Load balance control system of converter tilting device and control method thereof

Abstract

The invention provides a load balance control system of a converter tilting device and a control method thereof, and belongs to the field of converter control. The control system comprises a plurality of motors including a first motor and a second motor; the plurality of feedback encoders, the plurality of controllers and the plurality of frequency converters correspond to the plurality of motors; the motor feedback encoders are arranged on rotating shafts of all the motors and used for obtaining the first rotating speed and the second rotating speed; the master controller is used for generating an integral component and a first control reference value, and the slave controller is used for generating a second control reference value; the frequency converters are in data communication connection, the main frequency converter is used for synchronizing integral components to the driven frequency converter, and the main frequency converter and the driven frequency converter are respectively used for controlling the first motor and the second motor to execute first and second control reference values. The method is mainly used for solving the problems of overload, reverse dragging, unstable control and the like caused by non-uniform load distribution when the converter is driven by multiple motors to tilt, the tilting stability is improved, and the wear rate of equipment is reduced.

Description

Technical Field

[0001] This invention relates to the field of converter control technology, and more specifically to a load balance control system and control method for a converter tilting device. Background Technology

[0002] As a core piece of equipment in the steelmaking process, the converter's tilting system is responsible for performing key actions such as tapping steel and slag. Existing converter tilting devices mostly adopt a multi-motor drive system. Especially in large-tonnage converters, in order to increase the driving power and distribute the transmission load, a "one master and three slave" structure is usually adopted, that is, one master motor and three slave motors jointly drive the converter body to tilt.

[0003] In this multi-motor drive structure, each motor is connected to a large gear ring via a coupling, reducer, and so on, to achieve synchronous output. However, uneven load distribution is prone to occur among the motors during operation. Although some existing technologies attempt to improve the load imbalance problem of converter tilting systems by using synchronous control methods, these solutions generally rely on specific high-performance frequency converters, resulting in high system costs, complex configurations, long commissioning cycles, and significant shortcomings in localization and standardization.

[0004] With the rapid iteration of existing industrial control products, especially certain frequency converters, frequency converters with flexible expansion capabilities and free programming functions are gradually showing potential for multi-motor coordinated control. Therefore, there is an urgent need for a converter tilting load balancing control method based on existing frequency converter platforms that is easy to standardize and deploy, in order to achieve an efficient, stable, and locally replaceable converter tilting control solution. Summary of the Invention

[0005] The purpose of this invention is to provide a load balance control system and control method for a converter tilting device, which is mainly used to solve problems such as overload, back drag and unstable control caused by uneven load distribution when a converter is tilted by multiple motors in the prior art.

[0006] To achieve the above objectives, embodiments of the present invention provide a load balancing control system for a converter tilting device, comprising: multiple motors, including a first motor and a second motor, both connected to the transmission device of the converter; multiple feedback encoders corresponding to the multiple motors, disposed on the rotation shaft of each motor, for real-time acquisition of a first rotational speed of the first motor and a second rotational speed of the second motor; multiple controllers corresponding to the multiple motors, wherein a master controller corresponding to the first motor is used to generate an integral component and a first control reference value based on a set rotational speed of the control system and the first rotational speed, and a slave controller corresponding to the second motor is used to generate a second control reference value based on the set rotational speed, the second rotational speed, and the integral component; and multiple frequency converters corresponding to the multiple motors, the multiple frequency converters having data communication connections, wherein the master frequency converter corresponding to the first motor is used to synchronize the integral component to the slave frequency converter corresponding to the second motor, the master frequency converter is also used to control the first motor to execute the first control reference value, and the slave frequency converter is also used to control the second motor to execute the second control reference value.

[0007] On the other hand, the present invention provides a load balancing control method for a converter tilting device. The control method includes: determining a first motor and a second motor among a plurality of motors; acquiring a first speed of the first motor and a second speed of the second motor in real time; generating an integral component and a first control reference value based on a set speed and the first speed, and generating a second control reference value based on the set speed, the second speed, and the integral component; and controlling the first motor to execute the first control reference value and controlling the second motor to execute the second control reference value.

