JP5843796B2 - Press machine - Google Patents

Description

  The present invention relates to a large press device, and more particularly to a large capacity press device driven by a plurality of servo motors.

  A servo press machine driven by a servo motor can perform various slide motions. For this reason, for example, it is possible to perform an operation that makes it easy to perform the drawing process by decelerating immediately before the press load, or an operation that reduces noise during the press process. Further, productivity can be improved by so-called pendulum operation in which the slide is moved up and down near the bottom dead center of the slide. A large servo press apparatus employs a multi-point drive that pressurizes a slide at a plurality of points. Along with this, the servomotor to be driven is also increased in size and capacity, so that driving by a plurality of motors is used. A large capacity servo press can be realized by driving multiple motors. As a servo motor of this servo press, a permanent magnet servo motor is used as shown in Patent Document 1.

  On the other hand, one of the factors that determine the maximum current that can be passed through a permanent magnet motor is the demagnetization of the permanent magnet. In a permanent magnet motor, if a current exceeding the maximum current determined by the magnet material and motor structure used in the motor is passed, the magnet will permanently demagnetize, and even if the current is returned to a small value, the magnetic flux density of the demagnetized magnet will be There is a problem of causing irreversible demagnetization without recovering the original magnetic flux density (hereinafter abbreviated as permanent demagnetization). For example, a motor using a ferrite magnet has a smaller current that causes permanent demagnetization as the temperature is lower, and a motor using a neodymium magnet has a smaller current that causes permanent demagnetization as the temperature is higher.

  In a drive motor that requires a large maximum torque such as a servo press, the maximum current of the motor may flow at the time of pressing, which may cause permanent demagnetization at this time. For this reason, it is necessary to determine whether or not the magnet has caused permanent demagnetization. In particular, when the load at both points is not equal in a two-point slide, the load on the motor at one point increases, and there is a high possibility that permanent demagnetization will increase, so demagnetization determination is necessary.

  Further, since a ferrite magnet has a smaller coercive force than a neodymium magnet, a high torque motor using a ferrite magnet has a higher potential to cause permanent demagnetization than a high torque motor using a neodymium magnet. For this reason, it is particularly important to determine whether or not a motor using a ferrite magnet has caused permanent demagnetization than a motor using a neodymium magnet.

  In order to determine permanent demagnetization, Patent Document 2 detects the no-load operation of the motor, compares the voltage detected at that time with a predetermined reference value, and determines the degree of permanent demagnetization. In Patent Document 3, dq axis conversion is used to determine the permanent demagnetization amount by comparing the q axis voltage during actual operation with its reference value.

JP 2012-6075 A JP 2009-22091 A JP 2005-51892 A

  Regarding the determination of permanent demagnetization of the servo motor for driving the servo press, the known method has the following problems. The method described in Patent Document 2 is suitable for applications where all motors can be driven without load by coasting operation, such as railway vehicles, but with servo press machines, complete load-free operation is achieved during operation. It is difficult to apply because it is difficult to do. In addition, although the method described in Patent Document 3 can determine the demagnetization state even when there is no load, since the motor constant is required for the determination, the motor constant has non-linearity or receives a constant fluctuation. Then, there is a problem that demagnetization cannot be accurately determined.

  The present invention has been made with respect to the above-mentioned problems, and the object of the present invention is not to make all servomotors for servo press driving driven by a plurality of permanent magnet motors unloaded, It is an object of the present invention to provide a press device that can accurately determine the permanent demagnetization state of a permanent magnet of a servo motor even if there is a variation of the above.

In order to solve the above problems, the present invention is a press device that is driven by a plurality of permanent magnet motors and each motor is mechanically connected.
A load determination unit that determines a light load state and issues a command to perform demagnetization determination of the magnet of the permanent magnet motor;
A no-load state setting means for setting at least one motor to determine a demagnetization based on a command of the load determination unit to a no-load state;
A voltage detection unit for detecting an induced voltage of the motor in a no-load state of the motor for determining the demagnetization;
A reference value calculation unit for calculating a voltage reference value obtained from the operating state of the motor;
A comparison unit for comparing the induced voltage with a voltage reference value;
A determination unit for determining a demagnetization state of the permanent magnet of the motor is provided.

  Further, in the press apparatus described above, the determination unit determines that the permanent magnet is in a demagnetized state when an induced voltage of the motor for determining demagnetization is smaller than the voltage reference value.

  Further, in the press device described above, the determination unit determines a demagnetization state of the permanent magnet based on a permanent demagnetization factor that is a ratio between the induced voltage of the motor to be demagnetized and the voltage reference value. To do.

  Further, in the press device described above, the determination unit further displays a demagnetization state of the permanent magnet with the permanent demagnetization factor.

  Further, in the press device described above, the no-load state setting means is a gain switching unit that sets a current command to the motor for determining demagnetization to zero, and the voltage detection unit is a control system for the motor in the no-load state. Alternatively, the induced voltage is detected from the motor terminal voltage.

  In the press device described above, the gain switching unit sets the current command to the motor for determining demagnetization to zero, and sets the remaining motor gain to 100% or more so as to compensate for the gain. Features.

  In the press apparatus described above, the total torque generated from the motor is the same when viewed from the torque command when demagnetization is determined and when demagnetization is not determined.

  Further, in the press device described above, the no-load state setting means is a circuit breaker that cuts off power to the motor for determining demagnetization, and the voltage detection unit generates an induced voltage from a terminal voltage of the motor in the no-load state. Is detected.

  Further, in the press apparatus described above, the load determination unit determines that the load is light when torque commands to the plurality of permanent magnet motors are smaller than a predetermined value.

  Further, in the press device described above, the load determination unit determines whether the load is light based on a rotation angle of a crankshaft of the press device.

  The present invention uses the function of a plurality of drive motors, and when the load is light, the torque of a specific motor is set to zero, the torque is output by another motor, and the induced voltage observed by a motor with zero torque is observed. The permanent demagnetization state is grasped, and this is sequentially performed by other motors. The entire apparatus can provide a press apparatus that can determine permanent demagnetization while generating torque from the motor and continuing the operation.

  In other words, according to the first aspect of the present invention, even in an operating state with a load, a no-load state can be set on a specific axis, and a voltage can be detected without a current flowing. The permanent demagnetization state of the motor can be determined.

  According to the second aspect of the invention, in addition to the above effect, permanent demagnetization is determined by comparing the induced voltage of the motor with the voltage reference value, so that even slight demagnetization can be accurately determined.

