Control method for a multi-transmission drive system, drive system and storage medium

Abstract

The embodiment of the application provides a kind of control method of multi-transmission device driving system, driving system and storage medium, belong to transmission device control field.The control method includes: when detecting main device failure, the torque of each variable frequency transmission device before failure is acquired and total torque before failure is calculated;New main device is selected according to preset priority;Integral initial value is calculated based on total torque before failure and slave device quantity;Integral initial value is input into the integral regulator of new main device and it starts to operate from the initial value;The output torque of each slave device is controlled based on the integral component of new main device and torque distribution coefficient, so that the sum of the torque output by all devices before and after switching remains unchanged.The application can realize automatic switching without stopping when the main device fails, avoid device output mutation and speed fluctuation, and ensure the production continuity and equipment safety of driving system.

Description

Technical Field

[0001] This invention relates to the field of transmission device control technology, and more specifically to a control method, drive system, and storage medium for a multi-transmission device drive system. Background Technology

[0002] Multi-motor variable frequency drive coordinated control is widely used in applications such as metallurgical converter tilting devices, large rotary kilns, mine hoists, and ship propulsion systems, where multiple motors need to drive the same load shaft together through reducers or couplings. In the aforementioned rigid coupling structure, the actual speeds of all motors are forced to synchronize by mechanical hard connections, therefore the output torque of each motor must always remain equal. If a torque difference occurs, an internal circulating torque will be generated on the main shaft instead of being transmitted to the load end to do work. This can cause gearbox gear breakage at best, and excessive torsion and breakage of the main shaft or motor overload tripping at worst.

[0003] Taking a metallurgical converter tilting device as an example, four AC variable frequency motors are typically used to drive the converter body. Due to the harsh environment at the smelting site, the variable frequency drive device is prone to failure and tripping. In the traditional master-slave torque control mode, once the master motor fails, the torque command link is interrupted instantly. After the slave motors lose their torque commands, they immediately enter an uncontrollable state, resulting in sudden changes in output torque and drastic fluctuations in speed. Due to the rigid connection, this torque change will generate extremely destructive spikes, requiring immediate shutdown for handling, making online non-stop switching impossible. Operators need to manually select available motors and reconfigure the master-slave relationship, causing repeated production stoppages, severely affecting the production rhythm, and posing significant safety hazards due to the large impact on the equipment.

[0004] Therefore, how to complete system reconfiguration within milliseconds when the main device (especially the main device that performs integral regulation) fails, achieve automatic switching of the device without stopping the machine, and ensure that the output of each device does not fluctuate during the switching process is a technical problem that urgently needs to be solved in the field of multi-drive rigid coupling drive. Summary of the Invention

[0005] The purpose of this invention is to provide a control method, drive system, and storage medium for a multi-drive system, which solves the technical problems in existing rigidly coupled multi-drive systems where the master device cannot be reconfigured online without shutting down when the master device fails, the total driving torque is prone to sudden changes during the switching process, and the integral value of the new master device cannot be continued.

[0006] To achieve the above objectives, embodiments of the present invention provide a control method for a multi-drive system, the multi-drive system including multiple variable frequency drives coupled to the same main drive shaft and a controller connected to each of the variable frequency drives. The control method includes: when a fault is detected in the master drive among the multiple variable frequency drives, acquiring the torque of each variable frequency drive before the fault, and calculating the total torque of the main drive shaft before the fault; selecting the slave drive with the highest priority as the new master drive among the multiple slave drives (excluding the master drive) according to a preset priority; calculating an initial integral value based on the total torque before the fault and the number of slave drives; inputting the initial integral value into the integral regulator of the new master drive, and starting the operation of the integral regulator of the new master drive from the initial integral value; and controlling the output torque of each slave drive based on the integral component and torque distribution coefficient output by the integral regulator of the new master drive, so that the sum of the output torques of the multiple variable frequency drives before and after the master drive is switched remains unchanged.

[0007] Optionally, during steady-state operation when no fault is detected in the master unit among the plurality of variable frequency drives, the controller periodically sends control word information to the variable frequency drives in each communication cycle when communicating with the plurality of variable frequency drives, so that the speed controller of the master unit operates in proportional-integral mode, the slave unit operates in proportional mode and uses the integral component output by the integral regulator of the master unit as the feedforward torque of the slave unit.

[0008] Optionally, when the speed controller of the main device operates in proportional-integral mode, its output torque is calculated by the following formula: ; in, The torque output by the main device. This is the speed deviation value. For proportional gain, is the integration time constant.

[0009] Optionally, the output torque of the slave device is calculated by the following formula: ; in, Let be the output torque of the i-th slave device. For proportional gain, This is the speed deviation value. The torque distribution coefficient is... The integral component is the output of the integral regulator of the main device.

