JP2020175967A - Belt conveyor driving device and belt conveyor driving program - Google Patents

Abstract

To provide a belt conveyor driving device which can stably start up.SOLUTION: A belt conveyor driving device comprises an inverter start circuit for supplying an AC current for starting an electric motor for rotating a pulley disposed in a belt conveyor to the electric motor, and a commercial operation circuit for supplying an AC current of a commercial power supply to the electric motor and driving the electric motor. After the electric motor is started, an AC current is supplied from the inverter start circuit to the electric motor until a rotational speed of the electric motor reaches a constant speed. After the rotational speed reaches the constant speed, the AC current is supplied from both the inverter start circuit and the commercial operation circuit to the electric motor while the AC current supplied from the inverter start circuit to the electric motor is reduced. After the supply of the AC current from the inverter start circuit to the electric motor is ended, the AC current is supplied from the commercial operation circuit to the electric motor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a belt conveyor drive device for driving a belt conveyor and a belt conveyor drive program.

In the belt conveyor drive device, for example, it is important in constructing a system to suppress a sudden tension fluctuation of the conveyor belt at the time of starting a long-distance down belt conveyor and to prevent a runaway peculiar to the belt conveyor. The down long-distance belt conveyor is a belt conveyor in which the conveyor belt is arranged so as to have a down slope and the machine length is several hundred meters or more.

Patent Document 1 discloses a belt conveyor drive device capable of changing torque-velocity characteristics. In the prior art of Patent Document 1, when the belt conveyor is started, a current is supplied from the inverter to the electric motor for driving the belt conveyor, and after a certain period of time, the current supply source to the electric motor is switched from the inverter to the commercial power source.

Japanese Unexamined Patent Publication No. 48-49174

However, in the prior art disclosed in Patent Document 1, when the current supply source is switched from the inverter device to the commercial power source, the current path is once opened, so that the impact torque (electric motor) caused by the inrush current is accompanied by the opening operation. There is a problem that the conveyor belt may escape due to the occurrence of steep torque fluctuations) and the opening of the current path.

The present invention has been made in view of the above, and an object of the present invention is to obtain a belt conveyor driving device capable of stably starting a belt conveyor.

In order to solve the above-mentioned problems and achieve the object, the belt conveyor drive device according to the present invention includes an inverter starting circuit for supplying an alternating current for starting an electric motor for rotating a pulley provided on the belt conveyor to the electric motor, and a commercial product. It includes a commercial operation circuit that supplies an alternating current of a power source to the electric motor to operate the electric motor. After the electric motor is started, alternating current is supplied from the inverter starting circuit to the electric motor until the rotation speed of the electric motor reaches a constant speed, and after reaching a constant speed, the inverter starting circuit to the electric motor. After the alternating current is supplied to the motor from both the inverter starting circuit and the commercial operation circuit while the supplied alternating current is decreasing, and the alternating current is no longer supplied from the inverter starting circuit to the motor, An alternating current is supplied from the commercial operation circuit to the electric motor.

According to the present invention, there is an effect that a stable start of the belt conveyor becomes possible.

The figure which shows the structural example of the belt conveyor system 100 which includes the belt conveyor drive apparatus 200 which concerns on Embodiment 1 of this invention. Flow chart for explaining the processing operation from the start of the operation of the belt conveyor 500 by the belt conveyor drive device 200 to the end of the operation. Timing chart for explaining the processing operation from the start of the operation of the belt conveyor 500 by the belt conveyor drive device 200 to the end of the operation. The figure which conceptually shows the path through which an electric current flows in a belt conveyor drive device 200. The figure which shows the structural example of the belt conveyor system 100A including the belt conveyor drive device 200A which concerns on Embodiment 2 of this invention. A flowchart for explaining the processing operation from the start of the operation of the belt conveyor 500A by the belt conveyor drive device 200A to the end of the operation. A timing chart for explaining the processing operation from the start of the operation of the belt conveyor 500A by the belt conveyor drive device 200A to the end of the operation.