  According to the invention of claim 3, in addition to the above effect, demagnetization is determined by the permanent demagnetization ratio of the ratio between the induced voltage of the motor and the voltage reference value, so that the tendency of demagnetization can be grasped.

  According to invention of Claim 4, in addition to the said effect, the demagnetization state of a motor can be notified clearly.

  According to invention of Claim 5, in addition to the said effect, a no-load state is controllably implementable, without providing special apparatuses, such as a circuit breaker.

  According to the inventions of claims 6 and 7, in addition to the above effects, the torque of the entire motor viewed from the torque command is set to the same value regardless of the current state of each motor. Since all the torques of the motor can be made the same afterwards, stable operation can be continued in a controlled manner regardless of whether or not the demagnetization determination is performed.

  According to the eighth aspect of the invention, in addition to the above effect, the winding circuit is interrupted from the inverter by the circuit breaker, so that a no-load state can be realized reliably.

  According to invention of Claim 9, in addition to the said effect, the state of load torque can be clarified and it can be discriminate | determined reliably whether demagnetization determination may be performed.

  According to the invention of claim 10, in addition to the above effect, not only can the press work be determined without being affected by the press load, but also the high load press work, using the operating characteristics of the servo press machine. There is no influence on itself.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a control system showing Embodiment 1 of the present invention. The flowchart which similarly shows operation | movement of a control system. The block block diagram of the control system which shows Example 2 of this invention. FIG. 5 is a block diagram of a control system showing Embodiment 4 of the present invention. The flowchart which similarly shows operation | movement of a control system.

  The present invention uses the functions of a plurality of drive motors, and when the load is light, when a specific motor is in a no-load state, torque is generated by another motor, and the induced voltage observed by the motor in the no-load state It is characterized by grasping the permanent demagnetization state. Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Example 1)
1 and 2 show an example of a servo press device 1 driven by a plurality of motors. FIG. 1 shows that a servo press device 1 includes a drive unit related to the present invention, two servo motors 11a and 11b for driving the drive unit, inverters 21a and 21b as elements for controlling the servo motor, It is explanatory drawing of the servo press apparatus which shows the basic composition of only the speed / torque control part 31 and the demagnetization determination part 41. The servo press apparatus of FIG. 1 is an eccentric press and has a structure in which intermediate gears mesh with each other. The servo motors 11a and 11b are AC servo motors (permanent magnet motors) in which a permanent magnet is housed in a rotor. As the permanent magnet, for example, a neodymium magnet or a ferrite magnet is used.

  Next, the drive unit will be described. The eccentric part of the eccentric ring 3a is engaged with the hole of the large diameter part of the connecting rod 4a. The lower end portion of the connecting rod 4 a is connected to the slide 2. Moreover, the eccentric part of the eccentric ring 3b is engaged with the hole of the large diameter part of the connecting rod 4b. The lower end of the connecting rod 4 b is connected to the slide 2. Main gears 141a and 141b are connected to one ends of the eccentric rings 3a and 3b, respectively.

  The eccentric rings 3a and 3b, that is, the main gears 141a and 141b rotate at their center portions 142a and 142b, respectively. This central portion is referred to herein as an eccentric shaft (crankshaft).

  The main gear 141a is engaged with the intermediate small gear 131a, and the intermediate large gear 132a connected to the intermediate gear shaft is engaged with the drive gear 121a. The drive gear 121a is connected to the drive shaft of the servo motor 11a. The main gear 141b is engaged with the intermediate small gear 131b, and the intermediate large gear 132b connected to the intermediate gear shaft is engaged with the drive gear 121b. The drive gear 121b is connected to the drive shaft of the servo motor 11b.

  Further, the intermediate large gears 132a and 132b are meshed with each other, and the main gears 141a and 141b are mechanically connected to each other through this. In the illustrated example, the main gears 141a and 141b rotate in opposite directions in synchronization with each other. Thus, the slide 2 is driven by the servo motors 11a and 11b while the left and right main gears 141a and 141b are synchronized. In this way, the two servo motors are mechanically connected via the gear.

  An inverter 21a is connected to a terminal of the servo motor 11a, and a variable voltage for driving the motor and an AC voltage with a variable frequency are applied. Similarly, an inverter 21b is connected to a terminal of the servo motor 11b, and a variable voltage for driving the motor and an AC voltage with a variable frequency are applied. The inverters 21 a and 21 b are respectively PWM controlled by the operation of the position / speed / torque control unit 31. The demagnetization determination unit 41 determines whether the magnet of each servo motor is permanently demagnetized.

  The demagnetization determination unit 41 is a main part of the present invention. The demagnetization determination unit 41 determines a timing for performing a demagnetization determination by determining a light load state based on the magnitude of the torque command, and determines whether the motor is permanently demagnetized. When performing the demagnetization determination, issue a gain change command to the position / speed / torque control unit 31 and input the motor speed, voltage command, and motor temperature to each servo motor to perform the demagnetization determination. Display the judgment result. Details will be described later.

  Encoders 12a and 12b for detecting the rotational positions of the motors 11a and 11b are connected to the respective motors on the opposite load side of the drive shafts of the servo motors 11a and 11b.

  The position / speed / torque control unit 31 in FIG. 1 includes a position command calculation unit 311, a position / speed control unit 312, a gain switching unit 313 (a, b), and a vector control unit 301 (a, b) shown in FIG. Consists of.

  The position command calculation unit 311 calculates and outputs the rotational position command of the servo motor 11a or 11b every moment. The rotational position command is calculated based on a motion command (not shown) of the slide 2 and input to the position / speed control unit 312. The position / speed control unit 312 operates according to the deviation between the rotational position command from the position command calculation unit 311 and the position detection value from the encoder 12b, and outputs a torque command τc.

  The position / speed control unit 312 is a position control unit that operates in accordance with the deviation between the rotational position command and the position detection value, and the deviation between the speed command output from the position control unit and the speed detection value obtained from the position detection value of the encoder. As is well-known, it is comprised from the speed control part which respond | corresponds according to it.

  Here, as described above, the signal of the encoder 12b attached to the motor 11b is used as the feedback signal of the position / speed control unit 312. Of the two servo motors 11a and 11b, the servo motor 11b is a master side motor. The master-side motor 11b is given a torque to drive the servo press device at the time of demagnetization determination, and determines the demagnetization of the other servomotor 11a during this drive.

  The torque command τc of the servo motor 11a or 11b is input to the gain switching units 313a and 313b. The gain of the gain switching unit 313a or 313b determines the ratio of the output current flowing from each of the inverters 21a and 21b. That is, the gain of the gain switching unit 313a or 313b determines the ratio of the motor torque generated by each motor to the torque command τc.

