Industrial systems, industrial machinery

Abstract

To suppress the increase of harmonics generated by switching in industrial systems with multiple converters.SOLUTION: The industrial system includes a first industrial machine and a second industrial machine. The first industrial machine includes a first converter that includes a first switching circuit and converts AC power received from a grid power source into DC power and a first controller that controls the first switching circuit, and the second industrial machine includes a second switching circuit, The second industrial machine includes a second converter that converts AC power received from a grid power source into DC power, and a second controller that controls the second switching circuit. Based on communication with the second controller, the first controller drives the first switching circuit using a carrier wave with a phase different from that of the carrier wave used to drive the second switching circuit.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to industrial systems and industrial machines. [Background technology]

[0002] In factories, various industrial machines including injection molding machines are operated using commercial power supplied by electric power companies. Injection molding machines are machines that manufacture molded products using resin such as plastic as a base material. Patent Document 1 (JP 2022-077586 A) describes an injection molding machine that converts three-phase AC power supplied from a commercial power source into DC power using a converter, and then converts the converted DC power back into AC power using a servo amplifier to drive a servo motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-077586 Summary of the Invention [Problem to be solved by the invention]

[0004] In a factory, multiple injection molding machines may be provided with multiple control devices that control the switching circuits of the converters included in each of the multiple converters. When the switching circuits included in each of the multiple converters are switched in phase, harmonics generated by the switching are superimposed, increasing the distortion of the input AC power (fundamental wave). This increase in distortion becomes power supply noise for devices connected to the same power supply system, which can cause malfunctions, etc.

[0005] The present disclosure has been made to solve such problems, and its purpose is to suppress an increase in harmonics generated by switching in industrial machinery in which power conversion is performed by multiple converters each controlled by multiple control devices. [Means for solving the problem]

[0006] An industrial system according to one embodiment includes a first industrial machine and a second industrial machine. The first industrial machine includes a first converter including a first switching circuit and converting AC power received from a grid power supply into DC power, and a first control device that controls the first switching circuit. The second industrial machine includes a second converter including a second switching circuit and converting AC power received from a grid power supply into DC power, and a second control device that controls the second switching circuit. The first control device drives the first switching circuit using a carrier wave with a phase different from that of a carrier wave for driving the second switching circuit, based on communication with the second control device. Effect of the Invention

[0007] According to the industrial machine according to the present disclosure, in an industrial machine in which power conversion is performed by a plurality of converters each controlled by a plurality of control devices, an increase in harmonics generated by switching is suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an outline of the configuration of an injection molding system as an industrial system in a first embodiment. [Diagram 2] FIG. 1 is a block diagram for illustrating a configuration of an injection molding system as an industrial system in a first embodiment. [Diagram 3] FIG. 2 is a diagram for explaining a configuration of a switching circuit in a converter. [Figure 4] 4 is a flowchart for explaining the operation of the control device. [Diagram 5]FIG. 2 is a diagram for explaining the phase of a switching circuit. [Figure 6] FIG. 11 is a diagram for explaining the phase of a switching circuit in a comparative example. [Figure 7] FIG. 11 is a diagram showing an outline of the configuration of an injection molding machine in a second embodiment. [Figure 8] FIG. 11 is a block diagram for explaining the configuration of an injection molding machine in a second embodiment. [Figure 9] FIG. 11 is a block diagram for explaining the configuration of an injection molding machine 50 according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0010] [Embodiment 1] In the following, an injection molding system 1000 serving as an industrial system in the first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an outline of the configuration of an injection molding system 1000 serving as an industrial system in the first embodiment.

[0011] Injection molding system 1000 as an industrial system in the first embodiment includes injection molding machine 50A and injection molding machine 50B. In the first embodiment, injection molding machine 50A as an industrial machine and injection molding machine 50B as an industrial machine have the same configuration, and hereinafter, injection molding machine 50A and injection molding machine 50B will be collectively referred to simply as "injection molding machine 50."

[0012] The injection molding machines 50A and 50B are industrial machines that are driven by power supplied from a power system Pw1. More specifically, the injection molding machines 50A and 50B convert AC power received from the power system Pw1 into DC power using converters 200A and 200B, respectively. The injection molding machine 50A supplies the converted DC power to servo amplifiers Sa1 and Sa1. The injection molding machine 50B supplies the converted DC power to servo amplifiers Sa3 and Sa4. The frequency of the AC power supplied from the power system Pw1 is, for example, 50 Hz or 60 Hz.

[0013] <Injection molding machine configuration> Each of the injection molding machines 50A and 50B is a horizontal injection molding machine having a mold clamping device 60 and an injection device 61. The injection molding process performed by each of the injection molding machines 50AA and 50B includes processes such as a mold clamping process, an injection process, a pressure holding process, a cooling process, a mold opening process, an ejection process, and a plasticization process. Each of the injection molding machines 50A and 50B repeatedly executes a cycle of the injection molding process. Each of the injection molding machines 50A and 50B is capable of molding molded products of various shapes and materials, and performs the injection molding process according to the type of shape and material.

