JP2010260094A - Method and apparatus for controlling servo press device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a servo press device which can realize a size reduction in a power supply converter and an efficiency improvement in a servo press device comprising the power supply converter and an energy accumulating device and, at the same time, can optimize the capacity of the energy accumulating device, and to provide an apparatus using the method. <P>SOLUTION: The servo press device comprises a power supply converter 21, an energy accumulating device 23, an inverter 22, an alternating-current motor 1 driven by an inverter, and a slide variably driven by the alternating-current motor 1. In the servo press device, a control pattern for controlling a charge/discharge state of the energy accumulating device 23 based on an operating pattern of a pressing machine is selected. That is, in a voltage pattern selecting part 211, a voltage pattern that determines a voltage of a direct current bus line of the power supply converter 21 is selected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a control method of a servo press apparatus and an apparatus using the same.

A servo press system has been proposed that includes an energy storage device, reduces the inflow of instantaneous power necessary for a press load from an AC power supply, and reduces the required power equipment of the AC power supply (Patent Document 1).
Also, a servo press system that controls a DC power supply (power converter) in accordance with a press operation pattern has been proposed in order to secure energy by press working (Patent Document 2).

JP 2004-344946 A JP 2007-331023 A

The method of Patent Document 1 is effective in reducing AC power supply facilities. Further, the method of Patent Document 2 makes use of the method of Patent Document 1 and further helps to improve the press capability. However, Patent Document 2 does not specifically show a method of controlling the power converter, and there is a problem that the converter control method corresponding to the press operation is not clear.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the size of the energy storage device, to reduce the size of the power converter and to reduce the loss, and to use the control method of the servo press device. To provide an apparatus.

  The present invention selects the control pattern of the converter according to the press operation pattern, thereby controlling the charge / discharge state of the energy storage device.

The invention of claim 1 includes an AC power source, a power source converter that converts AC from the AC power source into DC, an energy storage device connected to a DC side of the power source converter, and the power source converter. In a servo press apparatus having a motor-side converter connected to a direct current side and a motor driven by the motor-side converter and having a slide driven at a variable speed by the motor, based on a press operation pattern of the press machine A control pattern for controlling a charge / discharge state of the energy storage device is selected.

According to a second aspect of the present invention, in the control method for the servo press device according to the first aspect, the control pattern of the energy storage device is synchronized with the press operation pattern of the press machine. It is.

According to a third aspect of the present invention, in the control method of the servo press device according to the second aspect, the synchronization of the control pattern with the press operation pattern is a temporal synchronization with the press operation pattern, a synchronization with the crank angle, or The control method of the servo press device is characterized by being synchronized with these corresponding signals.

According to a fourth aspect of the present invention, in the control method of the servo press apparatus according to the first to third aspects, the control pattern of the energy storage device is a drive pattern of the power converter or a bidirectional converter connected to the energy storage device. There is a control method of a servo press device.

According to a fifth aspect of the present invention, in the method for controlling a servo press apparatus according to the fourth aspect, the drive pattern is a voltage command or / and a current command for a power converter or bidirectional converter. It is.

According to a sixth aspect of the present invention, in the control method of the servo press device according to the first to fifth aspects, the control pattern includes a conversion capacity of a power converter or a bidirectional converter, a storage capacity of an energy storage device, a press load pattern, a press speed pattern A control method of a servo press device characterized in that a set value of a control pattern and a change point of the set value are calculated before operation or obtained by simulation and registered.

A seventh aspect of the present invention is a servo press control device including the control method according to the first to sixth aspects.

According to the invention of claim 1, since the control pattern for controlling the charge / discharge state of the energy storage device is selected based on the press operation pattern,
The energy storage device can be miniaturized, and the power converter can be miniaturized and loss can be reduced.

According to the invention of claim 2, since the energy storage state of the energy storage device is controlled in synchronization with the press operation pattern, the energy storage device can be reliably downsized, the power converter can be downsized and the loss can be reduced. be able to.

According to the invention of claim 3, since the synchronization is set to time or a slide angle, the invention of claim 2 can be easily realized.

According to the invention of claim 4, since the power converter or the bidirectional converter is controlled, the control of claim 1 can be realized without adding a new device.

According to the invention of claim 5, since the control pattern of any of the converters is a voltage command or / and a current command, the converter can be reliably operated.

According to the sixth aspect of the present invention, the setting value and the change point of the command pattern can be specifically determined, so that the effect can be further effective.

According to the seventh aspect of the present invention, a servo press apparatus having the effects described in the first to sixth aspects can be realized.

