JP2009017740A - Controller of industrial machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of industrial machine driven by a servo-motor capable of checking a maximal voltage and current controllable by an inverter, operating the machine in high efficiency, and more highly improving the operation capability of the machine. <P>SOLUTION: The controller of the industrial machine has an AC motor 1, an inverter 14 for driving the AC motor 1, an electric-energy storage unit 13 to secure energy on operating the machine driven by the AC motor 1, and a controlling unit for controlling the AC motor 1. The controller controls a DC voltage at the side of a DC current in the inverter 14, a torque command or a signal equivalent to the torque command of the AC motor 1, and a reactive current in the current driving the AC motor 1 to zero or a negative level in accordance with its rotational speed of the AC motor 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an industrial machine control apparatus that controls a machine by driving a motor, and more particularly to an industrial machine control apparatus that requires a large torque temporarily during operation.

  There is a press machine as an industrial machine that requires a large motor torque temporarily during operation. In such a press machine, there has been proposed a method in which press working is performed by a servo motor (Patent Document 1). This servo motor driven press machine has an electrical energy storage device that releases the energy required for press processing from the energy storage device, while the charge storage signal is sent to the energy storage device during the entire processing cycle. By gradually accumulating energy from the power supply, the capacity of the power supply equipment is reduced.

Aside from this, a method for controlling the reactive current of the motor in accordance with the DC power supply voltage of the inverter that drives the AC motor (permanent magnet synchronous motor) has been proposed. (Patent Documents 2 to 4).
JP 2004-344946 A JP 2000-228892 A JP 2003-33097 A Japanese Patent Laid-Open No. 2006-20397

Patent Document 1 of the conventional example describes a press machine using an energy storage device, but does not describe how to control a motor in relation to electrical energy stored in the energy storage device. . Patent Documents 2 to 4 describe a method for controlling the reactive current of an AC motor according to a DC voltage. In the industrial machine which is the subject of the present application, the torque during work is larger than the torque during acceleration / deceleration operation, and at this time, a large current flows. In addition, since the drive energy of the motor is supplied from the energy storage device, the output voltage of the storage device also decreases. The above-mentioned document only controls the reactive current according to the power supply voltage, and does not comprehensively control the reactive current according to the DC voltage or the rotational speed in consideration of the motor torque or its equivalent value. For this reason, the maximum voltage and the maximum current that can be controlled by the inverter cannot be taken into account, and since the optimum current does not flow to the motor, the loss may increase and the efficiency may decrease.

  The present invention has been made with respect to the above-mentioned problems, and its object is to consider the maximum voltage and maximum current that can be controlled by the inverter, and to operate with high efficiency and to further increase the working capacity of the machine. An object of the present invention is to provide a servo motor drive type industrial machine control device capable of performing

  The invention according to claim 1 is an AC motor, an inverter that drives the AC motor, an electrical energy storage device that secures energy during operation of a machine that is driven by the AC motor, and a control device for controlling the AC motor. A control device for an industrial machine having a control device, wherein the AC motor is driven according to a DC voltage on the inverter DC side, a torque command of the AC motor or a torque command equivalent signal, and a rotational speed of the AC motor. Control reactive current to zero or negative.

  According to a second aspect of the present invention, in the industrial machine control device according to the first aspect, the AC motor is driven in accordance with a ratio between the DC voltage and the rotational speed and the torque command or a torque command equivalent signal. Control reactive current to zero or negative.

  According to a third aspect of the present invention, in the control device for an industrial machine according to the first or second aspect, the torque command or the torque command equivalent signal is limited according to the DC voltage.

  According to a fourth aspect of the present invention, in the industrial machine control device according to the first to third aspects, the torque command or torque command equivalent signal is an effective current of the AC motor or a signal corresponding thereto.

  The invention of claim 5 is a signal for instructing the reactive current of the AC motor as in the industrial machine control device according to claims 1 to 4, and a signal for instructing the reactive current of the AC motor from another index, And a more appropriate command signal is used as the actual reactive current command.

  The invention of claim 6 controls an AC motor, an inverter that drives the AC motor, an electrical energy storage device that secures energy during operation of a machine driven by the AC motor, and the AC motor. An industrial machine control device having a control device for controlling the reactive current of the AC motor to zero or negative according to an operation pattern of the industrial machine.

