JP2022178156A - Motor driving control system, and motor driving control method - Google Patents

Abstract

To provide a motor driving control system capable of continuously driving a motor at minimum necessary power supply capacity even when emergency such as commercial power source loss occurs.SOLUTION: A motor driving control system according to one embodiment comprises a plurality of first inverters for independently driving a plurality of motors by a vector control system, using first power supplied from a commercial power supply; and a second inverter for collectively driving the plurality of motors by a V/F control system during power supply loss by which no first power can be supplied from the commercial power supply, using second power supplied from a power generator.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor drive control system and a motor drive control method.

In a typical motor drive control system, an inverter drives a motor using power supplied from a commercial power source. For such a motor drive control system, several motor drive control methods have been proposed for continuing to drive the motor even in an emergency when the commercial power supply is lost.

Japanese Patent No. 5316080 Japanese Patent No. 5218938 Japanese Patent No. 6119475

A large amount of electric power is required to operate a wide-range motor drive control system with a large number of motors. Therefore, the capacity of the emergency power supply to be used when the commercial power supply is lost also increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor drive control system and a motor drive control method capable of continuing to drive a motor with the minimum necessary power capacity even in the event of an emergency such as a loss of commercial power supply. .

An electric motor drive control system according to one embodiment includes a plurality of first inverters that independently drive a plurality of electric motors in a vector control method using first electric power supplied from a commercial power supply, and a second inverter that collectively drives the plurality of electric motors by a V/F control method using the second power supplied from the generator when the power source fails to supply the first power.

An electric motor drive control method according to one embodiment includes:
The plurality of first inverters independently drive the plurality of electric motors by a vector control method using the first electric power supplied from the commercial power supply,
When the first electric power cannot be supplied from the commercial power supply, the second inverter uses the second electric power supplied from the generator to collectively drive the plurality of electric motors in a V/F control method. do.

According to the present invention, it is possible to continue driving the electric motor with the minimum required electric power even in an emergency such as loss of the commercial power supply.

1 is a diagram showing a schematic configuration of an electric motor drive control system according to a first embodiment; FIG. FIG. 10 illustrates how the mechanical interlock connects the electric motor to the second inverter; 4 is a flow chart showing an operation procedure of an electric motor drive control system; It is a figure which shows roughly the structure of the electric-motor drive control system which concerns on 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings. The following embodiments do not limit the invention.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of an electric motor drive control system according to the first embodiment. 1 includes a converter 10, a plurality of first inverters 20, a plurality of mechanical interlocks 30, a control device 40, a second inverter 50, a control device 60, a plurality of A base electric motor 70 and a generator 80 are provided. Here, the control device 40 and the control device 60 respectively correspond to the first control device and the second control device. Each component of the motor drive control system 1 will be described below.

The converter 10 converts AC power supplied from a 400V commercial power supply 100 having a frequency of 50 Hz or 60 Hz into DC power. Note that the voltage (effective value) of the AC power is not limited to 400V, and is allowed to increase or decrease within a predetermined fluctuation range (for example, from -10% to +10%) with respect to 400V.

A relay 110 and a first circuit breaker 111 are installed between the converter 10 and the commercial power supply 100 . The relay 110 is installed on the primary side of the first circuit breaker 111 . Relay 110 disconnects commercial power supply 100 and converter 10 when, for example, an abnormal state of commercial power supply 100 continues for a predetermined period of time. The first circuit breaker 111 is composed of, for example, an MCCB (Molded Case Circuit Braker). First circuit breaker 111 disconnects commercial power supply 100 and converter 10 when an overcurrent flows from commercial power supply 100 toward converter 10, for example.

The multiple first inverters 20 use the DC power supplied from the converter 10 to independently drive the multiple electric motors 70 . Each first inverter 20 is configured by, for example, a VVVF (Variable Voltage Variable Frequency) inverter capable of converting DC power into AC power whose voltage and frequency are respectively variable. FIG. 1 shows four first inverters 20 and electric motors 70, but the number of these is not particularly limited as long as it is plural.

A second circuit breaker 112 is installed between each first inverter 20 and the converter 10 . The second circuit breaker 112 is composed of, for example, a DCCB (Direct Current solid state Circuit Braker). Second circuit breaker 112 disconnects first inverter 20 and converter 10 when an overcurrent flows from converter 10 toward first inverter 20 .

