Energy-saving driving system for injection molding machine

Abstract

The utility model relates to the field of injection molding machines, in particular to an energy-saving driving system for an injection molding machine. The energy-saving driving system for the injection molding machine comprises a three-phase alternating current power supply, a first filter circuit, an IGBT rectifier bridge, a second filter circuit and a first IGBT inverter bridge which are sequentially connected in series, wherein the first IGBT inverter bridge is used for being connected with a main pump motor of the injection molding machine, the first filter circuit is used for filtering power supply side harmonic waves, and the second filter circuit is used for filtering motor side alternating current harmonic waves. According to the utility model, electric energy generated by the motor can be fed back to a power grid when the motor decelerates, thereby achieving the purpose of energy saving.

Description

Technical Field

[0001] The utility model relates to the field of injection molding machines, in particular to an energy-saving driving system for injection molding machines. Background Art

[0002] In order to achieve better control accuracy, the injection molding machine will frequently start and stop the main pump motor 6 during the control process. In order to increase controllability, the current control method on the market is speed control or pressure control of the driver. In terms of motor deceleration energy release, a hydraulic solenoid valve is used to release energy or a brake resistor 20 is added to the driver side of the motor to release energy.

[0003] Figure 1 The diagram shows a principle block diagram of an existing drive system using a brake resistor 20 to release energy, including a three-phase AC power supply 1, a three-phase thyristor rectifier bridge 10, an IGBT three-phase inverter bridge 30 connected in series, and a brake resistor 20 connected in parallel with the IGBT three-phase inverter bridge 30. The IGBT three-phase inverter bridge 30 is connected to the main pump motor 6. When the main pump motor 6 is running in the first and third quadrants, the main pump motor 6 absorbs energy from the power supply side for use by various mechanisms of the injection molding machine. When the main pump motor 6 is running in the second and fourth quadrants (deceleration), the main pump motor 6 can be understood as a generator. The main pump motor 6 will generate electrical energy, which will be converted into direct current through the IGBT and released into the atmosphere in the form of brake heat energy through the brake resistor 20 on the DC side, which will cause a lot of energy waste. Summary of the invention

[0004] The technical problem to be solved by the utility model is to overcome the defects of the prior art and provide an energy-saving drive system for an injection molding machine, which can feed back the electric energy generated by the motor to the power grid when the motor slows down to achieve the purpose of energy saving.

[0005] In order to solve the above technical problems, the technical solution of the utility model is: an energy-saving drive system for an injection molding machine, comprising a three-phase AC power supply, a first filter circuit, an IGBT rectifier bridge, a second filter circuit and a first IGBT inverter bridge connected in series in sequence; wherein,

[0006] The first IGBT inverter bridge is used to connect the main pump motor of the injection molding machine, the first filter circuit is used to filter out power supply side harmonics, and the second filter circuit is used to filter out motor side AC harmonics.

[0007] Furthermore, the energy-saving drive system for the injection molding machine also includes a second IGBT inverter bridge, which is connected in parallel with the first IGBT inverter bridge and is used to connect to the electric pre-molding motor of the injection molding machine.

[0008] Furthermore, the main pump motor and the electric pre-plasticizing motor are configured to work in a time-sharing manner.

[0009] Furthermore, the first filtering circuit is an LCL filtering circuit.

[0010] Furthermore, the second filtering circuit is a filtering capacitor.

[0011] In order to further protect the entire drive circuit and the motor, the energy-saving drive system for the injection molding machine also includes a circuit breaker, which is connected in series between the three-phase AC power supply and the first filter circuit or between the first filter circuit and the IGBT rectifier bridge.

[0012] After adopting the above technical solution, when the main pump motor is running in the first and third quadrants, the main pump motor absorbs energy from the power supply side for use by various mechanisms of the injection molding machine. When the main pump motor is running in the second and fourth quadrants, the main pump motor will generate electric energy, which is inverted into direct current through the first IGBT inverter bridge and passed through the DC side, and then inverted into alternating current by the IGBT rectifier bridge and fed back to the power grid, thereby returning the electric energy originally consumed in the braking resistor to the power grid. In this way, the function of the injection molding machine is realized, and the purpose of full energy saving can be achieved, creating higher value for customers. In addition, during the operation of the main pump motor, the harmonics are filtered out by the first filter circuit, and the AC part of the DC side is filtered out by the second filter circuit, thereby ensuring that when the main pump motor is equivalent to an electric motor, the main pump motor can be accurately controlled, and when the main pump motor is equivalent to a generator, the quality of the electric energy returned to the power grid can be guaranteed, achieving the purpose of high power grid quality, high equipment power factor, and low feedback harmonic content. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the principle block diagram of the existing injection molding machine drive system;

[0014] Figure 2 This is a principle block diagram of the energy-saving drive system for an injection molding machine of the utility model;

[0015] In the figure, 1, three-phase AC power supply; 2, first filter circuit; 3, IGBT rectifier bridge; 4, second filter circuit; 5, first IGBT inverter bridge; 6, main pump motor; 7, second IGBT inverter bridge; 8, electric pre-plasticizing motor; 9, circuit breaker; 10, thyristor three-phase rectifier bridge; 20, brake resistor; 30, IGBT three-phase inverter bridge. DETAILED DESCRIPTION

[0016] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings.

[0017] Embodiment 1

[0018] like Figure 2As shown, an energy-saving drive system for an injection molding machine includes a three-phase AC power supply 1, a first filter circuit 2, an IGBT rectifier bridge 3, a second filter circuit 4 and a first IGBT inverter bridge 5 connected in series in sequence; wherein,

[0019] The first IGBT inverter bridge 5 is used to connect the main pump motor 6 of the injection molding machine, the first filter circuit 2 is used to filter out power supply side harmonics, and the second filter circuit 4 is used to filter out motor side AC harmonics.