[0014] The injection molding machine 50A includes a plurality of servo motors used in the injection molding process, and servo amplifiers Sa1 and Sa2 that drive the plurality of servo motors. Each of the servo amplifiers Sa1 and Sa2 generates a three-phase AC voltage from the DC voltage converted by the converter 200A to drive the servo motor. The injection molding machine 50B includes a plurality of servo motors used in the injection molding process, and servo amplifiers Sa3 and Sa4 that drive the plurality of servo motors. Each of the servo amplifiers Sa3 and Sa4 generates a three-phase AC voltage from the DC voltage converted by the converter 200B to drive the servo motor.

[0015] Each of the injection molding machines 50A and 50B includes a clamping device 60 that clamps a mold, an injection device 61 that melts and injects an injection material, and a display device 30. Each of the injection molding machines 50A and 50B is placed on an XY plane. The direction perpendicular to the XY plane is defined as the Z-axis direction. The positive direction of the Z-axis in FIG. 1 may be referred to as the upper side or upward, and the negative direction as the lower side or downward.

[0016] As shown in FIG. 1, the injection molding machine 50A and the injection molding machine 50B have the same configuration indicated by the same reference numerals. Therefore, hereinafter, for ease of explanation, the configuration of the injection molding machine 50A will be described, and the description of the configuration of the injection molding machine 50B will not be repeated. In the injection molding machine 50A of the first embodiment, the mold clamping device 60 includes a bed 11, a fixed platen 12, a mold clamping housing 13, a movable platen 14, tie bars 15, a mold clamping mechanism 16, molds 17, 18, and a ball screw 51. The bed 11 holds the fixed platen 12, the mold clamping housing 13, and the movable platen 14. The fixed platen 12 is fixed to the bed 11. The mold clamping housing 13 is configured to be slidable on the bed 11 in the X-axis direction. Similarly, the movable platen 14 is configured to be slidable on the bed 11 in the X-axis direction.

[0017] The tie bar 15 is disposed between the fixed platen 12 and the clamping housing 13, and connects the fixed platen 12 and the clamping housing 13. The tie bar 15 includes a plurality of bars. The injection molding machine 50A in the first embodiment is provided with the tie bar 15 including four bars. In one aspect, the tie bar 15 may include five or more bars.

[0018] The movable platen 14 is configured to be slidable in the X-axis direction between the fixed platen 12 and the clamping housing 13. The clamping mechanism 16 is provided between the clamping housing 13 and the movable platen 14. The clamping housing 13 in the first embodiment is configured to include a toggle mechanism. The clamping mechanism 16 may be configured to include a direct pressure type clamping mechanism. The direct pressure type clamping mechanism refers to a clamping cylinder.

[0019] The molds 17 and 18 are provided between the fixed platen 12 and the movable platen 14. The molds 17 and 18 are configured to be opened and closed by driving the mold clamping mechanism 16. The ball screw 51 converts rotational motion into linear motion to open and close the mold clamping mechanism 16.

[0020] The injection device 61 includes a base 62, a heating cylinder 63, the screw 23, a driving mechanism 24, a hopper 64, the injection nozzle 26, a nozzle touch device 27, and a thermocouple 65. The base 62 is disposed on the positive side of the X-axis of the bed 11, and holds the driving mechanism 24 and the like. The screw 23 is disposed inside the heating cylinder 63. The driving mechanism 24 rotates the screw 23 about the X-axis direction as its central axis, and drives the screw 23 itself to slide in the X-axis direction.

[0021] The hopper 64 is provided on the positive side of the Z axis of the heating cylinder 63. The injection nozzle 26 is provided at the end of the heating cylinder 63 on the negative side of the X axis. The nozzle touch device 27 slides the injection device 61 in the X axis direction to bring the injection nozzle 26 into contact with the sprue bush of the mold 18. The thermocouple 65 may be disposed near the injection nozzle 26 and near the heating cylinder 63. The thermocouple 65 is a temperature sensor that detects the temperature at the location where it is disposed. In one aspect, the injection molding machine 50A may be provided with another temperature sensor other than the thermocouple 65.

[0022] The display device 30 is provided on the negative side of the Y axis of the injection molding machine 50A. The arrangement of the display device 30 is not limited to the negative side of the Y axis of the injection molding machine 50A. For example, the display device 30 may be provided on the positive side of the Y axis of the injection molding machine 50A, or the injection molding machine 50A may be provided as a separate entity. The display device 30 includes a display 30D and an input device 30B.

[0023] Input device 30B includes, for example, a plurality of buttons. In one aspect, display device 30 may include a plurality of displays, speakers, and the like. Display 30D and input device 30B may be integrally provided as a touch panel. Note that, although an example of a horizontal injection molding machine has been described in FIG. 1, each of injection molding machines 50A and 50B of the first embodiment is not limited to the horizontal type and may be a vertical injection molding machine.

[0024] In the injection molding machine 50A of the first embodiment, the base 62 includes therein a converter 200A, a control device 10A, and servo amplifiers Sa1 and Sa2. The converter 200A is a power converter that converts AC power supplied from a power supply system Pw1 into DC power. The converter 200A is controlled by a control signal transmitted from the control device 10A.

