JP2004088864A - Motor drive for rolling line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive for rolling line capable of continuous operation even if one inverter device is failed and stopped. <P>SOLUTION: This motor drive comprises a converter for converting an AC input into DC, an inverter for converting the output into an AC output of arbitrary frequency and voltage, a speed controller, a current controller, and a speed sensorless vector control inverter device with a frequency calculation part. Respective outputs of the plurality of speed sensorless vector control inverter devices 1-1 and 1-2 are connected with respective primary windings of a plurality of induction motors 2-1 to 2-n having a plurality of primary windings in parallel through a selective changing means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor drive device for driving a plurality of induction motors in a steel rolling line, and in particular, a plurality of induction motors are driven at the same time, such as a table drive device in a steel rolling line, and furthermore, failure of the drive device and The present invention relates to an electric motor drive device for a rolling line that improves the system operation rate so that operation can be continued even in the event of a disaster.
[0002]
[Prior art]
As this type of apparatus, for example, Japanese Patent Application Laid-Open No. 7-241094 is known. In this device, a plurality of induction motors are connected in parallel to the output side of an inverter device. Further, the control of the inverter device employs sensorless vector control in which the exciting current component and the torque current component are controlled independently without using a speed sensor.
[0003]
In the motor drive device having the above configuration, one inverter device is connected in parallel to a plurality of induction motors, but no consideration is given to making the inverter device redundant so as to improve the system operation rate.
[0004]
[Problems to be solved by the invention]
Reliability is required for a motor drive device in a rolling line. Once the motor drive unit stops due to a disaster or breakdown, the only way to restart it is to stop the operation once and resolve the failure. . However, with a conventional motor drive device in which a plurality of induction motors are driven in parallel by one inverter device, if the inverter device fails, the motor cannot be driven until the inverter device is restored, which causes a problem in plant operation. It was.
[0005]
Accordingly, an object of the present invention is to provide a motor drive device for a rolling line that allows continuous operation even if one inverter device fails and stops in consideration of the redundancy of the inverter device.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an electric motor driving device for a rolling line according to the present invention includes a converter that converts an AC input into a DC, an inverter that converts this output into an AC power of an arbitrary frequency and voltage, and an arithmetic operation. A speed control unit that compares the estimated speed of the induction motor with the speed reference to obtain a torque reference, and calculates D and Q axis current references from the torque reference and the amount of magnetic flux of the induction motor. The reference is compared with the output current of the inverter after D and Q coordinate conversion, respectively, to obtain a D and Q axis voltage reference and a three-phase voltage reference, and the inverter is PWM-controlled by this output. A speed sensorless vector control system using a current control unit and a frequency calculation unit configured to calculate the output frequency reference of the inverter from the Q-axis voltage reference and the impedance of the induction motor. Each of the primary windings of a plurality of induction motors having a plurality of primary windings is connected via selection switching means to respective outputs of the plurality of speed sensorless vector control inverters. And connected in parallel.
[0007]
In order to achieve the above object, an electric motor driving device for a rolling line according to the present invention includes a converter that converts an AC input into a DC, an inverter that converts this output into an AC power of an arbitrary frequency and voltage, and an arithmetic operation. A speed control unit that compares the estimated speed of the induction motor with the speed reference to obtain a torque reference, and calculates D and Q axis current references from the torque reference and the amount of magnetic flux of the induction motor. The reference is compared with the output current of the inverter after D and Q coordinate conversion, respectively, to obtain a D and Q axis voltage reference and a three-phase voltage reference, and the inverter is PWM-controlled by this output. A speed sensorless vector control system using a current control unit and a frequency calculation unit configured to calculate the output frequency reference of the inverter from the Q-axis voltage reference and the impedance of the induction motor. An inverter device is constructed, and the output of any of N (K> N) speed sensorless vector control inverter devices out of K (K> 2) speed sensorless vector control inverter devices is N primary windings. And connected in parallel to a plurality of induction motors having
[0008]
ADVANTAGE OF THE INVENTION According to this invention, even if one inverter apparatus fails and stops, the electric motor drive device for rolling lines which can be operated continuously can be provided.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment)
Hereinafter, a first embodiment of a motor drive device for a rolling line according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of a motor drive device for a rolling line according to the present invention.
[0010]
Each of the inverter devices 1-1 and 1-2 converts a commercial power supply into direct current, and obtains an output of an arbitrary voltage and frequency under the control of the control unit. This output is connected to respective primary windings of a plurality of induction motors 2-1,..., 2-N having two primary windings for driving a table or the like of a steel rolling line. That is, the inverter device 1-1 supplies power to one of the windings WU1, WV1, and WW1, respectively, and drives a plurality of induction motors 2-1,..., 2-N in parallel. 2 is configured to supply power to the other windings WU2, WV2, and WW2, respectively, and to drive a plurality of induction motors 2-1,..., 2-N in parallel.