[0008] Through the above technical solution, the control system of the present invention provides a reference signal to the slave motor through the main motor. The slave motor frequency converter automatically adjusts the output frequency or torque according to the integral component of the main motor speed controller and its own load feedback to achieve load balancing.

[0009] The key technical aspect of this invention is its reliance on existing CERI frequency converters, making it suitable for a "one master, three slaves" load balancing control system for converter tilting devices. This invention effectively controls the consistency of output torque from multiple motors, significantly reducing "backdragging" or "tooth pushing" phenomena during converter tilting, improving tilting stability, and lowering equipment wear. Since all load coordination logic is implemented within the CERI frequency converter, it is suitable for low-cost retrofitting and localized replacement in steel plants.

[0010] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0011] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a structural diagram of a converter tilting system based on existing technology; Figure 2 This is a block diagram of the existing master-slave control system. Figure 3 This is a structural block diagram of the load balance control system of the converter tilting device provided in an embodiment of the present invention; Figure 4 This is a schematic flowchart of the load balancing control method for a converter tilting device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the principle of converter tilting load balancing based on the free programming function of a CERI frequency converter according to an embodiment of the present invention. Figure 6 This is a flowchart illustrating the implementation of converter tilting load balancing based on the free programming function of a CERI frequency converter according to an embodiment of the present invention. Figure 7 This is a specific control flowchart provided according to an embodiment of the present invention. Detailed Implementation

[0012] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0013] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with relevant laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0014] Before introducing the various embodiments of the present invention, a brief description of the prior art will be given first.

[0015] As attached Figure 1As shown, existing converter tilting devices generally adopt a "one master, three slave" multi-motor drive structure. The system typically consists of one master motor (M1) and three slave motors (M2, M3, M4), each controlled by a corresponding frequency converter VFD1~VFD4. The master motor is directly controlled by the master frequency converter (VFD1), while the slave frequency converters (VFD2~VFD4) control the slave motors with reference to the torque output of the master frequency converter (VFD1), achieving synchronous operation through an internal "follow" control mode.

[0016] However, the applicant found that, for at least the following four reasons, uneven load distribution is very likely to occur among the motors during operation: 1) Structural errors and assembly deviations: There are manufacturing errors and assembly differences in the connection between the motors and transmission mechanisms in the drive system, such as backlash, coupling flexibility, and installation alignment accuracy; 2) Uneven load distribution: The mass distribution of molten steel and slag inside the converter may produce asymmetrical loads; 3) Response differences: Different motors and their control systems have different torque responses, which can easily lead to inconsistent outputs; 4) Single control strategy: In the traditional master-slave control mode, the slave motor usually simply follows the torque signal of the master motor, lacks load closed-loop regulation capability, and is difficult to achieve dynamic balance.

[0017] Based on this, the applicant further discovered that the above problems may lead to the following four types of technical defects in the system during operation: 1) Uneven load causes individual motors to operate under overload, affecting their service life; 2) The "push-pull" effect between multiple motors exacerbates the wear of the transmission system; 3) Poor smoothness of tilting action, which easily generates impact and vibration, reducing control accuracy; 4) Frequent system maintenance and decreased operational reliability.

[0018] Traditional master-slave control methods are shown in the appendix. Figure 2 As shown: VFD1 is used as the master frequency converter, featuring dual closed-loop control for speed and torque. The speed of the master frequency converter is given by the PLC, and its torque output serves as the torque input for the slave frequency converters (VFD2~VFD4). However, in this control method, the three slave frequency converters only have an inner torque loop, lacking a speed loop. Furthermore, in this type of structure, most slave frequency converters do not possess independent closed-loop control functionality; their control is typically based on torque following (i.e., receiving the output torque from the master frequency converter). Specifically, traditional master-slave control methods mainly employ the following typical control technology characteristics: Technical Feature 1: The driven frequency converter adopts torque following control.

[0019] Under this control method, the driven frequency converter receives the output torque of the master frequency converter as its own operating torque reference and ignores its own load changes. This method only ensures that the motor torque tends to be consistent and cannot detect uneven load conditions, resulting in significant differences in output torque between multiple motors. Once the system load is uneven (such as the converter being unbalanced by molten steel on one side), some motors will be in an overload or reverse drag state, causing uneven load distribution.