[0025] In the injection molding machine 50B of the first embodiment, the base 62 includes therein a converter 200B, a control device 10B, and servo amplifiers Sa3 and Sa4. The converter 200B is a power converter that converts AC power supplied from a power supply system Pw1 into DC power. The converter 200B is controlled by a control signal transmitted from the control device 10B. The control devices 10A and 10B are electrically connected via a network NW1. The servo amplifiers Sa1 to Sa4 generate three-phase AC voltages from DC voltages and supply the three-phase AC power to the corresponding servo motors.

[0026] <Power conversion> 2 is a block diagram for explaining the configuration of injection molding system 1000 as an industrial system in the first embodiment. As described above, injection molding machine 50A in the first embodiment includes converter 200A, control device 10A, and servo amplifiers Sa1 and Sa2 inside base 62. Injection molding machine 50B in the first embodiment includes converter 200B, control device 10B, and servo amplifiers Sa3 and Sa4 inside base 62. In the first embodiment, converter 200A and converter 200B have the same configuration. Control device 10A and control device 10B also have the same configuration.

[0027] The converters 200A and 200B have switching circuits 40A and 40B, respectively. The control devices 10A and 10B are electrically connected to the converters 200A and 200B, respectively. The switching circuits 40A and 40B are circuits that convert AC power from a three-phase AC power supply Pw1 into DC power, and are supplied with three-phase AC power from the power supply Pw1.

[0028] Each of the switching circuits 40A, 40B is a full-bridge type rectifier circuit including a diode and a switching element. The control devices 10A, 10B supply control signals to gate terminals of the switching elements included in the switching circuits 40A, 40B to switch the state of the switching elements between an on state and an off state. The switching circuit 40A supplies DC power converted from AC power to the servo amplifiers Sa1, Sa2. The switching circuit 40B supplies DC power converted from AC power to the servo amplifiers Sa3, Sa4.

[0029] As shown in Fig. 2, the control device 10A and the control device 10B are configured to be able to communicate with each other via a network NW1. In the network NW1, communication is performed using, for example, Ethernet (registered trademark) or EtherCat (Ethernet for Control Automation Technology) as a protocol. The control device 10A and the control device 10B perform time synchronization, frequency synchronization, or phase synchronization via the network NW1. As a result, the control device 10A and the control device 10B each perform processing based on the same time information.

[0030] The protocol used in the network NW1 may be any protocol other than Ethernet and EtherCat as long as it can synchronize timers between the control devices 10A and 10B. The control devices 10A and 10B may be connected to the same NTP (Network Time Protocol) server. The network NW1 may be either wired or wireless, or may include both wired and wireless networks.

[0031] <Converter configuration> Fig. 3 is a diagram for explaining the configuration of switching circuit 40A in converter 200A. As described above, converter 200B has a similar configuration to converter 200A shown in Fig. 3. Therefore, in the following, for ease of explanation, the configuration of converter 200A will be explained, and the explanation of the configuration of converter 200B will not be repeated.

[0032] The converter 200A has capacitors C1, C2, and an inductor L1 in addition to the switching circuit 40A. The converter 200A receives AC power from three phases, R, S, and T, of a power system Pw1, converts each of the three-phase AC power into DC power, and supplies the DC power to a load.

[0033] The switching circuit 40A is a circuit having six switching elements TR1-TR6 and six diodes D1-D6. In the first embodiment, the switching circuit 40A is PWM (Pulse Width Modulation) controlled by the control device 10A. Each of the switching elements TR1-TR6 is a semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide Semiconductor Field Effect Transistor).

[0034] Diodes D1 to D6 are connected to the switching elements TR1 to TR6, respectively. Specifically, the diodes D1 to D6 are connected between the collectors and emitters of the switching elements TR1 to TR6, respectively. The collectors of the switching elements TR1 to TR6 are connected to the cathodes of the diodes D1 to D6, respectively. The emitters of the switching elements TR1 to TR6 are connected to the anodes of the diodes D1 to D6, respectively.

[0035] The collectors of the switching elements TR1, TR3, and TR5 are connected to a high-voltage power line HP1, and the emitters of the switching elements TR2, TR4, and TR6 are connected to a low-voltage power line LP1.

[0036] A control signal S1 is applied to the gate of the switching element TR1, and a control signal S2 is applied to the gate of the switching element TR2. The control signal S2 is a signal of opposite phase to the control signal S1. That is, the switching elements TR1 and TR2 are switched between the on state and the off state in a complementary manner.

[0037] Similarly, a control signal S3 is applied to the gate of the switching element TR3, and a control signal S4 is applied to the gate of the switching element TR4. The control signal S3 is a signal in opposite phase to the control signal S4. That is, the switching elements TR3 and TR4 are switched between the on state and the off state in a complementary manner.

[0038] Similarly, a control signal S5 is applied to the gate of switching element TR5, and a control signal S6 is applied to the gate of switching element TR6. The control signal S5 is a signal of opposite phase to the control signal S6. That is, the switching elements TR5 and TR6 are switched between the on and off states in a complementary manner. The switching elements TR1 and TR2, the switching elements TR3 and TR4, and the switching elements TR5 and TR6 are switched between the on and off states in the same cycle.