  The invention of claim 7 is the industrial machine control device according to any one of claims 1 to 6, wherein the industrial machine is a press machine. The invention of claim 8 is the industrial machine control device according to claims 1 to 6, wherein the industrial machine is an injection molding machine. A ninth aspect of the present invention is the industrial machine control device according to the first to sixth aspects, wherein the industrial machine is a construction machine.

  According to the first aspect of the present invention, operation with less loss can be performed, and the operation range can be expanded by this control, so that the capacity of the machine driven by the motor can be increased. According to the invention of claim 2, in addition to the effect of claim 1, the calculation can be simplified. According to the third aspect of the invention, in addition to the effect of the first or second aspect, a decrease in the DC voltage can be suppressed, so that the entire machine can be operated properly. According to invention of Claim 4, in addition to the effect of Claims 1 thru | or 3, control can be performed easily. According to the invention of claim 5, since it is possible to easily select a control system to be mixed between the control system set by the system of claims 1 to 4 and the control system set by another control index, flexible operation is possible. it can. According to the invention of claim 6, more optimal operation can be performed, and the capacity of the machine can be further increased.

  Furthermore, according to the invention of claim 7, it can be used for a press machine which requires a large motor torque temporarily during operation. According to invention of Claim 8, it can utilize for the injection molding machine which requires a big motor torque temporarily during a driving | operation. According to invention of Claim 9, it can utilize for the construction machine which requires a big motor torque temporarily during driving | operation.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  A press machine driven by an AC motor will be described as an example of an industrial machine that temporarily needs a large motor torque during operation.

  FIG. 1 shows a simplified press machine to which the present invention is applied. Here, the example applied to the crank press as a press machine is shown. A main gear 3 is engaged with a gear 2 connected to the shaft 1S of the AC motor 1, and a crank mechanism (crankshaft 4, connecting rod 5) is connected to the main gear 3. The slide 6 is formed to be movable up and down with respect to the stationary bolster 7 by the crank mechanism. The forward rotation, reverse rotation, and speed of the AC motor 1 are freely controlled by a control device that will be described later, and the crankshaft 4 is freely rotated, so that the slide motion can be set freely and various slides that are freely set It is possible to use by switching the motion, and various workpieces can be processed with slide motion suitable for each processing. As the AC motor 1, a synchronous motor, an induction motor, a reluctance motor, or the like can be used. Here, the AC motor will be described as a permanent magnet synchronous motor.

Since the AC motor 1 is controlled and the slide is freely driven to perform press molding,
a) Noise can be reduced by suppressing the impact speed at the time of molding.
b) During molding, difficult-to-process materials can be easily processed by controlling the speed.
c) Productivity is improved by increasing the speed of the non-molding zone.
It is possible to freely perform driving that brings about such effects.

  FIG. 2 shows a control device for driving the AC motor 1. The AC voltage from the AC power supply 11 is converted into a DC voltage by the rectifier 12. As the rectifier 12, a combination of a diode bridge and a DC / DC converter, a rectifier capable of direct current voltage control, or a four-quadrant converter having the same configuration as an inverter can be used.

  The output DC voltage of the rectifier 12 is supplied to an inverter 14 that is a driver circuit via an electrical energy storage device 13 that electrically stores energy. As the electrical energy storage device 13, a large-capacity electrolytic capacitor, a large-capacity electric double layer capacitor, or a secondary battery is used. The inverter 14 outputs AC of variable voltage and variable frequency to drive the AC motor 1. The rotational position ?? and the rotational speed? Of the AC motor 1 are detected by the encoder 15, the current of the AC motor 1 is detected by the current detector 16, and the DC power supply voltage of the inverter 14 is detected by the voltage detector 17.

  With such a configuration, most of the energy required for the AC motor 1 during the press work is supplied from the electrical energy storage device 13, and a part thereof is supplied from the AC power supply 11 via the rectifier 12. Since the rectifier 12 is composed of a device whose output current and voltage can be controlled, the current value sent from the AC power source 11 to the electrical energy storage device 13 can be controlled to an appropriate value. Therefore, the current maximum value and the maximum power value of the AC power supply 11 can be suppressed, and the power supply capacity can be effectively used.

  The speed control unit 21 operates in accordance with a position command or speed command from a higher-level press machine control unit (not shown) and the rotational position θ or rotational speed ω from the encoder 15, and an effective current as a signal proportional to torque. Iq * is output. The reactive current command calculation unit 22 outputs a reactive current command Id * based on the DC voltage Vdc from the voltage detector 17, the rotational speed ω from the encoder 15, and the active current command Iq * from the speed control unit 21. This operation will be described later.

