Method for realizing open-closed loop control of frequency converter based on Intouch HMI

Abstract

The invention relates to the field of frequency conversion control, in particular to a method for realizing open / closed loop control of a frequency converter based on an Intouch HMI (Human Machine Interface), which comprises the following steps of: configuring at least one tension leveler clamping roller motor frequency conversion open / closed loop switching button on an Intouch HMI man-machine interface; inserting a data block DB in the PLC program, wherein the data block DB is used for storing activation state data of the corresponding switching button; the PLC transmits corresponding activation state data to the frequency converter in real time through a DP bus; two groups of control parameters are preset in each frequency converter, the first group of control parameters are used for controlling a tension leveler clamping roller motor under the speed open-loop mode operation, and the second group of control parameters are used for controlling the tension leveler clamping roller motor under the speed closed-loop mode operation; and each frequency converter calls a corresponding control parameter according to the received activation state data, and is used for controlling the operation in a speed open / closed loop mode. The method has the advantages that the'closed-loop and open-loop 'switching is quickly completed through one key of the Intouch HMI, the fault recovery time is shortened, and the downtime is remarkably shortened.

Description

Technical Field

[0001] This invention relates to the field of frequency converter control, and more particularly to a method for realizing open-loop and closed-loop control of frequency converters based on IntouchHMI. Background Technology

[0002] In the continuous casting process of slabs, the straightening machine is a key piece of equipment in the continuous casting line, using clamping rollers to pull the slab out of the sector section. To ensure the accuracy of the casting speed and the quality of the slab, each clamping roller motor adopts a control scheme of "speed closed loop + encoder feedback": the encoder detects the motor speed in real time, and the frequency converter makes closed-loop adjustments based on the feedback value to ensure stable casting speed.

[0003] However, the continuous casting environment is harsh (high temperature, moisture, dust), making encoders prone to failure. Once an encoder fails, the corresponding strain gauge immediately reports a fault and shuts down the machine. When two or more clamping rollers stop simultaneously, the total drawing force on the rectifier side drops sharply, easily leading to a "cannot draw the billet" phenomenon, resulting in horizontal billet, production stoppage, or even equipment damage. In this situation, the faulty motor must be quickly switched from closed-loop to open-loop (without encoder) operation to restore the drawing torque.

[0004] The existing practices have the following shortcomings: Maintenance personnel need to go to the site to disconnect the wires and change the parameters, which is a complicated and time-consuming process. Some fault locations are in confined spaces with high temperatures, making manual operation difficult and posing safety hazards. After the parameters are modified, the closed loop needs to be re-adjusted, and manual intervention is required again when restoring the closed loop, which is inefficient. Summary of the Invention

[0005] The purpose of this invention is to provide a method for realizing open-loop and closed-loop control of frequency converters based on IntouchHMI, which can eliminate the need for on-site maintenance personnel when encoder failure occurs, thereby shortening the fault handling time and improving the safety and continuity of continuous casting production.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI includes: Configure at least one frequency converter open / closed loop switching button for the clamping roller motor of the tension straightener on the IntouchHMI human-machine interface; Insert a data block DB into the PLC program. The data block DB is used to store the activation status data of the corresponding toggle button. The PLC transmits the corresponding activation status data to the frequency converter in real time via the DP bus; Each frequency converter has two sets of preset control parameters. The first set of control parameters is used to control the clamping roller motor of the tension leveler in the speed open-loop mode operation, and the second set of control parameters is used to control the clamping roller motor of the tension leveler in the speed closed-loop mode operation. Each frequency converter calls the corresponding control parameters based on the received activation status data for speed control in open / closed loop operation.

[0007] Each switch button is used to drive the corresponding frequency converter, and each frequency converter is used to drive the corresponding clamping roller motor of the tension leveler.

[0008] Each bit in the data block DB is used to store the activation status data of the corresponding toggle button.

[0009] Setting the corresponding bit in data block DB to "1" means the corresponding frequency converter switches to speed open-loop mode to drive the clamping roller motor of the tension leveler; setting the corresponding bit in data block DB to "0" means the corresponding frequency converter maintains speed closed-loop mode to drive the clamping roller motor of the tension leveler.

