JP2014128081A - Control device, actuator system and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently improve the torque of a stepping motor.SOLUTION: In a control device 20, a speed controller 215 outputs a signal indicating, among others, a desired value It of pulse current within a predetermined multiple of an upper limit value to a field weakening compensator 216. When setting a boost voltage in response to a desired value ωt of rotational speed, a boost command processing section 218 sets a higher boost voltage with increasing desired value ωt, and sets such a boost voltage as can supply a current that is the predetermined multiple of the upper limit value to a stepping motor 32. An overload detection section 219 acquires detection values of current magnitude from a current detector 26 and a current detector 27 to detect an overload condition of the stepping motor 32.

Description

  The present invention relates to a control device, an actuator system, and a control method.

  Industrial robots that contribute to automation of various tasks generally have actuators. This actuator includes, for example, a stepping motor as a drive source. Stepping motors are relatively inexpensive and have the property that torque is large in regions where the rotational speed is low. Therefore, an actuator having a stepping motor is suitable for work that can utilize this property. On the other hand, in the region where the rotational speed is high, the torque of the stepping motor is remarkably reduced due to a strong counter electromotive force (counter electromotive voltage).

  In recent years, techniques for improving the reduction in torque have been proposed (see, for example, Patent Documents 1 and 2). The control device disclosed in Patent Document 1 mitigates the influence of back electromotive force generated in a stepping motor by performing field weakening current control when the motor output of the stepping motor satisfies a predetermined condition.

JP 2004-320847 A

  However, the improvement in torque by the control device disclosed in Patent Document 1 is limited, and the torque decreases in a state where the rotation speed is equal to or higher than a predetermined rotation speed.

  The present invention has been made in view of the above problems, and an object thereof is to efficiently improve the torque of a stepping motor.

In order to achieve the above object, a control device according to the first aspect of the present invention provides:
Drive means for changing a voltage of a drive signal for driving the stepping motor during driving of the stepping motor and outputting the drive signal having a current value larger than a predetermined upper limit value to the stepping motor is provided. It is characterized by that.

  You may make it provide the overload detection means which detects the overload state of the said stepping motor while the said drive signal is output by the said drive means.

  The overload detection means may calculate an estimated value of the temperature of the stepping motor, and determine that the stepping motor is in an overload state when the estimated value of temperature exceeds a predetermined threshold value. .

  The overload detection means may calculate an estimated value of the temperature of the stepping motor based on the current value of the drive signal.

  The drive means may output a drive signal having a voltage value corresponding to any one of a rotation speed of the rotation shaft of the stepping motor and a target value of the rotation speed.

Rotation angle output means for outputting a target rotation angle of the rotation shaft of the stepping motor;
Rotation angle detection means for detecting the rotation angle of the rotation shaft;
Deviation calculating means for calculating a deviation between the target rotation angle and the rotation angle;
Speed calculating means for calculating a target rotational speed of the rotary shaft based on the deviation;
With
The drive unit may output a drive signal defined by at least a current corresponding to the target rotation speed and a voltage corresponding to a rotation state of the rotation shaft to the stepping motor.

  The drive unit may output a drive signal having a voltage corresponding to a target rotation speed of the rotation shaft of the stepping motor.

Comprising a speed detecting means for detecting the rotational speed of the rotary shaft;
The driving unit may output a driving signal having a voltage corresponding to the rotation speed.

  The drive unit may output a drive signal having a voltage corresponding to a target rotation angle of the rotation shaft of the stepping motor.

  The driving means may output a driving signal having a voltage corresponding to the deviation.

  The drive means may change the voltage of the drive signal to a voltage value based on a predetermined condition.

  The drive means may change the voltage of the drive signal to a voltage set in advance according to the rotation state of the rotary shaft.

  The drive unit may change the voltage of the drive signal to a plurality of different voltages.

A discriminating means for discriminating whether a deviation between the rotational speed of the rotary shaft and the target rotational speed is a value indicating a region exceeding a maximum response frequency region of the stepping motor;
Field current control means for performing control to weaken the field current of the drive signal when the determination means determines that the deviation is a value indicating the region;
You may make it provide.

  The driving unit may include a booster circuit, and the voltage of the drive signal may be changed by controlling the booster circuit.

In order to achieve the above object, an actuator system according to a second aspect of the present invention provides:
A stepping motor,
The control device according to any one of claims 1 to 15, which controls the stepping motor;
It is characterized by providing.

In order to achieve the above object, a control method according to a third aspect of the present invention includes:
A driving step of changing a voltage of a driving signal for driving the stepping motor during driving of the stepping motor and outputting the driving signal having a current value larger than a predetermined upper limit value to the stepping motor; It is characterized by that.

  In the driving step, an overload detection step of detecting an overload state of the stepping motor while the drive signal is output may be included.

  In the overload detection step, an estimated value of the temperature of the stepping motor may be calculated, and when the estimated value of the temperature exceeds a predetermined threshold value, it may be determined that the stepping motor is in an overload state. .

  In the overload detection step, an estimated value of the temperature of the stepping motor may be calculated based on the current value of the drive signal.

  In the driving step, a driving signal having a voltage value corresponding to either the rotation speed of the rotation shaft of the stepping motor or a target value of the rotation speed may be output.

A rotation angle output step of outputting a target rotation angle of the rotation shaft of the stepping motor;
A rotation angle detection step of detecting a rotation angle of the rotation shaft;
A deviation calculating step of calculating a deviation between the target rotation angle and the rotation angle;
A speed calculating step for calculating a target rotational speed of the rotating shaft based on the deviation;
Including
In the driving step, a driving signal defined by at least a current corresponding to the target rotation speed and a voltage corresponding to the rotation state of the rotating shaft may be output to the stepping motor.