Each mechanical interlock 30 switches the connection destination of each electric motor 70 to either one of the first inverter 20 and the second inverter 50 under the control of the control device 40 and the control device 60 . In FIG. 1, mechanical interlock 30 connects electric motor 70 to first inverter 20 .

FIG. 2 is a diagram showing a state in which the mechanical interlock 30 connects the electric motor 70 to the second inverter 50. As shown in FIG. In the connection configuration shown in FIG. 2 , the electric motor 70 is driven by the second inverter 50 .

Each control device 40 controls each first inverter 20 based on the state of relay 110 . In this embodiment, a speed detector 71 (PLG: Plus Generator) is installed in each electric motor 70 . A speed detector 71 detects the rotational speed of the electric motor 70 . The control device 40 controls the output voltage and output frequency of the first inverter 20 based on the rotation speed detected by the speed detector 71 . That is, the control device 40 controls the first inverter 20 using a vector control method.

The second inverter 50 uses AC power supplied from the generator 80 via the generator power supply line 101 to collectively drive the plurality of electric motors 70 . Like the first inverter 20, the second inverter 50 can also be composed of a VVVF inverter. However, in this VVVF inverter, a diode rectifier for converting alternating current to direct current is installed in the front stage of the inverter circuit. Note that the number of second inverters 50 is preferably one, but may be less than the number of first inverters 20 .

Control device 60 controls second inverter 50 based on the state of relay 110 . In this embodiment, the control device 60 proportionally controls the output voltage and the output frequency of the second inverter 50 . That is, the control device 60 controls the first inverter 20 using the V/F control method.

Each electric motor 70 is, for example, an AC motor. Various rotating devices can be connected to each electric motor 70 .

The generator 80 is, for example, a 200V AC generator with a frequency of 50 Hz or 60 Hz. It should be noted that the voltage (effective value) of the output power of the generator 80 is not limited to 200V, and is allowed to increase or decrease within a predetermined fluctuation range (for example, from -10% to +10%) with respect to 200V.

FIG. 3 is a flow chart showing the operation procedure of the motor drive control system 1. As shown in FIG. Here, the operation of switching the driving of the electric motor 70 between the first inverter 20 and the second inverter 50 will be described.

First, control device 40 and control device 60 determine whether or not a loss of commercial power has occurred based on the state of relay 110 (step S1). In step S1, if relay 110 maintains connection between commercial power supply 100 and converter 10, commercial power supply has not been lost. In this case, the control device 40 starts driving each first inverter 20 (step S2). In step S2, each first inverter 20 drives each electric motor 70 independently by the vector control method.

On the other hand, in step S1, when relay 110 disconnects commercial power supply 100 and converter 10, controllers 40 and 60 determine that a loss of commercial power supply has occurred. In this case, the control device 40 stops driving the first inverter 20 (step S3).

Subsequently, the mechanical interlock 30 performs a switching operation (step S4). In step S4, the mechanical interlock 30 switches the connection destination of the electric motor 70 from the first inverter 20 (see FIG. 1) to the second inverter 50 (see FIG. 2).

Finally, the generator 80 starts to drive, and the control device 60 starts to drive the second inverter 50 (step S5). In step S5, the second inverter 50 collectively drives the electric motors 70 by the V/F control method.

According to the present embodiment described above, when the commercial power supply is lost, the second inverters 50, which are fewer in number than the first inverters 20, collectively control all the electric motors 70 by the V/F control method, which is simpler than the inverter control method. drive effectively. Therefore, the power supply capacity of the generator 80, that is, the power supplied to the second inverter 50 can be minimized. Therefore, even if an emergency such as loss of commercial power occurs, the electric motor 70 can continue to be driven with the minimum required electric power.

Especially in this embodiment, the number of second inverters 50 is one. The supply voltage of the second inverter 50 is approximately 200V, which is half the supply voltage of the first inverter 20 (approximately 400V). By adopting the generator 80 with a small power supply capacity in this way, the electric motor 70 can be reliably driven by an inexpensive emergency power supply.

(Second embodiment)
FIG. 4 is a diagram schematically showing the configuration of an electric motor drive control system according to the second embodiment. In FIG. 4, the same reference numerals are given to the same components as in the first embodiment described above, and detailed description thereof will be omitted.

A motor drive control system 2 according to this embodiment is incorporated in a continuous casting facility 200 . Here, the continuous casting equipment 200 will be briefly described.