[0010] It also includes a speed encoder, which is used to monitor the speed of the clamping roller motor of the tension leveler. If the speed encoder exceeds the set range during the operation of the clamping roller motor of the tension leveler, the corresponding switching button is triggered, so that the corresponding frequency converter switches from speed closed-loop mode to speed open-loop mode to drive the clamping roller motor of the tension leveler.

[0011] Compared with the prior art, the beneficial effects of the present invention are: 1. The IntouchHMI allows for quick one-click switching between closed-loop and open-loop operation, shortening fault recovery time and significantly reducing downtime. 2. When an encoder failure causes the straightening machine to stop, the frequency converter is immediately switched to speed open-loop mode via IntouchHMI to drive the corresponding clamping roller motor, ensuring that the total drawing torque does not decrease, thereby avoiding "unable to draw the billet" and horizontal billet accidents, significantly reducing the risk of major production stoppages, and improving production safety and continuity. 3. Maintenance personnel do not need to enter high-temperature, high-humidity, or confined areas to disconnect wires and change parameters. All operations are completed in HMI, reducing labor intensity and safety hazards simultaneously. 4. After switching, the PLC remembers the current mode, and you can seamlessly return to the closed loop by clicking again; the HMI displays the open / closed loop status of each roller in real time, which is convenient for operation monitoring and subsequent maintenance. Attached Figure Description

[0012] Figure 1 This is the logic diagram for the casting flow tracking control of a continuous casting machine.

[0013] Figure 2 This is the interface for switching the open and closed loops of the straightening motor on the continuous casting machine.

[0014] Figure 3 This is a schematic diagram of the clamping roller structure.

[0015] In the diagram: 1. Encoder; 2. Clamping roller motor of tension leveler; 3. Reducer; 4. Clamping roller; 5. Slab; 6. Base of tension leveler. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0017] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0018] Example 1 A method for implementing open-loop and closed-loop control of frequency converters based on IntouchHMI, see [link to relevant documentation]. Figure 3 The system includes a tension leveler clamping roller motor 2, a reducer 3, an encoder 1, a PLC, and a frequency converter. The tension leveler clamping roller motor 2 drives the clamping roller to rotate through the reducer. The encoder 1 is fixedly mounted on the reducer 3. The tension leveler clamping roller motor 2 is driven by a corresponding frequency converter. The PLC is connected to the frequency converter and is a Siemens PLC. The frequency converter is a Siemens 6ES70 series. Specifically, it includes the following: S1. Configure the IntouchHMI human-machine interface, see Figure 2 Create 24 new toggle buttons in the pull-and-align window of the IntouchHMI human-machine interface and configure the toggle buttons as shown in Table 1.

[0019] Table 1: Switch Button Configuration Table.

[0020] S2. Insert a data block DB into the PLC program. The data block DB is used to store the activation status data of the corresponding toggle buttons, including: Clicking the switch button once in the IntouchHMI human-machine interface sets the corresponding bit in the data block DB to "1", activating the stored memory "open-loop control"; Clicking the switch button again sets the corresponding bit in the data block DB to 0, activating the storage memory "closed-loop control". Store the results of the open-loop and closed-loop control switching logic into the newly created data block DB980, as shown in Table 2.

[0021] Table 2: Logic table for open / closed loop switching button.

[0022] S3 and PLC transmit open-loop and closed-loop control storage signal DB980 data to the frequency converter through function block SFC15 in Siemens programming software.

[0023] S4. Each frequency converter has two sets of preset control parameters. The first set of control parameters is used to control the clamping roller motor of the tension leveler in the closed-loop speed operation mode, and the second set of control parameters is used to control the clamping roller motor of the tension leveler in the open-loop speed operation mode. Both the first and second sets of control parameters include main parameters such as P100, P130, P578, and P579. P100 and P130 are used for setting the open and closed loop modes, and P578 and P579 are used for switching between motor data groups 1 and 2.

[0024] S5. Each frequency converter calls the corresponding control parameters based on the received activation status data for speed control in open / closed loop operation.

[0025] Example 2 Taking the Siemens 6ES70 series frequency converter of the straightening system of a certain continuous casting machine in a steel plant as an example, this paper introduces the steps of realizing open-loop and closed-loop control of the frequency converter based on Intouch HMI for clamping roller 1: S1. In the Siemens S7 program, use the HMI interface to set the open / closed loop control storage variable DB980.DBX0.0 to 0 or 1 using the variable DB970.DBX863.0: variable DB980.DBX0.0 = 0 for speed closed loop mode, variable DB980.DBX0.0 = 1 for speed open loop mode.