  In the driving step, a driving signal having a voltage corresponding to a target rotation speed of the rotation shaft of the stepping motor may be output.

A speed detecting step for detecting a rotational speed of the rotary shaft;
In the driving step, a driving signal having a voltage corresponding to the rotation speed may be output.

  In the driving step, a driving signal having a voltage corresponding to a target rotation angle of the rotation shaft of the stepping motor may be output.

  In the driving step, a driving signal having a voltage corresponding to the deviation may be output.

  In the driving step, the voltage of the driving signal may be changed to a voltage value based on a predetermined condition.

  In the driving step, the voltage of the driving signal may be changed to a voltage set in advance according to the rotation state of the rotating shaft.

  In the driving step, the voltage of the driving signal may be changed to a plurality of different voltages.

A determination step of determining whether a deviation between a rotation speed of the rotation shaft and the target rotation speed is a value indicating a region exceeding a maximum response frequency region of the stepping motor;
A field current control step for performing control to weaken a field current of the drive signal when the deviation is determined to be a value indicating the region in the determination step;
May be included.

  In the driving step, the voltage of the driving signal may be changed by controlling a booster circuit.

  According to the present invention, the torque of the stepping motor can be improved efficiently.

It is a figure which shows the external appearance of the actuator system which concerns on embodiment. It is a block diagram which shows the function structure of an actuator system. It is a figure explaining the field weakening current calculated from the target value of a motor output. It is a figure which shows the coordinate transformation from the electric current of a rotating coordinate system to the electric current of a stationary coordinate system. It is a circuit diagram which shows the outline | summary of a booster circuit. It is a flowchart which shows the process which a control apparatus performs. It is a flowchart which shows the current control process by a field weakening compensator and a coordinate converter. It is a flowchart which shows the pressure | voltage rise process by a pressure | voltage rise command process part and a pressure | voltage rise circuit. It is a figure which shows the relationship between the target value of rotational speed, and a motor power supply voltage. It is a flowchart which shows the overload detection process by an overload detection part. It is a figure which shows the temperature transition of a stepping motor. It is a figure which shows the relationship between a rotational speed and a torque. It is a figure which shows the relationship between the target value of rotational speed, and a motor power supply voltage. It is a circuit diagram which shows the outline | summary of the booster circuit which concerns on other embodiment. It is a block diagram which shows the structure of the function of the actuator system which concerns on other embodiment. It is a block diagram which shows the structure of the function of the actuator system which concerns on other embodiment. It is a block diagram which shows the structure of the function of the actuator system which concerns on other embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an overview of an actuator system 10 according to an embodiment. As shown in FIG. 1, the actuator system 10 includes a control device 20, a linear actuator 30, a motor cable 41, and an encoder cable 42.

  The linear actuator 30 includes a housing 31, a stepping motor 32, a ball screw 33, a slider 34, and an encoder 35.

  The housing 31 is a hollow member that protects internal members. A stepping motor 32, a ball screw 33, and an encoder 35 are accommodated in the housing 31.

  The rotation shaft of the stepping motor 32 is connected to the ball screw 33. The stepping motor 32 rotates the ball screw 33 according to the pulse power input from the control device 20 via the motor cable 41. As a result, the slider 34 moves in the X-axis direction. The position of the slider 34 is proportional to the rotation angle of the stepping motor 32. For example, when the slider 34 is at a position closest to the stepping motor 32 as shown in FIG. 1, the rotation angle is 0 °. When the stepping motor rotates from this state and the rotation angle becomes 720 °, the slider 34 moves, for example, by 2 cm in the + X-axis direction.

  The encoder 35 is, for example, a magnetic rotary encoder. The encoder 35 detects the rotation angle and rotation speed of the stepping motor 32. In addition, the encoder 35 outputs a signal indicating the detected value of the rotation angle and the rotation speed to the control device 20 via the encoder cable 42. The encoder 35 is not limited to a magnetic type, and may be an optical type or other type of encoder.

  The controller 20 rotates the stepping motor 32 to a predetermined rotation angle by supplying pulse power to the stepping motor 32. Further, the control device 20 acquires the detected value of the rotation angle and rotation speed of the stepping motor 32 from the encoder 35 via the encoder cable 42.

  Next, functions of the control device 20 will be described with reference to FIG. FIG. 2 shows a functional configuration of the actuator system 10. As shown in FIG. 2, the control device 20 includes a calculation unit 21, a booster circuit 22, current controllers 23 and 24, a PWM inverter 25, and current detectors 26 and 27.

  The calculation unit 21 executes various processes by executing a program using, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a storage device, and the like as resources. The calculation unit 21 includes a position command generation unit 211, a first subtractor 212, a position controller 213, a second subtracter 214, a speed controller 215, a field weakening compensator 216, a coordinate converter 217, and a boost command processing unit 218. And an overload detection unit 219.

  The position command generation unit 211 generates a position command signal indicating the target value θt of the rotation angle of the stepping motor 32 according to the program to be executed. Further, the position command generation unit 211 outputs the generated signal to the first subtractor 212. Note that the position command generation unit 211 may acquire the target value θt from the outside of the calculation unit 21. For example, the position command generation unit 211 may acquire a value input by the user to the control device 20.

  The first subtractor 212 calculates a deviation θd between the rotation angle target value θt output from the position command generator 211 and the rotation angle detection value θ detected by the encoder 35. The first subtractor 212 outputs a signal indicating this deviation θd to the position controller 213.