[0020] Specifically, this embodiment is relative to Figure 1 In the prior art, the thyristor three-phase rectifier bridge 10 is replaced by an IGBT rectifier bridge, and the brake resistor 20 is eliminated. When the main pump motor 6 operates in the first and third quadrants, the AC power output by the three-phase AC power supply 1 is converted into DC power by the IGBT rectifier bridge 3, and then inverted into AC power by the first IGBT inverter bridge 5, so that the main pump motor 6 operates, and the main pump motor 6 absorbs the energy on the power supply side for use by various mechanisms of the injection molding machine. When the main pump motor 6 operates in the second and fourth quadrants, the main pump motor 6 will generate electrical energy, which is inverted into DC power by the first IGBT inverter bridge 5 and passes through the DC side, and then inverted into AC power by the IGBT rectifier bridge 3 and fed back to the power grid, thereby returning the electrical energy originally consumed in the brake resistor 20 to the power grid, so that the function of the injection molding machine is realized, and the purpose of full energy saving can be achieved, creating higher value for customers. Moreover, during the operation of the main pump motor 6, harmonics are filtered out by the first filter circuit 2, and the AC part of the DC side is filtered out by the second filter circuit 4, thereby ensuring that when the main pump motor 6 is equivalent to an electric motor, precise control of the main pump motor 6 can be achieved, and when the main pump motor 6 is equivalent to a generator, the quality of the electric energy returned to the power grid can be guaranteed, thereby achieving the goals of high power grid quality, high equipment power factor, and low feedback harmonic content.

[0021] The first filter circuit 2 may be, but is not limited to, an LCL filter circuit, including two inductors and a capacitor, the two inductors are connected in series, and the common end of the two inductors is grounded through the capacitor. The second filter circuit 4 may be, but is not limited to, a filter capacitor.

[0022] Embodiment 2

[0023] Based on the first embodiment, Figure 2 As shown, the energy-saving drive system for the injection molding machine further includes a second IGBT inverter bridge 7, which is connected in parallel with the first IGBT inverter bridge 5 and is used to connect to the electric pre-molding motor 8 of the injection molding machine.

[0024] Some large injection molding machines have an electric plasticizing function. In this embodiment, a second IGBT inverter bridge 7 is provided so that the electric energy generated by the electric pre-plasticizing motor 8 during deceleration can be returned to the power grid through the second IGBT inverter bridge 7 and the IGBT rectifier bridge 3, so that the electric pre-plasticizing motor 8 can also achieve energy saving during operation.

[0025] Embodiment 3

[0026] On the basis of the second embodiment, the main pump motor 6 and the electric pre-plasticizing motor 8 are configured to work in time-sharing mode.

[0027] Specifically, in a large injection molding machine system, the main pump motor 6 and the electric pre-plasticizing motor 8 can realize fast time-sharing control, that is, the main pump motor 6 and the electric pre-plasticizing motor 8 will not operate at the same time. The IGBT rectifier bridge 3 can operate independently, converting the city power into direct current to supply power to the first IGBT inverter bridge 5 and the second IGBT inverter bridge 7 behind. The first IGBT inverter bridge 5 is responsible for the operation of the main pump motor 6, and the second IGBT inverter bridge 7 is responsible for the operation of the electric pre-plasticizing motor 8. They are independent of each other, but do not operate at the same time, which also saves investment costs to a certain extent.

[0028] Embodiment 3

[0029] Based on the first or second embodiment, the energy-saving drive system for the injection molding machine further includes a circuit breaker 9, which is connected in series between the three-phase AC power supply 1 and the first filter circuit 2 or between the first filter circuit 2 and the IGBT rectifier bridge 3.

[0030] In this way, the entire energy-saving drive system and the motor can be protected.

[0031] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without departing from the technical concept of the utility model through the above description. The technical scope of the utility model is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An energy-saving drive system for an injection molding machine, characterized in that: It comprises a three-phase AC power supply (1), a first filter circuit (2), an IGBT rectifier bridge (3), a second filter circuit (4) and a first IGBT inverter bridge (5) which are connected in series in sequence; wherein: The first IGBT inverter bridge (5) is used to connect to a main pump motor (6) of an injection molding machine, the first filter circuit (2) is used to filter out power supply side harmonics, and the second filter circuit (4) is used to filter out motor side AC harmonics.

2. The energy-saving drive system for an injection molding machine according to claim 1, characterized in that: It also comprises a second IGBT inverter bridge (7), which is connected in parallel with the first IGBT inverter bridge (5) and is used to connect to the electric pre-molding motor (8) of the injection molding machine.

3. The energy-saving drive system for an injection molding machine according to claim 2, characterized in that: The main pump motor (6) and the electric pre-plasticizing motor (8) are configured to work in a time-sharing manner.

4. The energy-saving drive system for an injection molding machine according to claim 1, characterized in that: The first filter circuit (2) is an LCL filter circuit.

5. The energy-saving drive system for an injection molding machine according to claim 1, characterized in that: The second filter circuit (4) is a filter capacitor.

6. The energy-saving drive system for an injection molding machine according to claim 1, characterized in that: It also comprises a circuit breaker (9), wherein the circuit breaker (9) is connected in series between the three-phase AC power supply (1) and the first filter circuit (2) or between the first filter circuit (2) and the IGBT rectifier bridge (3).

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