It is a structural example of the apparatus with which this invention is applied. It is embodiment of the control apparatus with which this invention is applied. It is an example of operation | movement of the control system of FIG. It is another example of operation | movement of the control system of FIG. It is another operation example of the control system of FIG. It is other embodiment of the control apparatus with which this invention is applied. It is another embodiment of the control apparatus to which the present invention is applied. It is another embodiment of the control apparatus with which this invention is applied. FIG. 9 is an operation example of the control method of FIG. 8. FIG.

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

FIG. 1 shows a servo press machine simply expressed as an example 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 crank mechanism is formed so that the slide 6 can be moved up and down with respect to the stationary bolster 7.

Since the crankshaft 4 is freely rotationally driven by forward rotation, reverse rotation and variable speed control of the AC motor 1, not only the crank mechanism but also other mechanisms such as a slide motion, a slide motion suitable for a molded body including stationary, or Various slide motions such as forward and reverse pendulum motions can be freely set, and switching between these can be used. For this reason, the precision, productivity, and adaptability with respect to a press-molded body can be expanded.

As the AC motor 1, a synchronous motor using a permanent magnet, an induction motor, a reluctance motor, or the like can be used. Further, a DC motor may be used instead of an AC motor. Here, the AC motor 1 will be described as a permanent magnet synchronous motor. Further, FIG. 1 shows a crank press as an example, but a press machine having another structure, for example, a structure using a ball screw or a structure using a linear motor may be used.

(First embodiment)
FIG. 2 shows an embodiment of an apparatus for controlling the servo press machine of FIG.
AC power from the AC power supply 20 is input to the power converter 21. The power converter 21 bidirectionally converts alternating current into direct current or direct current into alternating current. The DC bus 31 on the DC side of the power converter 21 is connected to the DC side of the inverter 22 and to the energy storage device 23. As the energy storage device 23, a secondary battery, a large capacity electrolytic capacitor, an electric double layer capacitor, or a combination thereof is used.

The illustrated energy storage device 23 is directly connected to the DC bus 31, but if the terminal voltage of the energy storage device 23 and the voltage of the DC bus 31 are different, a DC / DC converter capable of bidirectional power control is used. Both may be connected (detailed in FIG. 7 of the third embodiment). The AC side of the inverter 22 is connected to the AC motor 1. In addition, although a reactor etc. are connected to the alternating current power supply 20 side of the power converter 21, it is abbreviate | omitting in FIG.

The rotational speed and rotational position of the AC motor 1 are detected by the encoder 24. A command for the rotational speed of the motor is issued from the motion command unit 205. The position / speed / current control unit 206 operates in accordance with the position / speed command from the motion command unit 205 and the feedback signal from the encoder 24 and the current detector 207, and performs rotational position control, speed control, and current control of the AC motor 1. The inverter 22 is PWM controlled via the PWM control unit 208.

Since this control is well known as position / speed / current control of the permanent magnet synchronous motor, detailed description thereof is omitted. Further, although this example will be described hereinafter assuming that a speed command is issued from the motion command unit 205, there are cases where a rotational position command is issued from the motion command unit 205 or a torque command, that is, a current command is issued.

A signal from the motion command unit 205 is output as follows. That is, the press operation pattern unit 203 performs the press operation based on the operation method selection unit 201 such as continuous operation, safe one-step operation, inching operation, and manual pulse generator operation and the operation input unit 202 of the molding condition and operation speed input unit. A pattern is decided. When an operation start signal is output from the operation command unit 204, the motion selected by the press operation pattern unit 203 is output from the motion command unit 205 as a function of time or a function of slide angle. The operation pattern can be set as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-192467.

On the other hand, the press operation pattern selected by the press operation pattern unit 203 is input to the voltage pattern selection unit 211, and a voltage pattern for controlling the DC voltage of the DC bus 31 is selected based on the press operation pattern. The voltage command selected by the voltage pattern selection unit 211 is output from the voltage command unit 212 as a time function in synchronization with the motion command of the motion command unit 205 by the operation start signal from the operation command unit 204.

From voltage command unit 212, a signal for operating power supply converter 21 is output to voltage / current control unit 213. The voltage / current control unit 213 receives the voltage command from the voltage command unit 212 and the feedback signal from the voltage detector 214 and the current detector 215 for detecting the voltage of the DC bus 31 to control the voltage and current of the power converter 21. The control is performed and the PWM control unit 216 is controlled. Thus, the power converter 21 is PWM-controlled.

Power supply converter 21 also detects an AC voltage in order to synchronize the current of AC power supply 20 with the voltage phase. When this configuration is used, the power source current can be controlled to be a sine wave and a power factor of 1. Needless to say, not only the power factor is controlled to power factor = 1 but also control other than power factor = 1 can be performed by using ineffective control together.