  The position controller 213 calculates the target value ωt of the rotational speed based on the deviation θd output from the first subtractor 212. The position controller 213 outputs a signal indicating the target value ωt to the second subtractor 214 and the boost command processing unit 218.

  The second subtracter 214 calculates a deviation ωd between the rotational speed target value ωt output from the position controller 213 and the rotational speed detection value ω detected by the encoder 35. The second subtracter 214 outputs a signal indicating this deviation ωd to the speed controller 215.

  The speed controller 215 calculates a target value such as a target value It of the pulse current supplied to the stepping motor 32, a duty ratio, and a pulse period based on the deviation ωd output from the second subtractor 214. The speed controller 215 outputs a signal indicating the calculated target value It or the like to the field weakening compensator 216. At this time, even if the target value It of the pulse current exceeds the predetermined upper limit value (for example, rated current) for the stepping motor 32, the speed controller 215 is a predetermined multiple (for example, 1.5 times) of the upper limit value. ), A signal indicating the target value It of the pulse current is output to the field weakening compensator 216. When the target value It of the pulse current exceeds a predetermined multiple of the upper limit value, the speed controller 215 sets the predetermined multiple of the upper limit value as the target value It of the pulse current, and sets the target value It of the pulse current, etc. Is output to the field weakening compensator 216.

  The field weakening compensator 216 calculates the d-axis current Id and the q-axis current Iq of the rotating coordinate system based on the pulse current target value It output from the speed controller 215. The field weakening compensator 216 calculates the target value Pt of the motor output based on the target value It of the pulse current and the detected value ω of the rotational speed. When the target value Pt satisfies a predetermined condition, the field weakening compensator 216 executes field weakening current control by using the d-axis current Id as the field weakening current. The field weakening compensator 216 outputs signals indicating the currents Id and Iq to the coordinate converter 217.

  Here, field-weakening current control will be described with reference to FIG. The upper part of FIG. 3 is a characteristic diagram showing the relationship between torque τ and rotational speed ω, where the horizontal axis is torque τ and the vertical axis is rotational speed ω. A characteristic La indicated by a one-dot chain line in the figure is a characteristic indicating a maximum response frequency region of the stepping motor 32 when the field weakening current control is not executed. Specifically, the characteristic La is a characteristic when a rated current is applied to a two-phase (A phase, B phase) motor and a full step drive is performed. As indicated by the characteristic La, the torque of the stepping motor 32 is significantly reduced in the region where the rotational speed is high.

  The field weakening compensator 216 sets a field weakening compensation output region in advance. The field weakening compensation output region is a region on the right side of the solid line Lb in FIG. 3 and is a hatched region. The solid line Lb is defined using an inversely proportional curve with a constant motor output. The field weakening compensator 216 executes field weakening current control if the target value Pt of the motor output is within the field weakening compensation output region. On the other hand, if the target value Pt is outside this field weakening compensation output region, the field weakening compensator 216 drives the stepping motor 32 according to the characteristic La originally provided.

  Specifically, the field weakening compensator 216 obtains in advance a motor output constant Pm that defines the solid line Lb. The constant Pm is calculated in advance from the equation Pm = K × ωs × I. Here, K represents a torque constant (Nm / A), ωs represents a boundary rotational speed (rad / sec), and I represents a rated current (A). K, ωs, and I are values inherent to the stepping motor 32. Further, the field weakening compensator 216 calculates the target value Pt of the motor output from the equation Pt = K × ω × It. When the target value Pt exceeds the constant Pm, the field weakening compensator 216 executes field weakening current control. On the other hand, when the target value Pt is equal to or less than the constant Pm, the field weakening compensator 216 does not execute field weakening current control.

  When the field weakening current control is executed, the field weakening compensator 216 calculates the phase φ from the equation φ = cos−1 (Pm / Pt). Further, the field weakening compensator 216 calculates the d-axis current Id based on the formula Id = It × sinφ. Further, the field weakening compensator 216 calculates the q-axis current Iq based on the formula Iq = It × cosφ.

  Here, in order to facilitate understanding, a specific example will be described. For example, when the target value Pt of the motor output is indicated by a point Pb in FIG. 3, since the point Pb is in the field weakening compensation output region, the field weakening compensator 216 executes field weakening current control. The relationship between the currents It, Id, and Iq in this case is shown in the lower part of FIG. Here, the d-axis current Id is a so-called field weakening current. Since the current Id is a negative value as shown in the lower part of FIG. 3, it acts in a direction to cancel the influence of the counter electromotive force.

  Returning to FIG. 2, the coordinate converter 217 converts the currents Id and Iq of the rotating coordinate system output from the field weakening compensator 216 into the currents Iα and Iβ of the stationary coordinate system. A specific example of this conversion is shown in FIG. The coordinate converter 217 outputs signals indicating the currents Iα and Iβ to the current controllers 23 and 24, respectively.

  The boost command processing unit 218 determines whether to boost the motor power supply voltage applied to the stepping motor 32 based on the target value ωt of the rotational speed output from the position controller 213. Further, when boosting, the boost command processing unit 218 determines the voltage value of the motor power supply voltage after boosting (hereinafter referred to as boosted voltage). In this embodiment, the boost command processing unit 218 sets the boost voltage higher as the rotation speed target value ωt is larger, and can supply a current that is a predetermined multiple of the upper limit value to the stepping motor 32. , Set the boost voltage. Then, the boost command processing unit 218 outputs a signal indicating the result of these determinations to the boost circuit 22.

  The booster circuit 22 is a circuit that boosts the control device power supply voltage applied from the outside of the control device 20 to obtain the motor power supply voltage of the stepping motor 32. The control device power supply voltage is, for example, DC 24V. The booster circuit 22 applies a motor power supply voltage to the PWM inverter 25. The booster circuit 22 will be described with reference to FIG.