  For example, when the gain value is set to 100% and the torque command is 100%, the motor outputs 100% torque as the motor. That is, the torque of the two motors is 200%. If the torque command is 50%, the motor outputs 50% torque as the motor. When the gain value is set to 200%, even if the torque command is 50%, the motor outputs 100% torque as the motor. If the torque command is 25%, the motor outputs 50% torque as the motor. put out. The setting of the gain value of the gain switching unit will be described later.

  The output of the gain switching unit 313a is an actual torque command τca that commands the torque generated by the servo motor 11a. The actual torque command τca from the gain switching unit 313a is input to the Id / Iq current command unit 314a, and the d-axis current command Idca and the q-axis current command Iqca of the servo motor 11a suitable for the torque command are output. The operation of the Id / Iq current command unit 314a includes, for example, a method (maximum torque control) in which an Id / Iq current command is issued so that the motor torque is maximized with respect to the actual torque command τca. The d / q-axis current command Idca / Iqca from the Id / Iq current command unit 314a is input to the Id / Iq current control unit 317a.

  On the other hand, u and v phase output alternating current iua / iva (not shown) from the inverter 21a is detected by the current detector 315a. The signal detected by the current detection unit 315a is detected as a current detection signal Idfa / Iqfa on the d / q axis by the coordinate conversion unit 316a. The Id / Iq current control unit 317a operates according to the command signal from the Id / Iq current command unit 314a and the detection signal from the coordinate conversion unit 316a, and outputs a signal Vdca / Vqca that commands the d / q axis voltage.

  The signal Vdca / Vqca is converted into a three-phase voltage command signal vuca, vvca, vwca of the stationary coordinate system via the coordinate conversion unit 318a and input to the PWM control unit 319a. In the PWM control unit 319a, a PWM control signal is generated, and the inverter 21a is PWM-controlled. Thus, the current of the servo motor 11a is controlled according to the actual torque command τca.

  The inverter 21a is controlled by the configuration of the Id / Iq current command unit 314a, current detection unit 315a, coordinate conversion unit 316a, Id / Iq current control unit 317a, coordinate conversion unit 318a, and PWM control unit 319a shown in FIG. The method of controlling the alternating current of the servo motor 11a is well known as vector control of a permanent magnet motor, and detailed description thereof is omitted. A control unit composed of these elements is shown as a vector control unit 301a surrounded by a broken line in FIG. It is also well known that the Id / Iq current control unit 317a performs non-interference control of the voltage between the d / q axes.

  The output of the gain switching unit 313b is an actual torque command τcb that commands the torque generated by the servo motor 11b. The control configuration from the output of the gain switching unit 313b to the inverter 21b is the same as the configuration for controlling the servo motor 11a described above, and is indicated by a broken line vector control unit 301b in FIG. The operation of the vector control unit 301b is the same as that of the servo motor 11a.

  Next, a method for determining the permanent demagnetization state, which is a feature of the present invention, will be described. When operating the servo press device with multiple motors, determine whether the load torque is less than a predetermined value, and if it is smaller, place at least one motor in a no-load state and measure the induced voltage. Then, it is determined whether or not a permanent demagnetization state has been reached (hereinafter simply referred to as demagnetization determination). At this time, the other motors are in a load state (torque is applied) to operate the servo press device.

  Returning to FIG. 1, due to the structure of the eccentric press, when the slide 2 is near the top dead center as shown in the figure (at an angle near the top dead center), the mass of the slide is applied only in the vertical direction of the eccentric portion. That is, in order to maintain the slide mass, the eccentric shaft receives almost no force in the rotational direction, that is, torque. Also, press work is not performed near top dead center. From these, the rotational torque of the motor is small near the top dead center.

  The configuration and operation of the demagnetization determination unit 41 in FIG. 1 will be described with reference to FIG. The demagnetization determination unit 41 in FIG. 1 includes an instruction unit 401 that instructs a demagnetization determination timing and a demagnetization determination command, comparison units 402a and 402b that compare demagnetization states of the motors, and a demagnetization result based on the comparison result. It consists of a subsystem of a determination display unit 416 that determines the state and displays the determination result.

  2 includes a load (torque) determination unit 411, a determination motor setting unit 412, and a determination operation command unit 413. First, as described above, the load determination unit 411 determines whether the value of the torque command τc is smaller than a predetermined value (the load is light), and determines that the load is small when the torque is smaller than the predetermined value. A command (signal) for determining demagnetization is issued. At this time, since the load state is detected by the torque command, the state of the load torque can be clarified and it can be reliably determined whether or not the demagnetization determination can be performed.

  The predetermined value of the torque command τc determined above is 50% of the torque command τc when there are two motors as shown in FIG. When one motor is brought into a no-load state by a servo press device operated by N motors, the predetermined value is [(N−1) / N] × 100% of the torque command τc.

  When performing the demagnetization determination, first, in order to determine the demagnetization of the servo motor 11a, the servo motor 11a is unloaded and the motor state is measured. After this measurement is completed, the servo motor 11b is unloaded and the state of the motor is measured in order to determine the demagnetization of the servo motor 11b. Determination of the motor to be measured is performed by the determination motor setting unit 412.

  Even if one motor is unloaded, the servo press device of FIG. 1 has two motors mechanically connected by gears, so the torque from the other motor is transmitted to the entire device, causing problems in operation. Absent. Further, since the torque at the time of demagnetization determination is smaller than 50% of the total torque, even if the motor is operated with one motor, the torque as commanded can be generated. Hereinafter, this will be described in detail.

  Normally, the gain of the gain switching unit 313 is set to a value of 100% for both of the switching units 313a and 313b when the demagnetization determination operation is not performed. Since both gains are 100%, the servo motors 11a and 11b perform the same operation and both perform the same torque operation. That is, the two servo motors 11a and 11b generate the same torque in proportion to the torque command τc from the position / speed control unit 312.

  When performing demagnetization determination, first, the servo motor 11a is set to a no-load state, and demagnetization determination of this motor is performed. FIG. 2 shows the state at this time. As shown in FIG. 2, when two motors are used, the gain of the gain switching unit 313a is set to 0%, and the gain of the gain switching unit 313b is set to a value of 200% so as to compensate for this gain. That is, when there are N motors, the gain of the gain switching unit of the control unit other than the motor 11a to be in a no-load state is set to [N / (N−1)] × 100%. In this manner, the gain switching unit 313a functions as a no-load state setting unit because the motor that performs demagnetization determination with the gain set to 0% is set to the no-load state. The other gain switching units operate similarly when the gain is set to 0%.