[0011]
FIG. 2 shows a detailed configuration of the inverter device 1-1. Note that the inverter device 1-2 has exactly the same configuration, and a description thereof will be omitted.
[0012]
The AC voltage of the commercial power supply is converted into a DC voltage by the converter 3A. The inverter 3B receives the DC voltage, converts the DC voltage into an AC voltage having an arbitrary frequency and voltage, and drives the induction motor 2 via the output circuit breaker 9 at a variable speed. This is the main circuit configuration of the motor drive device for a rolling line according to the present invention.
[0013]
The schematic configuration of the control unit used in the present invention is as follows.
[0014]
The control unit is so-called sensorless vector control, and includes a speed control unit 4, a current control unit 5, and a frequency calculation unit 8.
[0015]
The speed controller 4 generates current references Idr and Iqr for the D-axis and the Q-axis based on the speed reference fr and the estimated speed fm of the induction motor 2 obtained by calculation.
[0016]
The current controller 5 compares these signals with the D-axis current Id and the Q-axis current Iq converted from the current detector 6 into the D-axis and the Q-axis, respectively, and outputs a voltage reference Vr. The PWM controller 7 PWM-modulates this signal, outputs a gate pulse Gp of the inverter 3B, and controls the inverter 3B.
[0017]
On the other hand, the frequency calculator 8 calculates the output frequency reference fo of the inverter 3B from the Q-axis voltage reference Vqr generated by the current controller 5.
[0018]
Next, a detailed configuration of the speed control unit 4 will be described.
[0019]
The speed reference fr is compared with the estimated speed fm output from the estimated speed calculator 46. The estimated speed fm is obtained by subtracting the slip frequency fs from the output frequency reference fo obtained from the frequency calculator 8.
[0020]
The torque is calculated by the speed control calculator 41 so that the speed deviation obtained as the difference between the speed reference fr and the estimated speed fm is zero, and the torque reference Tr is obtained. The Q-axis current reference Iqr is obtained by dividing the torque reference Tr by the magnetic flux amount 43 of the induction motor using the divider 42. Further, the magnetic flux amount 43 of the induction motor is converted into a D-axis current reference Idr by a magnetic flux saturation function 44. On the other hand, the slip frequency fs is obtained by dividing the Q-axis current reference Iqr by the magnetic flux amount 43 of the induction motor using the divider 45.
[0021]
The detailed configuration of the current control unit 5 is as follows.
[0022]
Two phases, for example, a U-phase current and a W-phase current of an arbitrary one side winding of the induction motor 2 are detected by the current detector 6 and input to the current coordinate converter 51. The current coordinate converter 51 converts the U-phase current and the W-phase current into a Q-axis current Iq and a D-axis current Id based on the phase signal φ obtained by integrating the output frequency reference fo by the integrator 55.
[0023]
The Q-axis current control calculator 52 compares the Q-axis current reference Iqr, which is the output of the speed control unit 4, with the Q-axis current Iq, and calculates a Q-axis voltage reference Vqr for reducing the difference between the two to zero. Generate. The D-axis current control calculator 53 compares the D-axis current reference Idr, which is the output of the speed control unit 4, with the D-axis current Id, and calculates a D-axis voltage reference Vdr for reducing the difference between the two to zero. Generate.
[0024]
The voltage coordinate converter 54 converts the Q-axis voltage reference Vqr and the D-axis voltage reference Vdr into a three-phase voltage reference Vr based on the phase signal φ from the integrator 55. The three-phase voltage reference Vr is supplied to the PWM controller 7, where a gate pulse Gp to be supplied to the switching element of each arm of the inverter 3B is generated.
[0025]
The detailed configuration of the frequency calculation unit 8 is as follows.
[0026]
The Q-axis induced voltage calculator 81 calculates a Q-axis induced voltage Eq from the Q-axis voltage reference Vqr generated by the Q-axis current control calculator 52 of the current controller 5 and the impedance 82 of the induction motor. 83. The Q-axis induced voltage Eq output from the Q-axis induced voltage calculator 81 is converted by the frequency converter 83 into an output frequency reference fo.
[0027]
The estimated speed fm from the estimated speed calculator 46 input to the aforementioned speed control calculator 41 is obtained by subtracting the slip frequency fs from the corrected output frequency reference fo during power running by the estimated speed calculator 46 and correcting the slip frequency fs during regeneration. It is determined by adding the slip frequency fs to the output frequency reference fo.