  FIG. 5 is a circuit diagram showing an outline of the booster circuit 22. As shown in FIG. 5, the booster circuit 22 includes a DC / DC controller 221, a coil L1, a diode D1, a transistor T1, resistors R1, R5, and R6, a boosted voltage adjusting unit 222, and a capacitor C1.

  The DC / DC controller 221, the coil L1, the diode D1, the transistor T1, the resistors R1, R5, and R6, and the capacitor C1 constitute a basic circuit as a circuit that boosts the voltage. Specifically, when the DC / DC controller 221 turns on the gate voltage applied from the output port P2 to the transistor T1, energy is accumulated in the coil L1. Further, when the gate voltage applied to the transistor T1 is turned off, the energy accumulated in the coil L1 is released as a component of the motor power supply voltage. The DC / DC controller 221 boosts the motor power supply voltage to a voltage value higher than the control device power supply voltage by repeatedly turning on and off the gate voltage.

  The DC / DC controller 221 selects whether or not to boost in accordance with the signal CPU1 input from the boost command processing unit 218 to the input port P1. For example, when the voltage applied to the input port P1 is on, the DC / DC controller 221 boosts the motor power supply voltage by repeating on / off of the gate voltage. On the other hand, when the voltage applied to the input port P1 is off, the DC / DC controller 221 does not boost the motor power supply voltage. In this case, the motor power supply voltage is equal to the control device power supply voltage and is 24V.

  Further, when the motor power supply voltage is boosted, the DC / DC controller 221 keeps the voltage at the point Pa acquired through the input port P3 constant by adjusting the on / off timing of the gate voltage. As a result, the boosted voltage is maintained at a predetermined voltage value.

  The boost voltage adjusting unit 222 includes resistors R2 to R4 and transistors T2 to T4. The boost voltage adjusting unit 222 causes the resistors R2 to R4 to conduct in response to the signals CPU2 to CPU4 output from the boost command processing unit 218. For example, when each of the signals CPU2 to CPU4 is on, on, and off, the resistors R2 and R3 are made conductive and the resistor R4 is not made conductive. Thereby, the ratio between the boosted voltage and the voltage at the point Pa changes according to the resistance values of the resistors R2 to R4 and the on / off states of the signals CPU2 to CPU4. Here, since the voltage at the point Pa is constant, the boosted voltage has a voltage value corresponding to the changed ratio. Specifically, the boost voltage adjusting unit 222 boosts the motor power supply voltage in eight ways according to the signals CPU2 to CPU4. Note that the value of the boosted voltage can be arbitrarily set by changing the resistance values of the resistors R2 to R4, R5, and R6.

  Returning to FIG. 2, the current controller 23 outputs a control signal to the PWM inverter 25, thereby setting the current amount of the A-phase signal output from the PWM inverter 25 as the current Iα. Further, the current controller 23 stabilizes the amount of current output from the PWM inverter 25 by acquiring the detected value of the amount of current from the current detector 26. In this embodiment, the resistance value of the current detector 26 is smaller than that when the rated current is the upper limit in order to supply a current equal to or higher than the rated current to the stepping motor 32.

  Similarly to the current controller 23, the current controller 24 acquires the current amount detection value from the current detector 27, thereby maintaining the current amount of the B-phase signal output from the PWM inverter 25 at the current Iβ. In this embodiment, in order to be able to supply a current equal to or higher than the rated current to the stepping motor 32, like the current detector 26, the resistance value of the current detector 27 is smaller than that when the rated current is the upper limit. It has become.

  The PWM inverter 25 outputs A-phase and B-phase pulse signals to the stepping motor 32 as drive signals for driving the stepping motor. The current amounts of the pulse signals of the A phase and the B phase are maintained at the currents Iα and Iβ by the current controllers 23 and 24, respectively. The voltages of the A-phase and B-phase pulse signals are motor power supply voltages supplied from the booster circuit 22.

  The overload detection unit 219 detects the overload state of the stepping motor 32 by acquiring the detection value of the current amount from the current detector 26 and the current detector 27.

  The control device 20 rotates the stepping motor 32 by the above-described components cooperating. Next, processing executed by the control device 20 will be described with reference to FIG.

  First, the position command generation unit 211 generates a position command indicating the target value θt of rotation angle (step S101). Next, the first subtracter 212 calculates a deviation θd between the target value θt of the rotation angle and the detected value θ (step S102). The position controller 213 calculates the target value ωt of the rotation speed based on the deviation θd (step S103). The second subtracter 214 calculates a deviation ωd between the target value ωt of rotation speed and the detected value ω (step S104). The speed controller 215 calculates a target value It of the pulse current based on the rotational speed deviation ωd (step S105).

  Subsequently, the field weakening compensator 216 and the coordinate converter 217 execute a current control process (step S106). This current control process will be described with reference to FIG.

  First, the field weakening compensator 216 acquires the target value It of the pulse current and the detected value ω of the rotational speed (step S111).

  Next, the field weakening compensator 216 calculates the target value Pt of the motor output based on the target value It and the detected value ω of the pulse current (step S112).

  The field weakening compensator 216 determines whether or not the target value Pt is within the field weakening compensation output region by comparing the calculated target value Pt with a preset constant Pm (step S113).

  When it is determined that the target value Pt is within the field weakening compensation output region (step S113; Yes), the field weakening compensator 216 performs field weakening current control. Specifically, the field weakening compensator 216 calculates currents Id and Iq including a field weakening current component. (Step S114).

