A multi-motor cooperative control method and system based on virtual synchronous axis and dynamic impedance matching

Abstract

This application discloses a multi-motor cooperative control method and device based on a virtual synchronous shaft and dynamic impedance matching. The method includes: a coordinator collecting real-time torque data transmitted by all nodes; the coordinator obtaining the system average torque based on each torque data and sending it to each node; each node obtaining the torque deviation based on its own torque and the system average torque; each node adjusting its damping coefficient based on its own torque deviation to obtain the current virtual damping coefficient; each node generating a personalized speed based on its current virtual damping coefficient, the virtual shaft speed reference of the previous cycle, and the real-time output torque, thereby enabling each node to control according to its own personalized speed. This application abandons the traditional master-slave master-slave follower architecture and no longer simply treats droop control and torque compensation as two independent superimposed processes. Instead, it constructs a virtual, rigid synchronous mechanical shaft as a unified reference system for all motors.

Description

Technical Field

[0001] This application relates to the field of motor control technology, specifically to a multi-motor cooperative control method and system based on virtual synchronous shaft and dynamic impedance matching. Background Technology

[0002] For transmission-type mechanisms, such as scraper conveyors and belt conveyors, multiple electric motors are mainly used for driving. When multiple electric motors drive together, due to differences in the structure of the motors themselves, different load distributions, and variations in the stress of the scraper conveyor chain and the tension of the belt, different motors will produce different output power, resulting in a relatively serious power imbalance problem.

[0003] In existing technologies, the main methods for multi-machine power balancing are:

[0004] Master-slave torque control: The slave inverter operates in torque mode, taking the torque command from the master inverter as the given value. This method has high balancing accuracy, but it has extremely high requirements for real-time communication. Once the master inverter fails or communication is interrupted, the entire system will be paralyzed, resulting in poor reliability.

[0005] Pure droop control (frequency-torque droop): This method simulates the characteristics of a grid generator, causing the speed of each motor to decrease as the load increases. It requires no high-speed communication and is highly reliable. However, it is essentially a differential regulation method, and load balancing comes at the cost of speed accuracy. Furthermore, when there are significant differences in mechanical characteristics or sudden load changes, the balancing speed is slow, and steady-state errors exist.

[0006] Therefore, there is an urgent need for a control strategy that can ensure high reliability while achieving fast and accurate power balance. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching to at least solve one of the above-mentioned technical problems.

[0008] One aspect of the present invention provides a multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching, the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching comprising:

[0009] The coordinator collects real-time torque data transmitted by all nodes;

[0010] The coordinator obtains the system average torque based on the various torque data and sends it to each node.

[0011] Each node obtains its torque deviation based on its own torque and the system's average torque;

[0012] Each node adjusts its damping coefficient based on its own torque deviation to obtain the current virtual damping coefficient;

[0013] Each node generates a personalized speed based on its current virtual damping coefficient, the virtual shaft speed reference of the previous cycle, and the real-time output torque, thereby enabling each node to control itself according to its personalized speed.

[0014] Optionally, the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching further includes:

[0015] The coordinator corrects the virtual shaft speed reference of the previous cycle based on the system's average torque.

[0016] Optionally, the coordinator obtains the system average torque based on the various torque data using the following formula:

[0017] ;

[0018] in, The system average torque; The real-time torque data transmitted to the i-th node.

[0019] Optionally, the torque deviation is obtained by the following formula:

[0020] ;

[0021] in, This refers to torque deviation; Real-time torque data transmitted to the i-th node; This represents the system's average torque.

[0022] Optionally, the current virtual damping coefficient is obtained by the following formula:

[0023] ;

[0024] in, For the new virtual damping coefficient, This is the virtual damping coefficient from the previous round. This is the proportionality coefficient. The integral coefficient is... These are the differential coefficients. Let be the torque deviation at node i.

[0025] Optionally, the personalized speed is obtained using the following formula:

[0026] ;

[0027] in, This serves as the virtual axis speed reference for the previous cycle. This represents the current virtual damping coefficient; To output torque in real time.