[0028]
In the figure, reference numeral 10 denotes a failure detection device for detecting a failure of the inverter 1-1, which issues a master / slave switching signal described later.
[0029]
Next, a description will be given of the sharing of operation signals between the inverter devices 1-1 and 1-2 with reference to FIG.
[0030]
Now, it is assumed that the inverter device 1-1 has the configuration shown in FIG. In this state, the Q-axis current reference Iqr of the inverter 1-1 is connected to the Q-axis current calculator 52 of the inverter 1-2. The inverter that gives the Q-axis current reference, that is, the torque reference, like the inverter device 1-1 is called a master inverter, and the inverter that receives the torque reference from the master, like the inverter device 1-2, is called the slave inverter. Call. As shown in FIG. 2, the inverter 1-1 may be operated by switching to a slave inverter. Therefore, a circuit for receiving the Q-axis current reference Iqr from the inverter 1-2 is also added.
[0031]
Next, a configuration of a control circuit that performs an operation at the time of an inverter failure will be described. The failure detection device 10 detects a failure of the inverter device 1-1 based on a voltage or current abnormality signal of the converter 3A and the inverter 3B. When the failure signal is input to the failure detection device 10, the output circuit breaker 9 is opened, and a master / slave selection signal is issued. Be able to continue driving as a master. In this way, the means for disconnecting the inverter device due to the failure of the inverter device 1-1 and continuing the operation is referred to as selection switching means.
[0032]
Next, the operation of the electric motor driving device for a rolling line according to the first embodiment of the present invention configured as described above will be described with reference to FIGS.
[0033]
As is clear from the configuration of FIG. 1, a plurality of induction motors 2-1,..., 2-n for driving the table of the rolling line are provided by both the inverter 1-1 and the inverter 1-2. Powered. Further, as described in the control configuration of FIG. 2, the inverter device 1-2 is controlled on the basis of the Q-axis current reference Iqr of the inverter device 1-1 as the master inverter, that is, the torque reference. And the load sharing of the inverter device 1-2 is substantially the same.
[0034]
In addition, as shown in FIG. 2, when one of the inverters is stopped due to a disaster or a failure, the stopped one of the inverters is completely disconnected by opening the output circuit breaker 9, and the other inverter is used. Thus, a degenerate operation in which a primary current is supplied from one primary winding of the induction motor 2 and driven is possible.
[0035]
In FIG. 1, the number of inverters is two and the number of primary windings of the motor is also two. However, the number of inverters is N (N is an arbitrary integer of 2 or more) and the number of primary windings is The number may be N.
[0036]
As described above, according to the rolling line motor drive device of the present invention, it is possible to provide a rolling line motor drive device that can be continuously operated even if one inverter device is stopped.
[0037]
(Second embodiment)
FIG. 3 is a block diagram of a motor driving device for a rolling line according to a second embodiment of the present invention. Regarding each part of the second embodiment, the same parts as those of the rolling line motor drive device according to the first embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. This second embodiment is different from the first embodiment in that a combined inverter device 1A in which these are housed in the same housing is used instead of the inverter devices 1-1 and 1-2 in FIG. Is a point.
[0038]
Thus, by installing one composite inverter device 1A instead of the two inverter devices 1-1 and 1-2, the same effect as in the first embodiment can be obtained. In this case, even if the Q-axis current reference Iqr is not necessarily transferred, the basic control portion of the two inverters is shared, and the gate pulse Gp generated here is simultaneously transmitted to the two inverter devices 1-1, 1-l. 2 to the inverter 2.
[0039]
(Third embodiment)
FIG. 4 is a block configuration diagram of a rolling line motor drive device according to a third embodiment of the present invention. Regarding each part of the third embodiment, the same parts as those of the rolling line motor drive device according to the first embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. The third embodiment is different from the first embodiment in that the number of inverter devices is changed to 1-1, 1-2, 1- 1 instead of the inverter devices 1-1 and 1-2 in FIG. The point that the number of windings of the electric motor 2 is not the same as the number of inverter devices as described above, but the number of windings is smaller than the number of inverter devices. In FIG. 4, the number of windings is two.
[0040]
In FIG. 4, two units of the inverter devices 1-1 and 1-2 form one group, and outputs of these two units are divided into two primary units of induction motors 2-1,..., 2-m. Each is connected in parallel to the winding.