The belt conveyor drive device and the belt conveyor drive program according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1
FIG. 1 is a diagram showing a configuration example of a belt conveyor system 100 including the belt conveyor driving device 200 according to the first embodiment of the present invention. The belt conveyor system 100 shown in FIG. 1 controls the rotation of the belt conveyor 500, the conveyor driving electric motor 300 for rotating the drive pulley 501 of the belt conveyor 500 via the speed reducer 400, and the conveyor driving electric motor 300. A belt conveyor drive device 200 for driving the belt conveyor 500 and a step-down transformer 600 for lowering the voltage of the high-voltage distribution system to a voltage input to the belt conveyor drive device 200 are provided.

The conveyor drive electric motor 300 is, for example, a cage-type electric motor. In the following, the "conveyor drive electric motor" may be referred to as an "electric motor" for the sake of simplicity.

The belt conveyor 500 is, for example, a long-distance down belt conveyor. As described above, in the downward long-distance belt conveyor, it is important in the construction of the system to suppress the sudden tension fluctuation of the conveyor belt 510 at the time of starting and to prevent the escape (the machine starts to move unintentionally). The belt conveyor drive device 200 according to the present embodiment has a configuration for controlling the start of the electric motor 300 so as to prevent such a sudden tension fluctuation and escape. In the following, the configuration of the belt conveyor drive device 200 will be described with reference to FIG. 1, and then the operation of the belt conveyor drive device 200 will be described with reference to FIG.

The belt conveyor drive device 200 includes a commercial operation circuit 210 that supplies an alternating current of a commercial power source to the electric motor to operate the electric motor, an inverter start circuit 220 that supplies an alternating current for starting the electric motor to the electric motor, and an inverter start circuit. It includes a 220 and a control unit 230 that controls a commercial operation circuit 210.

In the commercial operation circuit 210, the low-voltage circuit breaker 1 which is an overcurrent circuit breaker for short-circuit protection of the electric circuit, the switch 2 whose opening and closing is controlled by the control unit 230, and the electric motor are operated with an overload for a long time. This includes an overload protection device 10 for suppressing overheating.

The low voltage circuit breaker 1 is provided in the electric circuit on the output side of the step-down transformer 600.

The inverter start circuit 220 starts the low-voltage circuit breaker 3 which is an overcurrent circuit breaker for short-circuit protection of the electric circuit, the synchronous detection transformer 12, the switch 4 whose opening and closing is controlled by the control unit 230, and the electric motor. It includes a voltage conversion unit 11 that changes an output voltage and an output frequency, an output reactor 13, and a switch 5 that is open / closed controlled by a control unit 230.

The switch 4 is provided in the electric circuit on the input side of the voltage conversion unit 11. The switch 5 is provided in the electric circuit on the output side of the voltage conversion unit 11.

The voltage conversion unit 11 includes a converter with a regeneration function that converts an AC voltage into a DC voltage, and an inverter that converts the DC voltage into an AC voltage.

For example, when the commercial power supply or the inverter power supply is not supplied to the electric motor, for example, when the drive pulley 501 rotates due to the weight of the load placed on the conveyor belt 510 of the long-distance down belt conveyor, the electric motor operates as a generator. In order to input the electric power (regenerative electric power) generated by the electric motor to the commercial system in this way, a converter with a regenerative function is used. There are two types of regenerative methods: a resistance regeneration method in which the regenerative power is consumed by a resistor, and a power supply regeneration method in which the regenerative power is returned (input) to the commercial system. In the present embodiment, the power supply regeneration method is adopted in consideration of the fact that the regenerative energy of the long-distance down belt conveyor is relatively high. Details of the converter with a regenerative function are disclosed in, for example, International Publication No. 2012/172589 and JP-A-2007-001712, and thus the description thereof will be omitted below.