  In the case of FIG. 2, the motor 11b is the master motor, and for this reason, the encoder switching unit 421 is switched so as to detect the position signal of the motor 11b from the encoder 12b. The determination operation command unit 413 issues an operation command that sets the value of the gain switching unit 313b to 200% and the value of the gain switching unit 313a to 0%. Thus, the operation of the servo press device is continued only with the motor 11b, and the motor 11a is brought into a no-load state.

  In this way, the gain switching units 313a and 313b set the servo motor to the no-load state by setting the gain to 0%, and thus become the no-load state setting means.

  When the gains of the gain switching units 313a and 313b are given in this way, the generated torque of all the motors viewed from the torque command τc can be made the same even when the demagnetization determination is not performed and during the demagnetization determination. As a result, a stable operation can be continued in a controlled manner regardless of whether or not the demagnetization determination is performed.

  In the demagnetization determination state of the motor 11a, only the gain of the gain switching unit 313a is set to 0%, and the current commands Idca and Iqca from the Id / Iq current command unit 314a are set to zero. In the configuration of this control system, the current flowing through the motor winding can be brought into the zero current state only when the magnitude and phase of the output voltage of the inverter 21a and the terminal voltage of the servo motor 11a match. Thus, a state in which no current flows through the motor 11a, that is, a no-load state is realized.

  In this unloaded state, if the d-axis is taken in the direction of the magnetic flux of the rotor magnet, the d-axis component Vdca of the output of the Id / Iq current control unit 317a is zero, and only the q-axis component Vqca has a certain value. This value is a no-load voltage of the motor, that is, a voltage corresponding to the induced voltage. Since the induced voltage is detected from the signal of the control system, a special device for voltage detection such as a voltage sensor is unnecessary. The Id / Iq current control unit 317a is a voltage detection unit that detects an induced voltage of the motor 11a when the motor is in a no-load state.

  On the other hand, the reference value calculation unit 414a calculates a voltage reference value corresponding to the operation (rotation) state of the motor 11a. That is, with reference to the rotation speed from the encoder 12a and the temperature detector 13a provided in the motor 11a, the no-load induced voltage of the motor in a state where the magnet is not permanently demagnetized is calculated. Usually, a value obtained by multiplying the induced voltage coefficient by the rotational speed is an induced voltage calculation value. The induced voltage coefficient is a function of the motor temperature, that is, the magnet temperature, and is stored in the reference value calculation unit 412a as a function pattern of temperature according to the magnet characteristics. Alternatively, the reference value calculation unit 412a calculates approximately as a linear function of temperature. The no-load induced voltage thus obtained is used as a voltage reference value. The induced voltage calculation value, that is, the voltage reference value is a voltage at the temperature when the magnet is not permanently demagnetized.

  The demagnetization state comparison unit 415a compares the q-axis component Vqca (induced voltage) of the voltage with the voltage reference value. The q-axis component Vqca is proportional to the q-axis voltage vector when the terminal voltage of the motor 11a is drawn as a d-axis reference vector. This proportionality coefficient is determined from the configuration of the control system, the PWM control method, the characteristics of the power device of the inverter, and the DC voltage applied to the inverter. That is, when the device configuration is determined, the proportionality coefficient can be determined. Needless to say, when the demagnetization state comparison unit 415a compares both Vqca and the induced voltage calculation value, the both are aligned on the same coordinate axis and the same dimension. Alternatively, the magnitude of the AC voltage that is the output of the coordinate transformation 318a can be obtained as an induced voltage, which can be used in place of Vqca (induced voltage) and compared with the voltage reference value.

  Thus, the induced voltage of the motor in the current state is obtained from the signal of the control calculation unit (vector control unit), and the voltage reference value when there is no permanent demagnetization determined from the rotation speed and the motor temperature is obtained in the demagnetization state comparison unit 415a. Compare. If permanent demagnetization has occurred, the magnetic flux has decreased, so the output voltage component Vqca (induced voltage) of the Id / Iq current control unit 28a is smaller than the voltage reference value, so that the induced voltage is smaller than the voltage reference value. Thus, permanent demagnetization can be determined. In this way, the magnitudes of both are compared and stored, or the ratio of both (= the current no-load voltage / voltage reference value obtained from Vqca) is stored as a permanent demagnetization factor, and permanent demagnetization is performed. It is a standard of whether or not. The storage is performed in the comparison unit 402a.

  Next, the demagnetization determination of the servo motor 11b is performed. The determination method is the same as in the case of the motor 11a, and is performed by switching the positions of the servo motor 11a and the servo motor 11b described above. That is, when determining the demagnetization of the servo motor 11b, the encoder switching unit 421 switches the servo motor 11a to the master side to perform the rotational position control, and the operation is continued only by the motor 11a. Comparison / storage of the demagnetization state of the motor 11b is performed in the comparison unit 402b by switching the gain values of the gain switching units 313a and 313b. That is, the same as that performed by the motor 11a as described above is performed.

  At this time, in the apparatus in which the two motors operate at the same rotation speed and current, the motor temperature necessary for calculating the voltage reference value is detected by the temperature detector 13b of the servo motor 11b. Alternatively, the temperature detector may not be attached to both motors, but may be attached to only one of them and set to a temperature common to both motors.

  In this way, although the press apparatus is in operation, the servo motors 11a and 11b are sequentially placed in the no-load state by the functions of the determination motor setting unit 412 and the determination operation command unit 413, and Determine the demagnetization state.

  Next, from the result of comparing whether or not the permanent demagnetization is demagnetized by the demagnetization state comparison unit 415a or 415b, the determination display unit 416 determines whether the magnet is permanently demagnetized. The determination is made from the relationship between the voltage reference value of each motor and the no-load induced voltage. For example, the determination is made from the value of the permanent demagnetization factor that is the ratio of the no-load induced voltage and the voltage reference value. Since there are variations in magnets and detection errors in the determination, it is determined whether or not the permanent demagnetization state is taken into consideration.

