JP2002052592A - Motor controller for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a constitution of respective units of a controller for controlling a plurality of motors used for an injection molding machine. SOLUTION: First and second three-phase inverters 12 and 13 are respectively connected to three-phase windings of a three-phase double winding motor 11, and servo controllers 14 and 15 are respectively connected to the three-phase inverters. The controllers each has the same constitution, and can be switched to a master/a slave. The first controller of the master controls the first three- phase inverter based on an output from an encoder 16, and the second controller of the slave controls the second three-phase inverter based on outputs from a second current sensor and the encoder 16 according to a control command from the first controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a motor control device for an injection molding machine, and more particularly to a motor control device for an injection molding machine for controlling a servomotor used in an electric injection molding machine or a hybrid molding machine. .

[0002]

2. Description of the Related Art Driving systems of an injection molding machine are roughly classified into a hydraulic system and an electric system. In the past, the hydraulic system was the mainstream, but now the electric system, which has the characteristics of high rigidity of the power transmission mechanism, good controllability of the position and speed of the movable part, and high energy conversion efficiency, It is becoming mainstream. In addition, the hydraulic system has a feature that the power control of the drive unit can be easily and accurately performed, which is not provided by the electric system. Therefore, a hybrid system combining the electric system and the hydraulic system has been developed.

FIG. 5 shows a configuration of a general electric injection molding machine. The electric injection molding machine includes a hopper 51 for temporarily storing a raw material, a heating cylinder 52 for plasticizing the raw material supplied from the hopper 51, and a raw material stored in the hopper 51 which is measured and supplied to the heating cylinder 52. At the same time, an injection device 54 including a screw 53 for injecting the raw material plasticized by the heating cylinder 52, and a fixed platen 5 to which dies 55 and 56 are attached, respectively.
7 and a movable platen 58, a toggle link 59 for moving the movable platen 58, and a mold clamping mechanism 61 including a tie bar 60 for guiding the movable platen 58 and restricting the moving direction. The electric injection molding machine includes an injection motor 62 for moving the screw 53 back and forth, and a measuring motor 6 for rotating the screw 53.
3. An injection device moving motor 64 for moving the entire injection device 54 back and forth, a mold opening / closing motor 65 for moving the movable platen 58, and an ejector motor for moving an eject pin 66 incorporated in the movable platen 58 back and forth. 67, the movable platen 5 according to the thickness of the molds 55 and 56.
8 and a plurality of drive motors (servo motors) such as a mold thickness corresponding motor 68 for moving the toggle link 59.

A plurality of driving motors 62 to 65, 67, 6
8 are individually driven and controlled. For example, when each of the driving motors is a three-phase motor, as shown in FIG. 6, each of the driving motors 62 to 65, 67, and 68 is provided with a servo controller 71 via a three-phase inverter 70. Connected. Each drive motor is provided with an encoder 72 for detecting its rotation and a current sensor 73 for detecting the magnitude of the drive current supplied from the three-phase inverter 70. The detection signal from the sensor 73 is fed back to the servo controller 71.

The servo controller 71 includes an encoder 72 and a current sensor 7 under the control of a host controller (not shown).
A control signal is output to the three-phase inverter 70 based on the detection signal fed back from 3. The three-phase inverter 70 generates U, V, and W three-phase signals (drive currents) in accordance with a control signal from the servo controller 71,
Supply to three-phase motor. Thus, the three-phase motor rotates by the designated rotation amount at the timing designated by the host controller.

As described above, in the electric injection molding machine,
Under the control of the host controller, each of the motors 42 to 47 is independently controlled by a corresponding servo controller to perform injection molding.

[0007]

The hydraulic drive system has the feature that it is possible to increase the transmitted energy per unit time with a relatively small device, so that a large-sized (high-output) injection molding machine is used. Still employs a hydraulic drive system. However, there is a considerable demand for adopting an electric drive system or a hybrid system for a large injection molding machine.

In order to adopt an electric drive system or a hybrid system for a large injection molding machine, a large output motor is required. In order to control a high-output motor, the maximum withstand voltage of the inverter is increased, the maximum current is increased, and the corresponding voltage of a control system such as a servo controller is increased from 200V class to 4%.
It must be increased, such as by changing to a 00V class.

On the other hand, the maximum output torque of the motor required in the injection molding machine differs for each movable part. For example, the maximum output torque required of the motor for opening and closing the mold and the required output torque of the ejector motor are different. There is a considerable difference from the maximum output torque. Further, even during the molding cycle, the output torque required of the motor is not constant, and there are times when a large torque is required and times when a small torque is sufficient. Therefore, when an electric drive system or the like is adopted for a large injection molding machine, a motor corresponding to the maximum output torque and torque change required for each movable unit,
There is a problem that an inverter and a servo controller must be prepared, and a control device for each motor cannot be shared.