The inverter includes a plurality of switching elements such as an IGBT (Insulated Gate Bipolar Transistor). The switching element performs a switching operation by, for example, a gate drive signal input from the control unit 230. The switching element may be any element capable of switching operation by the gate drive signal, and is not limited to the IGBT. The gate drive signal is a signal in which the pulse width modulation signal output from the control unit is amplified to a voltage having a value at which the switching element can be driven by a driver (not shown). The gate drive signal is a square wave signal that takes a binary value of H level or L level. The output current of the inverter changes as the on-duty of the gate drive signal changes.

The synchronous detection transformer 12 measures the voltage and phase of the commercial power supply. The control unit 230 controls the inverter output of the voltage conversion unit 11 so as to match the measured value. When the voltage and phase of the commercial power supply and the inverter output match (synchronize), the switch 2 of the commercial operation circuit 210 is closed, and the commercial power supply and the inverter power supply are operated in parallel. The parallel operation of the commercial power supply and the inverter power supply is a state in which current is supplied to the electric motor from both the inverter start circuit 220 and the commercial operation circuit 210.

For example, the phase of the inverter output voltage of the voltage converter 11 when the rotation speed of the motor reaches the rated speed while the current is being supplied from the voltage converter 11 to the motor is output from the step-down transformer 600 for commercial use. If the parallel operation of the commercial power supply and the inverter power supply is started when the phase of the power supply voltage is out of phase, the inrush current due to the voltage difference is input to the motor, and the conveyor belt 510 undulates up and down. A "surging phenomenon" can occur.

In order to avoid such a problem, in the belt conveyor drive device 200, after the rotation speed of the electric motor reaches the rated speed, the output of the voltage conversion unit 11 is adjusted so that the voltage and phase of the commercial power supply and the inverter output match. Frequency and voltage are controlled. Then, when the phases match with each other, parallel operation of the commercial power supply and the inverter power supply is started. By this operation, the generation of the inrush current is suppressed and the surging phenomenon can be suppressed.

The control unit 230 is a microcomputer including a processor 231, a memory 232, an input / output interface 233, and a bus 234. The processor 231 and the memory 232 and the input / output interface 233 are connected to each other by the bus 234.

The processor 231 is composed of, for example, a CPU (Central Processing Unit), and controls the functions of the control unit 230 (commercial operation circuit 210 and inverter start circuit 220) by executing a predetermined program stored in the memory 232. Function) is realized.

The input / output interface 233 transmits an opening / closing operation signal of the switch 2, the switch 4, the switch 5, and the like via the bus 234.

Next, the operation of the belt conveyor drive device 200 will be described with reference to FIGS. 1 to 4.

FIG. 2 is a flowchart for explaining the processing operation from the start of the operation of the belt conveyor 500 by the belt conveyor drive device 200 to the end of the operation. FIG. 3 is a timing chart for explaining the processing operation from the start of the operation of the belt conveyor 500 by the belt conveyor drive device 200 to the end of the operation. FIG. 4 is a diagram conceptually showing a path through which a current flows in the belt conveyor drive device 200.

In step S1, when a signal indicating "on" for the operation of the belt conveyor drive device 200 is input to the control unit 230, the control unit 230 changes the state of the switch 4 from OFF to ON, and the switch 5 The state of is changed from OFF to ON.

In step S2, when an operation command indicating the start of operation of the belt conveyor drive device 200 is input to the control unit 230, the control unit 230 that has input the operation command receives a gate drive signal for driving the switching element of the voltage conversion unit 11. Start generation. As a result, the current is supplied from the inverter start circuit 220 to the electric motor (step S3).

When the gate drive signal is generated, the inverter output frequency and the inverter output current start to increase as shown in FIG. In the first conceptual diagram from the left in FIG. 3, the current when the current is supplied from the inverter start circuit to the electric motor is shown by a dashed line. The current flowing at this time is input to the electric motor via the switch 4, the voltage conversion unit 11, and the switch 5.