[0028] Optionally, the coordinator obtains the virtual axis speed reference of the previous cycle based on the system average torque using the following formula:

[0029] ;

[0030] This is the corrected virtual axis velocity reference; The system average torque; Set the total speed value. Set the total speed value. This is a correction factor.

[0031] This application also provides a multi-motor cooperative control system based on virtual synchronous shaft and dynamic impedance matching. The multi-motor cooperative control system based on virtual synchronous shaft and dynamic impedance matching includes a coordinator and multiple nodes. The coordinator and multiple nodes cooperate to implement the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching as described above.

[0032] This application abandons the traditional master-slave architecture and no longer simply treats "droop control" and "torque compensation" as two independent superimposed processes. Instead, it constructs a virtual, rigid synchronous mechanical shaft as a unified reference frame for all motors. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching according to an embodiment of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0035] In this embodiment, the ingenuity of the invention lies in abandoning the traditional "master-slave" master-slave follower architecture, and no longer simply treating "droop control" and "torque compensation" as two independent superimposed processes. Instead, a virtual, rigid synchronous mechanical shaft is constructed as a unified reference frame for all motors.

[0036] Virtual Synchronous Shaft: This is a theoretically absolutely rigid, torsional-free ideal drive shaft. All motor rotors are "virtually" rigidly connected to this shaft, so they must maintain absolute speed synchronization.

[0037] Dynamic impedance matching: When each motor drives this virtual axis, its own mechanical characteristics (such as inertia and damping) are replaced by a dynamically adjustable virtual impedance. The goal of the system is to adjust the virtual impedance of each motor in real time so that the power (or torque) output by all motors to the virtual axis naturally reaches a balance, just like a perfectly matched mechanical system.

[0038] This approach shifts the control problem from "how to compensate for imbalances" to "how to build an inherently balanced system," thereby achieving high-precision load distribution at its source.

[0039] This application provides a multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching, the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching includes:

[0040] The coordinator collects real-time torque data transmitted by all nodes;

[0041] The coordinator obtains the system average torque based on the various torque data and sends it to each node.

[0042] Each node obtains its torque deviation based on its own torque and the system's average torque;

[0043] Each node adjusts its damping coefficient based on its own torque deviation to obtain the current virtual damping coefficient;

[0044] Each node generates a personalized speed based on its current virtual damping coefficient, the virtual shaft speed reference of the previous cycle, and the real-time output torque, thereby enabling each node to control itself according to its personalized speed.

[0045] In this embodiment, the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching further includes:

[0046] The coordinator corrects the virtual shaft speed reference of the previous cycle based on the system's average torque.

[0047] In this embodiment, the coordinator obtains the system average torque based on various torque data using the following formula:

[0048] ;

[0049] in, The system average torque; The real-time torque data transmitted to the i-th node.

[0050] In this embodiment, the torque deviation is obtained by the following formula:

[0051] ;

[0052] in, This refers to torque deviation; Real-time torque data transmitted to the i-th node; This represents the system's average torque.

[0053] In this embodiment, the current virtual damping coefficient is obtained using the following formula:

[0054] ;

[0055] in, For the new virtual damping coefficient, This is the virtual damping coefficient from the previous round. This is the proportionality coefficient. The integral coefficient is... These are the differential coefficients. Let be the torque deviation at node i.

[0056] In this embodiment, the personalized speed is obtained using the following formula:

[0057] ;

[0058] in, This serves as the virtual axis speed reference for the previous cycle. This represents the current virtual damping coefficient; To output torque in real time.

[0059] In this embodiment, the coordinator obtains the virtual axis speed reference of the previous cycle based on the system average torque using the following formula:

[0060] ;

[0061] This is the corrected virtual axis velocity reference; The system average torque; Set the total speed value. This is a correction factor (which can be set as needed).

[0062] It is understood that the technical solution of this application is a periodically operating technical solution. The following description of this application in a periodically operating manner will be further elaborated. It is understood that this example does not constitute any limitation on this application.