[0010] Optionally, inputting the initial integral value into the integral regulator of the new master device and enabling the integral regulator of the new master device to start operating from the initial integral value includes: in the same or immediately following communication cycle when a master device fault is detected, deactivating the integral enable position of the new master device and activating both its hold and set bits; writing the initial integral value into the integrator setting parameter of the new master device and simultaneously writing it into the integrator setting parameter of each slave device; activating the set position of the new master device for at least one communication cycle and loading the value in the integrator setting parameter as the output value of the integral regulator; deactivating the set and hold bits of the new master device and activating its integral enable position, causing its integral regulator to accumulate from the loaded output value.

[0011] Optionally, when a fault is detected in the main device among the plurality of variable frequency drive devices, the control method further includes: sending a pulse blocking signal to the current main device to reduce the torque output by the current main device to zero.

[0012] Optionally, the controller determines whether the frequency converter is faulty based on at least one of the acquired status word fault bit, ready signal, encoder status, and bus timeout information for each frequency converter.

[0013] Optionally, before selecting the slave device with the highest priority as the new master device, the control method further includes: when the maximum value of the sum of the torques output by the remaining variable frequency drive devices other than the master device is lower than a first preset torque threshold, reducing the speed of the remaining variable frequency drive devices to a preset speed using a ramp function; when the number of remaining variable frequency drive devices other than the master device is lower than a preset safety number, controlling all variable frequency drive devices to stop.

[0014] Secondly, the present invention provides a multi-drive system, the system comprising: multiple variable frequency drives coupled to the same main drive shaft; and a controller connected to each variable frequency drive via a control bus to implement the control method of the multi-drive system described above.

[0015] Thirdly, the present invention provides a machine-readable storage medium storing instructions for causing a machine to execute the control method of the multi-drive system described in any one of the preceding claims of this application.

[0016] Through the above technical solution, when the main unit fails, the torque of each device before the failure is acquired and the total torque of the main drive shaft is calculated. This total torque reflects the actual load borne by the main drive shaft before the failure. Then, the controller selects a new main unit from the remaining slave units (excluding the main unit) according to a preset priority, and calculates an initial integral value based on the total torque before the failure and the number of slave units. This initial integral value is assigned to the integral regulator of the new main unit, and it starts operating from this initial value, thus ensuring that the initial state of the new main unit's integral regulator precisely matches the current load. Based on this, the output torque of each slave unit is controlled based on the integral component and torque distribution coefficient of the new main unit's output. Since all slave units share the same integral component, and the output torque of each unit is dominated by this integral component, the sum of the output torques of multiple variable frequency drive units remains unchanged before and after switching the main unit. This avoids sudden changes in total output and speed drops caused by main unit failure, achieving uninterrupted continuous operation without downtime, eliminating the impact risk of torque sudden changes on the mechanical system, and ensuring the production continuity of the rigidly coupled multi-drive system.

[0017] 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

[0018] 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 schematic diagram of the structure of a converter tilting device provided in an embodiment of the present invention; Figure 2 A flowchart illustrating a control method for a multi-transmission drive system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a multi-transmission device drive system provided in an embodiment of the present invention. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] To facilitate understanding of this invention, the following describes two existing technical solutions related to this invention and their shortcomings.

[0022] For the load balancing scheme of independent PI speed regulators for each device, all variable frequency drives operate in speed control mode, and each is equipped with a complete PI (proportional) speed regulator. Integral (Integral) regulators. To achieve load balancing, small deviation compensations are typically added to the respective speed setpoints, or the speed droop characteristic is utilized. However, since each device has an independent integral regulator, after long-term operation, even with the same integral time parameters, factors such as slight differences in encoders, parameter drift, and inconsistent sampling delays can cause the accumulated values ​​of each integrator to gradually diverge. In steady state, the speeds of each device are forced to synchronize by mechanical hard connections, the speed deviation approaches zero, and the proportional term output also approaches zero. The final output of the device is entirely determined by its individual integral term. Once the accumulated values ​​of each integrator differ, the output torque of each variable frequency drive device will diverge accordingly, and the dynamic mutual interference of multiple integrators can easily cause system oscillations. Furthermore, due to the lag of proportional-integral regulation, when one device fails and exits, the integrators of the remaining devices continue to accumulate according to the state before the failure, unable to instantaneously match the new load distribution relationship, inevitably resulting in torque fluctuations.