[0020] Technical Feature 2: No real-time feedback and coordination mechanism between motors has been established.

[0021] The master and slave motors have only a one-way control relationship (frequency / speed), and there is no data communication link between the frequency converters, so they cannot share operating status (such as current, torque, encoder angle, etc.). Therefore, there is no feedback closed loop between the motors, and dynamic adjustment cannot be achieved. The control system cannot sense which motor is carrying a heavy load, nor can it correct the output of a lightly loaded motor, resulting in a "push-pull" phenomenon that impacts the gear ring and transmission device.

[0022] Technical Feature 3: The automatic adjustment strategy is not enabled on the driven frequency converter.

[0023] In existing solutions, the driven frequency converter typically uses the torque output of the main frequency converter as a reference, lacking real-time adjustability. This control strategy ignores the real-time load variation characteristics of the mechanical system. During the tilting process of the furnace body, due to the uneven distribution of slag and molten steel, the instantaneous load fluctuates with the angle change. The driven motor cannot make corresponding torque adjustments, resulting in slow system response and poor control accuracy.

[0024] Technical Feature 4: Protection relies on specific high-performance frequency converters.

[0025] In some solutions, the system relies on specific high-performance frequency converters for protection. This system has a complex structure, a long commissioning cycle, and several major technical defects: 1) Weak control coupling and lack of real-time adjustment mechanism: There is only simple signal transmission (such as torque channel) between the master and slave frequency converters, which does not constitute a true multi-motor closed-loop coordination system. Once the load changes, the current of the master motor increases, but the slave motor still outputs according to the predetermined ratio, and dynamic torque compensation cannot be achieved; 2) Reliance on specific equipment or complex system integration: Some existing solutions use high-end specific frequency converters or redundant master control systems (such as virtual spindle, spindle bus ring network, etc.). Although the performance is superior, the cost is high, the configuration is complex, and the commissioning cycle is long, which is not conducive to localization and maintenance.

[0026] This invention aims to overcome the aforementioned technical problems existing in the "one master and three slave" multi-motor drive converter tilting control system in the prior art, including: lack of torque coordination mechanism during multi-motor operation, uneven load distribution, easy overload or reverse drag of individual motors, affecting equipment life and system safety; simple control logic between master and slave frequency converters, lack of real-time status feedback and data interaction, isolated operating status of each motor, and inability to achieve closed-loop load self-adjustment; control strategy relies on specific equipment or unconventional platforms, resulting in long debugging cycles, high costs, and difficult maintenance, which is not conducive to localization and promotion. More specifically, the key technical problems to be solved by this invention include, but are not limited to: 1) how to build a sharing and synchronization mechanism for multi-motor status data within the CERI frequency converter platform; 2) how to realize the dynamic correction of output torque of slave motors according to the operating status of master motors to achieve real-time load balancing; 3) how to complete load deviation judgment within the frequency converter to reduce dependence on PLC; 4) how to deploy this solution in an engineering-feasible manner, simplify the debugging process, and ensure system robustness.

[0027] In response, the first aspect of this invention provides a load balancing control system for a converter tilting device, which may include: multiple motors, multiple feedback encoders corresponding to the multiple motors, multiple controllers, and multiple frequency converters. The main technical objective of this invention is to provide a method for implementing converter tilting load balancing based on CERI frequency converters. This method utilizes the logic processing capabilities and communication interfaces of certain frequency converters to achieve real-time load monitoring, torque coordination adjustment, and abnormal deviation protection linkage among the motors in a "one master, three slave" structure, thereby achieving the technical effects of improving converter tilting stability, reducing equipment wear, and enhancing system reliability and localization adaptability.

[0028] The system includes multiple motors, including a first motor and a second motor, both connected to the converter's drive system. Multiple feedback encoders are mounted on the rotation shafts of each motor to acquire the first motor's first rotational speed and the second motor's second rotational speed in real time. The main controller for the first motor generates an integral component and a first control reference value based on the control system's set rotational speed and the first rotational speed. The slave controller for the second motor generates a second control reference value based on the set rotational speed, the second rotational speed, and the integral component. Multiple frequency converters are interconnected via data communication. The main frequency converter for the first motor synchronizes the integral component to the slave frequency converter for the second motor. The main frequency converter also controls the first motor to execute the first control reference value, and the slave frequency converter controls the second motor to execute the second control reference value.

