JPH11289793A - Motor injection molding machine equipped with higher harmonic control type power supply generating converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power factor of power supply through suppression of harmonic while saving power of a motor by providing a motor drive with an inverter and a converter having power recovery and harmonic suppression function. SOLUTION: The power recovery converter comprises a converter section 11 including switching elements, e.g. IGBT elements, a smoothing capacitor 12 interposed between an inverter section 10 and the converter section 11, a reactor 13 interposed between a commercial power supply and the converter section 11, a power supply voltage phase detecting section 14, a DC voltage control section 15, a noninterference current control section 16, a switching control section 17, and a three phase/two phase coordinate converting section 18. The switching control section 17 delivers a switching command for matching the actual converter input voltage with a converter input voltage command operated at the noninterference current control section 17 in a PWM control section and suppresses the switching element at the converter section 11 based on the switching command thus controlling the converter input voltage to a desired level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric injection molding machine using an electric motor as a drive source in an injection device or a mold opening / closing device.

[0002]

2. Description of the Related Art As is well known, in an electric injection molding machine, functions such as injection, mold opening and closing, metering, and ejector are realized by individually provided motors. An example of a driver in such a motor will be described with reference to FIG. 3, the driver 30 includes an inverter unit 40 and a rectifier circuit unit 50. The inverter unit 40 includes a plurality of switching elements, and the rectifier circuit unit 5
0 is realized by a capacitor input type diode rectifier circuit.

[0003] However, such a driver cannot perform power regeneration, and a current containing large harmonics flows. For this reason, the following problems occur.

A) A regenerative electric power of a motor generated at the time of opening / closing of an injection molding machine or deceleration of injection is consumed as heat by a resistor 61 provided in a dynamic brake (DB) circuit section 60. Therefore, from the viewpoint of energy saving, wasteful energy is consumed, and there arises a problem such as an increase in size due to heat generation of the resistor 61 and means for radiating the heat.

B) Since the input current contains large harmonics,
The power factor is low, resulting in an increase in power equipment and electricity rates.
In addition, a fire accident has occurred in power supply equipment such as a power factor correction circuit due to the harmonic current, and regulations on the harmonic current have begun.

[0006]

On the other hand, a conventional electric injection molding machine uses A
Although there is a countermeasure example using a passive circuit such as a C reactor or a DC reactor, the effect of suppressing harmonics and the effect of improving the power factor therefrom are small.

In a conventional electric injection molding machine,
As a countermeasure against regenerative power, there is also a system in which power regeneration is enabled by replacing the rectifier circuit unit 50 with a power regeneration converter. However, as described above, only countermeasures against the harmonics are provided by the passive circuit, and the effect of suppressing the harmonics and the effect of improving the power factor therefrom are small.

In view of such problems, an object of the present invention is to provide an electric motor equipped with a power regeneration converter capable of reducing power consumption by regenerating the power of a motor and improving the power factor by suppressing harmonics. An object of the present invention is to provide an injection molding machine.

[0009]

According to the present invention, there is provided an electric injection molding machine having a motor as a drive source, wherein a driver of the motor has an inverter, a power supply regenerative function and a harmonics suppressive function. An electric injection molding machine comprising a power regeneration converter of a mold is provided.

The power regenerative converter includes a converter section including a plurality of switching elements, a smoothing capacitor provided between the inverter and the converter section, and a DC voltage at the smoothing capacitor to detect a voltage detection value. A voltage detector to be output, the DC voltage in the smoothing capacitor matches the voltage command value according to the deviation between the voltage detection value and the voltage command value, and the input current is power factor 1 during power running operation, and during regenerative operation. Input current is power factor-
A DC voltage control unit that calculates and outputs a current command value that becomes a sine wave of 1; a power supply voltage phase detection unit that detects a power supply voltage phase; and a current that detects a power supply current and outputs a current detection value A detector and a three-phase-2 coordinate converter for converting the detected value of the power supply current into a two-phase rotating coordinate system synchronized with the power supply voltage phase based on the power supply voltage phase detected by the power supply voltage phase detector
Receiving a phase conversion unit, the phase of the power supply voltage, and the current command value, performing current control on the two-phase rotating coordinate system, and converting the input current command value such that an actual current matches the current command value. A non-interacting current control unit that calculates and outputs
A switching command is output such that an actual converter input voltage matches the converter input voltage command value, and the converter input voltage is controlled to a desired value by controlling a switching element in the converter unit based on the switching command. A switching control unit.

