowchart shown in Fig. 7 as a second modified embodiment. Fig. 10 is a graph showing, as an example, the change in the control method corresponding weighting coefficient in the second modified embodiment. Fig. 10A shows the first term g s The graph shows the weighting coefficient a(k) for the control method (k), where the horizontal axis is the elapsed time and the vertical axis is the first term g s (k) shows the magnitude of the weighting coefficient a(k) for the control method. cq 1 shows a graph of the weighting coefficient b(k) corresponding to the control method (k), the horizontal axis of which is the elapsed time, and the vertical axis of which is the second q term g cq 11A shows the magnitude of the weighting coefficient b(k) corresponding to the control method of (k). The symbols ● and ○ indicate values ​​at each control timing. The symbol ● indicates the case where the first parameter r=0.8, and the symbol ○ indicates the case where the first parameter r=0.2. FIG. 11 is a diagram showing the simulation results for a linear permanent magnet synchronous motor as an example. FIG. 11A shows the weighting coefficient b(k) corresponding to the control method of (k). The symbols ● and ○ indicate values ​​at each control timing. The symbols ● and ○ indicate the case where the first parameter r=0.8, and the symbol ○ indicates the case where the first parameter r=0.2. m The horizontal axis represents the elapsed time, and the vertical axis represents the position X m Figure 11B shows the velocity v m The graph shows the time elapsed on the horizontal axis and the velocity v on the vertical axis. m Fig. 11C shows the d-axis current i d The horizontal axis represents the elapsed time, and the vertical axis represents the d-axis current i d Fig. 11D shows the q-axis current i q 11E shows a graph of the control method, where the horizontal axis represents elapsed time and the vertical axis represents the control method. In FIG. 11E, 0 represents position control and 1 represents torque control (q-axis current control).

[0092] For example, the first term g in the kth control s The weighting coefficient a(k) for the control method (k) is given by Equation 10-1, and the second q term g cq The weighting coefficient b for the control method (k) is given by the following equation 10-2.cd (k) The control method corresponding weight coefficient c is the same as that in the above-described embodiment.

[0093] [Number]

[0094] Here, the first parameter r is a preset constant where 0 < r < 1. The larger this first parameter r is, the gentler the change in the control method corresponding weight coefficient. The second a parameter a set and the second b parameter b set are determined by the weight coefficient determination processes S151b to S154b shown in FIG. 9 instead of the weight coefficient determination processes S151a to S154a shown in FIG. 8 above.

[0095] In FIG. 9, the voltage pattern selection unit 123 first determines whether the position X m acquired by the position measurement unit PS in process S11 exceeds the valid possible position X m_SW (S151b). As a result of this determination, if it has not exceeded (NO), the voltage pattern selection unit 123 then executes process S154b and ends the weight coefficient determination processes S151b to S154b for determining this control method corresponding weight coefficient. On the other hand, as a result of the said determination, if it has exceeded (YES), the voltage pattern selection unit 123 then executes process S152b.

[0096] In this process S152b, the voltage pattern selection unit 123 determines whether the absolute value |i q * - i q | is less than the second deviation threshold value △i q . As a result of this determination, if it is not less than (NO), the voltage pattern selection unit 123 then executes process S154b and ends the said weight coefficient determination processes S151b to S154b. On the other hand, as a result of the said determination, if it is less than (YES), the voltage pattern selection unit 123 then executes process S153b and ends the said weight coefficient determination processes S151b to S154b.

[0097] In this process S153b, the voltage pattern selection unit 123 selects the second q term g cq and 2d term g cd Weighting coefficient b for each control method set , c is set to b0, c0, and the first term g s Control method corresponding weighting coefficient a set Set to 0 (a set =0, b set =b0, c=c0, b0, c0>0).

[0098] In S154b, the voltage pattern selection unit 123 selects the first term g s (k) Control method corresponding weighting coefficient a set is set to a0, and the second q term g cq (k) and paragraph 2d g cd (k) Weighting coefficient b for each control method set , set c to 0, c0 (a set = a0, b set =0, c=c0, a0, c0>0).

[0099] Paragraph 1g s An example of a graph of the weighting coefficient a(k) corresponding to the control method of (k) is shown in FIG. 10A. cq An example of a graph of the weighting coefficient b(k) corresponding to the control method of (k) is shown in Figure 10B. In the example shown in Figure 10, the transition from position control to torque control starts at the fifth control timing, but the first term g s (k) control method corresponding weight coefficient a(k) and 2q term g cq The control method corresponding weighting coefficient b(k) of (k) changes gradually and continuously at each subsequent control timing, and the transition progresses gradually. As can be seen by comparing the cases when the first parameter r is 0.2 (○) and 0.8 (●), the larger the first parameter r, the more gradual the change in the control method corresponding weighting coefficient when the first parameter r is 0.8 (●) than when it is 0.2 (○).

[0100] An example of a simulation is shown in Figure 11. In Figure 11, the control method is switched from position control to torque control (q-axis current control) at time t1. As can be seen from Figure 11, the switching did not cause control instability or significant waveform disturbance, and the switching was successful.