The continuous casting facility 200 includes a ladle 201, a tundish 202, a mold 203, a plurality of support rolls 204, and the like, as shown in FIG. Molten steel 210 is stored in the ladle 201 . This molten steel 210 is transferred from a ladle 201 through a tundish 202 . The transferred molten steel 210 is injected from the tundish 202 into the mold 203 and processed into a cast slab. The slab is processed into a flat plate shape while being curved by the rotation of a plurality of support rolls 204 . In this way a slab with a given thickness is cast.

In the continuous casting facility 200 configured as described above, if the support rolls 204 are stopped for a long time during casting due to a failure on the power supply side, a problem occurs in which the cast slab solidifies and adheres to the support rolls 204. obtain.

Therefore, in this embodiment, the electric motor drive control system 2 is used to rotate each of the plurality of support rolls 204 . Specifically, an electric motor 70 is coupled to each support roll 204 .

The configuration of the electric motor drive control system 2 is the same as that of the electric motor drive control system 1 described in the first embodiment. Therefore, in normal times, the first inverter 20 uses the electric power supplied from the commercial power supply 100 to drive the electric motor 70 by the vector control method. On the other hand, when the commercial power source 100 is lost, the second inverter 50 uses the electric power supplied from the generator 80 to drive the electric motor 70 by the V/F control method.

Since the supply voltage of the generator 80 is lower than the supply voltage of the commercial power supply 100, the rotation speed of each support roll 204 at the time of loss of commercial power supply is smaller than that in normal times. However, since the support rolls 204 continue to rotate, it is possible to avoid the problem that the cast piece solidifies and adheres to the support rolls 204 .

According to the present embodiment described above, as in the first embodiment, when the commercial power supply is lost, the second inverters 50, which are fewer in number than the first inverters 20, are controlled by a V/F control method that is simpler than the inverter control method. drives all the electric motors 70 collectively. Therefore, the power supply capacity of the generator 80, that is, the power supplied to the second inverter 50 can be minimized. Therefore, even if an emergency such as loss of commercial power occurs, the electric motor 70 can continue to be driven with the minimum required electric power.

Note that the electric motor drive control system 2 is applied to the continuous casting facility 200 in this embodiment. However, the application of the motor drive control system is not limited to driving the support rolls 204 of the continuous casting facility 200, but can also be connected to other rotating equipment.

Although several embodiments and modifications have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The novel system described herein can be implemented in various other forms. Also, various omissions, substitutions, and modifications may be made to the form of the system described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and modifications as fall within the scope and spirit of the invention.

1, 2: Motor Drive Control System 20: First Inverter 30: Mechanical Interlock 40: Controller 50: Second Inverter 60: Controller 100: Commercial Power Source 204: Support Roll

Claims (9)

a plurality of first inverters that independently drive a plurality of electric motors by a vector control method using a first electric power supplied from a commercial power supply;
a second inverter for collectively driving the plurality of electric motors in a V/F control system using the second electric power supplied from the generator when the first electric power cannot be supplied from the commercial power supply; and A motor drive control system comprising: 2. The electric motor drive control system according to claim 1, wherein said second inverter is one. 3. The electric motor drive control system according to claim 1, further comprising a mechanical interlock that switches connection destinations of said plurality of electric motors to one of said plurality of first inverters and said second inverters. a plurality of first control devices that individually control the plurality of first inverters;
4. The electric motor drive control system according to any one of claims 1 to 3, further comprising a second control device that controls said second inverter. 5. The electric motor drive control system according to claim 1, wherein said plurality of first inverters and said second inverters are VVVF inverters. 6. The motor drive control system according to any one of claims 1 to 5, wherein said second power is lower than said first power. 7. The motor drive control system according to claim 6, wherein said commercial power source is a 400V system, and said generator is a 200V system. 8. The electric motor drive control system according to any one of claims 1 to 7, wherein the plurality of electric motors are connected to a plurality of support rolls for processing the cast slab into a flat plate shape. The plurality of first inverters independently drive the plurality of electric motors by a vector control method using the first electric power supplied from the commercial power supply,
When the first electric power cannot be supplied from the commercial power supply, the second inverter uses the second electric power supplied from the generator to collectively drive the plurality of electric motors in a V/F control method. do,
Electric motor drive control method.

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