When the rotation speed of the electric motor reaches a steady speed (constant speed: for example, 50 Hz), the control unit 230 controls the inverter output so that the voltage and phase of the commercial power supply and the inverter output match. The rotation speed of the electric motor is measured by a rotation speed detector (not shown). The process of step S4 is repeated in the control unit 230 until the voltage and phase of the commercial power supply and the inverter output match (steps S4 and No).

When the voltage and phase of the commercial power supply and the output of the inverter match (steps S4, Yes), a synchronization detection signal is input to the control unit 230. As a result, the control unit 230 detects that the rotation speed of the electric motor has reached the steady speed and the voltage and phase of the commercial power supply and the inverter output are synchronized.

In step S5, the control unit 230 that has detected synchronization changes the state of the switch 2 from OFF to ON so that current is supplied to the electric motor from both the inverter start circuit 220 and the commercial operation circuit 210. In the second conceptual diagram from the left in FIG. 3, the current when the current is supplied to the electric motor from both the inverter starting circuit 220 and the commercial operation circuit 210 is shown by a dashed line.

After the rotation speed reaches a constant speed, the control unit 230 gradually reduces the on-duty of the gate drive signal to gradually reduce the inverter output current. As a result, the alternating current supplied from the inverter starting circuit 220 to the electric motor is reduced, while the alternating current supplied from both the inverter starting circuit 220 and the commercial operation circuit 210 to the electric motor is continued (step S6).

In step S7, the control unit 230 measures, for example, the value of the inverter output current detected by the current detector, and determines whether or not the inverter output current has become zero. The process of step S7 is repeated until the inverter output current becomes zero (steps S7, No).

When the inverter output current becomes zero (step S7, Yes), that is, when the AC current supply from the inverter start circuit 220 to the motor is cut off, the control unit 230 switches the current supply source to the motor to a commercial power source. Therefore, the state of the switch 5 is changed from ON to OFF (step S8). As a result, a current is supplied from the commercial operation circuit 210 to the electric motor (step S9). In the third conceptual diagram from the left in FIG. 3, the current when the current is supplied from the commercial operation circuit 210 to the electric motor is shown by a dashed line.

In step S10, when a stop command indicating the stop operation of the belt conveyor drive device 200 is input to the control unit 230 (steps S10, Yes), the control unit 230 that has input the stop command turns the state of the switch 5 from ON. By changing it to OFF, the current supply to the electric motor is stopped (step S11).

In step S12, when a signal indicating the operation preparation "off" of the belt conveyor drive device 200 is input to the control unit 230, the control unit 230 changes the state of the switch 4 from ON to OFF.

As described above, the belt conveyor drive device 200 according to the first embodiment includes an inverter start circuit 220 that supplies an alternating current to the electric motor to start the electric motor 300 that rotates the drive pulley 501 provided in the belt conveyor 500. It includes a commercial operation circuit 210 for operating the electric motor by supplying an alternating current of a commercial power source to the electric motor. In the belt conveyor drive device 200, after the electric motor is started, alternating current is supplied from the inverter starting circuit 220 to the electric motor until the rotation speed of the electric motor reaches a constant speed, and after the constant speed is reached, the inverter starting circuit 220 After the AC current supplied from the inverter start circuit 220 to the motor is reduced, the AC current is supplied to the motor from both the inverter start circuit 220 and the commercial operation circuit 210, and the AC current supply from the inverter start circuit 220 to the motor is stopped. , AC current is supplied from the commercial operation circuit 210 to the electric motor.

In the prior art, the current path was once opened when switching from the inverter start circuit to the commercial operation circuit, but in the belt conveyor drive device 200 according to the present embodiment, when switching from the inverter start circuit to the commercial operation circuit, By providing a period in which both are operated in parallel, the current path is not opened. Therefore, the inrush current accompanying the opening operation is suppressed, and the generation of impact torque (steep torque fluctuation in the motor) caused by the inrush current is suppressed. In addition, since escape due to the opening of the current path is suppressed, stable start of the belt conveyor becomes possible.