  As a result of the determination, if the servo motor 11a or 11b is in the permanent demagnetization state, the determination display unit 416 displays that the magnet is in the permanent demagnetization state. There are several methods for display on the determination display unit 416. If one motor has a current no-load voltage that is lower than the voltage reference value by a certain percentage, it is displayed as an alarm state indicating that it is permanently demagnetized, or an alarm status indicates which motor is permanently demagnetized. There is a way to display as. At this time, there are a method of displaying in accordance with the degree of permanent demagnetization such as green, yellow, and red from the magnitude of the permanent demagnetization rate, or a method of displaying numerical values such as the permanent demagnetization factor. In this example, the determination display unit 416 in FIG. 2 uses the determination display unit 416 as a display for inputting an operation pattern of the press device, and displays the display on the display (416i). The indication is “Permanent demagnetization has occurred in the magnet of the No. ○ motor. Please operate with a load within ○%” or “Permanent demagnetization of the motor magnet has occurred. Please contact me. "

  These display units are installed near the press device and displayed. Further, when the department that monitors the device is not only near the display unit but also the device is remote, the display content may be sent to the monitoring department using a communication line. In this way, the state of the motor can be remotely monitored, and it also serves as a monitoring device that monitors the state of the press device.

  Since the determination operation of the demagnetization state is executed as a software algorithm, an example of a flow for performing these operations is shown in FIG. 3 also indicates which subsystems in FIG. 2 are involved in the demagnetization determination unit 41.

  First, in a normal operation state before the flow starts, the press apparatus is in the state shown in FIG. The motor 11b is a master motor, and the gains of the gain switching units 313a and 313b are all set to 100%. The encoder switching unit 421 is switched to detect the encoder signal of the motor 11 b, and the position detection signal of the motor 11 b is input to the position / speed control unit 312.

  When the flow of demagnetization determination starts, first, the load (torque) determination unit 411 determines whether or not the absolute value of the torque command τc is smaller than a predetermined value (S101). The predetermined value serving as the determination criterion is described above. If the absolute value of the torque command value τc is larger than the predetermined value (No in S101), the process is terminated without determining the demagnetization state. If the absolute value of the torque command τc is smaller than the predetermined value (Yes in S101), a demagnetization determination is performed. The determination motor setting unit 412 selects the motor 11a for determining demagnetization. The gains of the gain switching units 313a and 313b are switched to gains for determining the demagnetization of the motor 11a (S102). As described above, the gain value is normally 100%. However, when determining demagnetization, the gains of the gain switching unit are set to specific values. Thus, the motor 11a is brought into a no-load state.

  The operations of S101 and S102 after the start of the demagnetization determination flow are performed by the load determination unit 411, the determination motor setting unit 412 and the determination operation command unit 413 in the instruction unit 401.

  Next, as a function of the rotational speed of the motor 11a and the motor temperature, an induced voltage in a no-load state when not in a permanent demagnetization state, that is, a voltage reference value is calculated by the reference value calculation unit 414a (S103). Then, the output voltage component Vqca (induced voltage) of the Id / Iq current control unit 317a is detected (S104). The demagnetization state comparison unit 415a compares the detected value with the reference value and stores the permanent demagnetization state of the permanent magnet of the motor 11a. For example, the permanent demagnetization factor is stored (S105). This storage is stored in a storage unit (not shown) provided in the comparison unit 402a. The operations in S103 to S105 are performed in the comparison unit 402a.

  Next, in order to determine the demagnetization state of the motor 11b, the gain of the gain switching unit 313a is temporarily returned to a normal value (S106), and the motor 11b is switched to the motor 11a and changed to the master motor (S107). That is, the encoder switching unit 421 switches so as to detect the signal of the encoder 12a of the motor 11a, changes this so that the detection signal is fed back to the position / speed control unit 312, and controls the position / speed. Thus, the process for determining the demagnetization state of the motor 11b is entered.

  Next, the gain of the gain switching unit 313b is switched to a gain for determining demagnetization of the motor 11b (S108). As described above, the gain value is normally 100%. However, when determining demagnetization, the gains of the gain switching unit are set to specific values. In this way, the motor 11b is brought into a no-load state. A series of processes so far are performed by the determination motor setting unit 412 and the determination operation command unit 413. The operations in S106 to S108 are performed again in the instruction unit 401.

  Then, as a function of the rotation speed of the motor 11b and the motor temperature, an induced voltage in a no-load state when not in a permanent demagnetization state, that is, a voltage reference value is calculated by the reference value calculation unit 414b (S109). Next, the output voltage component Vqcb (induced voltage) of the Id / Iq current control unit 317b is detected (S110). Thus, the demagnetization state comparison unit 415b compares the detected value with the reference value, and the permanent magnet of the motor 11b stores the permanent demagnetization state. For example, the permanent demagnetization factor is stored (S111). This storage is stored in a storage unit (not shown) provided in the comparison unit 402b. The operations in S109 to S111 are performed in the comparison unit 402b.

  From the demagnetized state of the motor 11a and the motor 11b thus calculated and stored, the determination display unit 416 determines whether each motor is permanently demagnetized. Since there are variations in magnets and detection errors in the determination, it is determined whether or not the permanent demagnetization state is taken into consideration (S112). If it is determined that it is not in the demagnetized state, the process for ending the demagnetization determination is entered (No in S112). On the other hand, when it is determined that the magnet is in a demagnetized state (Yes in S112), the determination display unit 416 displays that the magnet is in a permanent demagnetized state (S113). The method of determination and display is as described above.

  As described above, since a series of processes for demagnetization determination ends, the normal state in which the gain of the gain switching unit 313 is not demagnetized, that is, the gains of all the gain switching units 313a and 313b are returned to 100% ( In step S114, the motor 11b is switched to become a master motor (S115), and a series of demagnetization determinations is completed.

  When the permanent demagnetization is performed after the determination of the permanent demagnetization, the command from the torque command τc to the actual torques τca to τcb can be limited depending on the degree of the permanent demagnetization. Alternatively, the operation pattern can be changed so that the actual motor torque is not affected by demagnetization.

  In the flow of FIG. 3, it is determined whether or not the permanent demagnetization state is obtained by one measurement and comparison, but there is a possibility that an error may occur in one measurement. For this reason, the permanent demagnetization factor may be calculated a plurality of times under some conditions to determine the permanent demagnetization comprehensively. That is, after calculating the permanent demagnetization factor with each motor a predetermined number of times, the average of the demagnetization factors stored at the time of execution may be calculated to determine whether or not the permanent demagnetization is performed.

  In addition, since the two motors are sequentially unloaded, if the measurement time affects the operation, conversely, it is determined whether the torque command is smaller than the predetermined value when each motor to be measured is unloaded. May be.