[0023] For a single integrator (PI) P) Master-Slave Scheme: This scheme designates only one device as the master device through the configuration between the drive systems (rather than through the PLC system), enabling its integral regulator to operate in PI (proportional) mode. The primary integrator operates in P (proportional) mode, while the secondary integrators operate only in P (integral) mode, receiving the integral component from the primary integrator as feedforward to address the issue of inconsistent integration among multiple integrators. However, in this scheme, the primary integrator's identity is pre-defined during the design of the variable frequency drive system and cannot be dynamically changed online; it can only be manually modified after shutdown and tripping. When the primary integrator fails, the integral component is instantly lost, and all secondary integrators immediately switch to P (proportional) control. Because there is no integral term to eliminate steady-state error, even with minimal speed deviation, the output of each secondary integrator immediately drops, creating a severe load gap and causing a speed drop. Therefore, the system can only be restarted manually after shutdown, failing to achieve continuous automatic operation without shutdown.

[0024] As can be seen from the prior art, the technical problem to be solved by this invention is how to achieve online reconfiguration of master-slave mode without stopping the system when the master device fails, ensure that the sum of the output torques of each variable frequency drive device remains unchanged before and after the switchover, and continue the integral value of the new master device. Therefore, this invention provides a control method for a multi-drive device drive system.

[0025] Figure 1 This is a schematic diagram of the structure of a converter tilting device provided in an embodiment of the present invention. Figure 1 As shown, taking a metallurgical converter tilting device as an example, four variable frequency drive devices are all coupled to the same main drive shaft via variable frequency motors. In this embodiment of the invention, the variable frequency drive device refers to the inverter body used to control the variable frequency motor, which internally includes software / hardware modules such as a speed controller and a vector control unit. This device can be configured with an encoder interface to receive motor speed feedback signals and drive the corresponding AC variable frequency motor. For simplicity, the inverter, encoder, and motor are collectively referred to as a variable frequency drive device as a single functional unit.

[0026] Each variable frequency drive operates in speed loop vector control mode. A programmable logic controller (PLC) exchanges synchronous data with each drive via an industrial real-time bus, with a communication cycle in milliseconds (e.g., 1ms). It should be noted that in this embodiment, a Siemens SINAMICS S120 series frequency converter is used as a specific example of each variable frequency drive for illustration.

[0027] The driving capacity of the metallurgical converter tilting device is designed as follows: when all four devices are in normal operation, it can run at the maximum set speed; when one device fails and is shut down, the remaining three devices can still maintain normal production speed; when two devices are shut down and only two devices remain, the speed must be reduced immediately to prevent single device overload; if another device fails, the machine must be stopped immediately and the brakes applied, and production cannot continue.

[0028] In this embodiment of the invention, the controller reads the diagnostic information of each variable frequency drive device every communication cycle and determines whether the variable frequency drive device is faulty based on the diagnostic information. The diagnostic information includes the status word fault bit, ready-to-run signal, encoder status, and bus timeout information for each variable frequency drive device.

[0029] During steady-state operation when no fault is detected in the main unit of the variable frequency drive, the controller periodically sends control word information to each variable frequency drive in each communication cycle to achieve dynamic management of the integrator state. This enables the speed controller of the main unit to operate in proportional-integral (PI) mode, the slave unit to operate in proportional (P) mode, and the integral component output by the integral regulator of the main unit as the feedforward torque, thereby achieving uniform distribution of steady-state load under mechanical hard connection conditions.

[0030] Specifically, the bit signals related to integral control in the control word information include: hold integral bit (parameter p1476 for Siemens S120 series frequency converters) and set integrator value trigger bit (parameter p1477 for Siemens S120 series frequency converters).

[0031] When a variable frequency drive is designated as the master device, the controller sets its hold integral bit to 0, allowing its integral regulator to accumulate freely, and simultaneously sets its integrator value trigger bit to 0. When a variable frequency drive is designated as the slave device, the controller sets its hold integral bit to 1, enabling it to accept the written integrator setpoint, and simultaneously sets its integrator value trigger bit to 1, ensuring that the output of its integral regulator remains equal to the integrator setpoint.

[0032] By combining the aforementioned bit signals, the operating mode of the speed controller for each variable frequency drive is configured: when both the integral bit and the integrator value trigger bit are 0, the speed controller operates in proportional-integral mode; when both are 1, the speed controller operates in proportional mode. The controller dynamically defines the identity of each device (i.e., determines the master or slave device) by sending the aforementioned control word to each variable frequency drive in each communication cycle. All variable frequency drives have the same hardware configuration and preset parameters, and none have a preset master / slave identity. This identity definition is entirely implemented by the controller's program logic, rather than relying on the fixed parameter configuration of each variable frequency drive itself. Therefore, the identity of the master / slave device can be changed online without downtime, overcoming the shortcomings of existing technologies where master / slave identities are pre-fixed and cannot be adjusted online.

