JP3661578B2 - Motor controller for injection molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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 servo motor used in an electric injection molding machine or a hybrid molding machine.
[0002]
[Prior art]
The drive system of the injection molding machine is roughly divided into a hydraulic system and an electric system. Previously, the hydraulic system was the mainstream, but now the electric system has the characteristics that the power transmission mechanism has high rigidity, the controllability of the position and speed of the movable part is good, and the energy conversion efficiency is high. It is becoming mainstream. In addition, since the hydraulic system has a feature not available in the electric system in that the force control of the drive unit can be performed easily and accurately, a hybrid system combining the electric system and the hydraulic system has been developed.
[0003]
FIG. 5 shows a configuration of a general electric injection molding machine. This electric injection molding machine has a hopper 51 for temporarily storing the raw material, a heating cylinder 52 for plasticizing the raw material supplied from the hopper 51, a raw material stored in the hopper 51, and supplying it to the heating cylinder 52. At the same time, the injection device 54 including a screw 53 for injecting the plasticized material by the heating cylinder 52, the fixed platen 57, the movable platen 58, and the movable platen 58 to which the molds 55 and 56 are respectively attached are moved. And a mold clamping mechanism 61 including a tie bar 60 that guides the toggle link 59 and the movable platen 58 and restricts the moving direction thereof. The electric injection molding machine includes an injection motor 62 for moving the screw 53 back and forth, a metering motor 63 for rotating the screw 53, and an injection device moving motor 64 for moving the entire injection device 54 forward and backward. The mold opening / closing motor 65 for moving the movable platen 58, the ejector motor 67 for moving the eject pin 66 built in the movable platen 58 back and forth, the movable platen 58 and the toggle link according to the thickness of the dies 55, 56 A plurality of driving motors (servo motors) such as a mold thickness handling motor 68 for moving 59 are provided.
[0004]
The plurality of drive motors 62 to 65, 67, 68 are individually driven and controlled. For example, when each driving motor is a three-phase motor, each of the driving motors 62 to 65, 67, 68 has a servo controller 71 via a three-phase inverter 70 as shown in FIG. 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. Detection signals from the sensor 73 are fed back to the servo controller 71.
[0005]
The servo controller 71 outputs a control signal to the three-phase inverter 70 based on the detection signal fed back from the encoder 72 and the current sensor 73 under the control of a host controller (not shown). The three-phase inverter 70 generates U, V, and W three-phase signals (drive currents) in response to a control signal from the servo controller 71 and supplies it to the three-phase motor. Thus, the three-phase motor rotates by the instructed rotation amount at the timing instructed from the host controller.
[0006]
As described above, in the electric injection molding machine, the motors 42 to 47 are independently controlled by the corresponding servo controllers under the control of the host controller, and injection molding is performed.
[0007]
[Problems to be solved by the invention]
The hydraulic drive system has the feature that it is possible to increase the transmission energy per unit time with relatively small equipment, so the hydraulic drive system is still adopted for large (high output) injection molding machines. Has been. However, there are many requests for adopting the electric drive system or the hybrid system for large-sized injection molding machines.
[0008]
In order to employ an electric drive system or a hybrid system in a large injection molding machine, a high output motor is required. In order to control a high-output motor, the maximum withstand voltage of the inverter is increased or the maximum current is increased, and the corresponding voltage is also applied to a control system such as a servo controller, for example, from 200 V class to 400 V class. It must be enlarged, such as changing to.
[0009]
On the other hand, the maximum output torque of the motor required in the injection molding machine is different for each movable part. For example, the maximum output torque required for the mold opening / closing motor and the maximum output torque required for the ejector motor And there is a big difference. Also, even during the molding cycle, the output torque required for the motor is not constant, and there are cases where a large torque is required and a case where a small torque is sufficient. Therefore, when an electric drive system is adopted for a large injection molding machine, a motor, an inverter and a servo controller corresponding to the maximum output torque and torque change required for each movable part must be prepared. There is a problem that the motor control device cannot be shared.
[0010]
An object of the present invention is to make it possible to share each part of a control device for controlling a motor used in an injection molding machine. In other words, an object of the present invention is to provide a control device for controlling a motor with a large maximum output by using a circuit for a control device for controlling a motor with a small maximum output.
[0011]
JP-A-7-298865 discloses an invention for driving a six-phase induction motor using two inverters, and JP-A 2000-41392 discloses two three-phase windings, respectively. A brushless DC motor formed by connecting an inverter circuit 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 the purpose of sharing the control device of the present invention, nor do they disclose or suggest any means for achieving the purpose. .
[0012]
[Means for Solving the Problems]
According to the present invention, in the motor control device for an injection molding machine, an AC motor having a plurality of three-phase windings, a plurality of three-phase inverters connected to the plurality of three-phase windings, A plurality of servo controllers respectively connected to the three-phase inverter , the plurality of servo controllers are connected to each other, and the phases of the drive currents supplied from the plurality of three-phase inverters to the plurality of three-phase windings coincide with each other A motor control device for an injection molding machine is obtained, which is characterized by doing so .