Further, the current value may be detected from the AC side of the power converter 21 as shown in FIG. 2 or may be detected from the DC side of the power converter 21. Furthermore, the illustrated power converter 21 can perform not only the power running operation that receives power from the AC power source 20 but also the regenerative operation that returns power to the AC power source 20. However, when the regenerative power returned from the AC motor 1 is small, only the power running operation is performed. Possible circuit configurations, for example, diode rectifiers and DC / DC converters.

In the embodiment of FIG. 2, the voltage pattern is selected in correspondence with the operation pattern, the storage state of the energy storage device 23 is given as the voltage command of the power converter 21, and this is controlled in synchronization with the motion command of the press operation pattern. There is a special feature. That is, charge / discharge control of the energy storage device 23 is selected as a voltage pattern, and is implemented as voltage control of the power converter 21.

As described above, the energy storage device 23 is a secondary battery, a large capacity electrolytic capacitor, an electric double layer capacitor, or a combination thereof. This embodiment is particularly effective when a large-capacity capacitor such as a large-capacity electrolytic capacitor or an electric double layer capacitor, which is an energy storage device in which the energy storage amount is greatly related to the DC voltage, is used alone or in combination.

The voltage setting value and the voltage pattern for changing the setting value can be set as follows. From the slide press operation pattern including the press load and acceleration / deceleration, the required motor power is known in advance. Also, based on the conversion capacity of the power converter 21 and the capacity of the energy storage device 23, it is possible to calculate in advance what kind of value the voltage setting value is to be used and at what point the voltage setting value should be changed. It can be grasped by simulation.

From this result, the voltage change point is determined as a pattern in advance according to the form of the voltage pattern, that is, the voltage value and the elapsed time from the start of operation or top dead center, and the power converter 21 is selected with the voltage pattern selected along with the start of operation. Is controlled to control charging / discharging of the energy storage device 23. Since the load operation status can be predicted by the operation pattern, the optimal voltage pattern manages the state of the energy storage device, and the capacity of the energy storage device with respect to the system capacity, that is, the power and energy required by the load, Make settings to maximize the capacity of the power converter.

In other words, by selecting the optimum voltage pattern according to the operation pattern, the capacity of the energy storage device and the capacity of the power converter can be reduced, and the system capacity can be minimized. The voltage pattern may be set at the time of trial pressing of the press, or the voltage pattern set by the calculation or the like may be confirmed and corrected.

In this way, an optimum voltage pattern corresponding to the press operation pattern is obtained and registered in advance. If the operation pattern is determined as described above, a voltage pattern corresponding to the operation pattern can be selected. In this description, the single operation of the press device is described, but the same applies to the case where a plurality of presses are automatically operated, and the press operation pattern may be given from a higher order command system.
Hereinafter, some voltage pattern examples selected for several operation patterns will be shown and their operations will be described.

Example 1
Next, an example of the operation of the drive device shown in FIG. 2 will be described.
FIG. 3 is a diagram for explaining this operation. In FIG. 3, (a) is an operation pattern of a press, that is, a servo motor speed command (= actual rotation speed), (b) is a required torque of the motor, and (c) is a motor input necessary for performing this operation. (D) shows the DC voltage command pattern (solid line) and actual DC voltage (broken line) of the DC bus, and (e) shows the input power (solid line) of the power converter and the output power (broken line) of the energy storage device.

The work on the servo press machine is basically the same load when pressing the same parts with the same mold and working with the same productivity. In the example shown, the operation pattern from t31 to t37 is repeated. . Here, acceleration is from t31 to t32, constant speed from t32 to t35, and during this time, a press load is applied from t33 to t34, and further, deceleration from t35 to t36, and stop waiting from t36 to t37. As will be described later, the voltage command value of the voltage command pattern is changed at t306 and t311.

The voltage setting value and the time point when the setting value is changed can be set as follows. The driving method of the slide, that is, the motor speed and acceleration / deceleration are set in advance. The point of time when the press load is applied can be grasped from the mold shape, the operation method, and the like, and the acceleration / deceleration torque can be understood from the mold information and motor speed change such as acceleration / deceleration of the slide. From these, the required torque of the motor is known. From these operation patterns, the required motor power is known in advance.