[0039] The inductor L1 has three inductors (reactors) inserted in the R phase, S phase, and T phase between the system power supply Pw1 and the switching circuit 40A. The capacitor C1 has three capacitors arranged between the R phase and the S phase, between the R phase and the T phase, and between the T phase and the S phase. The capacitor C1 functions as a noise filter for removing harmonics, noise, and the like. The capacitor C2 is connected between the high-voltage power line HP1 and the low-voltage power line LP1. The capacitor C2 is a so-called smoothing capacitor, and smoothes the DC voltage output by the switching circuit 40A.

[0040] The control device 10A includes a CPU 101, a memory 102, and a communication interface 103. The control device 10A applies control signals S1-S6 to each of the switching elements TR1-TR6, respectively, and switches the state of each of the switching elements TR1-TR6 between an on state and an off state to perform PWM control. That is, each of the switching elements TR1-TR6 is successively switched between an on state and an off state in a specific period. Hereinafter, the specific period will be referred to as a "switching period." The switching period is determined based on a preset carrier wave (for example, a triangular wave). Hereinafter, the frequency of the carrier wave will be referred to as a "carrier frequency."

[0041] The memory 102 includes a read only memory (ROM) and a random access memory (RAM), and stores programs and the like executed by the CPU 101. The CPU 101 loads the programs stored in the ROM into the RAM and executes them.

[0042] In one aspect, the control device 10A may be configured with a dedicated hardware circuit. That is, the control device 10A may be realized by an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like. The control device 10A may also be realized by appropriately combining a processor, a memory, an ASIC, an FPGA, or the like. The control device 10A communicates with the control device 10B via the communication interface 103.

[0043] <Operation of the control device 10A> The operation of the control device 10A will be described below using a flowchart. Fig. 4 is a flowchart for explaining the operation of the control device 10A. The flowchart shown in Fig. 4 is realized by the CPU 101 of the control device 10A executing a program loaded into the memory 102.

[0044] The control device 10A executes the flowchart shown in Fig. 4, for example, when power supply to the control device 10A starts from a state in which power is not supplied to the control device 10A. In the first embodiment, power is supplied to both the control devices 10A and 10B by supplying power to the injection molding machines 50A and 50B.

[0045] The control device 10A acquires the carrier frequency of the switching circuit 40A (step S101). The carrier frequency of the switching circuit 40A is the frequency of a carrier wave used to drive the switching circuit 40A. The control device 10A determines the switching period by using a carrier wave (for example, a triangular wave) stored in advance in the memory 102. More specifically, the control device 10A determines the switching period of the switching circuit 40A based on a voltage comparison between the carrier wave and a target voltage command value (DC voltage). In this embodiment, since the voltage command value is a DC voltage, the switching period is determined to a unique value based on the carrier frequency. In step S101, the control device 10A reads data related to the carrier wave from the memory 102 and acquires the frequency of the carrier wave.

[0046] In the first embodiment, the switching period of the switching circuit 40A is determined based on the carrier frequency of the carrier wave as, for example, 0.1 ms. In other words, the switching frequency of the switching circuit 40A in the first embodiment is 10 kHz. Note that the switching frequency of the switching circuit 40A may be another frequency, such as, for example, 15 kHz or 20 kHz.

[0047] The control device 10A acquires the carrier frequency of the switching circuit 40B in the control device 10B connected to the network NW1 (step S102). The carrier frequency of the switching circuit 40B is stored in advance in the memory 102 of the control device 10B.

[0048] In this embodiment, the switching frequency of the switching circuit 40B is 10 kHz, similar to the switching frequency of the switching circuit 40A. The switching frequency of the switching circuit 40B may be a frequency different from the switching frequency of the switching circuit 40A. For example, the switching frequency of the switching circuit 40B may be an integer multiple of the switching frequency of the switching circuit 40A.

[0049] The control device 10A determines the start timing for starting the driving of the switching circuits 40A, 40B based on the acquired carrier frequencies of the switching circuits 40A, 40B (step S103). At this time, the control device 10A determines the start timing for the switching circuits 40A, 40B so that the phase of the carrier wave of the switching circuit 40A differs from the phase of the carrier wave of the switching circuit 40B.

[0050] The control device 10A transmits the start timing of the switching circuit 40B determined in step S103 to the control device 10B (step S104). Next, the control device 10A starts driving the switching circuit 40A based on the start timing determined in step S103 (step S105). The control device 10B also starts driving the switching circuit 40B at the start timing transmitted from the control device 10A in step S104. Since the control devices 10A and 10B synchronize their timers by communication over the network NW1, the control device 10B can drive the switching circuit 40B at the start timing received from the control device 10A.

[0051] <Phase of Carrier Wave of Switching Circuits 40A and 40B> The phase of the carrier wave of the switching circuits 40A and 40B will be described below. Fig. 5 is a diagram showing a ripple current flowing through inductor L1 to explain the phase of the carrier wave of the switching circuits 40A and 40B. In Fig. 5, a waveform Wv1 of a current value flowing from the top to inductor L1 of converter 200A, a waveform Wv2 of a current value flowing through inductor L1 of converter 200B, and a waveform Wv3 obtained by combining the waveforms Wv1 and Wv2 are each shown by a solid line.