[0013]
The motor control device for an injection molding machine includes an encoder for detecting rotation of the AC motor, and a plurality of sets of current sensors for detecting drive currents respectively supplied to the plurality of three-phase windings, The plurality of servo controllers, based on the output from the set of current sensors for detecting the drive current supplied to the three-phase winding corresponding to each servo controller, and the output from the encoder, the servo controller The three-phase inverters respectively corresponding to the above are controlled.
[0015]
Alternatively, the motor control device for an injection molding machine includes an encoder for detecting the rotation of the AC motor and a plurality of sets of current sensors for detecting drive currents respectively supplied to the plurality of three-phase windings. One of the plurality of servo controllers is connected to the encoder and the plurality of sets of current sensors as a master controller, and another servo controller is connected to the master controller as a slave controller, and the master controller The three-phase inverter corresponding to the master controller is controlled based on the output from the set of current sensors for detecting the drive current supplied to the three-phase winding corresponding to the controller and the output from the encoder. And before responding to each slave controller Slave control for controlling the three-phase inverter corresponding to each slave controller based on the output from the set of current sensors for detecting the drive current supplied to the three-phase winding and the output from the encoder A signal 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.
[0016]
Incidentally, Examples AC motor are available three-phase double winding AC motor.
[0017]
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, and when a large torque is not required. A motor control device for an injection molding machine is obtained in which any one of the plurality of three-phase inverters and a servo controller connected thereto are controlled by the AC motor.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 shows a first embodiment of the present invention. The 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 a first and a second that supply driving currents to the two three-phase windings, respectively. Three-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 that is attached to the motor 11 and detects its rotation. And first and second current sensors 17 and 18 for detecting drive currents supplied to the three-phase windings, respectively.
[0020]
The three-phase double winding motor 11 has two U, V, and W phase windings (U1, V1, W1, U2, V2, and W2) having a phase angle of 120 degrees with each other. It is a roll. The windings are as shown in FIG. 2 (b) assuming that ordinary three-phase windings are represented as shown in FIG. 2 (a).
[0021]
The 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. Both of these three-phase inverters 12 and 13 have the capability of supplying at least half of the drive current necessary to obtain the maximum output required for the three-phase double winding motor 11.
[0022]
The first and second servo controllers 14 and 15 have the same configuration (operate with the same software) and correspond to a motor having a maximum output that is half of the maximum output required for the three-phase double winding motor 11. Has control ability. These first and second servo controllers 14 and 15 can be switched between master and slave, respectively. Here, the first servo controller 14 is set as a master and the second servo controller 15 is set as a slave. Yes. The first servo controller 14 set as the master is connected to a host controller (not shown). The second servo controller 15 set as the slave is connected to the first servo controller 14 set as the master.
[0023]
The encoder 16 detects the rotation of the three-phase double winding motor 11, generates a predetermined number of pulses for each rotation, and outputs the pulses to the first and second servo controllers 14 and 15. The first and second servo controllers 14 and 15 determine the rotation speed of the three-phase double winding motor 11 from the number of pulses input per unit time and the three-phase double winding motor 11 from the total number of pulses. The amount of rotation can be determined.
[0024]
The first and second current sensors 17 and 18 detect drive currents flowing through the windings U1 and V1 and the windings U2 and V2, respectively, and detect the detected values as the first and second servo controllers 14 and 15, respectively. Output to. The first and second servo controllers 14 and 15 control the three-phase inverter based on the detected value and the rotation speed and rotation amount of the three-phase double winding motor.
[0025]
Next, operation | movement of this motor control apparatus for injection molding machines is demonstrated.
[0026]
First, the first servo controller 14 receives an operation command from a host controller (not shown). When the command is to generate a large torque, the first servo controller 14 outputs a necessary control command to the second servo controller 15. The first servo controller 14 then supplies a synchronization signal to the second servo controller 15.
[0027]
Next, the first servo controller 14 outputs a control signal to the first three-phase inverter 12 in accordance with an operation command from the host 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 in accordance with a control command from the first servo controller 14.
[0028]
The first and second three-phase inverters 12 and 13 generate drive currents according to control signals from the first and second servo controllers 14 and 15, respectively, and supply them to the three-phase double winding motor 11. To do. Thereby, the three-phase double winding motor 11 rotates.
[0029]
The encoder 16 detects the rotation of the three-phase double winding motor 11 and outputs a detection pulse to the first and second servo controllers 14 and 15. The first and second current sensors 17 and 18 detect the driving currents flowing through the windings U1 and V1 and the windings U2 and V2, respectively, and detect the detected values as the first and second servo controllers 14, 15 is output.
[0030]
The first servo controller 14 changes the control signal to the first three-phase inverter 12 based on the detection value from the first current sensor 17 and the detection pulse from the encoder 16. Similarly, the second servo controller 15 changes the control signal to the second three-phase inverter 13 based on the detection value from the second current sensor 18 and 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, and the rotational torque, speed, etc. of the three-phase double winding motor 11 are controlled. Is done.