[0029] In one embodiment, the main structure of the converter tilting control system is a converter tilting drive motor, with each motor connected to the same transmission device (converter gear ring), arranged in a "one master and three slave" configuration. Figure 3As shown, the first motor is a master motor (M1): the master motor serves as the reference motor in the system, and its output signal is used as the control reference for the slave motors. The second motor consists of three slave motors (M2, M3, and M4), which can also be called slave motors: they are used to collaboratively drive the converter to tilt, and their torque is dynamically adjusted according to the status of the master motor. Multiple motors are connected to the gearbox of the transmission device in a four-point suspension configuration to drive the converter to tilt. Furthermore, the four motors achieve load balance through a master-slave control method of "one master and three slaves." The transmission device and the tilting motors can be controlled one-to-one, meaning one speed control device corresponds to one tilting motor.

[0030] In one embodiment, a feedback encoder can be installed on the converter main shaft, such as on the converter motor shaft, to acquire the speed information of the tilting motor in real time and feed it back to the corresponding frequency converter. All frequency converters have independent power supplies and coordinated control logic. In one embodiment, multiple frequency converters can be connected via ProFinet, for example, via a PowerLink module connected in fiber optic form, with continuous data communication between the master and slave frequency converters at fixed intervals. Alternatively, the communication network between frequency converters can also be established through the communication interface (such as CAN, Modbus, etc.) built into the CERI frequency converter to create a master-slave data interaction link, achieving control data synchronization between the master and slave motors.

[0031] In one embodiment, multiple frequency converters have built-in current feedback modules to monitor the current of multiple motors. This allows for cyclic monitoring of the speed error and torque balance between the first and second motors, determining whether the converter is under load balance. In other words, each CERI frequency converter has a built-in current detection function, which can be used to acquire the output current of its corresponding motor in real time as a basis for load assessment. For example, a load balancing algorithm can be implemented within the CERI frequency converter using a user-defined logic module. If the converter is not under load balance, control parameters for the first motor can be generated by the main controller, or control parameters for the second motor can be generated by the slave controller.

[0032] Continue to refer to the attached document. Figure 3As shown, all four frequency converters operate in speed control mode and accept the same speed setting. First, one frequency converter is selected as the master converter and uses a proportional-integral controller (PIC), while the other three act as slave converters and use proportional controllers. Simultaneously, the integral component of the master converter's speed regulator is superimposed on the output of the slave converters, thereby achieving torque distribution during the control process. It is worth noting that each frequency converter in this invention is a relatively independent closed-loop control system. This ensures the control accuracy of both the master and slave converters while maintaining controllable slave speeds even when the converter tilting mechanical shaft is disconnected. Specifically, the master frequency converter collects encoder speed feedback and its own current feedback, and generates control reference values ​​(spindle speed, spindle current, spindle torque, etc.) through internal logic processing, broadcasting them to the slave frequency converters. Each slave frequency converter receives data from the master frequency converter, monitors its own operating status, calculates correction coefficients using load balancing logic, and dynamically adjusts its output torque.

[0033] Furthermore, the free programming function of the CERI frequency converter enables load balancing for multi-motor drives. In one embodiment, the first control reference value is the main torque applied to the first motor, and the main controller adopts a proportional-integral mode, generating the integral component and the main torque using the following formula. :

[0034]

[0035] in, To set the rotational speed for the control system. The first rotational speed, The proportional coefficient used in the proportional calculation process of the controller. For integral components, The process of time integration for the controller.

[0036] In one embodiment, the second control reference value is the slave torque to be applied to the second motor, and the slave controller adopts a proportional mode, generating the slave torque according to the following formula. :

[0037] in, This is the second rotational speed.