[0052] 5 shows a triangular ripple current generated in inductor L1 by any one of switching elements TR1-TR6. The triangular wave indicating the ripple current generated in inductor L1 is generated due to the switching of switching elements TR1-TR6. The period of the triangular wave of the ripple current flowing in inductor L1 is the same as the switching period of switching circuit 40A.

[0053] 5 is the period of the ripple current flowing through inductor L1, but is also the switching period of switching circuits 40A and 40B. As described above, since the switching period is uniquely determined by the carrier frequency of the carrier wave, the phase of the triangular wave of the ripple current flowing through inductor L1 is also synchronized with the phase of the carrier wave used in switching circuit 40A.

[0054] As shown in Fig. 5, a ripple current is generated in the inductor L1 of the converter 200A from timing Tm2, ​​and the current value gradually increases. If the ripple current of the converter 200A shown in Fig. 5 is caused by the switching of the switching element TR1 in the switching circuit 40A, the switching element TR1 in the switching circuit 40A is in the ON state during the period from timing Tm2 to timing Tm3. Moreover, the current value of the ripple current flowing through the inductor L1 of the converter 200A gradually decreases from timing Tm3. That is, the switching element TR1 in the switching circuit 40A is switched to the OFF state at timing Tm3.

[0055] On the other hand, a ripple current is generated in the inductor L1 of the converter 200B from timing Tm1, and the current value gradually increases. If the ripple current of the converter 200B shown in FIG. 5 is caused by the switching of the switching element TR1 in the switching circuit 40B, the switching element TR1 in the switching circuit 40B is in the ON state during the period from timing Tm1 to timing Tm2. Also, the current value of the ripple current flowing through the inductor L1 of the converter 200B gradually decreases from timing Tm2. That is, the switching element TR1 in the switching circuit 40B is switched to the OFF state at timing Tm2.

[0056] In this manner, in the injection molding system 1000 as an industrial system of this embodiment, the phases of the carrier waves of the switching circuits 40A and 40B are different, so that the phase of the ripple current generated by the switching element included in the switching circuit 40A and the phase of the ripple current generated by the switching element included in the switching circuit 40B are not in phase with each other.

[0057] The control device 10A determines the start timing at which the phase difference of the carrier frequency between the switching circuits 40A and 40B is maximum based on the number of other control devices connected to the control device 10A and the carrier frequencies of the switching circuits 40A and 40B. In the first embodiment, the number of other control devices connected to the control device 10A is one (control device 10B). The phase difference at which the switching period is maximum in the total of two control devices 10A and 10B is 180 degrees, which is 360 degrees divided by two. The maximum phase difference means that the phase is determined so that the peaks of the carrier waves are most offset from each other.

[0058] Therefore, the control device 10A determines the start timing of switching so that the switching period of the switching element included in the switching circuit 40A is delayed by 180 degrees from the switching period of the switching element included in the switching circuit 40B. In other words, when the number of connected devices is one, the phase of the switching circuit 40A and the phase of the switching circuit 40B are opposite to each other.

[0059] As shown in the lower part of Fig. 5, the ripple current flowing through inductor L1 of converter 200A and the ripple current flowing through inductor L1 of converter 200B both return to the system power supply Pw1 as harmonic currents and are combined. That is, the waveform Wv3 shown in the lower part of Fig. 5 indicates the waveform of the current flowing through the system power supply Pw1 as a harmonic current.

[0060] In the injection molding system 1000 as the industrial system of the first embodiment, the control device 10A drives the switching circuit 40A using a carrier wave having a phase different from that of the carrier wave of the switching circuit 40B. As a result, the waveform Wv3, which is a composite wave of ripple currents, is smoothed as shown in the lower part of Fig. 5. The control device 10A drives the switching circuit 40A using a carrier wave having a phase shifted from that of the carrier wave of the switching circuit 40B by timer-synchronizing with the control device 10B via the network NW1.

[0061] <Comparative Example> 6 is a diagram for explaining the phase of the carrier waves of the switching circuits 40A, 40B in the comparative example. In the comparative example, the control devices 10A and 10B are not connected by the network NW1. When power is supplied to the injection molding machines 50A, 50B, the control devices 10A, 10B each start switching the switching circuits 40A, 40B. In the comparative example, the start timings of the switching circuits 40A, 40B are the same.

[0062] When switching of switching circuit 40A and switching of switching circuit 40B both start at timing Tm1, the phase of the ripple current flowing through inductor L1 of converter 200A and the phase of the ripple current flowing through inductor L1 of converter 200B are in phase, as shown in Fig. 6. That is, in Fig. 6, the phase of the carrier wave of switching circuit 40A and the phase of the carrier wave of switching circuit 40B are in phase.

[0063] In the comparative example, as shown in the lower part of Fig. 6, a current (waveform Wv3Z) in which the ripple current waveforms Wv1Z and Wv2 overlap flows into the power grid Pw1. Compared to the waveform Wv3, the waveform Wv3Z is not smoothed and has prominent peaks. When a harmonic current with prominent peaks flows into the power grid Pw1 as shown in the comparative example, the AC power of the power grid Pw1 is distorted.