This required motor power is supplied from the power converter and the energy storage device. What is the voltage setting value based on the conversion capacity of the power converter and the capacity of the energy storage device, and at what point the voltage setting If the value is changed, it is possible to grasp in advance by calculation or simulation whether the vehicle can be operated optimally. From this result, a voltage value is set, a change point is set in advance in synchronization with the press operation pattern, and the voltage set value is changed when the time or a value corresponding thereto is reached during operation. The voltage setting value and its changes may be confirmed and corrected at the time of trial press.

In the voltage pattern of FIG. 3 (d), since energy is required for acceleration and press load, the voltage command is set high, that is, set to increase the energy stored in the energy storage device, and in preparation for deceleration regenerative energy processing. The voltage command is previously set low, that is, set to reduce the stored energy of the energy storage device. When the operation pattern including the press load is determined in this way, the voltage pattern can be set.

Next, the operation of FIG. 3 will be described.
As shown in (a), the motor starts at t31, accelerates at a predetermined acceleration until t32, and operates at a predetermined speed from t32 to t35. During this time, a press work load is applied from t33 to t34. Consider a motion that decelerates at t35, reaches zero speed at t36, stops at t37, and completes the operation. The required torque of the motor requires acceleration torque from t31 to t32, load torque from t33 to t34, and deceleration torque from t35 to t36, as shown in (b). Since the motor input power is given by the number of revolutions × torque, power as shown in (c) is required. The motor input power in (c) is supplied as the sum of the power converter input power (solid line) and the energy storage device output power (broken line) as shown in (e).

As can be seen from (e) at time t31, the direct-current voltage command and the direct-current voltage are equal, so that necessary power is first supplied from the power supply converter as the motor accelerates. At t301, the input of the power converter becomes maximum, and no more power can be supplied. Therefore, the power necessary for the motor is supplied from the energy storage device in addition to the power converter. For this reason, the DC voltage decreases as indicated by the broken line (d). When the required motor power becomes zero at t302 (= t32), the power to compensate for the DC voltage drop is supplied from the power source, and becomes equal to the voltage command at t303, and the power converter input becomes zero.

Next, at t304 (= t33), a press load is applied, and the power converter operates at the maximum input. In this example, since the required power of the motor is insufficient only by the power supplied from the power converter, it is also supplied from the energy storage device. For this reason, the DC voltage continues to decrease until t305 (= t34) when the press load ends. Since the press load disappears at t305, the power from the power converter is supplied to the energy storage device, and the DC voltage increases after t305.

Further, at t306, the voltage command is changed as shown in the figure. When the DC voltage reaches the changed voltage command at t307, the power converter input becomes zero. When deceleration is started at time t308 (= t35), both the power converter and the energy storage device absorb the regenerative energy from the motor. For this reason, the DC voltage increases from the voltage command.

At t309, the regenerative power from the power converter exceeds the regenerative power from the motor, so that the energy storage device regenerates energy from the power converter to the power source to reduce the voltage increase from the voltage command. At t310, the DC voltage becomes equal to the voltage command, and then the motor regenerative power is regenerated from the power converter to the power source.

At time t311, when the voltage command is changed, the power converter takes power from the power source with the maximum input and supplies power to the energy storage device. The energy storage device receives the regenerative energy from the motor and the supply energy from the power source, the DC voltage rises, the voltage command and the DC voltage become equal at time t312, and the power converter input becomes zero. Thereafter, the DC voltage is maintained at the voltage command value.

As in the example shown in the figure, the power running voltage is lowered during operation to maintain this voltage, so that the absorption capacity of the energy storage device is increased when regenerative power is received from the motor. For this reason, the storage capability of the energy storage device can be utilized effectively. Since the operation pattern including the press load is known, a voltage pattern suitable for this can be selected. Since the voltage pattern is appropriate, the power supply system can be optimally operated, and the conversion capacity of the power converter and the storage capacity of the energy storage device can be used effectively.

  Note that the voltage command in the figure is issued every time according to the time, but it is also possible to give a voltage command by outputting a signal only when the voltage command is changed and the command value is changed. Moreover, although the change of a voltage value is 2 values in this example, it is good also as a multi-value more than 3 values. Furthermore, the voltage value may be changed at multiple locations and may be changed continuously. In this example, since the operation loss of each part is small and has been described ignoring this, the pattern is actually set in consideration of the loss. The subsequent voltage patterns are the same.

(Example 2)
This is a pattern without changing the voltage command value.
3 (f) and 3 (g) show examples in which the voltage pattern is different from the same operation pattern as in FIGS. 3 (a) to 3 (c). 3 (f) corresponds to (d), and FIG. 3 (g) corresponds to (e). As shown by the solid line in FIG. 3 (f), the voltage command value is not changed and given a constant value. Therefore, the operation is slightly different from that in FIG. 3D, and the DC voltage exceeds the voltage command value at t308 to t310, particularly at t309.