  Next, the startup timing of the algorithm shown in FIG. 3 will be described. Although the flow of FIG. 3 may be activated at a high frequency, since the motor is normally designed so as not to cause permanent demagnetization, this can be utilized. For this reason, the algorithm of FIG. 3 may be started at an appropriate period, for example, every several hours, or whenever the operation of the press machine is started. That is, the algorithm shown in the flow of FIG. 3 is activated at an appropriate period to operate the demagnetization determination unit 41, and the demagnetization determination can be performed when the condition is satisfied in the torque determination. Alternatively, since permanent demagnetization is likely to occur when a large torque is output, that is, when a large current is passed, the algorithm shown in FIG. 3 may be activated after a large torque is output. Alternatively, since the motor temperature is detected, FIG. 3 can be activated in a temperature state where permanent demagnetization is likely to occur depending on the type of permanent magnet. That is, control may be performed so that FIG. 3 is activated at a high temperature when the permanent magnet motor 1 is a neodymium magnet and at a low temperature when it is a ferrite magnet.

  If the algorithm shown in FIG. 3 is activated only at an appropriate time or condition in this way, the chance of giving a slight disturbance to the control system for demagnetization determination can be reduced. Further, if the condition for determining whether or not to perform the determination is clear, the determination algorithm can be simplified. For example, when the above algorithm is started only after the operation is stopped for a while, the motor temperature is close to room temperature, so it may be treated as a room temperature magnet characteristic and the voltage reference value calculation may be performed without detecting the motor temperature. . At this time, the temperature detector 13 attached to the motor can also be omitted.

  Further, when performing field weakening control to operate the permanent magnet motor 11 at high speed rotation, the current commands Idca and Iqca of the motor 11a are set to zero as described above for demagnetization determination in the high speed rotation state. Even if an attempt is made to realize a state in which no current flows through the motor, a reverse current may flow from the motor side to the inverter 21a due to the induced voltage of the motor. At this time, the above-described no-load state cannot be realized. In a motor that performs field weakening, in addition to the condition of the torque command τc in the torque determination unit 411, the absolute value of the rotational speed of the motor may be equal to or less than a predetermined value, that is, the rotation speed at which field weakening control is not performed. As a condition, it is determined whether or not to perform demagnetization determination.

  Furthermore, when the motor speed is low, the no-load induced voltage is small. For this reason, if the determination of demagnetization is performed in a state where the voltage at the low rotation speed is small, the determination error becomes large. In order to avoid this, the demagnetization determination may be performed in addition to the condition that the motor rotational speed is higher than a predetermined value.

  In this way, even in a press machine in which the motor always has torque, the permanent demagnetization state of the magnet can be accurately determined without being affected by the motor constant. In addition, if the permanent demagnetization state of the magnet is determined in this way, the cause can be determined promptly even if there is a motor driving problem. Further, since the determination is made in a state where the rotor of the motor is rotating, it can be determined even if permanent demagnetization occurs in a permanent magnet at a specific portion on the rotor.

  Further, since the demagnetization determination can be made only on the software with the control command set to zero based on the torque command without changing the configuration of the drive system, additional application to a conventional apparatus that does not perform the determination is easy.

  In the above example, in the no-load state, the d-axis component Vdca of the output of the Id / Iq current control unit 27a is zero and only the q-axis component Vqca has a certain value. , Γδ axes) or a control method, in the case where the d-axis component does not become zero, the vector sum of the d-axis component and the q-axis component may be used as the induced voltage of the motor in the current state.

  In this embodiment, the press device driven by two servo motors has been described, but permanent demagnetization can be similarly determined by a press device driven by three or more devices. At this time, instead of sequentially unloading the motors one by one, a plurality of motors may be unloaded simultaneously. At this time, a predetermined value that is a determination criterion of the torque determination unit and a gain of the gain setting unit are appropriately set so that a plurality of units can be simultaneously unloaded. Furthermore, the present method of determining the demagnetization state by sequentially applying no load to each motor can also be applied to a press apparatus in which the motors are not mechanically connected to each other.

  Furthermore, when multiple servo motors have the same specification and all motors always operate in the same manner, the demagnetization state of multiple motors is not judged and only one motor is unloaded, and the demagnetization judgment is representative. Thus, the determination of other motors may be omitted.

  Although the above embodiment has been described with respect to the press with an eccentric structure, it is needless to say that the press can be similarly applied to other press machines such as a crank press, a link mechanism, and a servo press with a ball screw mechanism.

  Furthermore, in a machine driven by a plurality of motors and the motors are mechanically connected directly or indirectly, a light load condition exists or a light load condition can be intentionally created. Even if it is a machine, what is intended by the present application can be applied.

(Example 2)
Next, Example 2 will be described with reference to FIG. In the first embodiment, the induced voltage of the motor that performs no-load operation is detected from the control signal, but the induced voltage of the motor can be measured from the actual motor terminal voltage. The idea of the demagnetization determination unit 41 of the second embodiment is the same as that of the first embodiment, but the measurement and detection of the motor voltage are different. In the second embodiment, the comparison unit is configured as indicated by broken lines 403a and 403b. In FIG. 4, parts having the same numbers as those in FIG.

  In the second embodiment shown in FIG. 4, the induced voltage used for determining the demagnetization state is not obtained from the control signal as in the first embodiment, but is obtained by measuring the actual terminal voltage of the motor.

  Instead of detecting the voltage Vqca in S104 of FIG. 3, the terminal voltage is detected by the voltage detector (voltage detector) 22a of FIG. 4, and the magnitude is converted into a vector q-axis component by the coordinate converter 417a. Measure the induced voltage. That is, Vqfa is measured as an induced voltage, is input to the demagnetization state comparison unit 415a instead of the previous Vqca, and is compared with the voltage reference value by the demagnetization state comparison unit 415a. Note that the calculation algorithm of the coordinate conversion unit 417a is the same as that used for vector calculation of the current component from the alternating current detected by the current detector 315a through the coordinate conversion unit 316a, and the voltage detector 22a. The voltage component is calculated and detected through the coordinate conversion unit 417a from the AC voltage detected in step (b).

  Since other operations are the same as those in the first embodiment, a description thereof will be omitted. Further, the magnitude of the voltage can be measured not only by performing coordinate conversion and vector calculation but also by rectifying the AC signal detected by the voltage detector 22a. The motor 11b is similarly measured and compared for determination.

  In the second embodiment, the voltage detectors 22a and 22b are necessary, but since the actual voltage is measured, the induced voltage can be detected with high accuracy. That is, since the voltage Vqca obtained from the control signal of the first embodiment is a control command signal, an error may occur between this value and the actual value, but the actual voltage is measured to obtain Vqfa, Since Vqfb is obtained, the induced voltage can be detected with high accuracy.