[0038] Specifically, when implementing this control system, system initialization is required first: select one frequency converter (such as VFD1) as the master station to collect the main motor current, torque, speed, and integral components of the speed controller; the remaining three frequency converters are set as slave stations to receive data from the master station. The control modes for the master and slave units are then set (master PI control, slave P control). In this converter tilting load balancing control, the master unit uses PI speed control, providing complete speed control capabilities, while the slave units use P speed control, relying solely on proportional control for tracking. This ensures both speed tracking and load balancing. Compared to a PI speed loop, using P control on the slave units reduces the risk of oscillations caused by integral accumulation. The integral components of the master unit are then defined. The torque is directly applied to the control output of the slave motor to ensure torque balance in steady state. This ensures that multiple motors share torque, effectively distributes the load, reduces torque oscillation, and prevents individual motors from being overloaded or underloaded.

[0039] Then, set the speed setting value. This information is then distributed to all drives. Speed ​​control calculations are performed using the aforementioned formula, including calculations for both the master and slave speed loops. Finally, torque distribution is performed, that is, the torque of the master drive is distributed... The torque of the slave motor acts directly on the main drive motor. The integral component of the P control output + host is controlled by its P control output. The decision is made jointly to achieve load balancing. Finally, load adjustment is performed, which involves cyclically monitoring speed error and torque balance. The parameters of the master PI controller and slave P controller are adjusted to ensure smooth load distribution.

[0040] The control system of this invention achieves converter tilting load balancing based on the following principle: the main motor serves as the system operating reference, and its operating status (such as frequency, current, and torque) is used as a real-time reference signal. The driven motor adopts a speed-current coordinated control strategy, which dynamically corrects the torque output according to a preset load balancing algorithm by comparing the current values ​​and output frequencies of the main and driven motors in real time, ensuring coordinated operation of multiple motors.

[0041] In one embodiment, the control system further includes a control panel for parameter setting, status display, and fault alarm information prompts. Additionally, when the main motor fails, any one of the three slave motors can switch to become the new main motor. That is, when one motor or device fails, the other three motors can continue to operate; furthermore, even if two motors fail, the remaining two can still drive the converter to complete the steelmaking process. Therefore, the control system of this invention possesses a "soft master-slave" mode switching function and has an optional fault-tolerant mechanism. That is, when the main frequency converter fails, it can automatically switch a slave motor to become the new master motor, maintaining system operation and improving system robustness and continuous operation capability.

[0042] Therefore, this invention, based on the existing CERI frequency converter platform, utilizes its built-in programmable multi-motor coordinated control function to propose a distributed torque coordinated control method. The key technical point is to achieve closed-loop load balancing control based on the existing multi-drive linkage control logic of the CERI frequency converter. The core lies in realizing a unified algorithm logic based on a programmable module within a "one master, three slaves" structure to achieve automatic dynamic load balancing between the master and slave motors. By fully utilizing the CERI frequency converter's internal PID regulation, program segment control, logic judgment module, and programmable module, it completes coordinated control and dynamic load adjustment between multiple axes within its internal structure; its control strategy possesses a certain degree of adaptive adjustment capability (such as deviation self-tuning).

[0043] In addition, the present invention has the following outstanding advantages: 1) Load balancing logic implemented within the frequency converter: Each CERI frequency converter can perform torque monitoring, load deviation calculation, and output adjustment through its internal user modules (such as arithmetic modules, control modules, logic modules, etc.). The main motor frequency converter can act as the data master station, and the driven frequency converter can act as the data slave station, thus constructing a closed-loop load regulation network.

[0044] 2) Supports adaptive load balancing: This invention supports real-time monitoring of parameters such as the output current and speed of each motor to automatically determine the load distribution status and dynamically adjust the output torque of the driven motor, thereby achieving true adaptive load balancing of the motor.

[0045] 3) Low cost, strong adaptability, and easy to promote: This solution is based on the existing CERI frequency converter platform, which facilitates batch deployment and subsequent maintenance in steel enterprises, and has good economic efficiency and engineering feasibility.

[0046] A second aspect of the present invention provides a load balancing method 200 for a converter tilting device, such as... Figure 4 As shown, the control method may include: Step S210: Determine the first motor and the second motor among the multiple motors.

[0047] In one embodiment, step S210 may include: Step S211: Based on the integer output value output after receiving fieldbus data, determine the first motor among multiple motors using the logic function block. Step S212: The motors other than the first motor are identified as the second motor.