[0031]
As described above, in this control device, a large torque can be generated in the three-phase double winding motor 11 without using a special inverter or controller for a high output motor.
[0032]
When the operation command received by the first servo controller 14 from the host control device is to generate a small torque, the servo controller 14 does not output a control command to the second servo controller 15. The first servo controller 14 controls the rotation of the three-phase double winding motor 11 independently. That is, the first servo controller 14 outputs a control signal to the first three-phase inverter 12 in accordance with an operation command from the host device, and the first three-phase inverter 12 outputs a drive current of 3 according to the control signal. It is supplied to the phase double winding motor 11. Then, the first servo controller 14 changes the control signal to the first three-phase inverter 12 based on the detection value from the first current sensor 17 and the detection pulse from the encoder 16.
[0033]
Thus, in this control device, only one servo controller is operated, and the other is stopped, so that a small torque can be generated in the three-phase double winding motor 11.
[0034]
As described above, according to the control device of the present invention, when a large torque is required, a motor is controlled using a plurality of inverters and a plurality of servo controllers, and when a large torque is not required, Control can be performed using one inverter and one servo controller. That is, by using the control device of the present invention, 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. From another point of view, 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 increased. The configuration can be easily changed accordingly. In this case, since different types of controllers and inverters are not required, costs can be reduced.
[0035]
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.
[0036]
The motor control device for an injection molding machine in FIG. 3 has a six-phase motor 31 instead of the three-phase double winding motor 11. The windings of the six-phase motor 31 are as shown in FIG. 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.
[0037]
As in the first embodiment, the first and second servo controllers 32 and 33 have the same configuration 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, the first servo controller 32 controls the first three-phase based on the detection values from the first and second current sensors 17 and 18 and the detection pulse from the encoder 16 under the control of the host device. A control signal to be output to the inverter 12 and a control command to be output to the second servo controller 33 are generated. Further, the second servo controller 33 controls the three-phase inverter 13 based only on the control command from the first servo controller 32.
[0038]
Also in the present embodiment, when the required torque is large, the drive current is supplied from both the first and second three-phase inverters 12 and 13 to the six-phase motor 31. When the required torque is small, the drive current is supplied to the six-phase motor 31 only from the first three-phase inverter 12. Thus, the control device according to the present embodiment can 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.
[0039]
In the first embodiment, an example using a three-phase double winding has been described. In the second embodiment, an example using a six-phase motor has been described. A six-phase motor may be used in this embodiment, and a three-phase double winding motor may be used in the second embodiment. 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]
【The invention's effect】
According to the present invention, in the 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. Thus, the AC motor can be controlled without using a special circuit for a high output motor, and a large torque can be generated to a small torque.
[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 diagram for explaining a configuration of a general electric injection molding machine.
FIG. 6 is a block diagram showing a motor control device of a general three-phase motor.
[Explanation 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 (5)

In the motor control device for injection molding machines,
An AC motor having a plurality of three-phase windings;
A plurality of three-phase inverters respectively connected to the plurality of three-phase windings;
A plurality of servo controllers respectively connected to the plurality of three-phase inverters;
A motor control apparatus for an injection molding machine, characterized in that the plurality of servo controllers are connected to each other so that phases of drive currents supplied from the plurality of three-phase inverters to the plurality of three-phase windings coincide with each other. .   An encoder for detecting the rotation of the AC motor; and a plurality of sets of current sensors for detecting drive currents respectively supplied to the plurality of three-phase windings. The three-phase inverters respectively corresponding to the servo controllers are controlled based on the output from the set of current sensors that detect the drive current supplied to the three-phase winding corresponding to and the output from the encoder The motor control device for an injection molding machine according to claim 1, wherein the motor control device is used.   An encoder for detecting the rotation of the AC motor; and a plurality of sets of current sensors for detecting drive currents respectively supplied to the plurality of three-phase windings, wherein one of the plurality of servo controllers A master controller is connected to the encoder and the plurality of sets of current sensors, and another servo controller is connected to the master controller as a slave controller, and the master controller is supplied to the three-phase winding corresponding to the master controller. The three-phase inverter corresponding to the master controller is controlled based on the output from the set of current sensors for detecting the drive current and the output from the encoder, and the three-phase corresponding to each slave controller. Before detecting the drive current supplied to the winding Based on the output from the set of current sensors and the output from the encoder, a slave control signal for controlling the three-phase inverter corresponding to each slave controller is generated, and each slave controller receives a signal from the master controller. 2. The motor control device for an injection molding machine according to claim 1, wherein the three-phase inverter corresponding to the slave controller is controlled based on the slave control signal.   The motor control apparatus for an injection molding machine according to any one of claims 1 to 3, wherein the AC motor is a three-phase double winding AC motor.   When a large torque is required, the AC motor is controlled using the plurality of three-phase inverters and the plurality of servo controllers. When a large torque is not required, the plurality of three-phase inverters 5. The motor control device for an injection molding machine according to claim 1, wherein any one of them and a servo controller connected thereto controls the AC motor.

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