[0101] In order to express the present invention, the present invention has been properly and sufficiently described above through the embodiments with reference to the drawings, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0102] S Electric motor drive control system M electric motor IV Inverter circuit PM PWM Modulator MC model predictive control unit CS current measurement section VS speed measurement section CV1 2-phase to 3-phase converter CV2 3-phase to 2-phase converter PS position measurement section SU subtraction part PC proportional control unit 11 Control section 12 Selection section 13 Inverter control unit 121 Voltage pattern generation unit 122 Prediction Department 123 Voltage pattern selection section

Claims

1. An electric motor drive control device that controls an electric motor driven by an output of an inverter circuit, a selection unit that generates a predetermined evaluation function and selects one output candidate from among a plurality of output candidates using the generated evaluation function; an inverter control unit that controls the inverter circuit so as to output the output candidate selected by the selection unit, the evaluation function is a function including a plurality of control method corresponding terms and a plurality of control method corresponding weighting coefficients corresponding to a plurality of mutually different control methods, when switching the control method, the selection unit sets a control method corresponding weighting coefficient corresponding to the control method after switching to be more dominant than a control method corresponding weighting coefficient corresponding to the remaining control method, and generates the evaluation function. Electric motor drive control device.

2. The selection unit a voltage pattern generation unit that generates a plurality of time-series voltage patterns that can be output by the inverter circuit, the plurality of output candidates being different from one another; a prediction unit that predicts, as a predicted value, a value of a predetermined physical quantity related to a control objective in accordance with the control method of the electric motor when each of a plurality of time-series voltage patterns generated by the voltage pattern generation unit is input to the electric motor; a voltage pattern selection unit that selects, from the plurality of time-series voltage patterns generated by the voltage pattern generation unit, a time-series voltage pattern that corresponds to a predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor predicted by the prediction unit, as the one output candidate. The electric motor drive control device according to claim 1.

3. a predetermined tool that moves using the electric motor as a power source; a position measuring unit for measuring a position of a predetermined point on the tool; the plurality of control methods include a first control method that performs control based on a position deviation of the tool or a speed deviation of the electric motor based on the position deviation, and a second control method that performs control based on a torque deviation of the electric motor or a current deviation of the electric motor based on the torque deviation, the selection unit switches between the first control method and the second control method based on a first comparison result of the position deviation and a predetermined first deviation threshold value relative to the target position and a second comparison result of the torque deviation or the current deviation and a predetermined second deviation threshold value; The electric motor drive control device according to claim 1.

4. when switching the control method, the selection unit continuously changes the plurality of control method corresponding weighting coefficients over time, thereby setting the control method corresponding weighting coefficient corresponding to the control method after switching to be more dominant than the control method corresponding weighting coefficients corresponding to the remaining control methods, and generates the evaluation function. The electric motor drive control device according to claim 1.

5. A motor drive control method for controlling an electric motor driven by an output of an inverter circuit, comprising: a selection step of generating a predetermined evaluation function and selecting one output candidate from among a plurality of output candidates using the generated evaluation function; an inverter control step of controlling the inverter circuit so as to output the output candidate selected in the selection step; the evaluation function is a function including a plurality of control method corresponding terms and a plurality of control method corresponding weighting coefficients corresponding to a plurality of mutually different control methods, In the selection step, when switching the control method, a control method corresponding weighting coefficient corresponding to the control method after switching is set to be more dominant than a control method corresponding weighting coefficient corresponding to the remaining control method, and the evaluation function is generated. Electric motor drive control method.

6. The selection step includes: a voltage pattern generating step of generating a plurality of time-series voltage patterns that can be output by the inverter circuit, the plurality of output candidates being different from one another; a prediction step of predicting, as a predicted value, a value of a predetermined physical quantity related to a control objective of the electric motor in accordance with the control method in a case where each of the plurality of time-series voltage patterns generated in the voltage pattern generation step is input to the electric motor; a voltage pattern selection step of selecting, from the plurality of time-series voltage patterns generated in the voltage pattern generation step, a time-series voltage pattern corresponding to a predicted value with the highest evaluation based on the evaluation function among the predicted values ​​of the electric motor predicted in the prediction step, as the one output candidate.

6. The electric motor drive control method according to claim 5.

7. a predetermined tool that moves using the electric motor as a power source; a position measuring unit for measuring a position of a predetermined point on the tool; the plurality of control methods include a first control method that performs control based on a position deviation of the tool or a speed deviation of the electric motor based on the position deviation, and a second control method that performs control based on a torque deviation of the electric motor or a current deviation of the electric motor based on the torque deviation, the selection step switches between the first control method and the second control method based on a first comparison result of the position deviation and a predetermined first deviation threshold value relative to the target position and a second comparison result of the torque deviation or the current deviation and a predetermined second deviation threshold value; 6. The electric motor drive control method according to claim 5.

8. In the selection step, when switching the control method, the plurality of control method corresponding weighting coefficients are continuously changed over time, so that the control method corresponding weighting coefficient corresponding to the control method after switching is set to be more dominant than the control method corresponding weighting coefficients corresponding to the remaining control methods, thereby generating the evaluation function.

6. The electric motor drive control method according to claim 5.

9. An electric motor, an inverter circuit that drives the electric motor; an electric motor drive control unit that controls the electric motor by controlling the inverter circuit, The electric motor drive control unit is the electric motor drive control device according to any one of claims 1 to 4. Electric motor drive control system.

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