[0064] Distortion of the AC power waveform on the input side can cause malfunctions in all devices connected to the power supply system Pw1. In the injection molding system 1000 as the industrial system of the first embodiment, the control devices 10A and 10B are synchronized via the network NW1, so that it is possible to start switching by shifting the phases of the carrier waves of the switching circuits 40A and 40B, and thus it is possible to suppress an increase in harmonics.

[0065] In addition, in this embodiment, since the peak of the harmonic wave can be reduced, the capacitance of the capacitor C1, which is a noise filter for removing the harmonic wave, can be reduced, and the manufacturing cost of the converters 200A and 200B can be reduced. In addition, it is possible that the phase of the carrier wave is unintentionally shifted due to deterioration caused by the switching circuits 40A and 40B being continuously driven for a long period of time. Even in such a case, in the injection molding system 1000 as the industrial system of the first embodiment, the phases of the carrier frequencies of the switching circuits 40A and 40B are reset so as to be different each time power is supplied to the injection molding machines 50A and 50B, so that it is possible to suppress the phases of the carrier waves of the switching circuits 40A and 40B from unintentionally becoming the same phase due to the shift in the phase of the carrier wave caused by deterioration or the like.

[0066] <Modification> In the above example, the injection molding machine 50 is applied as the industrial machine of the present embodiment, but the industrial machine of the present embodiment may be an industrial machine other than an injection molding machine. The industrial machine of the present embodiment may be various industrial machines such as an extruder, a press machine, a machine tool, a manufacturing robot, etc. In addition, the types of industrial machines included in the injection molding system 1000 as an industrial system may not be unified, and for example, the injection molding system 1000 as an industrial system may include both an injection molding machine and an extruder. To give a specific example, in FIG. 1, the injection molding machine 50B may be an extruder instead of an injection molding machine.

[0067] 4 described above, an example has been described in which power is supplied to both the control device 10A and the control device 10B in conjunction with the supply of power to the injection molding machines 50A and 50B. When the control device 10B is already driving the switching circuit 40B at a specific switching frequency at the time when power is supplied to the control device 10A, the control device 10A may start switching of the switching circuit 40A so that the phase of the carrier wave of the switching circuit 40A is different from the phase of the carrier wave of the switching circuit 40B that is already driven.

[0068] In the above example, the control device 10A determines the start timing so that the phase difference of the carrier waves is maximized. However, the phase difference of the carrier waves does not have to be maximized, but may be equal to or greater than a predetermined threshold. For example, when the number of connected devices is one, the predetermined threshold may be 60 degrees or greater. The predetermined threshold may be determined in advance by experiment or the like.

[0069] In addition, the injection molding machine 50A of the first embodiment may correspond to the "first industrial machine" in this disclosure. The injection molding machine 50B may correspond to the "second industrial machine" in this disclosure. The switching circuit 40A may correspond to the "first switching circuit" in this disclosure. The switching circuit 40B may correspond to the "second switching circuit" in this disclosure. The converter 200A may correspond to the "first converter" in this disclosure. The converter 200B may correspond to the "second converter" in this disclosure. The control device 10A may correspond to the "first control device" in this disclosure. The control device 10B may correspond to the "second control device" in this disclosure.

[0070] In the above example, the control device 10A determines the start timings of both the switching circuits 40A and 40B in step S103. However, the control device 10A may determine only the start timing of the switching circuit 40A. In this case, the control device 10A transmits information indicating the start timing of the switching circuit 40A to the control device 10B. Thereafter, the control device 10B determines the start timing of the switching circuit 40B so that the phase of the carrier wave of the switching circuit 40A is different from the phase of the carrier wave of the switching circuit 40B.

[0071] [Embodiment 2] In the first embodiment, a configuration in which two industrial machines, injection molding machines 50A and 50B, are provided in injection molding system 1000 as an industrial system has been described. However, the number of industrial machines included in injection molding system 1000 as an industrial system is not limited to two, and may be one, or may be three or more. In the second embodiment, a configuration in which one injection molding machine 50 has two converters 200A and 200B will be described. In the second embodiment, the description of the same configuration as in the first embodiment will not be repeated.

[0072] Fig. 7 is a diagram showing an outline of the configuration of an injection molding machine in embodiment 2. Fig. 8 is a block diagram for explaining the configuration of an injection molding machine 50 in embodiment 2. As shown in Figs. 7 and 8, injection molding machine 50 includes converters 200A and 200B in base 62. Inside injection molding machine 50, control devices 10A and 10B communicate with each other via network NW1.

[0073] In this way, the converters 200A, 200B to which AC power is supplied from the same power source system Pw1 may be provided in one injection molding machine 50. Even in this case, the present embodiment can be applied as long as the converters 200A, 200B are supplied with AC power from the same power source system Pw1 and timer synchronization is performed between the control devices 10A, 10B.

[0074] In the second embodiment as well, the phases of switching circuits 40A and 40B can be controlled so that the peaks of the ripple currents do not overlap, thereby suppressing an increase in harmonics generated by switching. Also, in the second embodiment as well, the peaks of the harmonics can be reduced, so that the capacitance of capacitor C1, which is a noise filter for removing harmonics, can be reduced, thereby reducing the cost of converters 200A and 200B.