  The reactive current command Id * from the reactive current command calculation unit 22 is input to the current control unit 23. On the other hand, the effective current command Iq * is also input to the current control unit 23. The current control unit 23 controls the current component detected by the current detector 16 based on the rotational position θ of the encoder 15 by using two current command components. The current control unit 23 is output as a PWM signal for operating the inverter 14. Thus, the inverter 14 is PWM controlled. The operation of the current control unit 23 is known as vector control of a permanent magnet synchronous motor, and detailed operation is omitted here.

Next, the operation principle of the reactive current command calculation unit 22 related to the present invention will be described. The torque T of the permanent magnet synchronous motor is given by the following equation when expressed in various quantities using d and q axis coordinates.
T = P {ΦIq + (Ld−Lq) Id · Iq} (Equation 1)
Here, Id is an ineffective portion of the armature current (d-axis current component), Iq is an effective portion of the armature current (q-axis current component), P is the number of pole pairs, Φ is the flux linkage of the permanent magnet, and Ld is d An axial inductance, Lq, is a q-axis inductance.
On the other hand, if the terminal voltage (phase voltage) E is the electrical rotation angular frequency of the motor ω and the resistance of the motor is ignored,
E = ω√ {(Φ + Ld · Id) ² + (Lq · Iq) ² } (Equation 2)
Can be expressed as

Since the phase voltage cannot exceed the maximum controllable voltage determined by the input DC voltage Vdc of the inverter 14, it is necessary to suppress it below this value. This is performed by reactive current Id control. The maximum phase voltage Emax that the inverter 14 can output is Emax = k · Vdc (Equation 3)
Therefore, Id for keeping the phase voltage at the maximum value is obtained by substituting (Equation 3) into (Equation 2) to obtain (Equation 4).
Id = [√ {(k · Vdc / ω) ² − (Lq · Iq) ² } −Φ] / Ld (Equation 4)
However, from the range of Id ≦ 0 (Equation 4), it can be seen that the reactive current Id is a function of not only the DC voltage Vdc but also the rotational speed ω and the effective current Iq.

  The reactive current command calculation unit 22 calculates the reactive current command Id * based on (Equation 4), that is, from the values of the DC voltage Vdc, the rotational speed ω, and the active current Iq. In this case, since there is a limit on the maximum value of the armature current (the vector sum of the reactive component and the effective component), the reactive current command is calculated so as not to exceed this.

  In these calculations, as can be seen from (Equation 4), among the three parameters, the DC voltage Vdc and the rotational speed ω are given in the form of (Vdc / ω). And the rotation speed ratio (Vdc / ω), and the reactive current Id can be obtained from the effective current Iq. In this way, calculation can be simplified.

  FIG. 3 is an example of the reactive current value calculated from (Equation 4) for keeping the motor phase voltage at the maximum controllable value. It can be seen that the smaller the Vdc, the greater the rotational speed ω, and the greater the effective component Iq, the greater the invalid component Id must be given as a negative value. The range where Vdc / ω is large is Idc = 0. As shown in this figure, since the reactive current is applied only to the place where it is really necessary, there is no wasteful flow of invalidity, and operation with less loss is possible. Further, the voltage and current can be controlled. Furthermore, the rotational speed and torque operation range can be expanded by this control than when this control is not performed, and the ability of the press machine driven by the motor can be enhanced.

  The reactive current command calculation unit 22 does not calculate (Equation 4), but calculates or experimentally obtains a reactive current command pattern for the three parameters in advance and registers it as a pattern in the memory in the control device. Then, it may be configured to read it.

  FIG. 4 shows an example of the press operation characteristics when the reactive current Id is applied in this way. Here, a large capacity capacitor is used as the electrical energy storage device 13. (A) is the rotational speed ω, (b) is the torque T, that is, the effective current Iq, (c) is the input DC voltage Vdc of the inverter 14, that is, the DC voltage of the electrical energy storage device 13, and (d) is invalid. Current Id is shown. Deceleration is started at time t1, and press work is started at the end of deceleration at t2. For this reason, the torque increases rapidly. At this time, since the energy required for the press starts to be taken from the electrical energy storage device 13, the stored energy decreases and the DC voltage Vdc starts decreasing. When the inverter reaches the maximum voltage at which output control is possible at time t3, reactive current Id flows. At time t4, the pressing operation is completed, and the motor only needs acceleration torque. Since the DC voltage is lowered, reactive current flows. The acceleration is completed at time t5, and the torque becomes almost zero. Although the DC voltage is reduced, it is not necessary to generate torque, so in this example, the reactive current supply is unnecessary and the reactive current becomes zero. The value of the reactive current is determined as determined by the above (Equation 4).