If there is a margin in the storage capacity of the energy storage device or the conversion capacity of the power converter, or if the operating speed is not high and voltage increase during deceleration is not a problem, or if the regenerative power of the motor is small, such constant It is also possible to determine the voltage command value and select the operation pattern. Since the operation pattern can be grasped in advance, a pattern in which the voltage command value does not change during operation can be determined.

(Example 3)
The power command and regenerative voltage command values are different patterns.
FIG. 4 shows another example of the operation pattern of the present invention. Unlike the previous example, the method of giving the voltage pattern gives the commands for the regenerative voltage and the power running voltage separately.
The regenerative voltage Vr and the power running voltage Vm are set as control targets for the DC voltage of the DC bus 31, and Vr> Vm is set. The power converter 21 performs a regenerative operation for returning power to the AC power source 20 with Vr as a target value when the DC voltage of the DC bus 31 increases to the regenerative voltage Vr or more, and when the DC voltage becomes less than the regenerative voltage Vr, the regenerative operation is performed. Stop operation.

Further, the power converter 21 performs a power running operation in which power is taken from the AC power source 20 with Vm as a target value when the DC voltage decreases to the power running voltage Vm or less, and when the DC voltage Vd exceeds the power running voltage Vm, the power running operation is performed. Stop. In this way, the power converter is not operated constantly, but is operated as necessary. Note that the operation start and operation stop may be determined by providing a slight hysteresis with respect to the voltage.

FIG. 4A shows an operation pattern of the press, that is, a servo motor speed command (= actual rotational speed). Although the required motor torque and the motor input power are not shown, they are the same as those shown in FIGS. (D) is the power running voltage command value Vm (solid line), regenerative voltage command value Vr (dashed line), and actual DC voltage (dashed line), and (e) is the input power (solid line) and energy storage of the power converter. The output power of the device (broken line) is shown. Similar to FIG. 3, the pattern from t41 to t47 is repeated.

Next, (d) and (e) of the operation of FIG. 4 will be described from the difference from FIG.
Since the power converter is stopped at time t41, the motor input power in (c) is supplied from the energy storage device. For this reason, the DC voltage decreases as shown in (d). When the power running voltage Vm is reached at t401, the power converter starts operating (power running starts), and the required motor power is not supplied from the energy storage device but supplied from the power converter.

The power converter operates so that this voltage is maintained until time t42 when the acceleration of the motor ends. However, since the output of the power converter becomes maximum at t402, power is also output from the energy storage device. Since the motor output becomes zero at t42 (= t403) after the end of acceleration, the power converter performs an operation to compensate for the DC voltage drop, and at time t404, the DC voltage becomes equal to the power running voltage command Vm and stops the operation of the power converter. (Powering ends). After this, since the required power on the motor side is zero, this voltage is maintained.

When a press load is applied at t53 (= t405), the power converter operates (powering starts) and power is supplied to the motor from both the energy storage devices, so the DC voltage also decreases. For this reason, the DC voltage continues to decrease until t44 (= t406) when the press load ends. Since there is no load at t406, the power from the power converter is supplied to the energy storage device, and the DC voltage rises after t406.

Next, at t407, the power running voltage Vm is changed as shown in the figure. When the DC voltage reaches the changed powering voltage Vm at t408, the power converter stops operating (powering ends). Since the power converter is stopped when deceleration is started at time t45 (= t409), the regenerative energy from the motor is supplied to the energy storage device. For this reason, the DC voltage rises.

When the regenerative voltage Vr is reached at t410, the regenerative operation starts (regeneration start), and the regenerative power from the motor is not supplied to the energy storage device, but is regenerated from the power converter to the AC power supply. In this way, the direct current is maintained constant from t410, the motor stops at time t412 (= t46), and the operation of the power converter stops (regeneration ends). During this time, at time t411, the power running voltage is changed as illustrated. Since the required power on the motor side is zero after t46, this voltage is maintained.

As in the example shown in the figure, the power running voltage is lowered during operation to maintain this voltage, so that the absorption capacity of the energy storage device is increased when regenerative power is received from the motor. For this reason, the storage capability of the energy storage device can be utilized effectively. That is, the energy storage device is actively involved in the transfer of required motor power, and the power converter operates only in the gray portion shown in (e) when the operating condition of the DC voltage is satisfied. Also the converter operating time is short.

In this way, the power converter repeats operation and stop according to the set value of the DC voltage, and the operation operation is performed only where the conditions are satisfied, so heat generation of the power element of the power converter can be reduced, and only that much. The fins for cooling the power element can be miniaturized. Conversely, the continuous rating can be increased with the same power converter. In addition, since no loss occurs at the time of stop, the operation efficiency of the power converter as a whole is improved.