According to the present invention, the motor may be
Motorized injection molding characterized in that motors for at least injection, opening and closing of molds, resin metering, and ejector are individually provided, and inverters in these motors are commonly connected in parallel to one power regeneration converter. Machine is provided.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration of a motor driver according to a preferred embodiment of the present invention will be described with reference to FIG. The power regeneration converter according to the present embodiment is provided between the inverter unit 10 and a commercial power supply as in the conventional case. The power supply regenerative converter includes a converter unit 11 including a switching element such as an IGBT element or the like, a smoothing capacitor 12 provided between the inverter unit 10 and the converter unit 11, and a reactor provided between the commercial power supply and the converter unit 11 ( LC filter) 13, power supply voltage phase detector 14, DC voltage controller 15, non-interfering current controller 1
6, switching controller 17, three-phase to two-phase coordinate converter 1
8 is included. Further, a voltage detector 19 that detects a DC voltage in the smoothing capacitor 12 and provides a detection result to the DC voltage controller 15 and a current on the commercial power supply side and detects the result to a three-phase / two-phase coordinate converter 18. And a current detector 20 for applying the current.

The DC voltage control unit 15 is provided with a deviation between a preset DC voltage command value Vdc ^* and a detection voltage Vdc from the voltage detector 19. as a result,
DC voltage control unit 15, a DC voltage at the smoothing capacitor 12 matches the DC voltage command value Vdc ^*, and the input current is a current command value such that the sine wave of the power factor 1 Id * ^(power supply voltage and in-phase component) Is calculated and output. During the regenerative operation of the motor, the deviation between the DC voltage command value Vdc ^* and the detection voltage Vdc becomes negative, so that the current command value Id
The polarity of ^* becomes negative, and power regeneration is performed. At this time, the power factor is controlled to -1.

The three-phase to two-phase conversion unit 18 detects a power supply current value, that is, a power supply current detection value from the current detector 20 based on the power supply voltage phase θd ^* detected by the power supply voltage phase detection unit 14. (Three-phase alternating current) is coordinate-transformed into a two-phase rotating coordinate system synchronized with the power supply voltage phase. Then, it outputs the power supply voltage, the in-phase component Id, and the quadrature component Iq.

The non-interacting current controller 16 controls the current on the two-phase rotating coordinate system, and includes a phase θd ^{* of} the power supply voltage, an in-phase component Id and a quadrature component Iq of the power supply current, and a current command value Id ^*. Receiving the command value Iq ^* of the orthogonal component of the power supply voltage, calculates a converter input voltage command value such that the actual current matches the current command value Id ^* . The command value I
q ^* is given 0. The converter input voltage command value includes a phase command value θp ^* , a three-phase voltage command value V
u ^* , Vv ^* , and Vw ^* are included. In any case, the non-interfering current control unit 16 performs
The phase alternating current is converted into a two-phase direct current, which simplifies the control.

The switching control unit 17 includes a well-known PWM
The control unit performs control, and outputs a switching command such that the actual converter input voltage matches the converter input voltage command value calculated by the non-interference current control unit 17. By controlling the switching elements, the converter input voltage is controlled to a desired value.

As described above, the polarity of the current command value Id ^* from the DC voltage control unit 15 changes according to power running and regeneration. Based on this current command value, the current flowing from the commercial power supply to the converter is controlled to a sine wave with a power factor of 1 during power running and a sine wave with a power factor of −1 during regeneration, and efficient power transfer is realized. You.