[0075] [Embodiment 3] In the second embodiment, a configuration in which one injection molding machine 50 is provided with two converters 200A, 200B has been described. However, the number of converters included in the injection molding machine 50 is not limited to two, and may be three. In the third embodiment, a configuration of an injection molding machine 50 further provided with converter 200C in addition to converters 200A, 200B will be described. In the third embodiment, the description of the same configuration as in the first and second embodiments will not be repeated. Converter 200C may correspond to the "third converter" in this disclosure.

[0076] 9 is a block diagram for explaining the configuration of injection molding machine 50 in embodiment 3. Injection molding machine 50 in embodiment 3 includes servo amplifiers Sa5 and Sa6 in addition to servo amplifiers Sa1 to Sa4. Injection molding machine 50A in embodiment 2 includes converter 200C in addition to converters 200A and 200B.

[0077] In the example of FIG. 9, the control devices 10A and 10B are housed inside the converters 200A and 200B, respectively. The converter 200C is a power converter that converts AC power supplied from a system power supply Pw1 into DC power. The converter 200C in the second embodiment includes the control device 10C and a switching circuit 40C. The converter 200C has a similar configuration to the converters 200A and 200B shown in the second embodiment. The switching circuit 40C supplies DC power converted from the AC power to the servo amplifiers Sa5 and Sa6.

[0078] 9, the control devices 10A, 10B, and 10C communicate with each other via a network NW1. As a result, the control devices 10A, 10B, and 10C are synchronized with each other via the network NW1. As a result, each of the control devices 10A, 10B, and 10C can start switching of the switching circuits 40A, 40B, and 40C so as to shift the phases of the carrier waves used in each of the switching circuits 40A, 40B, and 40C.

[0079] In the third embodiment, each of control devices 10A, 10B, and 10C controls so that the phase difference between the carrier waves used in each of switching circuits 40A, 40B, and 40C is 120 degrees. That is, control devices 10A-10C can maximize the phase difference between the carrier frequencies of switching circuits 40A-40C by setting the phase difference to an angle obtained by dividing 360 degrees by the number of control devices included in injection molding machine 50 of the second embodiment.

[0080] Also in the third embodiment, the phases of the carrier waves of switching circuits 40A-40C can be controlled so that the peaks of the ripple currents do not overlap, thereby suppressing an increase in harmonics generated by switching. Also in the third embodiment, the peaks of the harmonics can be reduced, so that the capacitance of capacitor C1, which is a noise filter for removing harmonics, can be reduced, thereby reducing the manufacturing cost of converters 200A, 200B, 200C.

[0081] As described in the first embodiment, a case may be considered in which a control device 10C is newly connected to the network NW1 when only the control devices 10A and 10B are connected to the network NW1. In this case, the control devices 10A to 10C may stop driving once and reset the start timing of each of the switching circuits 40A to 40C so that the phase difference is maximized.

[0082] Alternatively, the control devices 10A and 10B may not stop the switching of the switching circuits 40A and 40B, and the control device 10C may obtain the phase of the carrier wave of the switching circuits 40A and 40B and start the switching of the switching circuit 40C so that the phase of the carrier wave of the switching circuit 40C is different from the phase of the carrier wave of the switching circuits 40A and 40B. That is, the control devices 10A and 10B may not stop driving once even if the control device 10C is connected later. Furthermore, in the third embodiment, the control devices 10A to 10C may be provided separately from the converters 200A to 200C as described in the first embodiment. Note that, in the third embodiment, a configuration in which one injection molding machine 50 has the converters 200A to 200C has been described, but the converters 200A, 200B, and 200C may be provided in different industrial machines. For example, in an injection molding system 1000 serving as an industrial system according to a certain aspect, injection molding machine 50A may include converter 200A, injection molding machine 50B may include converter 200B, and injection molding machine 50C may include converter 200C.

[0083] In the above-mentioned first to third embodiments, the control device 10A is disposed inside the injection molding machine 50A. However, the control device 10A is not limited to being disposed inside the injection molding machine 50A, and may be disposed outside the injection molding machine 50A. Similarly, in each embodiment, the control devices 10B and 10C are not limited to being disposed inside the injection molding machines 50B and 50C, respectively, and may be disposed outside the injection molding machines 50B and 50C.

[0084] [Note] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0085] (1) An injection molding system 1000 as an industrial system includes an injection molding machine 50A and an injection molding machine 50B. The injection molding machine 50A includes a switching circuit 40A, a converter 200A that converts AC power received from a power supply system Pw1 into DC power, and a control device 10A that controls the switching circuit 40A. The injection molding machine 50B includes a switching circuit 40B, a converter 200B that converts AC power received from a power supply system Pw1 into DC power, and a control device 10B that controls the switching circuit 40B. The control device 10A drives the switching circuit 40A using a carrier wave with a phase different from that of a carrier wave for driving the switching circuit 40B based on communication with the control device 10B (S105).

[0086] (Item 2) In the industrial system described in item 1, the frequency of the carrier wave for driving the switching circuit 40A is the same as the frequency of the carrier wave for driving the switching circuit 40B.

[0087] (Item 3) In the industrial system described in item 2, the phase of the carrier wave for driving the switching circuit 40A is opposite to the phase of the carrier wave for driving the switching circuit 40B.