Furthermore, the capacity of the energy storage device can be optimized and optimized. That is, in order to make the best use of the storage capacity of the energy storage device, the voltage setting values of the regenerative voltage and the power running voltage are changed to control the storage amount of the energy storage device. In particular, it is effective when a large-capacity capacitor such as a large-capacity electrolytic capacitor or an electric double layer capacitor is used alone or in combination as an energy storage device in which the energy storage amount is greatly related to the DC voltage.
In this way, the voltage pattern of the power running voltage command and the regenerative voltage command value can be selected according to the operation pattern.

Although only the power running voltage Vm is changed in the example of FIG. 4, the regenerative voltage Vr can also be changed. Lowering the regenerative voltage Vr can advance the operation time of power regeneration, and is effective when the regenerative power from the motor is large or the capacity of the energy storage device is small. These setting values and the pattern setting of the change points can be performed in the same manner as described above.

Example 4
FIG. 5 is a chart schematically showing an operation example when applied to another operation pattern. (A) is the operation pattern of the press, that is, the speed command (= actual rotation speed), (b) is the torque of the motor, (c) is the motor input power required to perform this operation, and (d) is DC bus power running voltage command value Vm (solid line), regenerative voltage command value Vr (dashed line) and DC voltage (dashed line), (e) are the input power (solid line) of the power converter and the output power of the energy storage device (dashed line) Indicates. The illustrated operation pattern is characterized in that it decelerates before the press load, and the set value of the power running voltage Vm is changed at times t501 and t504.

As shown in (a), the motor starts at t51, accelerates at a predetermined acceleration from t52, then decelerates from t52 to t53, applies a press work load from t53 to t54, accelerates from t54 to t55, and then t56 Keeping the constant value until t56, the vehicle decelerates from t56, reaches zero speed at t57, stops at t58, and completes the work. Similar to the previous case, the operation pattern from t51 to t57 is repeated.

The required torque of the motor requires acceleration torque from t51 to t52 and t54 to t55, deceleration torque from t52 to t53 and t56 to t57, and load torque from t53 to t54 as shown in (b). Since the motor input power is given by the number of revolutions × torque, power as shown in (c) is required. The motor input power in (c) is supplied as the sum of the power converter input power (solid line) and the energy storage device output power (broken line) as shown in (e).

Since the power converter is stopped at time t51, the motor input power in (c) is supplied from the energy storage device as shown in (e). For this reason, the DC voltage decreases as shown in (d). At t501, the power running voltage Vm is changed. The direct-current voltage decreases until t502 (= t52) when the acceleration of the motor ends, but the power converter does not operate because the changed powering voltage is not reached.

Since the motor is decelerated from t502, the regenerative electric power from the motor is accumulated in the energy storage device, and the DC voltage increases until t503 (= t53) when the deceleration ends. In this way, the power converter is deactivated by utilizing the operation pattern in which regenerative power is output after power running power from the motor.

Next, when a press load is applied from t503, since the required motor power is supplied from the energy storage device, the DC voltage decreases. Then, the power running voltage Vm is changed at t504 after t503 when the load is applied. In this example, since the DC voltage at this time is lower than the changed Vm, the power converter immediately starts to operate (power running starts). In this example, since the required motor power is greater than the power supply limit power of the power converter, power is supplied to the motor from the power converter and the energy storage device from t504 to t505 (= t54).

Since power for accelerating the motor from t505 can be sufficiently supplied from the power converter, the power converter continues the power running operation and charges the energy storage device as shown in (e). When the DC voltage reaches the power running voltage Vm at t506, charging of the energy storage device is stopped, and the power converter operates so that this voltage is maintained until t55. Since the DC voltage slightly increases after the acceleration is completed, the operation of the power converter is stopped at t507 immediately after t55 (power running is completed). After this, since the required power on the motor side is zero, this voltage is maintained.

Since the power converter is stopped when deceleration is started at time t56 (= t508), the regenerative energy from the motor is supplied to the energy storage device. For this reason, the DC voltage rises. When the DC voltage reaches the regenerative voltage Vr at t509, the regenerative operation starts (regeneration start), and the regenerative power from the motor is regenerated from the power converter to the AC power supply. Thus, the direct current is kept constant from t509, the motor is stopped at time t510 (= t57), and the operation is stopped (regeneration is completed). Since the required power on the motor side is zero after t510, this voltage is maintained with the power converter stopped operating.