Further, when a cage type electric motor is used instead of a winding type electric motor for the electric motor driven by the belt conveyor drive device 200 according to the first embodiment, the following effects can be obtained. By switching the secondary resistance circuit, the winding type motor can be started by suppressing a sudden increase in starting torque. However, since the structure of the wound-wound motor is complicated, a skilled person is required to manufacture the wound-wound motor, but in recent years, the shortage of skilled workers has made it difficult to manufacture the wound-wound motor. Further, since the structure of the winding type motor is complicated, there is a demerit that the manufacturing cost is higher than that of the cage type motor. Therefore, in recent years, there has been an increasing demand for switching from a winding type electric motor to a cage type electric motor as a power source for a belt conveyor. By using the starting method of the belt conveyor drive device 200 according to the present embodiment, it is possible to start with less torque fluctuation even if a cage type electric motor is used. Further, by using a cage-type motor that is cheaper than a winding-type motor, the cost for constructing a belt conveyor system can be reduced. In addition, since the cage-type motor can be easily procured at the time of replacement, an increase in maintenance cost can be suppressed.

By reducing the primary voltage of the squirrel-cage motor with a starter, it is possible to suppress a sudden increase in starting torque. However, in this method, depending on the value of the voltage applied to the squirrel-cage motor, excess or deficiency of the starting torque occurs, and it is difficult to start stably and smoothly with little fluctuation in the belt tension. On the other hand, by using the starting method of the belt conveyor drive device 200 according to the present embodiment, it is possible to start with less torque fluctuation without causing excess or deficiency of starting torque.

Embodiment 2
FIG. 5 is a diagram showing a configuration example of a belt conveyor system 100A including the belt conveyor driving device 200A according to the second embodiment of the present invention. The belt conveyor drive device 200A shown in FIG. 5 includes a plurality of commercial operation circuits 210-1 to 210-3. The number of commercial operation circuits may be two or more, and is not limited to three. In the belt conveyor drive device 200A, a plurality of electric motors 300 are driven. Each of the plurality of electric motors 300 is, for example, a cage-type electric motor. One electric motor 300 is driven for one commercial operation circuit.

The control unit 230A of the belt conveyor drive device 200A uses a plurality of commercial operation circuits 210-1 to 210-3 to form a plurality of commercial power supply paths in order, resulting in an inrush current generated at the time of starting. It is configured to drive the belt conveyor 500A having a large load while suppressing the voltage drop.

The "No. 1 electric motor" is an electric motor 300 that is driven by an inverter power supply and is driven by parallel operation of one commercial power supply (commercial operation circuit 210-1) and an inverter power supply. The "No. 2 electric motor" is an electric motor 300 driven by a commercial power source (commercial operation circuit 210-2). The rotational force of the "No. 1 electric motor" and the "No. 2 electric motor" is transmitted to, for example, the drive pulley 501 via the speed reducer 400. The "No. 3 electric motor" is an electric motor 300 driven by a commercial power source (commercial operation circuit 210-3). The rotational force of the "No. 3 electric motor" is transmitted to, for example, the drive pulley 502 via the speed reducer 400. The belt conveyor 500A is provided with two drive pulleys 501 and 502, but the number of drive pulleys is not limited to two.

The commercial operation circuit 210-1 includes a low-pressure circuit breaker 1-1 which is an overcurrent circuit breaker for short-circuit protection of an electric circuit, a switch 2-1 whose opening and closing is controlled by a control unit 230A, and a switch 2-1. The current limiting reactor 14 which is connected in series to suppress the inrush current of the commercial power supply, the switch 6-1 which is connected in parallel to the current limiting reactor 14 and controlled to open and close by the control unit 230A, and the overload protection device 10 are connected. Be prepared.