[0010] It is an object of the present invention to provide a common control unit for controlling a motor used in an injection molding machine. In other words, the present invention
An object of the present invention is to provide a control device for controlling a motor having a large maximum output by utilizing a circuit for a control device for controlling a motor having a small maximum output.

Japanese Patent Application Laid-Open No. 7-298885 discloses an invention for driving a six-phase induction motor using two inverters. Japanese Patent Application Laid-Open No. 2000-41392 discloses two three-phase winding motors. A brushless DC motor in which inverter circuits are connected to respective lines is disclosed.
However, in these inventions, since the two inverters are connected to the same controller, it is necessary to change the configuration (software) of the controller according to the purpose of use. Therefore, the inventions described in these publications do not suggest any purpose of sharing the control device of the present invention, nor do they disclose or suggest any means for achieving the purpose. .

[0012]

According to the present invention, there is provided a motor control device for an injection molding machine for driving and controlling a motor used in an injection molding machine, comprising: an AC motor having a plurality of three-phase windings; A plurality of threes respectively connected to a plurality of three-phase windings
A motor control device for an injection molding machine, comprising: a phase inverter; and a plurality of servo controllers respectively connected to the plurality of three-phase inverters.

The motor control device for an injection molding machine includes an encoder for detecting rotation of the AC motor, a plurality of sets of current sensors for detecting drive currents supplied to the plurality of three-phase windings, respectively. Comprising, the plurality of servo controllers, based on an output from the set of current sensors for detecting a drive current supplied to the three-phase winding corresponding to each servo controller, and an output from the encoder. The three-phase inverters corresponding to the respective servo controllers are controlled.

Here, it is desirable that the plurality of servo controllers be connected to each other so that the phases of drive currents supplied from the plurality of three-phase inverters to the plurality of three-phase windings match.

Alternatively, the motor control device for an injection molding machine comprises: an encoder for detecting rotation of the AC motor; and a plurality of sets of currents for detecting drive currents respectively supplied to the plurality of three-phase windings. Sensors, one of the plurality of servo controllers is connected to the encoder and the plurality of sets of current sensors as a master controller, another servo controller is connected to the master controller as a slave controller, the master controller , Based on an output from the set of current sensors for detecting a drive current supplied to the three-phase winding corresponding to the master controller and an output from the encoder, In addition to controlling the inverter, each slave controller An output from the set of current sensors for detecting a drive current supplied to the corresponding said 3-phase windings,
A slave control signal for controlling the three-phase inverter corresponding to each slave controller is generated based on the output from the encoder, and each slave controller generates a slave control signal based on the slave control signal from the master controller. The three-phase inverter corresponding to the controller is controlled.

As the AC motor, a three-phase double-winding AC motor or a six-phase AC motor can be used.

According to the present invention, when a large torque is required, the AC motor is controlled using the plurality of three-phase inverters and the plurality of servo controllers, so that a large torque is not required. In this case, a motor control device for an injection molding machine is obtained, wherein one of the plurality of three-phase inverters and a servo controller connected to the inverter control the AC motor.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. A motor control device for an injection molding machine in FIG. 1 includes a three-phase double-winding motor 11 having two three-phase windings, and two three-phase motors 11.
A first and a second 3 for respectively supplying a drive current to the phase winding;
Phase inverters 12 and 13, first and second servo controllers 14 and 15 connected to the first and second inverters 12 and 13, respectively, and an encoder 16 attached to the motor 11 and detecting its rotation. , A first and a second for detecting a drive current supplied to each three-phase winding, respectively.
Current sensors 17 and 18.

The three-phase double-winding motor 11 is
Two U, V, and W phase windings (U1, V
1, W1 and U2, V2, W2), and these are stacked and wound. Assuming that a normal three-phase winding is represented as shown in FIG.
become that way.

First and second three-phase inverters 12 and 13
Have the same configuration, and are each configured using a plurality of power transistors and diodes, as shown in FIG. Then, these three-phase inverters 1
2 and 13 have the ability to supply at least half of the drive current required to obtain the maximum output required for the three-phase double winding motor 11.

The first and second servo controllers 14,
Reference numeral 15 has the same configuration (operates with the same software) and has a control capability corresponding to a motor having a maximum output that is half of the maximum output required for the three-phase double winding motor 11. These first and second servo controllers 14, 1
5 is capable of switching between master / slave, where the first servo controller 14 is the master,
The second servo controller 15 is switched to the slave. The first servo controller 14 set as the master is connected to a higher-level control device (not shown). Also, the second servo controller 1 set as a slave
5 is connected to the first servo controller 14 set as a master.