[0063] System initialization and parameter settings:

[0064] Peer nodes: All frequency converters are logically peer nodes, eliminating the need for a traditional master unit. However, a coordinator must be specified to receive the total speed setpoint. And perform the calculation.

[0065] In this embodiment, the coordinator is a global state management and broadcasting unit. Based on the priority sent by the nodes through broadcast, the coordinator is automatically selected according to election rules such as the highest priority or the lowest priority node D.

[0066] If a node does not receive a broadcast within the preset timeout period, it is determined that the current coordinator may be faulty. In this case, a new coordinator election will be triggered. The remaining online nodes will then re-elect a new coordinator according to the same election rules.

[0067] After the new coordinator takes over, it will begin global calculations and broadcasts from the current cycle, and the system will continue to run.

[0068] In this embodiment, each node is configured with a system-wide unique integer node identifier (Node ID). During election, the node with the largest node identifier has the highest priority and is elected as the coordinator. It is understood that the node identifier can be set as needed or randomly.

[0069] Virtual axis parameters: Define the reference angular velocity of the virtual synchronous axis. (Initial value) ).

[0070] Dynamic virtual impedance: Defines an online adjustable virtual damping coefficient D for each motor i. i D i The initial value can be the same, but it will change dynamically during operation. It is a key variable for achieving load balancing.

[0071] Within each control cycle Δt, the following steps are performed:

[0072] 1: Global state awareness and average torque calculation:

[0073] Each node i measures its own output torque T. i .

[0074] The coordinator collects the torques of all nodes and calculates the system average torque:

[0075] ;

[0076] And Broadcast to all nodes. This represents an ideal, uniformly distributed load level on the virtual synchronous axis.

[0077] 2: Dynamic virtual impedance adjustment:

[0078] Each node i independently calculates the deviation between its own torque and the average torque:

[0079] ;

[0080] This deviation is dynamically corrected by passing it through an impedance regulator (each node has an impedance regulator), thereby correcting its virtual damping coefficient D. i The regulator is a PI controller:

[0081] ;

[0082] in, For the new virtual damping coefficient, This is the virtual damping coefficient from the previous round; Let be the torque deviation at node i;

[0083] If T i >T avg If the load is large, then increase D. i This means that the "resistance" felt by the motor on the virtual shaft increases, and according to the drooping characteristics, its speed will tend to decrease. However, due to the rigid constraint of the virtual shaft, the actual result is that the system will seek a new balance by reducing its electromagnetic torque, thereby actively "unloading".

[0084] If T i <T avg If the load is small, then decrease D. i This means that the motor's "resistance" is reduced, and the system will tend to increase its electromagnetic torque to "load".

[0085] 3: Generation of Synchronization Speed ​​Based on Dynamic Impedance

[0086] All nodes use the same virtual axis velocity. and their respective updated virtual damping Each speed is calculated based on a unified downward formula:

[0087] ;

[0088] It is a globally consistent benchmark. When using the benchmark from the previous period, It ensures that the speed settings of all motors are adjusted around a central value of absolute synchronization.

[0089] 4: Global fine-tuning of virtual axis speed:

[0090] The coordinator can adjust the output based on feedback from the sum of the torques of all motors or the average speed. Make a minor adjustment to ensure that the average speed of the system remains stable during load distribution. Nearby. For example:

[0091] ;

[0092] This is equivalent to a global droop control, maintaining the overall descent characteristics of the system.

[0093] 5: Local speed closed-loop control

[0094] Each frequency converter Given a speed, internal closed-loop speed control is executed to drive the motor.

[0095] 6: Execute in a loop

[0096] Return to step 1 to achieve real-time load redistribution based on dynamic impedance matching.

[0097] This application also provides a multi-motor cooperative control system based on virtual synchronous shaft and dynamic impedance matching. The multi-motor cooperative control system based on virtual synchronous shaft and dynamic impedance matching includes a coordinator and multiple nodes. The coordinator and multiple nodes cooperate to implement the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching as described above.