[0033] Figure 2 This is a flowchart illustrating a control method for a multi-drive system according to an embodiment of the present invention. When the controller detects a fault in the main device, it executes the following... Figure 2 The control method shown includes the following steps S1 to S5.

[0034] Step S1: When a fault is detected in the main device among the plurality of variable frequency drive devices, the torque of each variable frequency drive device before the fault is obtained, and the total torque of the main drive shaft before the fault is calculated. Step S2: According to the preset priority, among the multiple slave devices other than the master device in the multiple frequency conversion drive devices, select the slave device with the highest priority as the new master device; Step S3: Calculate the initial integral value based on the total torque before the fault and the number of slave devices; Step S4: Input the initial integral value into the integral regulator of the new master device, and start the integral regulator of the new master device from the initial integral value; Step S5: Based on the integral component and torque distribution coefficient output by the integral regulator of the new master device, control the output torque of each slave device so that the sum of the output torques of the multiple frequency conversion drive devices before and after switching the master device remains unchanged.

[0035] For step S1, when the controller detects a fault in the current master device, it blocks the faulty device in the same or immediately following cycle and immediately acquires the torque values ​​output by all frequency converters (including the faulty master device itself) in the last stable communication cycle before the fault occurred. These torque values ​​are then added together to obtain the total mechanical load torque borne by the main drive shaft at the moment of the fault, i.e., the total torque before the fault. After the master device exits the faulty state, the remaining slave devices must share the original mechanical load to ensure that the spindle speed does not drop and the system does not shut down.

[0036] Therefore, in this embodiment of the invention, the controller first determines whether the current master device (j-th unit) is faulty through diagnostic information. If a fault exists, it sends a pulse blocking signal (corresponding to the OFF2 command) to the current master device, causing the torque output by the current master device to return to zero. It also reads the electromagnetic torque reported by each device during the last valid communication cycle before the fault. (Corresponding to parameter r0078 of Siemens SINAMICS S120 series frequency converter), calculate the total torque before the fault using the following formula:

[0037] in, i For indexes of multi-frequency drive devices, n The total number of devices. Due to the large rotational inertia and rigid connection of the mechanical transmission system, the mechanical load on the main drive shaft can be regarded as a constant load torque within a few milliseconds (1 to 3 communication cycles) during fault switching. Therefore, the total torque measured in the last cycle before the fault is used as the target value of total output to be maintained after the fault. This is a prerequisite for the method provided in this embodiment of the invention to achieve fluctuation-free switching of total output.

[0038] In the existing master-slave torque control mode, when the master unit fails, the slave units lose torque commands, and the system cannot know the current total load, relying solely on operator experience for resetting. This step, however, actively collects and calculates the total load through the controller, providing precise quantitative data for subsequent automatic reconfiguration, thereby achieving uninterrupted switching.

[0039] In this embodiment of the invention, after the controller acquires the total torque before the fault and isolates the faulty main device, and before selecting a new main device, the controller also needs to evaluate the overall driving capability of the remaining fault-free variable frequency drive devices. This evaluation is used to determine whether the remaining devices have the conditions to continue safe operation, avoiding the execution of invalid switching operations when the driving capability is insufficient.

[0040] It should be noted that the controller's assessment of the remaining drive capacity of the variable frequency drive is performed periodically. Within each communication cycle, the controller makes a judgment based on the current status and output capacity of each device, so as to take timely measures to reduce speed or stop the machine when the drive capacity is insufficient. Specifically, this includes the following two aspects of judgment.

[0041] Determining the maximum output torque capability of the remaining devices: The controller calculates the maximum sum of the torques that all remaining fault-free variable frequency drive devices (excluding the main device) can output. If this maximum value is lower than the first preset torque threshold (i.e., the normal drive capability threshold), it indicates that even if all remaining devices operate at full load, they cannot maintain the load torque required by the main drive shaft. Forcing full-speed operation will lead to device overload or speed drop. In this case, the controller will not execute the subsequent steps of selecting a new main device and writing and enabling the integrator of the new main device. Instead, it will directly use a ramp function to smoothly reduce the speed setpoint of the remaining devices to the preset speed value. During the speed reduction process, the speed controller of the multiple variable frequency devices still maintains the original master-slave cooperative control mode, that is, the main device operates in proportional-integral mode, and the slave device operates in proportional mode and receives the integral component as feedforward to ensure torque balance.

[0042] Determining the number of remaining devices: The controller counts the number of currently fault-free variable frequency drive devices. If this number is lower than a preset safety limit (for example, when the system is designed to require at least two devices to independently drive the load, the preset safety limit can be set to 2), it indicates that the remaining devices are no longer able to safely drive the load, and continued operation may cause equipment damage or a safety accident. In this case, the controller directly controls all variable frequency drive devices to stop and triggers the holding brake.