The commercial operation circuit 210-2 includes a low-voltage circuit breaker 1-2 which is an overcurrent circuit breaker for short-circuit protection of an electric circuit, a switch 2-2 whose opening and closing is controlled by a control unit 230A, and a switch 2-2. It includes a current limiting reactor 14 connected in series, a switch 6-2 connected in parallel to the current limiting reactor 14 and controlled to open and close by a control unit 230A, and an overload protection device 10.

The commercial operation circuit 210-3 includes a low-voltage circuit breaker 1-3 which is an overcurrent circuit breaker for short-circuit protection of an electric circuit, a switch 2-3 whose opening and closing is controlled by a control unit 230, and a switch 2-3. It includes a current limiting reactor 14 connected in series, a switch 6-3 connected in parallel to the current limiting reactor 14 and controlled to open and close by a control unit 230, and an overload protection device 10.

The control unit 230A includes a processor 231, a memory 232, an input / output interface 233, and a bus 234, similarly to the control unit 230 shown in FIG.

Next, the operation of the belt conveyor drive device 200A will be described with reference to FIGS. 5 to 7.

FIG. 6 is a flowchart for explaining the processing operation from the start of the operation of the belt conveyor 500A by the belt conveyor drive device 200A to the end of the operation. FIG. 7 is a timing chart for explaining the processing operation from the start of the operation of the belt conveyor 500A by the belt conveyor drive device 200A to the end of the operation.

In step S31, when a signal indicating "on" for the operation of the belt conveyor drive device 200A is input to the control unit 230A, the control unit 230A changes the state of the switch 4 from OFF to ON, and the switch 5 The state of -1 is changed from OFF to ON.

In step S32, when an operation command indicating the start of operation of the belt conveyor drive device 200A is input to the control unit 230A, the control unit 230A to which the operation command is input receives a gate drive signal for driving the switching element of the voltage conversion unit 11. Start generation. As a result, the current is supplied from the inverter start circuit 220 to the No. 1 motor (step S33).

Further, the control unit 230A that has input the operation command changes the state of the switch 6-1 from OFF to ON. When the No. 1 motor is driven, the No. 2 motor and the No. 3 motor indirectly mechanically connected to the No. 1 motor via the conveyor belt 510 rotate.

By generating the gate drive signal, the inverter output frequency and the inverter output current begin to rise. The current flowing at this time is input to the No. 1 motor via the switch 4, the voltage conversion unit 11, and the switch 5-1.

When the rotation speed of the No. 1 motor reaches a steady speed (constant speed), the control unit 230A controls the inverter output so that the voltage and phase of the commercial power supply and the inverter output match. The process of step S34 is repeated in the control unit 230A until the voltage and phase of the commercial power supply and the inverter output match (steps S34, No).

When the voltage and phase of the commercial power supply and the output of the inverter match (step S34, Yes), the synchronization detection signal is input to the control unit 230A. As a result, the control unit 230A detects that the rotation speed of the No. 1 motor reaches the steady speed and the voltage and phase of the commercial power supply and the inverter output are synchronized.

In step S35, the control unit 230A, which has detected synchronization, turns off the state of the switch 2-1 so that current is supplied to the No. 1 motor from both the inverter start circuit 220 and the commercial operation circuit 210-1. Change from to ON. At this time, the commercial power supply is supplied to the No. 1 motor via the switch 2-1 and the switch 6-1 of the commercial operation circuit 210-1.

After the rotation speed of the control unit 230A reaches a constant speed, the control unit 230 gradually reduces the on-duty of the gate drive signal to gradually reduce the inverter output current. As a result, while the AC current supplied from the inverter starting circuit 220 to the No. 1 motor decreases, the supply of the AC current from both the inverter starting circuit 220 and the commercial operation circuit 210-1 to the No. 1 motor continues ( Step S36).

In step S37, the control unit 230A measures, for example, the value of the inverter output current detected by the current detector, and determines whether or not the inverter output current has become zero. The process of step S37 is repeated until the inverter output current becomes zero (steps S37, No).