[0088] (4) In the industrial system described in any one of paragraphs 1 to 3, the control device 10A acquires the frequency of a carrier wave for driving the switching circuit 40A and the frequency of a carrier wave for driving the switching circuit 40B (S101, S102), and determines the timing to start driving the switching circuit 40A and the switching circuit 40B based on the frequency of the carrier wave for driving the switching circuit 40A and the frequency of the carrier wave for driving the switching circuit 40B (S103).

[0089] (Item 5) In the industrial system according to any one of items 1 to 4, the control device 10A communicates with the control device 10B via a network NW1, and the network NW1 is EtherNET or EtherCAT.

[0090] (Item 6) The industrial system according to any one of items 1 to 5 further includes a third industrial machine, the third industrial machine further including a converter 200C including a switching circuit 40C and configured to convert AC power received from a power supply system Pw1 into DC power, and a control device 10C configured to control the switching circuit 40C. The control device 10A drives the switching circuit 40A using a carrier wave having a phase different from that of the carrier wave for driving the switching circuit 40B and the carrier wave for driving the switching circuit 40C, based on communication with the control device 10B and the control device 10C (S105).

[0091] (Item 7) At least one of the industrial machines included in the industrial system according to any one of items 1 to 6 is an injection molding machine.

[0092] (Item 8) The industrial machine includes a converter 200A including a switching circuit 40A and converting AC power received from a power supply system Pw1 into DC power, a control device 10A controlling the switching circuit 40A, a converter 200B including a switching circuit 40B and converting AC power received from the power supply system Pw1 into DC power, and a control device 10B controlling the switching circuit 40B. Based on communication with the control device 10B, the control device 10A drives the switching circuit 40A using a carrier wave having a phase different from that of a carrier wave for driving the switching circuit 40B (S105). [Explanation of symbols]

[0093] 10A, 10B, 10C control device, 11 bed, 12 fixed platen, 13 mold clamping housing, 14 movable platen, 15 tie bar, 16 mold clamping mechanism, 17, 18 mold, 23 screw, 24 drive mechanism, 26 injection nozzle, 27 nozzle touch device, 30 display device, 30B input device, 30D display, 40A, 40B, 40C switching circuit, 50, 50A, 50B injection molding machine, 51 ball screw, 60 mold clamping device, 61 injection device, 62 base, 63 heating cylinder, 64 hopper, 65 thermocouple, 102 memory, 103 communication interface, 200A, 200B, 200C converter, 1000 injection molding system, C1, C2 capacitor, D1, D6 diode, HP1, LP1 power line, L1 Inductor, NW, NW1 network, Pw1 system power supply, S1~S6 control signal, Sa1~Sa6 servo amplifier, T period, TR1~TR6 switching element, Tm1~Tm3 timing, Wv1Z, Wv3Z, Wv1~Wv3 waveform.

Claims

1. 1. An industrial system comprising: A first industrial machine; A second industrial machine, The first industrial machine, a first converter including a first switching circuit and configured to convert AC power received from a power grid into DC power; a first control device that controls the first switching circuit; The second industrial machine, a second converter including a second switching circuit and configured to convert AC power received from the system power supply into DC power; a second control device that controls the second switching circuit; An industrial system, wherein the first control device drives the first switching circuit using a carrier wave having a phase different from that of a carrier wave for driving the second switching circuit based on communication with the second control device.

2. The industrial system according to claim 1 , wherein a frequency of a carrier wave for driving the first switching circuit is the same as a frequency of a carrier wave for driving the second switching circuit.

3. The industrial system of claim 2 , wherein a phase of a carrier wave for driving the first switching circuit is in anti-phase with respect to a phase of a carrier wave for driving the second switching circuit.

4. The first control device is obtaining a frequency of a carrier wave for driving the first switching circuit and a frequency of a carrier wave for driving the second switching circuit; The industrial system according to any one of claims 1 to 3, wherein a timing for starting to drive the first switching circuit and the second switching circuit is determined based on a frequency of a carrier wave for driving the first switching circuit and a frequency of a carrier wave for driving the second switching circuit.

5. The first control device communicates with the second control device via a network; The industrial system according to any one of claims 1 to 3, wherein the network is EtherNET or EtherCAT.

6. Further comprising a third industrial machine; The third industrial machine, a third converter including a third switching circuit and configured to convert AC power received from the system power supply into DC power; a third control device that controls the third switching circuit; The first control device is The industrial system according to any one of claims 1 to 3, wherein the first switching circuit is driven using a carrier wave having a phase different from that of a carrier wave for driving the second switching circuit and a phase of a carrier wave for driving the third switching circuit based on communication with the second control device and the third control device.

7. The industrial system according to any one of claims 1 to 3, wherein the first industrial machine and the second industrial machine are injection molding machines.

8. a first converter including a first switching circuit and configured to convert AC power received from a power grid into DC power; a first control device that controls the first switching circuit; a second converter including a second switching circuit and configured to convert AC power received from the system power supply into DC power; a second control device that controls the second switching circuit, The first control device is An industrial machine that drives the first switching circuit using a carrier wave having a phase different from a phase of a carrier wave for driving the second switching circuit based on communication with the second control device.

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