That is, in the case of the power supply regenerative converter of the harmonic suppression type as in the present invention, the input current is always controlled to a sine wave irrespective of the power running and the regeneration. Working without. However, at the time of power running and at the time of regeneration, the current command value Id
Due to the change in the polarity of ^*, the input current becomes a sine wave with a power factor of 1 during power running, and power is supplied from the commercial power supply to the converter unit 11 side, while the power factor is -1 during regeneration.
, And power is returned from the converter unit 11 to the commercial power supply.

FIG. 2 shows an application example of the power regeneration converter to an electric injection molding machine. Here, four motors M for an injection shaft, a mold opening / closing shaft, a resin measuring shaft, and an ejector shaft are individually provided as the motors M, and respective inverters 10-1 to 10-4 for these motors M are provided.
Are commonly connected in parallel to one power regeneration converter 100 described above.

[0020]

According to the present invention described above, the following effects can be obtained.

1) The running cost is reduced due to the energy saving effect by returning the regenerative electric power conventionally consumed as heat to the power supply.

2) Since the input current is controlled to a sine wave with a power factor of 1, the power supply equipment capacity and the electricity bill are reduced, and the problematic harmonic current is greatly reduced.

3) Multi-axis (injection /
By applying this power regeneration converter to the equipment that has a mold configuration, weighing, and ejector) motors, it becomes possible to use a common converter that connects a multi-axis inverter in parallel to one power regeneration converter. An increase in size can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a power regeneration converter according to a preferred embodiment of the present invention.

FIG. 2 is a diagram showing an application example of the power regeneration converter of FIG. 1 to an electric injection molding machine.

FIG. 3 is a diagram showing an example of a driver in a motor used in a conventional electric injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10, 10-1-10-4 Inverter part 11 Converter part 12 Smoothing capacitor 14 Power supply voltage phase detection part 15 DC voltage control part 16 Non-interference current control part 17 Switching control part 18 Three phase-two phase conversion part 19 Voltage detector Reference Signs List 20 current detector 100 power regeneration converter

Claims (3)

[Claims] 1. An electric injection molding machine having a motor as a driving source, wherein a driver of the motor includes an inverter and a harmonic suppression type power regeneration converter having a power regeneration function and a harmonic suppression function. An electric injection molding machine characterized by the following. 2. The electric injection molding machine according to claim 1, wherein the power regenerative converter includes: a converter unit including a plurality of switching elements; a smoothing capacitor provided between the inverter and the converter unit; A voltage detector that detects a DC voltage in the smoothing capacitor and outputs a voltage detection value, and a DC voltage in the smoothing capacitor matches the voltage command value according to a deviation between the voltage detection value and a voltage command value, and A DC voltage control unit that calculates and outputs a current command value such that the input current has a power factor of 1 during power running operation and a sine wave with a power factor of -1 during regenerative operation, and a power supply that detects the phase of the power supply voltage A voltage phase detection unit, a current detector that detects a power supply current and outputs a current detection value, and a power supply voltage phase detected based on the power supply voltage phase detected by the power supply voltage phase detection unit. 2 in synchronism with the detected value of the source current to the power supply voltage phase
A three-phase to two-phase conversion unit for performing coordinate conversion to a phase rotation coordinate system, and receiving the phase of the power supply voltage and the current command value,
A non-interacting current control unit that performs current control on a phase rotation coordinate system, calculates and outputs a converter input voltage command value such that an actual current matches the current command value, and A switching control section that outputs a switching command such that the converter input voltages match, and controls a switching element in the converter section based on the switching command to control the converter input voltage to a desired value. Characteristic electric injection molding machine. 3. The electric injection molding machine according to claim 1, wherein at least an injection motor, a mold opening / closing device, a resin metering device, and an ejector motor are individually provided as the motor, and an inverter in these motors is provided. An electric injection molding machine characterized by being connected in parallel to one of said power regeneration converters.