As in the example shown in the figure, since the operation pattern is known, the voltage pattern is selected according to this. In other words, when the power running voltage is changed in synchronization with the operation pattern, the energy storage device actively participates in the transfer of the required motor power, and the power converter is shown in gray (e) when the operating condition of the DC voltage is satisfied. Only the color part can be operated. Even in this way, the intention of the present invention can be realized. Also in this example, the regenerative voltage may be changed in the same manner as described above.

As described above, the optimum voltage pattern is selected based on the slide operation pattern including the press load and the slide speed, and the power converter is operated according to the selected voltage pattern in synchronization with the press operation.

(Second Embodiment)
FIG. 6 shows another embodiment of the motor driving apparatus of the servo press machine according to the present invention. In FIG. 6, the same reference numerals as those in FIG. 2 denote the same functions. The present embodiment is characterized in that the voltage pattern is output in synchronization with the slide position, that is, the crank angle, not the time.

The voltage pattern selection unit 601 selects a voltage pattern corresponding to the crank angle when the operation pattern is determined. The voltage pattern is selected corresponding to the press operation pattern as in the previous example. For example, in FIG. 3, t31 is set to 0 degree, t37 is set to 360 degrees, and the voltage pattern is given corresponding to the crank angle from the relationship between the time and the crank angle when the previous pattern operation is performed. The voltage pattern repeats from 0 degrees to 360 degrees.

On the other hand, the motor position signal (rotation angle signal) from the encoder 24 is input to the crank angle calculation unit 602 to calculate the crank angle. The voltage command unit 603 outputs a voltage pattern signal as a voltage command corresponding to the crank angle. In this way, the voltage command is output corresponding to the crank angle, and the power converter 21 is driven.

The crank angle may be calculated not from the encoder because it is attached to the motor shaft, but from the encoder attached to the crankshaft of the press or a linear scale that directly detects the position of the slide. Further, the crank angle may not be continuously detected, and a signal may be output only at an angle at which the voltage command value is changed.

(Third embodiment)
FIG. 7 shows another embodiment of the present invention of a motor drive device of a servo press machine. 7, the same reference numerals as those in FIG. 2 denote the same functions. In order to control charging / discharging of the energy storage device, a bidirectional converter is connected between the DC bus and the energy storage device, and this bidirectional converter is controlled.

The bidirectional converter 71 is connected between the DC bus 31 and the energy storage device 23, and supplies power to the energy storage device 23 from the DC bus 31 side according to its operation command, or supplies power to the DC bus 31 from the energy storage device 23. Supply. As a specific configuration example, when the voltage on the energy storage device 23 side is lower than the DC bus 31, it can be configured with a known buck-boost converter.

The illustrated one uses an electrolytic capacitor or an electric double layer capacitor as the energy storage device 23 and is advantageous for a configuration in which the state of the energy storage device can be easily controlled by voltage, but it can also be applied to a secondary battery.

The press operation pattern selected by the press operation pattern unit 203 is input to the voltage pattern selection unit 701, and the DC voltage pattern of the energy storage device 23 is selected based on the press operation pattern. The voltage command selected by the voltage pattern selection unit 701 is issued from the voltage command unit 702 as a time function in synchronization with the motion command of the motion command unit 205 by the operation start signal from the operation command unit 204.

The voltage / current control unit 703 performs voltage control and current control of the bidirectional converter 71 based on the voltage command from the voltage command unit 702 and the detected values of the input voltage and input current of the energy storage device 23, and the PWM control unit 714. The bi-directional converter 71 is PWM-controlled via As the voltage pattern in the pattern selection unit 701, various voltage patterns shown in the first embodiment can be selected.

On the other hand, power converter 21 operates in response to a command from voltage command unit 705 that gives a constant voltage command to DC bus 31. The operation is the same as the configuration example of FIG.
As described above, the voltage pattern is selected according to the operation pattern and the bidirectional converter is operated to control the energy storage state of the energy storage device, while the voltage of the DC bus is configured to be a predetermined value. In this example, since the voltage of the DC bus is almost constant regardless of the operating state, the control range on the drive side constituted by the inverter and the AC motor can be widened.

(Fourth embodiment)
FIG. 8 shows a motor drive device of a servo press machine showing still another embodiment of the present invention. 8, the same reference numerals as those in FIG. 2 denote the same functions. It is characterized in that the storage state of the energy storage device is given as a current command of the power converter, is selected corresponding to the operation pattern, and is controlled in synchronization with the press operation pattern.