[0048] Specifically, based on the free programming function of the existing CERI frequency converter, load balancing of multi-motor drives can be achieved. Its working principle can be found in the appendix. Figure 5 The flowchart is attached. Figure 6 For example, functions GDMKKRDT0 / 000~GDMKKRDT0 / 003 and GDMKKRDT0 / 011 can be used to read the K connector data sent by the PLC to distinguish which of the four frequency converters is the master, and the remaining three are slaves. The following is a specific determination step provided in one embodiment: When the GDMKKRDT0 / 011 function block receives fieldbus data and outputs an integer output value of 1 (0001 in binary), the difference of 0 between this value and the integer X1=1 obtained by the two integer subtraction function block SUB_IT0 / 007 is used as the selection signal for the eight real number multiplexers. At this time, the output Y=X0 of the eight real number multiplexers is used as the input X0 of the two real number multiplexers. The selection signal of the two real number multiplexers comes from the output of the B connector data reading function block GDMBRDT0 / 013. The input of the B connector data reading function block comes from bit 1 of PZD3 sent by the PLC.

[0049] 1) When the output of the function block for reading data from connector B is 0, the outputs of the two real-valued multiplexers are Y=X0. At this time, the first motor acts as the master motor, and the other three motors act as slave motors. The torque command of the slave motors (the integral component of the master speed controller) comes from the data K601 (additional torque source) written to connector K. 2) When the GDMKKRDT0 / 011 function block receives fieldbus data and outputs an integer output value of 2 (binary is 0010), the second motor becomes the master motor and the remaining three motors become slave motors. The torque of the slave motors is given by the integral component of the master speed regulator. 3) When the GDMKKRDT0 / 011 function block receives fieldbus data and outputs an integer output value of 4 (binary is 0100), the third motor becomes the master motor and the remaining three become slave motors. The torque of the slave motors is given by the integral component of the master speed regulator. 4) When the GDMKKRDT0 / 011 function block receives fieldbus data and outputs an integer output value of 8 (binary is 1000), the fourth motor becomes the master motor and the remaining three motors become slave motors. The torque of the slave motors is given by the integral component of the master speed regulator.

[0050] Additionally, function block GDMBRDT0 / 008 reads B connector data. When the frequency converter is used as a slave frequency converter, its output is 0. The output is inverted by function block NOTT0 / 009 and used as the value to write to the B connector data function block. This value is then written to B602 speed regulation integral lockout to ensure that the speed regulator of the slave frequency converter is a proportional regulator.

[0051] Step S220: Real-time acquisition of the first speed of the first motor and the second speed of the second motor.

[0052] Step S230: Generate an integral component and a first control reference value based on the set speed and the first speed, and generate a second control reference value based on the set speed, the second speed and the integral component.

[0053] The first control reference value is the master torque applied to the first motor, and the second control reference value is the slave torque applied to the second motor. Specifically, the integral component and the first control reference value are generated based on the set speed and the first speed, and the second control reference value is generated based on the set speed, the second speed, and the integral component, including: Using the proportional-integral (PI) mode, the integral component and the main engine torque are generated by the following formula. :

[0054]

[0055] Using the proportional mode, the slave torque is generated by the following formula. :

[0056] in, To set the rotation speed, The first rotational speed, For the second rotational speed, The scaling factor is used in the scaling calculation process. For integral components, This is the process of performing time integration.

[0057] In step S240, the first motor is controlled to execute the first control reference value, and the second motor is controlled to execute the second control reference value.

[0058] After the transmission system enters the operating mode, the output of each motor is controlled according to the following process to achieve load balance. The control flowchart is attached. Figure 7 The control principle is as follows: In this converter tilting load balance control, the master unit uses PI speed control, providing complete speed control capability, while the slave units use P speed control, relying solely on proportional control for tracking. This ensures both speed tracking and load balance. Compared to a PI speed loop, using P control on the slave units reduces the risk of oscillations caused by integral accumulation. The integral component of the master unit... The torque is directly applied to the control output of the slave motor to ensure torque balance in steady state. This ensures that multiple motors share torque, effectively distributes the load, reduces torque oscillation, and prevents individual motors from being overloaded or underloaded.