[0043] The above judgment logic is a necessary prerequisite after the main device failure is confirmed and before executing the new main device selection action. Only when the driving capability of the remaining devices meets the normal driving capability threshold and the number is not less than the preset safety number, will the controller continue to execute step S2 to select a new main device; otherwise, the controller will directly take measures to reduce speed or stop the machine to avoid secondary failures caused by forced switching.

[0044] For step S2, the controller selects the highest priority slave device from all remaining slave devices according to the preset priority rules and designates it as the new master device.

[0045] Preset priorities are used to determine a unique selection order among multiple available slave devices, avoiding selection conflicts or uncertainty. As a concrete example, when the controller determines that the current master device (e.g., device 2) has failed, it immediately obtains a list of all currently fault-free variable frequency drives (i.e., devices that have been cleared of faults) and sorts the list according to a preset priority rule (e.g., by device number in ascending order). The controller selects the device ranked first in the list as the new master device. For example, if the system has four devices (numbered 1, 2, 3, and 4), the current master device is device 2, and the remaining slave devices are devices 1, 3, and 4. When the preset priority is in ascending order by number, device 1 will be selected as the new master device; if device 1 is also unavailable (e.g., both devices fail simultaneously), then device 3 will be selected, and so on. Preset priorities can also be dynamically configured by the user based on factors such as the importance, runtime, and health status of the field equipment and stored in the controller, thus making production more flexible.

[0046] When multiple slave devices are available simultaneously, the preset priority ensures that the controller can always quickly and uniquely select a new master device without manual intervention or complex arbitration logic. Furthermore, the preset priority determination only involves numerical comparison and can be completed within millisecond-level communication cycles, meeting the real-time requirements of fault switching. This is in contrast to the existing single-integrator PI controllers described above. In the P-master-slave scheme, the identity of the master device is fixed during the design of the variable frequency drive system, and in case of failure, the parameters can only be manually modified after the system is shut down. However, the embodiment of this invention automatically selects a new master device based on a preset priority by the controller, without shutdown or manual intervention, realizing online dynamic reconfiguration of the master-slave identity of the devices.

[0047] For step S3, after obtaining the total torque before the fault and determining the new master unit, the controller needs to calculate a value that will serve as the initial integral value of the new master unit's integral regulator. This initial integral value represents the target torque share that each remaining fault-free unit (i.e., slave unit) should bear after the fault.

[0048] The formula for calculating the initial value of the integral is as follows:

[0049] in, This is the total torque before the fault (i.e., the sum of the torques output by all frequency converter drives during the last communication cycle before the fault). This is the number of currently remaining fault-free devices (i.e., the total number of original devices minus the number of faulty main devices and any other devices that have been decommissioned).

[0050] The initial integral value is calculated using the above-described equal-distribution method, assuming that all remaining devices have equal output capacity. During steady-state operation, this distribution method can further achieve non-uniform load distribution (e.g., when the motor capacities are different) through a torque distribution coefficient, while the initial integral value still serves as the reference value for the feedforward term of each device.

[0051] For step S4, the initial value of the integral obtained in step S3 is used... The integral regulator is loaded into the new master device and is allowed to accumulate normally from the initial value, thereby ensuring that its initial state precisely matches the current load. In this embodiment of the invention, this step is performed in the same or immediately following the communication cycle in which a master device fault is detected, and specifically includes the following sub-steps S41-S44.

[0052] Step S41: Disable the integration enable position of the new master device, and enable both its hold and set positions; Specifically, the controller sends a control word to the new master device, disabling its integral enable bit (i.e., prohibiting the integral regulator from autonomously accumulating), while simultaneously maintaining its hold integral bit and integrator value trigger bit in their original states, i.e., enabling them. Under this configuration, the new master device's integral regulator temporarily operates in the same state as the slave devices; that is, the output of the integral regulator is no longer determined by its internal accumulation but is equal to the external setpoint (i.e., the value in the integrator setpoint parameter). This configuration is used for subsequent writing of the initial integral value and triggering. It should be noted that during this process, the controller maintains the original control words of each slave device unchanged; that is, the slave devices continue to operate in proportional mode.

[0053] Step S42: Write the initial integration value into the new integrator setting parameter of the master device, and simultaneously write it into the integrator setting parameter of each slave device. Specifically, the controller will use the initial integral value calculated in step S3. Write the new integrator setting parameters of the master unit (e.g., parameter p1478 for Siemens S120 series frequency converters). Simultaneously, write this initial integral value to the integrator setting parameters of each slave unit. At this point, the initial integral value has been stored in the setting registers of each unit, but has not yet been loaded as the current output value of the integral regulator.