The press operation pattern selected by the press operation pattern unit 203 is input to the current pattern selection unit 801, and the current input to and output from the power converter is selected based on the press operation pattern. The current command selected by the current pattern selection unit 801 is issued from the current command unit 802 as a time function in synchronization with the motion command of the motion command unit 205 by the operation start signal from the operation command unit 204. Thereafter, the power supply converter 21 is PWM-controlled in the same manner as in the example of FIG.

Example 1
FIG. 9 shows an example of the current command selected by the current pattern selection unit 801. The operation pattern shown in FIG. 9A is the same as that of FIG. 3, and although not shown, the motor torque and the required motor power are also the same as those of FIG. (C) is the current command as the selected current pattern, (e) is the converter input power (solid line) and the power output from the energy storage device (broken line) when the power converter is controlled like the current command, (D) shows the resulting voltage of the DC bus 31. When the power factor of the AC power supply 20 is controlled to 1 by the power converter, the current command in (C) is proportional to the power converter input power in (e). The output of the energy storage device is the motor power requirement-power converter input.

In the illustrated example, the current command is a zero command until t901, the illustrated powering command is issued at t901, the zero command is issued at t904, the powering command at t905 (= t93), the zero command at t907, and then t908. A pattern that gives a regeneration command at (= t95) and a zero command at t910 is given. As described above, when the power command is given in the form of a current command of the power converter, the energy management directly controlled by the power converter can be performed.

  Further, the method of the previous embodiment can be used as a method for giving a current pattern. That is, it may be a function of the crank angle as in the second embodiment, or may be given as a command to the bidirectional converter that directly controls the energy storage device as in the third embodiment. In this example, since the operation loss of each part is small and has been described as being ignored, the pattern is actually set in consideration of the loss as in the case of the voltage command.

Furthermore, depending on how the current pattern is applied in the present embodiment, the energy stored in the energy storage may exceed or be less than the capacity of the energy storage device. That is, the DC bus voltage may exceed the upper limit value or be lower than the lower limit value. In order to prevent this, the upper and lower limits of the DC voltage may be given so that the current command value can be corrected when the upper and lower limits are exceeded. Furthermore, the control may be performed while selecting both the voltage command pattern and the current command pattern.

When the power source including the energy storage device is controlled by controlling the converter as described above, the energy storage device can be reduced in size while meeting the drive demand of the load, and the power converter can be reduced in size and loss can be reduced. it can.

The present invention is effective as a servo press control method.

DESCRIPTION OF SYMBOLS 1 AC motor 2 Gear 3 Main gear 4 Crankshaft 5 Connecting rod 6 Slide 7 Bolster 20 AC power supply 21 Power converter 22 Inverter 23 Energy storage device 24 Encoder 31 DC bus 201 Operation method selection 202 Operation input part 203 Press operation pattern part 205 Motion command part 206 Position / Speed / Current Control Unit 207 Current Detector 208 PWM Control Unit 211 Voltage Pattern Selection Unit 212 Voltage Command Unit 213 Voltage / Current Control Unit 214 Voltage Detector 215 Current Detector 216 PWM Control Unit

Claims (7)

AC power supply,
A power supply side converter that converts alternating current from an alternating current power source into direct current,
An energy storage device connected to the DC side of the power supply side converter;
A motor side converter connected to the DC side of the power source side converter;
Having a motor driven by the motor side converter,
In a servo press device having a slide that is driven at a variable speed by the motor,
A control method for a servo press device, wherein a control pattern for controlling a charge / discharge state of the energy storage device is selected based on a press operation pattern of the press machine. In the control method of the servo press apparatus according to claim 1,
A control method of a servo press device, wherein the control pattern of the energy storage device is synchronized with a press operation pattern of a press machine. In the control method of the servo press apparatus according to claim 2,
Control of servo press device characterized in that synchronization of control pattern with press operation pattern is time synchronization with press operation pattern, synchronization with crank angle, or synchronization with corresponding signals. Method. In the control method of the servo press device according to claims 1 to 3,
A control method of a servo press device, wherein the control pattern of the energy storage device is a drive pattern of the power converter or a bidirectional converter connected to the energy storage device. In the control method of the servo press apparatus of Claim 4,
The method of controlling a servo press device, wherein the drive pattern is a voltage command or / and a current command of a power converter or a bidirectional converter. In the control method of the servo press apparatus of Claim 1 thru | or 5,
The control pattern is calculated from the conversion capacity of the power converter or bidirectional converter, the storage capacity of the energy storage device, the press load pattern, the press speed pattern, the setting value of the control pattern, the change point of the setting value before the operation, or the simulation A control method for a servo press device, characterized in that the control method is obtained and registered. A servo press control device comprising the control method according to claim 1.