  On the other hand, when it is not determined that the target value Pt is within the field weakening compensation output region (step S113; No), the field weakening compensator 216 calculates currents Id and Iq that do not include the field weakening current component. (Step S115). Specifically, the field weakening compensator 216 sets the current Id to zero and the current Iq to a current amount equal to the current It.

  Thereafter, the coordinate converter 217 performs coordinate conversion of the currents Id and Iq in the rotating coordinate system to the currents Iα and Iβ in the stationary coordinate system (step S116).

  Returning to FIG. 6, following the current control process in step S106, the boost command processing unit 218 and the booster circuit 22 execute the boost process (step S107). This boosting process will be described with reference to FIG.

  First, the boost command processing unit 218 acquires the target value ωt of the rotational speed from the position controller 213 (step S121).

  Next, the boost command processing unit 218 determines whether or not the target value ωt of the rotation speed is equal to or greater than a predetermined threshold (step S122). The predetermined threshold is, for example, 400 rpm.

  When it is determined that the target value ωt is equal to or greater than the predetermined threshold (step S122; Yes), the boost command processing unit 218 sets the voltage of the signal CPU1 to on (step S123).

  Further, the boost command processing unit 218 calculates a boost voltage corresponding to the target value ωt (step S124). Specifically, as shown in FIG. 9, the boost command processing unit 218 divides a range equal to or higher than a predetermined threshold in a range of rated rotational speeds into a plurality of regions. The rated speed range is, for example, 0 to 1500 rpm. Then, the boost command processing unit 218 calculates a predetermined boost voltage corresponding to the region including the target value ωt. For example, when the target value ωt is in the region of 1000 to 1500 rpm, the boost command processing unit 218 calculates the boost voltage as 41V. When the target value ωt is within the range of 1500 to 2000 rpm, the boost command processing unit 218 calculates the boost voltage as 58V. As shown in FIG. 9, the boost command processing unit 218 equally divides the rotation speed region and sets the boost voltage at equal intervals. However, the boost command processing unit 218 may set the divided region and the boost voltage arbitrarily. Good.

  Thereafter, the boost command processing unit 218 sets the on / off voltages of the signals CPU2 to CPU4 in accordance with the calculated boosted voltage. As a result, the booster circuit 22 boosts the motor power supply voltage to a predetermined voltage (step S125).

  If it is not determined in step S122 that the target value ωt is equal to or greater than the predetermined threshold (step S122; No), the boost command processing unit 218 sets the voltage of the signal CPU1 to off (step S126). In this case, the booster circuit 22 does not boost the motor power supply voltage.

  Returning to FIG. 6, the PWM inverter 25 drives the stepping motor 32 by outputting a drive signal (step S108).

  The overload detection unit 219 detects the overload state of the stepping motor 32 by acquiring the detection value of the current amount from the current detector 26 and the current detector 27 (step S109). This overload state detection process is performed each time the overload detection unit 219 acquires a current amount detection value from the current detector 26 and the current detector 27. The overload state detection process will be described below with reference to FIG.

  First, the overload detection unit 219 acquires a detection value of the current amount from the current detector 26 and the current detector 27 (step S131).

  Next, the overload detection unit 219 calculates an estimated value of the temperature of the stepping motor 32 (step S132). Here, assuming that a constant current is supplied to the stepping motor 32, the transition of the temperature of the stepping motor 32 can be approximated to a first-order lag model as shown in FIG. Actually, the current of the stepping motor 32 changes. For this reason, the overload detection unit 219 performs discrete time calculation. For example, assuming that the temperature at the time of acquiring the current value is Temp [k], the detected value of the current amount of current is I [k], and the temperature at the time of acquiring the current value is Temp [k−1], The temperature at the time of acquiring the current value is calculated by Temp [k] = at · Temp [k−1] + bt · I [k] ^ 2. I [k] is calculated using the detected value Iα of the current amount of the A-phase signal from the current detector 26 and the detected value Iβ of the current amount of the B-phase signal from the current detector 27, and I [k] = Calculated by √ (Iα ^ 2 + Iβ ^ 2). At is an overload zero input response coefficient, and bt is an overload zero state response coefficient.

  Returning to FIG. 10, the overload detection unit 219 determines whether or not the calculated estimated value of the temperature of the stepping motor 32 exceeds a predetermined threshold value (step S133).

  When the estimated value of the temperature of the stepping motor 32 exceeds a predetermined threshold (step S133; Yes), the overload detection unit 219 determines that the stepping motor 32 is in an overload state (step S134). In this case, the control device 20 stops the power supply to the stepping motor 32, for example, by stopping the coordinate converter 217 from outputting signals indicating the currents Iα and Iβ to the current controllers 23 and 24. To do. Further, the control device 20 outputs an alarm by blinking an LED (not shown) or outputting a sound from a speaker (not shown). On the other hand, when the estimated value of the temperature of the stepping motor 32 does not exceed a predetermined threshold value (step S133; No), a series of operations ends.

  As described above, in the present embodiment, the speed controller 215 determines that the pulse current target value It exceeds the upper limit value, but is within a predetermined multiple (for example, 1.5 times) of the upper limit value. Then, a signal indicating the target value It of the pulse current is output to the field weakening compensator 216. Further, when the boost command processing unit 218 sets the boost voltage in accordance with the target value ωt of the rotation speed, the boost voltage is set higher as the target value ωt is larger, and a predetermined upper limit value is set in the stepping motor 32. The boosted voltage is set so that a double current can be supplied. As a result, it is possible to supply a current exceeding the upper limit value to the stepping motor 32. Further, even when the rotation speed of the stepping motor 32 is high, a decrease in torque can be suppressed.