The encoder 16 is a three-phase double winding motor 1
One rotation is detected, a predetermined number of pulses are generated for each rotation, and output to the first and second servo controllers 14 and 15. First and second servo controllers 14 and 15
Is the rotation speed of the three-phase double winding motor 11 from the number of pulses input per unit time, and 3 from the total number of pulses.
The rotation amount of the phase double winding motor 11 can be obtained.

The first and second current sensors 17, 18 are:
Drive currents flowing through the windings U1 and V1 and the windings U2 and V2 are detected, and the detected values are output to the first and second servo controllers 14 and 15, respectively. The first and second servo controllers 14 and 15 determine a value of 3 based on the detected value and the rotation speed and rotation amount of the three-phase double winding motor.
Control the phase inverter.

Next, the operation of the motor control device for an injection molding machine will be described.

First, the first servo controller 14
An operation command is received from a host controller (not shown). If the command is to generate a large torque, the first servo controller 14 outputs a necessary control command to the second servo controller 15.
In addition, the first servo controller 14
The synchronization signal is supplied to the servo controller 15.

Next, the first servo controller 14
A control signal is output to first three-phase inverter 12 in accordance with an operation command from a higher-level device. Similarly, the second servo controller 15 outputs a control signal to the second three-phase inverter 13 at a timing synchronized with the synchronization signal according to a control command from the first servo controller 14.

First and second three-phase inverters 12 and 13
Are the first and second servo controllers 14,
A drive current is generated in accordance with the control signal from 15 and supplied to the three-phase double-winding motor 11. Thereby, the three-phase double winding motor 11 rotates.

The encoder 16 is a three-phase double winding motor 1
One rotation is detected, and a detection pulse is output to the first and second servo controllers 14 and 15. Further, the first and second current sensors 17 and 18 are connected to the windings U1 and V1, respectively.
1 and drive currents flowing through the windings U2 and V2, respectively, and detect the detected values with the first and second servo controllers 1 and 2.
Output to 4,15.

The first servo controller 14 changes a control signal to the first three-phase inverter 12 based on a detection value from the first current sensor 17 and a detection pulse from the encoder 16. Similarly, the second servo controller 15 outputs the detection value from the second current sensor 18 and
The control signal to the second three-phase inverter 13 is changed based on the detection pulse from the encoder 16. As a result, the drive current supplied from the first and second three-phase inverters 12 and 13 to the three-phase double winding motor 11 changes,
The rotation torque, speed, and the like of the phase double winding motor 11 are controlled.

As described above, this control device can generate a large torque in the three-phase double winding motor 11 without using a special inverter or controller for a large output motor.

When the operation command received from the host controller by the first servo controller 14 is to generate a small torque, the servo controller 14 does not output a control command to the second servo controller 15. . Then, the first servo controller 14 alone controls the rotation of the three-phase double-winding motor 11. That is,
The first servo controller 14 outputs a control signal to the first three-phase inverter 12 according to an operation command from a higher-level device, and the first three-phase inverter 12 outputs a drive current to the three-phase two-phase inverter 2 according to the control signal. It is supplied to the heavy winding motor 11.
Then, the first servo controller 14 changes a control signal to the first three-phase inverter 12 based on a detection value from the first current sensor 17 and a detection pulse from the encoder 16.

Thus, in this control device, by operating only one of the servo controllers and suspending the other, a small torque can be generated in the three-phase double winding motor 11.

As described above, according to the control device of the present invention,
When a large torque is required, the motor is controlled using a plurality of inverters and a plurality of servo controllers. When a large torque is not required, the motor is controlled using a single inverter and a single servo controller. can do. That is, if the control device of the present invention is used,
It is possible to control motors of various magnitudes regardless of the maximum output torque, from a motor having a small maximum output torque to a motor having a large maximum output torque. From another viewpoint, since the control device of the present invention is configured by using a plurality of controllers and inverters having the same configuration, by changing the number, the size of the motor to be controlled can be reduced. The configuration can be easily changed accordingly.
In this case, since different types of controllers and inverters are not required, the cost can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, only differences from the first embodiment will be described.

The motor control device for the injection molding machine shown in FIG.
It has a six-phase motor 31 instead of the phase double winding motor 11. The windings of the six-phase motor 31 are as shown in FIG. Further, the encoder 16 is connected only to the first servo controller 32, and is not connected to the second servo controller 33. Furthermore, the first and second current sensors 17 and 18 are both connected to the first servo controller 32.