[0059] First, perform system initialization: Select one frequency converter (e.g., VFD1) as the master station to collect the main motor current, torque, speed, and integral components of the speed controller; set the remaining three frequency converters as slave stations to receive data from the master station. Set the control modes for the master and slave units (master PI control, slave P control).

[0060] Then, set the speed setting value. This information is then distributed to all drives. Speed ​​control calculations are performed using the aforementioned formula, including calculations for the master speed loop and the slave speed loop. Then, torque distribution is performed, that is, the torque of the main unit is distributed. The torque of the slave motor acts directly on the main drive motor. The integral component of the P control output + host is controlled by its P control output. The decision is made jointly to achieve load balancing. Finally, load adjustment is performed, which involves cyclically monitoring speed error and torque balance. The parameters of the master PI controller and slave P controller are adjusted to ensure smooth load distribution.

[0061] Example To further illustrate the technical solution of the present invention, the following detailed description of the structure and operation process of the present invention is provided through a specific embodiment of the load balance control of a four-motor converter tilting system. The components, functional modules, communication methods, and parameter configurations used in this example are all based on existing CERI frequency converters (such as CI880 and HCE880), and can be directly applied to converter tilting systems in steelmaking projects of iron and steel enterprises.

[0062] I. System Composition Combination Figure 3 As shown, the system consists of the following components: a main frequency converter VFD1, which controls the main motor M1, providing the operating frequency reference for the entire tilting system, and collecting spindle current, motor speed, and torque as a data broadcast source. Three slave frequency converters VFD2, VFD3, and VFD4 control three slave motors M2, M3, and M4 respectively, receiving control reference signals from the main frequency converter and dynamically adjusting their output torque according to their own load. A furnace body encoder is installed on the shaft of the converter tilting motor to acquire the motor speed in real time, and is connected to the main frequency converter and each slave frequency converter. The frequency converters have built-in current feedback modules, and all CERI frequency converters have real-time output current sampling capabilities to monitor the current of each motor as a basis for load judgment. Data communication between the frequency converters is achieved through ProFinet, or, for example, through a PowerLink module connected via fiber optic cable, thus constructing a master-slave data broadcast and feedback network. A control panel (optional) is used for parameter setting, status display, and fault alarm information prompts.

[0063] II. Operation Process like Figure 7As shown, during the initialization phase: after power-on, the main frequency converter VFD1 begins to collect parameters such as the integral component of the speed controller, its own output frequency, torque, and encoder feedback speed, and broadcasts them to the driven frequency converter at fixed intervals.

[0064] Driven inverter calculation and correction: The driven inverters (VFD2-VFD4) receive the main motor operating parameters (integral component of the speed controller) and acquire the output torque and encoder feedback speed. The system internally uses the following formula to determine load differences: Host speed loop calculation:

[0065] Slave speed loop calculation:

[0066] in, It is the integral component of the host PI controller.

[0067] Torque of the main unit The torque of the slave motor acts directly on the main drive motor. The output torque of the motor is determined by the P control output and the integral component of the main unit, so that the output torque of the motor gradually matches that of the main motor, thus achieving dynamic load balance.

[0068] Normal operation and cyclic execution: This collaborative control mechanism continuously executes between the master and slave frequency converters at a fixed cycle through ProFinet communication (e.g., via a PowerLink module connected in the form of optical fiber), realizing closed-loop operation and possessing the advantages of fast response, simple structure, and strong robustness.

[0069] This invention proposes an easily scalable converter tilting load balancing control system and method based on existing CERI frequency converters. The beneficial effects of this invention are: the control system and method can effectively control the consistency of output torque from multiple motors, significantly reducing "backdragging" or "tooth pushing" phenomena during converter tilting, improving tilting stability, and reducing equipment wear. Since all load coordination logic is implemented within the CERI frequency converter, it is suitable for low-cost retrofitting and localized replacement in steel plants.

[0070] In summary, the control system and method of this invention are implemented based on existing CERI frequency converters and are suitable for the "one master and three slave" load balancing control system of converter tilting devices. According to the free programming module, one motor is selected as the master motor and a reference signal is provided to the remaining three slave motors. The slave motor frequency converters automatically adjust their output frequency or torque based on the integral component of the master motor speed controller and their own load feedback to achieve load balancing. Furthermore, the control system has a "soft master-slave" mode switching function and an optional fault-tolerant mechanism. That is, when the master frequency converter fails, a slave motor can be automatically switched to become the new master motor to maintain system operation, thereby improving system robustness and continuous operation capability.