When the inverter output current becomes zero (step S37, Yes), that is, when the AC current supply from the inverter start circuit 220 to the No. 1 motor is cut off, the control unit 230A sets the current supply source to the No. 1 motor. The state of the switch 5-1 is changed from ON to OFF in order to switch to the commercial power supply (step S38). As a result, a current is supplied from the commercial operation circuit 210-1 to the No. 1 motor (step S39). After that, the control unit 230A changes the state of these switches from OFF to ON in the order of switch 2-2, switch 6-2, switch 2-3, and switch 6-3.

When the switch 2-2 and the switch 2-3 are turned on, an inrush current flows and a voltage drop occurs due to the impedance of the current path. When this voltage drop becomes a large value, the belt conveyor drive device 200A Operation may stop depending on the rated capacity of. In order to prevent this, a current is passed through the current limiting reactor 14 until a certain time (current limiting waiting time: for example, several seconds) elapses from the timing when the switch 2-2 and the switch 2-3 are turned on. After the flow waiting time has elapsed, the switch 6-2 and the switch 6-3 are turned on. As a result, the inrush current is suppressed, the power loss due to the current limiting reactor 14 is suppressed, and the operating efficiency of the belt conveyor system 100A can be improved.

In step S40, when a stop command indicating the stop of operation of the belt conveyor drive device 200A is input to the control unit 230A (step S40, Yes), the control unit 230A to which the stop command is input receives the switch 2-1 to the switch. By changing the state of 2-3 from ON to OFF, the current supply to the No. 1 motor to the No. 3 motor is stopped (step S41).

In step S42, when a signal indicating the operation preparation "off" of the belt conveyor drive device 200A is input to the control unit 230A, the control unit 230A changes the state of the switch 4 from ON to OFF.

As described above, in the belt conveyor drive device 200A according to the second embodiment, a plurality of electric motors are mechanically connected to each other by a conveyor belt of the belt conveyor, and one of the plurality of electric motors is started. After that, alternating current is supplied from the inverter start circuit to the motor until the rotation speed of the motor reaches a certain speed, and the inverter until a certain time elapses from the time when the rotation speed of the motor reaches a certain speed. AC current is supplied to the motor from both the starting circuit and the commercial operation circuit, and after a certain period of time, the AC current is supplied from the commercial operation circuit to the plurality of motors in sequence via the current limiting reactor. Will be.

With this configuration, along with the effect of the first embodiment, it is possible to sequentially start the electric motors while shifting the timing of starting the current supply to the plurality of electric motors. Therefore, when the timings of the current supply to the plurality of electric motors are simultaneous. Since the rated capacity of the inverter can be reduced as compared with the above, it is possible to drive the belt conveyor 500A having a high load while suppressing an increase in the manufacturing cost of the belt conveyor driving device 200A.

When the drive target of the belt conveyor drive device 200A according to the second embodiment is not a winding type electric motor but a cage type electric motor, the cost for constructing the belt conveyor system 100A can be reduced and the maintenance cost is increased. Can be suppressed.

Further, the belt conveyor drive program according to the present embodiment includes a step of starting the electric motor by an inverter starting circuit that supplies an AC current to start the electric motor for rotating the pulley provided in the belt conveyor, and after the electric motor is started. The step of supplying AC current from the inverter start circuit to the motor until the rotation speed of the motor reaches a constant speed, and after reaching a constant speed, the inverter while reducing the AC current supplied from the inverter start circuit to the motor. A step of supplying AC current from both the starting circuit and the commercial operation circuit to the motor, and a step of supplying AC current from the commercial operation circuit to the motor after the supply of AC current from the inverter starting circuit to the motor is stopped. Let the computer run.