  FIG. 12 is a diagram illustrating the relationship between the rotation speed and the torque. As shown in FIG. 12, when the upper limit value of the supply current for the stepping motor controlled by the control device is 1.2 A and the motor power supply voltage is 24 V, the upper limit value of the supply current for the stepping motor controlled by the control device is 1. .8A, when the motor power supply voltage is 41V, the upper limit value of the supply current to the stepping motor controlled by the control device is 1.8A, and when the motor power supply voltage is 58V, the rotation speed of the stepping motor increases respectively. , Torque decreases.

  On the other hand, the control device 20 of the present embodiment uses the stepping motor 32 having an upper limit value of 1.2 A, but allows the supply of current up to 1.5 times the upper limit value, that is, 1.8 A as the upper limit. As shown in FIG. 9, the motor power supply voltage is increased to 24 V when the rotational speed is 0 to 1000 rpm, 41 V when 1000 to 1500 rpm, and 58 V when 1500 rpm or more, so that the current up to 1.5 times the upper limit can be obtained. It can be supplied. Thereby, as shown in the characteristic of Embodiment 1 of FIG. 12, even if a rotational speed rises, the fall of a torque can be suppressed. For example, when the rotation speed is 1000 to 1500 rpm, the upper limit value of the supply current for the stepping motor controlled by the control device is 1.2 A, and the motor power supply voltage is 24 V, the maximum torque value is 200 to 300 N / m. In this embodiment, as shown in the characteristics of the first embodiment, the maximum value of torque is increased to 400 to 600 N / m by setting the upper limit value of the supply current to 1.8 A and the motor power supply voltage to 41 V. Can do. When the rotational speed is 1500 to 2000 rpm, the upper limit value of the supply current to the stepping motor controlled by the control device is 1.8 A, and the motor power supply voltage is 41 V. However, the maximum torque value is 300 to 400 N / m. In this embodiment, as shown in the characteristics of the first embodiment, the maximum value of the torque is increased to 400 to 600 N / m by setting the upper limit value of the supply current to 1.8 A and the motor power supply voltage to 58 V. Can do.

  In the characteristics of the first embodiment shown in FIG. 12, since the voltage is boosted at the timings of the rotation speeds of 1000 rpm and 1500 rpm, the current changes greatly and the torque further changes. For example, as shown in FIG. As shown in the characteristics of the second embodiment of FIG. 12, by setting many rotation speed timings for boosting between 500 to 1500 rpm and setting a small voltage to increase at each boost, The change in torque can be reduced.

  Furthermore, in the present embodiment, in consideration of supplying a current equal to or higher than the upper limit value to the stepping motor 32, the overload detection unit 219 calculates an estimated value of the temperature of the stepping motor 32, and the estimated value exceeds the threshold value. First, an overload state of the stepping motor 32 is detected. Thereby, the burning of the stepping motor 32 can be prevented.

  Although the embodiment has been described above, the present invention is not limited to the above embodiment. For example, the configuration of the booster circuit 22 is not limited to FIG. FIG. 14 is a circuit diagram showing an outline of a booster circuit 22 according to another embodiment. As shown in FIG. 14, the booster circuit 22 includes a DC / DC controller 221, a coil L1, a diode D1, a transistor T1, resistors R1, R5, and R6, and a capacitor C1. These circuit elements constitute a basic circuit as a booster circuit as in the above embodiment. The DC / DC controller 221 selects whether or not to boost the motor power supply voltage according to the signal CPU1 input from the boost command processing unit 218 to the input port P1. Thereby, the booster circuit 22 boosts the motor power supply voltage in accordance with the rotation speed.

  In the above embodiment, the boost command processing unit 218 determines whether to boost the motor power supply voltage applied to the stepping motor 32 based on the target value ωt of the rotational speed output from the position controller 213. did. However, as illustrated in FIG. 15, the boost command processing unit 218 may acquire the detected value ω of the rotation speed of the stepping motor 32 from the encoder 35. In this case, the boost command processing unit 218 determines to boost if the detected value ω is equal to or greater than a predetermined threshold, and further determines the boost voltage. At this time, as described above, the boost command processing unit 218 sets the boost voltage higher as the detected value ω is larger, and can supply the stepping motor 32 with a current that is a predetermined multiple of the upper limit value. Set the boost voltage. Then, the boost command processing unit 218 outputs a signal indicating the result of these determinations to the boost circuit 22. Thereby, the control apparatus 20 can apply a pulse voltage to the stepping motor 32 according to an actual rotational speed.

  The control device 20 has a mechanism that feeds back a detected value ω of the rotational speed of the stepping motor 32. The feedback mechanism is realized by the feedback control performed by the calculation unit 21 including the boost command processing unit 218, but is not limited thereto. For example, instead of the boost command processing unit 218 in the calculation unit 21, the control device 20 performs feedback control using a boost command processing circuit that is provided outside the calculation unit 21 and includes a discrete circuit (not shown). May be executed. In this case, the processing load on the calculation unit 21 can be suppressed, and as a result, the calculation unit 21 can be configured from an inexpensive CPU or the like.

  Further, as illustrated in FIG. 16, the boost command processing unit 218 may acquire a deviation θd between the target value θt of the rotation angle and the detected value θ from the first subtractor 212. This deviation θd is a physical quantity corresponding to the rotation speed of the stepping motor 32. In this case, if the deviation θd is greater than or equal to a predetermined threshold, the boost command processing unit 218 determines to boost and further determines the boosted voltage. At this time, the boost command processing unit 218 sets the boost voltage so that the greater the deviation θd is, the higher the boost voltage is set, and the stepping motor 32 can be supplied with a current that is a predetermined multiple of the rated current. . Then, the boost command processing unit 218 outputs a signal indicating the result of these determinations to the boost circuit 22. Thereby, the control apparatus 20 can perform a pressure | voltage rise process at higher speed.