[0071] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0072] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A load balance control system for a converter tilting device, characterized in that, include: Multiple motors, including a first motor and a second motor, are all connected to the transmission device of the converter; Multiple feedback encoders, corresponding to the multiple motors, are disposed on the rotating shaft of each motor and are used to acquire the first speed of the first motor and the second speed of the second motor in real time. Multiple controllers corresponding to the plurality of motors, wherein the master controller corresponding to the first motor is used to generate an integral component and a first control reference value based on the set speed of the control system and the first speed; the slave controller corresponding to the second motor is used to generate a second control reference value based on the set speed, the second speed, and the integral component; and The multiple frequency converters corresponding to the multiple motors are connected by data communication. The main frequency converter corresponding to the first motor is used to synchronize the integral component to the driven frequency converter corresponding to the second motor. The main frequency converter is also used to control the first motor to execute the first control reference value, and the driven frequency converter is also used to control the second motor to execute the second control reference value.

2. The control system according to claim 1, characterized in that, The first control reference value is the main torque that will be applied to the first motor. The main controller adopts a proportional-integral (PI) mode, and the integral component and the main controller torque are generated by the following formula: : in, The set rotational speed of the control system. For the first rotational speed, The proportional coefficient used in the proportional calculation process of the controller. For the integral component, The process of performing time integration for the controller.

3. The control system according to claim 2, characterized in that, The second control reference value is the slave torque applied to the second motor. The slave controller adopts a proportional mode and generates the slave torque according to the following formula. : in, This refers to the second rotational speed.

4. The control system according to claim 1, characterized in that, The first motor is a master motor, and the second motor has three slave motors. The multiple motors are connected to the gearbox of the transmission device via a four-point suspension configuration to drive the converter in tilting operations. When the main motor fails, any one of the three slave motors can be switched to become the new main motor.

5. The control system according to claim 1, characterized in that, The multiple frequency converters are connected to each other via PowerLink modules in the form of optical fibers, and data communication is continuously performed between the main frequency converter and the driven frequency converter at a fixed period.

6. The control system according to claim 1, characterized in that, The multiple frequency converters have built-in current feedback modules for monitoring the current of the multiple motors. This allows for cyclic monitoring of the speed error and torque balance between the first motor and the second motor, determining whether the converter is under load balance. If the converter does not reach load balance, the main controller generates control parameters for the first motor, and / or the slave controller generates control parameters for the second motor.

7. The control system according to claim 1, characterized in that, The control system also includes a control panel for parameter setting, status display, and fault alarm information prompts.

8. A load balancing control method for a converter tilting device, characterized in that, The control method includes: Identify the first and second motors among multiple motors; The first speed of the first motor and the second speed of the second motor are acquired in real time. An integral component and a first control reference value are generated based on a set rotational speed and a first rotational speed, and a second control reference value is generated based on the set rotational speed, the second rotational speed, and the integral component; and The first motor is controlled to execute the first control reference value, and the second motor is controlled to execute the second control reference value.

9. The control method according to claim 8, characterized in that, The determination of the first motor and the second motor among a plurality of motors includes: Based on the integer output value output after receiving fieldbus data, the first motor is determined from the plurality of motors by the logic function block; The motors other than the first motor are designated as the second motor.

10. The control method according to claim 8, characterized in that, The first control reference value is the master torque that will be applied to the first motor, and the second control reference value is the slave torque that will be applied to the second motor. The step of generating an integral component and a first control reference value based on a set rotational speed and a first rotational speed, and generating a second control reference value based on the set rotational speed, the second rotational speed, and the integral component, includes: Using a proportional-integral (PI) mode, the integral component and the main engine torque are generated by the following formula. : Using a proportional mode, the slave torque is generated by the following formula. : in, For the set rotation speed, For the first rotational speed, The second rotational speed, The scaling factor is used in the scaling calculation process. For the integral component, This is the process of performing time integration.

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