(Example 3)
Next, Example 3 will be described. Although the demagnetization determination is performed when the load is smaller than a predetermined value, a place where the load is small can be specified in the press machine. That is, in FIG. 1, due to the structure of the crank press, when the slide 2 is near the top dead center as shown, the mass of the slide is applied only in the vertical direction of the eccentric shaft. Here, little torque is applied to the eccentric shaft to maintain the slide mass. In addition, since the acceleration / deceleration is small in this vicinity, the speed change is small. Furthermore, of course, no press work is performed near the top dead center. Thus, the rotational torque of the motor is small near the top dead center. As a result, the servo press outputs a signal for determining the demagnetization state near the top dead center of the slide in operation.

  The position command calculation unit 311 in FIG. 2 also calculates a signal for commanding the angle of the eccentric shaft (that is, the crankshaft) of the press device 1, and therefore uses the crankshaft angle signal. Instead of the torque command τc from the position / speed control unit 312, the crankshaft angle signal is input to the torque determination unit 411. The torque determination unit 411 receives the crankshaft angle signal as input, determines whether the angle is near top dead center, and outputs a timing signal for operating the permanent magnet demagnetization determination of the permanent magnet motor 11a or 11b. Other than the change of the input signal of the torque determination unit 411 and the determination condition, the other can be realized in the same form as the above-described embodiment.

  If the control is executed as described above, in addition to the effect of the first or second embodiment, since the determination is made near the top dead center where the press is not performed, the press work, that is, the press load is surely not affected. Not only can the demagnetization determination be performed, but conversely, the demagnetization determination does not adversely affect the pressing operation itself that results in a high load state.

Example 4
FIG. 5 is a block diagram of a control system according to the fourth embodiment of the present invention. The method for creating the no-load state is different from that in the above embodiment. In FIG. 5, parts having the same numbers as those in FIG.

  The configuration of the vector control unit 301a from the output of the position command calculation unit 311, the position / speed control unit 312, and the gain switching unit 313a that controls the current of the motor 11a to the PWM control unit 319a, and further by the PWM control unit 319a The configuration for controlling the inverter 21a and supplying the current from the inverter 21a to the motor 11a is the same as in the above embodiment. The difference is that the circuit breaker 422a is connected to the current supply line to the inverter 21a and the motor 11a. In a normal operation state in which the demagnetization determination is not performed, the same operation as in the previous embodiment can be performed by closing the circuit breaker 422a. Further, the configuration of the demagnetization determination unit 41 is substantially the same as that of the second embodiment. The configuration of the element that controls the current of the motor 11b is the same as that of the motor 11a.

  Next, the demagnetization determination using the circuit breaker according to the fourth embodiment will be described with reference to FIGS. First, in a normal operation state in which the demagnetization determination is not performed, the encoder switching unit 421 is switched to detect the signal of the encoder 12b, and the motor 11b is used as a master motor. The gains of the gain switching units 313a and 313b are all 100%. Circuit breakers 422a and 422b are closed.

  With this state as an initial state, the torque determination unit 411 determines whether or not the absolute value of the torque command τc is smaller than a predetermined value (S201). If it is smaller, a signal for performing a demagnetization determination operation is issued, and the process proceeds to the next step. (Yes in S201). The determination motor setting unit 412 determines the motor 11a to be demagnetized. Then, in order to determine the demagnetization of the motor 11a, the determination operation command unit 413 outputs a signal for setting the gain of the gain switching unit 313b to 200% and the gain of the gain switching unit 313a to 0%. The motor 12b has a torque of 200% of the command, and the motor 11a has a torque of 0%. When the gains of the gain switching units 313a and 313b are given in this way, the total torque of the entire motor viewed from the torque command τc can be the same as when demagnetization is not determined and when demagnetization is determined.

  Then, the circuit breaker 422a is opened (S203). After waiting for a time until the circuit breaker is completely opened (S204), the reference value calculation unit 414a refers to the rotation speed from the encoder 12a and the motor temperature from the temperature detector 13a, and the motor causes permanent demagnetization. The no-load induced voltage in the absence is calculated as a voltage reference value (S205). The no-load induced voltage as the voltage reference value is calculated in the same manner as in the first embodiment.

  Next, the voltage of the motor 11a is detected. Since the circuit breaker 422a is opened, the induced voltage of the motor 11a rotating in a no-load state can be detected. The voltage detector 22a detects the terminal voltage of the motor 11a, and the coordinate converter 417a measures the magnitude as a vector component (S206). That is, the no-load induced voltage of the motor 11a in the current state is detected.

  As described above, the circuit breaker 422a operates as a no-load state setting unit because it opens the motor that performs demagnetization determination by opening. The other circuit breakers work in the same way when opened.

  In the demagnetization state comparison unit 415a, the magnitude of the voltage measured by the coordinate conversion unit 417a is compared with the voltage reference value calculated by the reference value calculation unit 414a. The method of the comparison operation is the same as that described in the first embodiment. Then, the comparison result is stored as the permanent demagnetization state of the permanent magnet of the motor 11a (S207). This storage is stored in a storage unit (not shown) provided in the comparison unit 403a. Thus, the comparison calculation for determining the demagnetization of the motor 11a is completed. S202 to S207 are steps for determining the demagnetization of the motor 11a.

  Next, the determination motor setting unit 412 sets a demagnetization detection state of the motor 11b. Then, in order to determine the demagnetization state of the motor 11b, the determination operation command unit 413 closes the circuit breaker 422a (S208), waits until it is completely closed (S209), and temporarily sets the gains of the gain switching units 313a and 313b. Returning to the normal value (S210), in order to change the motor 11a to the master motor, the encoder switching unit 421 switches so as to detect the signal of the encoder 12a, and the motor 11a is changed to the master motor (S211). That is, the detection signal of the encoder 12a is changed to be fed back to the position / speed control unit 312 to control the position / speed. Thus, the process for determining the demagnetization state of the motor 11b is entered.

  Initially, the gains of the gain switching units 313a and 313b are switched to gains for determining the demagnetization of the motor 11b (S212). As for the gain values, the gain switching unit 313a is set to 200%, the gain switching unit 313b is set to 0%, and the motor 11b is brought into a no-load state. Then, the circuit breaker 422b is opened (S213). Waiting for the time until the circuit breaker is completely opened (S214), the reference value calculation unit 414b refers to the rotation speed from the encoder 12b and the motor temperature from the temperature detector 13b, and the motor 11b is demagnetized. The no-load induced voltage in the absence state is calculated as a voltage reference value (S215). The calculation of the no-load induced voltage as the voltage reference value is performed in the same manner as in the first embodiment.