  As described above, the reactive current command Id * is output based on the values of the DC voltage Vdc, the rotational speed ω, and the active current Iq, so that the reactive current can flow only when it is really necessary. Since the current is commanded in consideration of the voltage and current that can be controlled by the inverter, the efficiency is improved, and the range of rotation speed and torque that can be controlled by the motor is expanded, so that the press working capacity can be increased.

  As can be seen from the above description, the value of the reactive current is determined by the DC voltage, the rotation speed, and the torque command or the torque command equivalent signal, so that the value of the DC voltage itself, the rotation speed, and the torque itself are individually large. Needless to say, it does not depend on the situation.

  FIG. 5 shows a modification of the present invention. 5, parts having the same part numbers as those in FIG. 2 represent the same parts as in FIG. This modification is different from that of FIG. 2 in the reactive current command method. The speed control unit 21 operates according to the position command or speed command from the upper press machine control unit (not shown) and the rotational position θ or speed ω from the encoder 15 and outputs a torque command signal T *. The torque command signal T * is input to the current command calculation unit 24, and an active current command Iq * and a reactive current command Id * corresponding to the torque command are output. In the current command calculation unit 24, for example, a method of instructing a current component so as to improve efficiency with respect to a torque command, a method of instructing a current component so as to minimize the armature current, or a power factor of the motor A method of instructing to become 1 is conceivable, and is appropriately selected depending on the purpose of use and motor specifications. On the other hand, a reactive current command Id * is also commanded from the reactive current command calculation unit 22. The current command selection unit 25 selects an appropriate one of the reactive current command from the current command calculation unit 24 and the reactive current command from the reactive current command calculation unit 22.

  As an example of a method of selecting a more appropriate one of the reactive current command output from the reactive current command calculation unit 22 and the reactive current command output from the current command calculation unit 24 in the current command selection unit 25, Compare the values and select a value with a larger absolute value. That is, since the reactive current command Id * is negative, a smaller value is selected. In this way, two types of control, such as control corresponding to DC voltage fluctuations and the high-efficiency control, can be automatically selected according to the driving situation. In brief, when the reactive current command from the reactive current command calculation unit 22 is zero, the reactive current command from the current command calculation unit 24 is selected, and when it is not zero, the reactive current command from the reactive current command calculation unit 22 is selected. It is also possible to select a command.

  As described above, when the command absolute value from the reactive current command calculation unit 22 is small, high-efficiency operation can be performed. When the command absolute value from the reactive current command calculation unit 22 increases, the rotational speed and torque correspond to the DC voltage. The operation which keeps up is enabled. As a result, a multipurpose, more optimal and flexible operation is possible according to various operating conditions, a more efficient operation can be performed, and the working capacity of the press machine can be further increased.

  FIG. 6 shows another embodiment of the present invention. 6, parts having the same part numbers as those in FIG. 2 represent the same parts as in FIG. This embodiment is characterized in that a reactive current command Id * is output from the press machine control unit 26 as a pattern. The press machine control unit 26 controls the entire press machine. The press machine control unit 26 outputs a position or speed command to the speed control unit 21 for the servo system, and outputs a reactive current command to the current control unit 23. In the press machine, since the position and speed of the slide 6 are given as the operation pattern, the position and speed of the AC motor 1 can be known. In addition, since the object to be pressed is also known, the required torque can be known, and the energy required for the press can also be known. As a result, the DC voltage fluctuation at the time of pressing can also be known from the capability of the energy storage device 13. Therefore, if the operation pattern is known, it can be analytically or experimentally determined in advance how to command the optimum reactive current. The press machine control unit 26 commands the reactive current thus determined.