[0041]
On the other hand, the two inverters 1-3 and 1-4 form another group, and the outputs of the two inverters are used as two primary motors of induction motors 2-m + 1,..., 2-n. Each is connected to a winding.
[0042]
Although the number of inverters is four and the number of windings of the induction motor is two here, the number of inverters is K (K> 2) and the number of windings of the induction motor is N (K> N). It can be extended.
[0043]
In the motor drive device of the rolling line as described above, even if one inverter device breaks down, if it is disconnected, only a certain portion of the entire motor drive capacity has an output of 50%. It becomes easy to continue driving. Further, since it is possible to freely select which roll of the table of the rolling line is to be driven by which inverter device, it is possible to configure the system according to the load characteristics.
[0044]
Furthermore, the inverter device has a standard capacity determined by the element rating. If the number of divisions and the number of motors to be driven are determined so that the standard capacity can be fully used, an overall cost-effective system configuration can be realized. Is also possible.
[0045]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a rolling line motor drive device that can be continuously operated even when one inverter device fails and stops.
[Brief description of the drawings]
FIG. 1 is a block diagram of a motor drive device for a rolling line according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing details of an electric motor driving device for a rolling line according to the first embodiment of the present invention.
FIG. 3 is a block diagram of a motor for a rolling line according to a second embodiment of the present invention.
FIG. 4 is a block diagram of a motor drive device for a rolling line according to a third embodiment of the present invention.
[Explanation of symbols]
1-1, 1-2, 1-3, 1-4 Inverter 1A Combined inverter 2-1, 2-2, 2-m, 2-m + 1, 2-n Induction motor 3A Converter 3B Inverter 4 Speed controller 5 Current Control Unit 6 Current Detector 7 PWM Controller 8 Frequency Calculator 9 Output Circuit Breaker 10 Failure Detector 41 Speed Control Calculator 42 Divider 43 Flux Amount of Induction Motor 44 Flux Saturation Function 45 Divider 46 Estimated Speed Calculator 51 Current coordinate converter 52 Q-axis current control calculator 53 D-axis current control calculator 54 Voltage coordinate converter 55 Integrator 81 Impedance of induction motor 82 Q-axis induced voltage calculator 83 Frequency converter

Claims (5)

A converter for converting AC input to DC,
An inverter that converts this output into AC power of any frequency and voltage;
A speed control unit that compares the estimated speed of the induction motor obtained by the calculation with the speed reference, and obtains a torque reference;
D and Q axis current references are calculated from the torque reference and the amount of magnetic flux of the induction motor, and the D and Q axis current references are compared with the D and Q coordinate converted output currents of the inverter, respectively. A current controller configured to obtain a Q-axis voltage reference and a three-phase voltage reference, and to perform PWM control on the inverter based on the output;
A speed sensorless vector control inverter device is configured by using a frequency calculation unit configured to calculate the output frequency reference of the inverter from the Q-axis voltage reference and the impedance of the induction motor,
Outputs of a plurality of the speed sensorless vector control inverters are connected in parallel to respective primary windings of a plurality of induction motors having a plurality of primary windings through selection switching means. An electric motor driving device for a rolling line, characterized in that: A converter for converting AC input to DC,
An inverter that converts this output into AC power of any frequency and voltage;
A speed control unit that compares the estimated speed of the induction motor obtained by the calculation with the speed reference, and obtains a torque reference;
D and Q axis current references are calculated from the torque reference and the amount of magnetic flux of the induction motor, and the D and Q axis current references are compared with the D and Q coordinate converted output currents of the inverter, respectively. A current controller configured to obtain a Q-axis voltage reference and a three-phase voltage reference, and to perform PWM control on the inverter based on the output;
A speed sensorless vector control inverter device is configured by using a frequency calculation unit configured to calculate the output frequency reference of the inverter from the Q-axis voltage reference and the impedance of the induction motor,
The output of any of N (K> N) speed sensorless vector control inverters out of the K (K> 2) speed sensorless vector control inverters is connected to N primary outputs via selection switching means. A motor drive device for a rolling line, wherein each of the plurality of induction motors having a winding is connected in parallel. The motor drive device for a rolling line according to claim 1 or 2, wherein a plurality of inverter devices are housed in one housing. The rolling line according to any one of claims 1 to 3, wherein one of the plurality of inverter devices is used as a master, and the slave inverter device is controlled according to a torque reference of the master inverter device. Motor drive. 2. The method according to claim 1, wherein when a failure detector detects a failure of the inverter device, the output of the failed inverter device is disconnected, and when the inverter device is a master, the master is switched to another inverter device. An electric motor drive device for a rolling line according to any one of claims 3 to 3.

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