[0054] Step S43: Set the new master device to active and maintain it for at least one communication cycle, and load the value in the integrator setting parameter as the output value of the integral regulator; Specifically, the controller activates the new master unit's integrator setting trigger position (e.g., setting parameter p1477 of the Siemens S120 series frequency converter to 1) and maintains this for at least one communication cycle. This trigger signal causes the new master unit's integral regulator to load the value in the integrator setpoint parameter (i.e., the initial integral value) as the current output value of the integral regulator in one go, thereby updating the integral regulator's output from the original value to this initial integral value, achieving seamless reconstruction of the integral value.

[0055] Step S44: Restore the setting and holding bits of the new master device to invalid, and at the same time enable its integral enable bit, so that its integral regulator starts accumulating from the output value after loading.

[0056] Specifically, the controller restores the new master unit's integrator value trigger bit (p1477) and hold integral bit (p1476) to invalid (i.e., set to 0, the same as normal PI mode), while simultaneously enabling its integral enable bit (set to 1). At this time, the new master unit's integral regulator exits the external setting mode and, starting from the loaded initial integral value, performs normal accumulation according to the speed deviation, and its speed controller reverts to the standard proportional-integral mode.

[0057] After completing the above sub-steps, a new balancing mode is entered. In the new balancing mode, the new master unit assumes the integral regulation function, while each slave unit continues to operate in proportional mode and receives the integral component from the new master unit as feedforward. All units work together to maintain the stable operation of the main drive shaft. The entire fault switching process is completed within 1-3 communication cycles.

[0058] Through the above process, the integral regulator of the new master unit completes the seamless transition from receiving external setpoints to autonomous accumulation within milliseconds, and its initial output value is precisely matched with the total load before the fault.

[0059] For step S5, after the integrator initialization and mode switching of the new master device are completed, the controller uses the integral component output by the new master device, combined with the proportional adjustment of each slave device, to control the output torque of all slave devices, ensuring that the total torque remains unchanged before and after the switch and that the system operates smoothly.

[0060] In this embodiment of the invention, when the main device receives a control word that enables integration, keeps the integration bit, and sets the integrator value trigger bit all invalid, its speed controller operates in proportional-integral mode, and the output torque is calculated by the following formula: ; in, The torque component output by the main device. The speed deviation value of the main device (the difference between the given speed and the actual speed). For proportional gain (p1470). This is the integration time constant (p1472).

[0061] The integral term in the above formula This is the integral component of the integral controller output, denoted as... The controller reads the integral component of the master device via the real-time bus during each communication cycle. (Corresponding to parameter r1482 of Siemens S120), this value reflects the current output of the master unit's integral regulator, and this integral component will be used as the feedforward torque source for each slave unit.

[0062] In steady-state operation and the new balanced mode after fault switching, each slave device is configured in proportional mode, and the behavior of its integral regulator is managed through bit signals in the control word. Specifically, when a slave device receives a control word that disables the integral enable bit, holds the integral bit, and enables the integrator value trigger bit, its integrator channel operates in setting mode. That is, the value of the integrator output is no longer determined by internal accumulation, but becomes the set value input in the integrator setpoint parameter (e.g., parameter p1478 of Siemens S120). In a specific embodiment, for example, when using a Siemens SINAMICS S120 series frequency converter, the slave device's integrator value trigger bit (parameter p1477) can be set to "1", or set to "1" by the controller in each communication cycle; simultaneously, its integrator setpoint parameter (p1478) is connected to an analog channel receiving a value from the controller via BICO (BiConnector) interconnection technology. .

[0063] Under the above configuration, the output torque of each slave device is determined by the following formula: ; in, For the first i The output torque of the slave device, This is the proportional gain of the speed controller (the parameters of each device are set to the same value after adjustment). For the first i The speed deviation value of the device. This is the torque distribution coefficient (usually 1 during steady-state operation, but can be set to different values ​​depending on the capacity of each motor or operating condition). This is the integral component output by the integral regulator of the current main unit.

[0064] The above formula shows that the output of the speed controller of the device includes a proportional term. and feedforward terms The proportional term is responsible for quickly responding to speed deviations, while the feedforward term is responsible for following the integral component of the main device, thereby achieving output balance.

[0065] During each communication cycle, the controller reads the integral component output from the integral regulator of the new master unit via the real-time bus. Obtain the feedforward torque value of each slave device This value is then written to the integrator setting parameters of each slave device via the bus (e.g., parameter p1478 of Siemens S120). Because the slave device's integrator setting trigger bit is active (p1477=1), its integral regulator output is forced to equal this setting value; therefore, the feedforward term... It directly becomes a component of the output torque of the slave device. When the slave device's setting position is continuously active, its integrator output continuously follows the externally given torque. This enables real-time updates of the feedforward mechanism.