[0098] This application has the following advantages:

[0099] From master-slave to peer-to-peer: This eliminates the traditional host bottleneck and single point of failure risk. All nodes make self-consistent decisions based on globally average information, resulting in a more robust system.

[0100] The introduction of a "virtual synchronous axis" elevates the control concept from "electrical synchronization" to "mechanical synchronization," providing a more intuitive control framework that is closer to the physical essence.

[0101] Dynamic impedance matching: Instead of simply "patching" speed commands, it dynamically adjusts the "personality" (virtual impedance) of each motor, allowing the system to spontaneously tend towards load balance from its inherent mechanism. This is a distributed, adaptive, feedforward balancing mechanism that offers faster response and smaller overshoot compared to traditional error feedback-based compensation.

[0102] Exceptional dynamic performance: When encountering impact loads, the motor with a sudden increase in load will immediately increase its D... i It acts like an "adaptive damper," rapidly suppressing torque growth and redirecting the load to other D values. i The smaller motor transfer rate enables inherent shock resistance.

[0103] Integrated parameter adaptation: Dynamic virtual impedance D i The adjustment process itself has the ability to adapt parameters, which can automatically adapt to different working conditions such as no load, light load, heavy load, and impact load, eliminating the need to design complex variable parameter strategies for the PI compensator.

[0104] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A multi-motor cooperative control method based on virtual synchronous axis and dynamic impedance matching, characterized in that, The multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching includes: The coordinator collects real-time torque data transmitted by all nodes; The coordinator obtains the system average torque based on the various torque data and sends it to each node. Each node obtains its torque deviation based on its own torque and the system's average torque; Each node adjusts its damping coefficient based on its own torque deviation to obtain the current virtual damping coefficient; Each node generates a personalized speed based on its current virtual damping coefficient, the virtual shaft speed reference of the previous cycle, and the real-time output torque through a droop formula, thereby enabling each node to control itself according to its own personalized speed.

2. The multi-motor cooperative control method based on virtual synchronous axis and dynamic impedance matching according to claim 1, wherein, The multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching further includes: The coordinator corrects the virtual shaft speed reference of the previous cycle based on the system's average torque.

3. The multi-motor cooperative control method based on virtual synchronous axis and dynamic impedance matching according to claim 2, wherein, The coordinator obtains the system average torque based on various torque data using the following formula: ； in, The system average torque; The real-time torque data transmitted to the i-th node.

4. The multi-motor cooperative control method based on virtual synchronous axis and dynamic impedance matching according to claim 3, characterized in that, The torque deviation is obtained by the following formula: ； wherein, is the torque deviation; is the real-time torque data transmitted by the i-th node; is the system average torque.

5. The method of claim 4, wherein the virtual synchronous axis and dynamic impedance matching based multi-motor cooperative control method is characterized by, The current virtual damping coefficient is obtained using the following formula: ； in, For the new virtual damping coefficient, This is the virtual damping coefficient from the previous round. This is the proportionality coefficient. The integral coefficient is... Let be the torque deviation at node i.

6. The method of claim 5, wherein the virtual synchronous axis and dynamic impedance matching based multi-motor cooperative control method is characterized by, The personalized speed is obtained using the following formula: ； wherein, is the virtual shaft speed reference of the previous cycle; is the current virtual damping coefficient; is the real-time output torque.

7. The method of claim 6, wherein the virtual synchronous axis and dynamic impedance matching based multi-motor cooperative control method is characterized by, The coordinator corrects the virtual axis speed reference of the previous cycle based on the system's average torque using the following formula: ； is a corrected virtual axle speed reference; is a system average torque; is a total speed setpoint, is a correction factor.

8. A multi-motor cooperative control system based on virtual synchronous axis and dynamic impedance matching, characterized in that, The multi-motor cooperative control system based on virtual synchronous shaft and dynamic impedance matching includes a coordinator and multiple nodes, which cooperate to implement the multi-motor cooperative control method based on virtual synchronous shaft and dynamic impedance matching as described in any one of claims 1 to 7.

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