  According to this method, since the reactive current command can be given from the operation pattern, the optimum command can be output without causing an operation delay. In addition, when there is a possibility that the fluctuation of the DC voltage that is the output of the electrical energy storage device 13 is different from the prediction due to the fluctuation of the power supply voltage of the AC power supply 11, the DC voltage may be detected as appropriate. Even if it does in this way, it can drive | operate with high efficiency, the work capability of a press machine can be raised more, and a more optimal driving | operation can be performed.

  FIG. 7 shows still another embodiment of the present invention. 7, parts having the same part numbers as those in FIG. 2 represent the same parts as in FIG. According to the above-mentioned embodiment, since a large amount of energy is taken from the electrical energy storage device in a short time during the pressing operation, the terminal voltage gradually decreases. When the voltage drops, the reactive voltage increases accordingly, and further energy is taken, so that the terminal voltage is further lowered. FIG. 7 is characterized in that the effective current is limited in accordance with the terminal voltage of the energy storage device, that is, the DC power supply voltage on the inverter input side, in order to prevent such a voltage drop of the electrical energy storage device. is there. The limiter 27 limits the effective current Iq * according to the DC voltage detection value of the voltage detector 17. The limit value in the limiter 27 is set so that the DC voltage drop is reduced. For example, it may be as follows. The maximum value of the electric power input from the AC power supply 11 to the apparatus is determined according to the capabilities of the power supply facility and the rectifier 12. When the DC voltage drops below a predetermined value, the output of the motor or, if necessary, the motor output including the loss of the converter and the motor becomes equal to the maximum power value from the AC power supply. Set the limit value. The output of the motor can be obtained from the torque command and the rotational speed, or the input side DC voltage and DC current of the inverter 14. In this way, a decrease in DC voltage is suppressed.

  In this way, the amount of energy used is suppressed, so that a voltage drop can be prevented and the entire machine can be operated properly.

  Although the press machine has been described above as an example, it goes without saying that the present invention can be applied to any industrial machine that requires a large motor torque temporarily during operation. In addition to the press machine, examples of such a machine include an injection molding machine and a construction machine driven by a servo motor.

It is a figure which shows an example of the press to which this invention is applied. It is a block diagram of the control apparatus with which this invention is applied. It is a figure which shows the example of the reactive current instruction | command shown in FIG. It is a figure explaining operation | movement of the apparatus shown in FIG. It is a figure which shows the modification of this invention. It is a block diagram of the control apparatus which shows the other Example of this invention. It is a block diagram of the control apparatus which shows the further another Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC motor 12 Rectifier 13 Electric energy storage device 14 Inverter 15 Encoder 16 Current detector 17 Voltage detector 21 Speed control part 22 Reactive current command calculating part 23 Current control part

24 Current command calculation unit 25 Current command selection unit 26 Press machine control unit 27 Limiter

Claims (9)

  An AC motor (1), an inverter (14) for driving the AC motor, an electrical energy storage device (13) for securing energy during operation of a machine driven by the AC motor, and the AC motor are controlled. A control device for an industrial machine having a DC voltage on the inverter DC side, a torque command of the AC motor or a torque command equivalent signal, and a rotational speed of the AC motor. A control device for an industrial machine, wherein the reactive current to be driven is controlled to be zero or negative.   2. The control device for an industrial machine according to claim 1, wherein a reactive current for driving the AC motor is controlled to be zero or negative in accordance with a ratio between the DC voltage and the rotation speed and the torque command or a torque command equivalent signal. A control device for an industrial machine.   3. The industrial machine control device according to claim 1, wherein the torque command or the torque command equivalent signal is limited according to the DC voltage.   4. The industrial machine control device according to claim 1, wherein the torque command or the torque command equivalent signal is an effective current of the AC motor or a signal corresponding thereto.   A signal for instructing the reactive current of the AC motor and a signal for instructing the reactive current of the AC motor from another index as in the industrial machine control device according to claim 1, and more appropriate A control device for an industrial machine, wherein the command signal is an actual reactive current command.   An AC motor (1), an inverter (14) for driving the AC motor, an electrical energy storage device (13) for securing energy during operation of a machine driven by the AC motor, and the AC motor are controlled. A control device for an industrial machine having a control device for controlling the reactive current of the AC motor to be zero or negative according to an operation pattern of the industrial machine.   7. The industrial machine control device according to claim 1, wherein the industrial machine is a press machine.   7. The industrial machine control device according to claim 1, wherein the industrial machine is an injection molding machine. 7. The industrial machine control device according to claim 1, wherein the industrial machine is a construction machine.

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