[0066] Because all variable frequency drive devices are rigidly coupled to the same main drive shaft via a reducer or coupling, the mechanical hard connection forces the actual speeds of each variable frequency drive device to be synchronized, and the speed deviation of each device approaches zero. Therefore, the proportional term in the output torque of each device contributes very little, and its output torque is mainly determined by the integral component. After the switch is completed, the integral regulator of the new master device starts accumulating from the initial integral value calculated in step S3. Each slave device receives the integral component of the new master device as feedforward, and the feedforward term in its output torque is equal to the torque distribution coefficient multiplied by this integral component, i.e. .

[0067] Since the output torque of all operating devices (the new master device and each slave device) is dominated by the same integral component, and the initial integral value is set to the average share of the total torque before the fault, the sum of the output torque of each device after the switch is basically equal to the total torque before the fault, thus achieving no sudden change in total output power and no drop in spindle speed, and completing a non-stop, trouble-free switch.

[0068] It should be noted that, although this embodiment uses load sharing... This invention is illustrated using an example, but it is not limited thereto. When the capacity or characteristics of each variable frequency drive device are different, the torque distribution coefficient can be adjusted. To achieve uneven load distribution, such as distribution according to rated power ratio.

[0069] To limit the excessive accumulation or abrupt changes in the integral component under abnormal operating conditions, constraints can be imposed by setting upper and lower limits for the integrator's output. For example, when using a Siemens SINAMICS S120 series frequency converter, parameters p1474 and p1475 are used to set the lower and upper limits of the integrator's output, respectively. Once the integral component exceeds this range, it will be clamped to the set boundary value, thereby avoiding torque surges caused by integral saturation.

[0070] Furthermore, the system's speed ramp is controlled by parameters p1120 (rise time) and p1121 (fall time). During normal start-stop and multi-fault fault-tolerant deceleration, the controller adjusts the speed ramp to ensure smooth spindle speed changes, further reducing mechanical shock. Especially in the drive capability assessment after step S1, if the speed needs to be reduced to a predetermined deceleration value, the controller will smoothly reduce the speed ramp value through a ramp function, whose parameters correspond to p1120 and p1121, ensuring a smooth and shock-free deceleration process.

[0071] In one specific embodiment of the present invention, a Siemens SINAMICS S120 series frequency converter is used. The speed controller integrator behavior of this series of frequency converters is managed collaboratively by multiple bits in the control word and the corresponding BICO parameters. The control word combinations of each device in steady state are shown in Table 1.

[0072] Table 1

[0073] For Siemens S120 series frequency converters, the control word of the new master unit is configured according to the following timing sequence during fault switching: Initial state: The control word of the new master device is the same as that of the slave device, that is, the integration bit p1476 is kept at 1, the integrator value trigger bit p1477 is set to 1, and the integration enable bit is 0; Write initial integral value: The controller writes the calculated initial integral value into the new integrator setting parameter p1478 of the main unit. During this period, the control word remains unchanged to ensure that the written value has been correctly written and can be used for subsequent loading. Execute reconstruction pulse: Change the integrator value setting trigger bit p1477 from 1 to 0 and then back to 1 (i.e., generate a pulse), triggering the integrator to load the value in p1478 into the integrator output all at once; Switch to master device mode: Switch the control word to master device mode, that is, keep the integration bit p1476=0, set the integrator value trigger bit p1477=0, and the integration enable bit=1, so that the integrator starts to accumulate normally from the current value that has been loaded.

[0074] The above parameter setting logic ensures seamless transfer of the integral component and zero output fluctuation during fault switching. It should be noted that the above parameter settings are illustrated using a Siemens SINAMICS S120 series frequency converter as an example, but the invention is not limited to this. Other brands of frequency converters can achieve equivalent functions through similar speed controller control words, and all should fall within the protection scope of this invention.

[0075] Figure 3 This is a schematic diagram of a multi-transmission drive system provided in an embodiment of the present invention. Figure 3 As shown, the system includes: multiple variable frequency drive devices, a controller, a human-machine interface, a variable frequency drive network, and a field testing unit.

[0076] In this configuration, multiple variable frequency drives are coupled to the same main drive shaft. Specifically, each variable frequency drive drives a corresponding AC variable frequency motor, and each motor is rigidly coupled to the same mechanical load shaft via a reducer or coupling. In one specific example, four variable frequency drives are configured, using Siemens S120 series frequency converters. Each drive is equipped with an encoder and operates in vector control mode with encoder feedback.