  As shown in FIG. 17, a dynamics model generation unit 220 may be provided in the calculation unit 21. The dynamics model generation unit 220 acquires the target value θt of the rotation angle, and generates a mechanical system dynamic model including the stepping motor 32, the ball screw 33, the slider 34, and the like based on the target value θt. In addition, the dynamics model generation unit 220 calculates the rotation speed ωm of the modeled stepping motor. The dynamics model generation unit 220 outputs a signal indicating the rotation speed ωm to the boost command processing unit 218. Note that the generated dynamics model may be a simple model in which only the rotation speed of the stepping motor 32 is modeled.

  The boost command processing unit 218 acquires the modeled rotational speed ωm from the dynamics model generation unit 220. If the rotation speed ωm is equal to or greater than a predetermined threshold value, the boost command processing unit 218 determines that the voltage is boosted and further determines the boost voltage. At this time, the boost command processing unit 218 sets the boost voltage so that the higher the rotation speed ωm, the higher the boost voltage, and the stepping motor 32 can be supplied with a current that is a predetermined multiple of the upper limit value. To do. Then, the boost command processing unit 218 outputs a signal indicating the result of these determinations to the boost circuit 22. Thereby, control device 20 can boost the motor power supply voltage more efficiently. For example, when an accurate prediction model is generated, the boost command processing unit 218 and the booster circuit 22 can boost the voltage to an appropriate voltage while predicting the rotation speed of the stepping motor 32. Further, when a use history of the control device 20 or the linear actuator 30 is acquired and a model is generated, boosting suitable for a device that has deteriorated over time can be executed.

  In the above embodiment, the position command generation unit 211 generates the target value θt of the rotation angle, but may generate a target value of the position of the slider 34 on the X axis instead of the rotation angle. The linear actuator 30 includes a rotary encoder as the encoder 35, but may include a linear encoder that detects the position of the slider 34.

  In the above embodiment, the boost voltage adjustment unit 222 includes the transistors T2 to T4. However, the boost voltage adjustment unit 222 may include four or more transistors. That is, the number of divisions in the range in which the boosting process is executed in the rated range of the rotational speed may be increased. In this case, the boosted voltage can be set more smoothly corresponding to the rotation speed. As a result, more efficient boosting can be realized.

  Further, the boost voltage adjusting unit 222 may include two or less transistors. That is, the number of divisions of the range in which the boosting process is executed in the rated range of the rotational speed may be reduced. In this case, the boost voltage adjusting unit 222 can be configured more simply.

  In the above-described embodiment, the stepping motor 32 is a drive source for the linear actuator 30, but the control device 20 may supply pulse power to a stepping motor provided in another device.

  In the above embodiment, the speed controller 215 calculates the pulse current target value It based on the rotational speed deviation ωd, but calculates the pulse current target value It based only on the rotational speed target value ωt. May be.

  In the above embodiment, the field weakening compensator 216 calculates the target value Pt of the motor output based on the detected value ω of the rotational speed, but may calculate it based on the target value ωt. Specifically, the field weakening compensator 216 may calculate the target value Pt based on the equation Pt = K × ωt × It.

  In the above-described embodiment, the field-weakening compensation output region is defined by the motor output constant Pm, but may be an arbitrary region. Further, as shown in FIG. 3, the field-weakening output region exceeds the maximum response frequency region of the stepping motor 32 and does not overlap the maximum response frequency region, but is not limited thereto. For example, field weakening current control may be efficiently executed by setting the field weakening compensation output region so as to overlap a part of the maximum response frequency region.

  Moreover, the control apparatus 20 may set a motor power supply voltage according to the rotation state also including angular acceleration, for example.

  In addition, in order to facilitate understanding in the above embodiment, the boost command processing unit 218 sets the signals CPU2 to CPU4 after calculating the boosted voltage, but is not limited thereto. For example, the boost command processing unit 218 in the embodiment may directly set on / off of the signals CPU2 to CPU4 from the target value ωt of the rotation speed. In this case, since the process for calculating the boosted voltage is omitted, the boosted voltage can be adjusted at a higher speed.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Actuator system 20 Control apparatus 21 Calculation part 211 Position command generation part 212 1st subtractor 213 Position controller 214 2nd subtractor 215 Speed controller 216 Field weakening compensator 217 Coordinate converter 218 Boost command processing part 219 Overload Detection unit 220 Dynamics model generation unit 22 Booster circuit 221 DC / DC controller 222 Booster voltage regulator 23, 24 Current controller 25 PWM inverter 26, 27 Current detector 28 Booster command processing circuit 30 Linear actuator 31 Housing 32 Stepping motor 33 Ball Screw 34 Slider 35 Encoder 41 Motor cable 42 Encoder cable C1 Capacitor CPU1, CPU2, CPU3, CPU4 Signal D1 Diode Id, Iq, Iα, Iβ Current It Pulse current Target value L1 coil La characteristic Lb solid line P1, P3 input port P2 output port Pa, Pb point Pm constant R1-R6 resistance T1-T4 transistor Th threshold value θ detected value of rotation angle θt target value of rotation angle θd deviation of rotation angle τ Torque φ Phase ω Rotational speed detection value ωt Rotational speed target value ωd Rotational speed deviation ωm Modeled rotational speed

Claims (31)