[0026] S2, the open-loop control storage variable DB980.DBX0.0 corresponds to bit CW1.B15 of the strain gauge control word 1, and is transmitted by function block sfc15.

[0027] S3. In the inverter's DriveMonitor software, select parameter P362, change the value from 0 to 12, and execute the call to copy motor data groups 1 to 2, so that there are 2 sets of motor data parameters in the inverter.

[0028] S5. Modify the parameters of motor data group 2 in the inverter's DriveMonitor software: change P60 value from 7 to 5, P100.2 value from 4 to 3, P130.2 value from 15 to 10, and P60 value from 5 to 7. At this time, motor data group 2 changes from speed closed-loop mode to speed open-loop mode.

[0029] S6. Modify the motor data group parameters P578 and P579 in the inverter's DriveMonitor software so that P578=1 and P579=0. Check that the currently valid motor data group parameter R011 should be 2. At this time, the motor data group 2 parameter is activated.

[0030] S7. Optimize the parameters of motor data group 2: Complete motor identification P115=3; No-load test P115=4; After optimizing the parameters of motor data group 2, the value of parameter P578 is changed from 1 to B3115 and the value of P579 is changed to 0. At this time, the switching between motor data group 1 and motor data group 2 is controlled by the open-loop control storage variable DB980.DBX0.0.

[0031] This invention enables a one-click "closed-loop to open-loop" switch via IntouchHMI, shortening fault recovery time and significantly reducing downtime. When an encoder failure causes the straightening machine to stop, IntouchHMI immediately switches the frequency converter to speed open-loop mode, driving the corresponding clamping roller motors to ensure that the total drawing torque does not decrease, thereby avoiding "unable to draw the billet" and horizontal billet accidents, significantly reducing the risk of major production stoppages and improving production safety and continuity. Maintenance personnel do not need to enter high-temperature, high-humidity, or confined areas to dismantle lines and change parameters; all operations are completed within the HMI, reducing labor intensity and safety hazards simultaneously. After switching, the PLC remembers the current mode, and a click again seamlessly returns to the closed-loop mode. The HMI displays the open / closed-loop status of each roller in real time, facilitating operation monitoring and subsequent maintenance.

Claims

1. A method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI, characterized in that, include: Configure at least one frequency converter open / closed loop switching button for the clamping roller motor of the tension straightener on the IntouchHMI human-machine interface; Insert a data block DB into the PLC program. The data block DB is used to store the activation status data of the corresponding toggle button. The PLC transmits the corresponding activation status data to the frequency converter in real time via the DP bus; Each frequency converter has two sets of preset control parameters. The first set of control parameters is used to control the clamping roller motor of the tension leveler in the speed open-loop mode operation, and the second set of control parameters is used to control the clamping roller motor of the tension leveler in the speed closed-loop mode operation. Each frequency converter calls the corresponding control parameters based on the received activation status data for speed control in open / closed loop operation.

2. The method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI according to claim 1, characterized in that, Each of the aforementioned switching buttons is used to drive the corresponding frequency converter, and each frequency converter is used to drive the corresponding tension leveler clamping roller motor.

3. The method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI according to claim 1, characterized in that, Each bit of the data block DB is used to store the activation status data of the corresponding toggle button.

4. The method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI according to claim 3, characterized in that, When the corresponding bit in the data block DB is set to "1", the corresponding frequency converter switches to speed open-loop mode to drive the clamping roller motor of the tension leveler; when the corresponding bit in the data block DB is set to "0", the corresponding frequency converter maintains speed closed-loop mode to drive the clamping roller motor of the tension leveler.

5. The method for implementing open-loop and closed-loop control of a frequency converter based on IntouchHMI according to claim 1, characterized in that, It also includes a speed encoder, which is used to monitor the speed of the clamping roller motor of the tension leveler. If the speed encoder exceeds the set range during the operation of the clamping roller motor of the tension leveler, the corresponding switching button is triggered, so that the corresponding frequency converter switches from speed closed-loop mode to speed open-loop mode to drive the clamping roller motor of the tension leveler.

Images