[0077] The controller (e.g., a programmable logic controller, PLC) connects to each variable frequency drive unit via a control bus (e.g., an industrial real-time Ethernet bus) to implement the control method for the multi-drive unit drive system described above. The controller and each variable frequency drive unit exchange data synchronously at the same time, with a communication cycle in milliseconds (e.g., 1ms). Within each communication cycle, the controller reads diagnostic information and torque data from each unit and issues control words and integral setpoints to perform fault detection, master-slave dynamic configuration, seamless integral reconfiguration, and torque distribution control.

[0078] Thirdly, embodiments of the present invention also provide a machine-readable storage medium storing instructions that, when executed by a processor, implement the control method of the multi-drive system described above.

[0079] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0080] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0081] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0082] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0083] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0084] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0085] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0086] 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.

[0087] 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 control method for a multi-transmission drive system, characterized in that, The multi-drive system includes multiple variable frequency drives coupled to the same main drive shaft and a controller connected to each variable frequency drive. The control method includes: When a fault is detected in the main device among the plurality of variable frequency drive devices, the torque of each variable frequency drive device before the fault is obtained, and the total torque of the main drive shaft before the fault is calculated. According to a preset priority, among the multiple slave devices other than the master device in the multiple frequency conversion drive devices, the slave device with the highest priority is selected as the new master device. Based on the total torque before the fault and the number of slave devices, the initial integral value is calculated; The initial integral value is input into the integral regulator of the new master device, and the integral regulator of the new master device starts operating from the initial integral value; and Based on the integral component and torque distribution coefficient output by the integral regulator of the new master device, the output torque of each slave device is controlled so that the sum of the output torques of the multiple frequency conversion drive devices before and after switching the master device remains unchanged.

2. The control method according to claim 1, characterized in that, During steady-state operation in which no main unit fault is detected in the plurality of variable frequency drive devices, In each communication cycle when communicating with multiple variable frequency drive devices, the controller periodically sends control word information to the variable frequency drive devices, so that the speed controller of the master device operates in proportional-integral mode, the slave device operates in proportional mode, and the integral component output by the integral regulator of the master device is used as the feedforward torque of the slave device.

3. The control method according to claim 2, characterized in that, When the speed controller of the main device operates in proportional-integral mode, its output torque is calculated by the following formula: ； in, The torque output by the main device. This is the speed deviation value. For proportional gain, is the integration time constant.

4. The control method according to claim 1, characterized in that, The output torque of the slave device is calculated by the following formula: ； in, Let be the output torque of the i-th slave device. For proportional gain, This is the speed deviation value. The torque distribution coefficient is... The integral component is the output of the integral regulator of the main device.

5. The control method according to claim 1, characterized in that, The step of inputting the initial integral value into the integral regulator of the new master device and causing the integral regulator of the new master device to start operating from the initial integral value includes: within the same or immediately following communication cycle in which a master device fault is detected. The integration enable position of the new master device is disabled, and its hold and set bits are both enabled; The initial integral value is written into the integrator setting parameter of the new master device, and simultaneously written into the integrator setting parameter of each slave device; The new master device is set to active and remains active for at least one communication cycle, and the value in the integrator setting parameter is loaded as the output value of the integral regulator. The set and hold bits of the new master device are restored to invalid, while its integral enable bit is enabled, so that its integral regulator starts accumulating from the output value after loading.

6. The control method according to claim 1, characterized in that, When a fault is detected in the main unit of the plurality of variable frequency drive devices, the control method further includes: A pulse blocking signal is sent to the current master device, causing the torque output by the current master device to return to zero.

7. The control method according to claim 1, characterized in that, The controller determines whether the frequency converter is faulty based on at least one of the acquired status word fault bit, ready signal, encoder status, and bus timeout information of each frequency converter.

8. The control method according to claim 1, characterized in that, Before selecting the slave device with the highest priority as the new master device, the control method further includes: When the maximum value of the sum of the torques output by the remaining variable frequency drive devices other than the main device is lower than the first preset torque threshold, the speed of the remaining variable frequency drive devices is reduced to the preset speed through a ramp function. When the number of the remaining variable frequency drive devices, excluding the main device, is lower than the preset safety number, all variable frequency drive devices are controlled to stop.

9. A multi-transmission drive system, characterized in that, The system includes: Multiple variable frequency drive devices are coupled to the same main drive shaft; The controller is connected to each of the variable frequency drives via a control bus to implement the control method for the multi-drive system as described in any one of claims 1 to 8.

10. A machine-readable storage medium storing instructions thereon, characterized in that, When the instructions are executed by the processor, they implement the control method for the multi-drive system as described in any one of claims 1 to 8.

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