  Drive means for changing a voltage of a drive signal for driving the stepping motor during driving of the stepping motor and outputting the drive signal having a current value larger than a predetermined upper limit value to the stepping motor is provided. A control device characterized by that.   The control device according to claim 1, further comprising an overload detection unit configured to detect an overload state of the stepping motor while the drive signal is output by the drive unit.   The said overload detection means calculates the estimated value of the temperature of the said stepping motor, and determines that the said stepping motor is in an overload state when the estimated value of the temperature exceeds a predetermined threshold value. Control device.   The control device according to claim 3, wherein the overload detection unit calculates an estimated value of the temperature of the stepping motor based on a current value of the drive signal.   5. The drive unit according to claim 1, wherein the drive unit outputs a drive signal having a voltage value corresponding to any one of a rotation speed of a rotation shaft of the stepping motor and a target value of the rotation speed. The control device according to item 1. Rotation angle output means for outputting a target rotation angle of the rotation shaft of the stepping motor;
Rotation angle detection means for detecting the rotation angle of the rotation shaft;
Deviation calculating means for calculating a deviation between the target rotation angle and the rotation angle;
Speed calculating means for calculating a target rotational speed of the rotary shaft based on the deviation;
With
The driving means outputs a driving signal defined by at least a current corresponding to the target rotation speed and a voltage corresponding to a rotation state of the rotating shaft to the stepping motor. The control device according to any one of 4.   The control device according to claim 6, wherein the driving unit outputs a driving signal having a voltage corresponding to a target rotation speed of a rotation shaft of the stepping motor. Comprising a speed detecting means for detecting the rotational speed of the rotary shaft;
The control device according to claim 6, wherein the driving unit outputs a driving signal having a voltage corresponding to the rotation speed.   The control device according to claim 6, wherein the driving unit outputs a driving signal having a voltage corresponding to a target rotation angle of a rotation shaft of the stepping motor.   The control device according to claim 6, wherein the driving unit outputs a driving signal having a voltage corresponding to the deviation.   The control device according to any one of claims 6 to 10, wherein the driving unit changes the voltage of the driving signal to a voltage value based on a predetermined condition.   The control device according to claim 11, wherein the driving unit changes a voltage of the driving signal to a voltage set in advance according to a rotation state of the rotating shaft.   The control device according to claim 12, wherein the driving unit changes the voltage of the driving signal to a plurality of different voltages. A discriminating means for discriminating whether a deviation between the rotational speed of the rotary shaft and the target rotational speed is a value indicating a region exceeding a maximum response frequency region of the stepping motor;
Field current control means for performing control to weaken the field current of the drive signal when the determination means determines that the deviation is a value indicating the region;
The control apparatus according to claim 6, further comprising:   15. The control device according to claim 1, wherein the driving unit includes a booster circuit, and changes the voltage of the drive signal by controlling the booster circuit. A stepping motor,
The control device according to any one of claims 1 to 15, which controls the stepping motor;
An actuator system comprising:   A driving step of changing a voltage of a driving signal for driving the stepping motor during driving of the stepping motor and outputting the driving signal having a current value larger than a predetermined upper limit value to the stepping motor; A control method characterized by that.   The control method according to claim 17, further comprising an overload detection step of detecting an overload state of the stepping motor while the drive signal is output in the drive step.   19. The overload detection step calculates an estimated value of the temperature of the stepping motor, and determines that the stepping motor is in an overload state when the estimated value of temperature exceeds a predetermined threshold. Control method.   The control method according to claim 19, wherein in the overload detection step, an estimated value of the temperature of the stepping motor is calculated based on a current value of the drive signal.   21. The drive step according to claim 17, wherein a drive signal having a voltage value corresponding to any one of a rotation speed of the rotation shaft of the stepping motor and a target value of the rotation speed is output in the drive step. 2. The control method according to item 1. A rotation angle output step of outputting a target rotation angle of the rotation shaft of the stepping motor;
A rotation angle detection step of detecting a rotation angle of the rotation shaft;
A deviation calculating step of calculating a deviation between the target rotation angle and the rotation angle;
A speed calculating step for calculating a target rotational speed of the rotating shaft based on the deviation;
Including
18. The driving step outputs a drive signal defined by at least a current corresponding to the target rotation speed and a voltage corresponding to a rotation state of the rotating shaft to the stepping motor. The control method according to any one of 20.   23. The control method according to claim 22, wherein in the driving step, a driving signal having a voltage corresponding to a target rotation speed of the rotation shaft of the stepping motor is output. A speed detecting step for detecting a rotational speed of the rotary shaft;
The control method according to claim 22, wherein in the driving step, a driving signal having a voltage corresponding to the rotation speed is output.   23. The control method according to claim 22, wherein in the driving step, a driving signal having a voltage corresponding to a target rotation angle of a rotation shaft of the stepping motor is output.   23. The control method according to claim 22, wherein in the driving step, a driving signal having a voltage corresponding to the deviation is output.   27. The control method according to claim 22, wherein in the driving step, the voltage of the driving signal is changed to a voltage value based on a predetermined condition.   28. The control method according to claim 27, wherein, in the driving step, the voltage of the driving signal is changed to a voltage set in advance according to a rotation state of the rotating shaft.   The control method according to claim 28, wherein in the driving step, the voltage of the driving signal is changed to a plurality of different voltages. A determination step of determining whether a deviation between a rotation speed of the rotation shaft and the target rotation speed is a value indicating a region exceeding a maximum response frequency region of the stepping motor;
A field current control step for performing control to weaken a field current of the drive signal when the deviation is determined to be a value indicating the region in the determination step;
30. The control method according to any one of claims 22 to 29, comprising:   31. The control method according to claim 17, wherein in the driving step, the voltage of the driving signal is changed by controlling a booster circuit.

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