Further, as the electric motor driven by the belt conveyor drive devices 200 and 200A according to the present embodiment, a high-slip electric motor having a certain value of speed drooping characteristics may be used. A high-slip electric motor is a motor in which the resistance of the car portion of a squirrel-cage motor is designed to be large and the slip is increased. By using a high-slip electric motor, load distribution is performed among a plurality of electric motors, and it is possible to construct belt conveyor drive devices 200 and 200A without increasing the rated capacity of the circuit that drives each motor. It is possible to suppress an increase in the manufacturing cost of the belt conveyor drive devices 200 and 200A.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1: Breaker 1-1: Breaker 1-2: Breaker 1-3: Breaker 2: Switch 2-1: Switch 2-2: Switch 2-3: Switch 3: Switch 4: Switch 4: Switch 5: Switch 5-1: Switch 5-2: Switch 5-3: Switch 6: Switch 6-1: Switch 6-2: Switch 6-3: Switch 10: Overload Protective device 11: Voltage converter 12: Synchronous detection transformer 13: Output reactor 14: Current limiting reactor 100: Belt conveyor system 100A: Belt conveyor system 200: Belt conveyor drive device 200A: Belt conveyor drive device 210: Commercial operation circuit 210- 1: Commercial operation circuit 210-2: Commercial operation circuit 210-3: Commercial operation circuit 220: Inverter start circuit 230: Control unit 230A: Control unit 231: Processor 232: Memory 233: Input / output interface 234: Bus 300: Conveyor drive Electric switch 400: Reducer 500: Belt conveyor 500A: Belt conveyor 501: Drive pulley 502: Drive pulley 510: Conveyor belt 600: Step-down transformer

Claims (5)

An inverter start circuit that supplies an alternating current to the electric motor that starts the electric motor that rotates the pulley provided on the belt conveyor, and
A commercial operation circuit that operates the electric motor by supplying the alternating current of the commercial power supply to the electric motor,
With
After the electric motor is started, an alternating current is supplied from the inverter starting circuit to the electric motor until the rotation speed of the electric motor reaches a constant speed.
After reaching a certain speed, the alternating current supplied from the inverter starting circuit to the electric motor decreases, and the alternating current is supplied to the electric motor from both the inverter starting circuit and the commercial operation circuit.
A belt conveyor drive device in which an alternating current is supplied from the commercial operation circuit to the electric motor after the supply of the alternating current from the inverter start circuit to the electric motor is stopped. The belt conveyor driving device according to claim 1, wherein the belt conveyor is a down belt conveyor having a down slope. The belt conveyor driving device according to claim 1 or 2, wherein the electric motor is a cage-type electric motor. The plurality of the electric motors are mechanically connected to each other by the conveyor belt of the belt conveyor.
After one of the plurality of electric motors is started, alternating current is supplied from the inverter starting circuit to the electric motor until the rotation speed of the electric motor reaches a constant speed.
After reaching a certain speed, the alternating current supplied from the inverter starting circuit to the motor is reduced, and the alternating current is supplied to the motor from both the inverter starting circuit and the commercial operation circuit.
After the supply of alternating current from the inverter start circuit to the electric motor is stopped, the supply of alternating current from the commercial operation circuit to the plurality of electric motors is sequentially performed via the current limiting reactor. The belt conveyor drive device according to any one of 3. A step of starting the electric motor by an inverter starting circuit that supplies an alternating current to the electric motor for starting the electric motor for rotating a pulley provided on a belt conveyor.
After the electric motor is started, a step of supplying an alternating current from the inverter start circuit to the electric motor until the rotation speed of the electric motor reaches a constant speed,
After reaching a certain speed, the AC current supplied from the inverter starting circuit to the electric motor is reduced, and the AC current of the inverter starting circuit and the commercial power supply is supplied to the electric motor to operate the electric motor. The step of supplying alternating current to the motor from both the operation circuit and
After the supply of the alternating current from the inverter start circuit to the electric motor is stopped, the step of supplying the alternating current from the commercial operation circuit to the electric motor
A belt conveyor drive program that causes a computer to execute.

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