  Next, the voltage of the motor 11b is detected. Since the circuit breaker 422b is opened, the induced voltage of the motor 11b rotating in a no-load state can be detected. The voltage detector 22b detects the terminal voltage of the motor 11a, and the coordinate converter 417b measures the magnitude as a vector component (S216). That is, the no-load induced voltage of the motor 11b in the current state is detected.

Then, the demagnetization state comparison unit 415b compares and calculates the voltage measured by the coordinate conversion unit 417b and the voltage reference value calculated by the reference value calculation unit 414b. And then. The comparison result is stored as the permanent demagnetization state of the permanent magnet of the motor 11b (S217). This storage is stored in a storage unit (not shown) provided in the comparison unit 403b. Thus, the comparison calculation for determining the demagnetization of the motor 11b is completed. S212 to S217 are steps for determining the demagnetization of the motor 11a.
Since the series of demagnetization determination is completed, the circuit breaker 422b is closed (S218), and the process waits until it is completely closed (S219). The gains of all the gain switching units 313a and 313b are returned to 100% (S220), and the encoder switching unit 421 is switched so that the motor 11b becomes the master motor (S221), and the normal operation state is restored.

  The determination display unit 416 determines whether each motor is permanently demagnetized from the demagnetization rates of the motor 11a and the motor 11b thus calculated and stored. Since there are variations in the magnets and detection errors in the determination, it is determined whether or not the permanent demagnetization state is taken into consideration (S222). If it is determined that it is not in the demagnetized state, the demagnetization determination is terminated (No in S222). On the other hand, when it is determined that the magnet is in a demagnetized state (Yes in S222), the determination display unit 416 displays that the magnet is in a permanent demagnetized state (S223). The display method is the same as in the first embodiment. As described above, a series of demagnetization determinations is completed.

  According to this embodiment, the motor terminal is opened with a circuit breaker and the actual voltage is measured, so that the induced voltage can be measured reliably and accurately. In other words, the influence on the inverter side is eliminated, and reliable and accurate measurement can be performed. Since the inverter does not exist if the terminal is opened by the circuit breaker, for example, in a field weakening system, no-load operation can be performed even in the high speed range where field weakening is performed, and the voltage measurement of the induced voltage is performed in this rotational speed range Can be implemented. Therefore, the demagnetization determination can be performed in a high speed region where field weakening is performed.

  Further, as a modification of the present embodiment, in this embodiment, it takes a little time to make a determination because the circuit breaker is operated. For this reason, there are cases where the demagnetization of two motors cannot be continuously determined for the convenience of the press operation. In this case, first, normal operation is performed after demagnetization determination is performed in a condition where one motor can perform demagnetization determination, and then the demagnetization is performed in a condition where demagnetization determination can be performed in another motor. Magnetic determination can also be performed.

  The above-described embodiments are merely examples, and needless to say, they can be combined or modified as appropriate.

1: Servo press machine (press machine)
2: Slide 11a, 11b: Servo motor (permanent magnet motor)
12a, 12b: Encoders 13a, 13b: Temperature detectors 21a, 21b: Inverters 22a, 22b: Voltage detectors, Voltage detector 31: Position / speed / torque control unit 41: Demagnetization determination units 301a, 301b: Vector control units 311: Position command calculation unit 312: Position / speed control unit 313a, 313b: Gain switching unit, no-load state setting means 314a: Id / Iq current command unit 315a: Current detector 316a: Coordinate conversion unit 317a: Id / Iq current Control unit, voltage detection unit 318a: coordinate conversion unit 319a: PWM control unit 401: instruction unit 402a, 402b: comparison unit 403a, 403b: comparison unit 411: load determination unit (torque determination unit)
412: Determination motor setting unit 413: Determination operation command unit 414a: Reference value calculation unit 415a: Demagnetization state comparison unit 416: Determination display unit, determination unit 417a: Coordinate conversion unit 421: Encoder switching unit 422a, 422b: Circuit breaker, No-load state setting means

Claims (10)

In a press device driven by a plurality of permanent magnet motors and mechanically connected to each motor,
A plurality of inverters each driving the plurality of permanent magnet motors ;
A load determination unit for determining a light load state during a press operation and issuing a command to perform demagnetization determination of the magnet of the permanent magnet motor;
A no-load state in which the current command to the inverter that drives at least one motor that determines the demagnetization based on the command of the load determination unit is output as zero and the motor is in an unloaded state while the inverter is in an operating state Setting means;
A voltage detection unit for detecting an induced voltage of the motor in a no-load state of the motor for determining the demagnetization;
A reference value calculation unit for calculating a voltage reference value obtained from the operating state of the motor for determining the demagnetization ;
A comparison unit for comparing the induced voltage with a voltage reference value;
A press apparatus comprising: a determination unit that determines a demagnetization state of a permanent magnet of a motor that determines the demagnetization. In the press apparatus of Claim 1,
The said determination part determines with a permanent magnet being in a demagnetization state, when the induced voltage of the motor which determines the said demagnetization is smaller than the said voltage reference value. In the press apparatus of Claim 1,
The said determination part determines the demagnetization state of a permanent magnet by the permanent demagnetization factor which is a ratio of the induced voltage of the motor which determines the said demagnetization, and the said voltage reference value. In the press apparatus of Claim 3,
Furthermore, the said determination part displays the demagnetization state of a permanent magnet by the said permanent demagnetization factor, The press apparatus characterized by the above-mentioned. In the press apparatus in any one of Claims 1-4,
The no-load state setting means is a gain switching unit that sets the current command to the inverter that drives the motor to determine demagnetization to zero,
The said voltage detection part detects the induced voltage from the control system of the said motor of a no-load state, or a motor terminal voltage, The press apparatus characterized by the above-mentioned. In the press apparatus of Claim 5,
The gain switching unit sets a current command to the motor for determining demagnetization to zero and sets the gain of the remaining motor to 100% or more so as to compensate for the gain. The press device according to claim 6, wherein
A press device characterized in that the total torque generated from a motor is the same when viewed from a torque command when demagnetization is determined and when demagnetization is not determined. In the press apparatus in any one of Claims 1-4,
The said reference value calculating part calculates the said voltage reference value with reference to the motor temperature obtained with the temperature detector provided in the motor which determines the said demagnetization . In the press apparatus in any one of Claims 1-8,
The load determination unit determines that the load is light when torque commands to the plurality of permanent magnet motors are smaller than a predetermined value. In the press apparatus in any one of Claims 1-8,
The said load determination part performs the determination of a light load state from the rotation angle of the crankshaft of the said press apparatus, The press apparatus characterized by the above-mentioned.

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