The first and second servo controllers 32,
33 has the same configuration as in the first embodiment, and can be switched between master and slave. Here, the first servo controller 32 is set as a master and the second servo controller is set as a slave, and the first servo controller 32 is connected to a host device (not shown). Then, under the control of the host device, the first servo controller 32 performs the first three-phase control based on the detection values from the first and second current sensors 17 and 18 and the detection pulse from the encoder 16. A control signal to be output to the inverter 12,
A control command to be output to the second servo controller 33 is generated. Further, the second servo controller 33 controls the three-phase inverter 13 based only on a control command from the first servo controller 32.

Also in the present embodiment, when the required torque is large, the first and second three-phase inverters 12,
13 supplies drive current to the six-phase motor 31. When the required torque is small, the drive current is supplied from only the first three-phase inverter 12 to the six-phase motor 31. In this way, even with the control device according to the present embodiment, it is possible to control motors of various sizes from those having a small maximum output torque to those having a large maximum output torque, regardless of the maximum output torque.

In the first embodiment, the three-phase two-phase
An example using a heavy winding is described. In the above-described second embodiment, an example using a six-phase motor has been described. However, in the first embodiment, a six-phase motor is used, and the second embodiment is used. Alternatively, a three-phase double-winding motor may be used. In any case, not only a motor having two three-phase windings but also a motor having more three-phase windings may be used.

[0040]

According to the present invention, in a motor control device for an injection molding machine, an AC motor having a plurality of three-phase windings is controlled using a combination of a plurality of three-phase inverters and a plurality of servo controllers. By doing so, the AC motor can be controlled without using a special circuit or the like for a large output motor, and a large torque to a small torque can be generated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a motor control device for an injection molding machine according to a first embodiment of the present invention.

2A is a connection diagram of windings used in a three-phase motor, and FIG. 2B is a connection diagram of windings used in a three-phase double winding motor.

FIG. 3 is a block diagram showing a motor control device for an injection molding machine according to a second embodiment of the present invention.

FIG. 4 is a connection diagram of windings used in a six-phase motor.

FIG. 5 is a view for explaining a configuration of a general electric injection molding machine.

FIG. 6 is a block diagram illustrating a motor control device of a general three-phase motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Three-phase double winding motor 12 First three-phase inverter 13 Second three-phase inverter 14 First servo controller 15 Second servo controller 16 Encoder 17 First current sensor 18 Second current sensor 31 6 Phase motor 32 first servo controller 33 second servo controller

Claims (7)

[Claims] 1. A motor control device for an injection molding machine for controlling the driving of a motor used in the injection molding machine.
An AC motor having a phase winding; a plurality of three-phase inverters respectively connected to the plurality of three-phase windings; and a plurality of servo controllers respectively connected to the plurality of three-phase inverters. A motor control device for an injection molding machine, characterized in that: 2. The plurality of servo controllers, comprising: an encoder for detecting rotation of the AC motor; and a plurality of sets of current sensors each detecting a drive current supplied to each of the plurality of three-phase windings. Is based on an output from the set of current sensors that detects a drive current supplied to the three-phase winding corresponding to each servo controller, and an output from the encoder. 2. The motor control device for an injection molding machine according to claim 1, wherein the three-phase inverter is controlled. 3. The plurality of servo controllers are connected to each other, and the phases of drive currents supplied from the plurality of three-phase inverters to the plurality of three-phase windings are matched. 2. A motor control device for an injection molding machine. 4. A servo controller comprising: an encoder for detecting rotation of the AC motor; and a plurality of sets of current sensors for respectively detecting drive currents supplied to the plurality of three-phase windings, respectively. One of the three controllers is connected to the encoder and the plurality of sets of current sensors as a master controller, the other servo controller is connected to the master controller as a slave controller, and the master controller is connected to the three-phase controller corresponding to the master controller. Based on the output from the set of current sensors that detect the drive current supplied to the windings and the output from the encoder, control the three-phase inverter corresponding to the master controller, and Driving current supplied to the corresponding three-phase winding Based on the output from the set of current sensors that detect
A slave control signal for controlling the three-phase inverter corresponding to each slave controller is generated, and each slave controller controls the three-phase inverter corresponding to the slave controller based on the slave control signal from the master controller. 2. The motor control device for an injection molding machine according to claim 1, wherein 5. The motor control device for an injection molding machine according to claim 1, wherein said AC motor is a three-phase double winding AC motor. 6. The motor control device for an injection molding machine according to claim 1, wherein said AC motor is a six-phase winding AC motor. 7. When a large torque is required, the AC motor is controlled using the plurality of three-phase inverters and the plurality of servo controllers, and when a large torque is not required, the AC motor is controlled. 7. A motor control for an injection molding machine according to claim 1, wherein one of said three-phase inverters and a servo controller connected thereto are controlled to said AC motor. apparatus.