A multi-permanent magnet synchronous motor position synchronization control method based on common differential mode separation

Abstract

This invention relates to a position synchronization control method for multiple permanent magnet synchronous motors based on common-mode and differential-mode separation, belonging to the field of multi-motor cooperative drive and control technology. This invention decouples the system control objective in terms of topology by constructing common-mode and differential-mode loops. The common-mode loop uses a unified speed controller to generate a common-mode current reference value based on a weighted average feedback speed. The differential-mode loop uses a nonlinear synchronization controller for each motor, which generates a differential-mode current reference value based on the synchronization deviation input, combined with an adaptive nonlinear gain and a recovery coefficient. The adaptive gain is the maximum value between a first gain based on mechanical clearance constraints and a second gain based on disturbance rejection requirements, and the recovery coefficient is dynamically adjusted in segments according to the deviation and its rate of change. This invention achieves complete decoupling of speed tracking and position synchronization, significantly improving synchronization accuracy and disturbance rejection capability under current saturation constraints, and is suitable for high-performance multi-motor cooperative drive applications such as space servo mechanisms and precision transmissions.

Description

Technical Field

[0001] This invention belongs to the field of multi-motor cooperative drive and control technology, specifically relating to a position synchronization control method for multiple permanent magnet synchronous motors based on common-differential mode separation. Background Technology

[0002] With the development of modern industrial technology, single-motor drives can no longer meet the energy demands for ultra-high power and high reliability. Therefore, multi-motor cooperative drive systems are widely used in fields such as machining, precision transmission, and aerospace. However, in practical applications such as space servo mechanisms, three-motor systems face severe synchronization challenges. Especially during system startup and acceleration or when subjected to asymmetrical load impacts, the system is often constrained by the maximum current saturation limit of the drivers. In this situation, how to effectively balance the overall speed tracking performance of the system with the positional consistency between individual motors has become a key issue restricting the high-performance operation of space servo mechanisms.

[0003] To improve the synchronization performance of multi-motor systems, deviation coupling control is widely used. However, in traditional deviation coupling control, there is command interaction between the closed-loop speed loop and the coupled feedback, leading to an inherent contradiction between speed tracking and position synchronization. Although the coupling can be alleviated by adjusting different bandwidths, the response often lags when dealing with nonlinear constraints such as current saturation during the startup phase, and the bandwidth boundary is difficult to define.

[0004] To address the aforementioned issues, existing technologies have proposed various improved deviation coupling control strategies. One type of approach focuses on introducing new physical quantities into the compensation stage. For example, Chinese patent CN106887976A proposes incorporating the acceleration of each motor into the compensation stage, enabling each motor to accelerate at its maximum acceleration to improve the system's dynamic tracking performance. Another type of approach aims to expand the target dimension of synchronous control. For instance, Chinese patent CN111525844A proposes a dual deviation coupling structure that simultaneously designs speed compensators and torque compensators to achieve dual synchronization of speed and torque in multi-motor systems. Furthermore, research has also focused on improving synchronization performance by refining the control algorithms of individual motors. For example, advanced algorithms such as sliding mode control and active disturbance rejection control are used to replace traditional PI controllers to enhance the system's disturbance rejection capability.

[0005] Although the aforementioned improvements enhance the synchronization performance of multi-motor systems from different perspectives, fundamentally, their control architecture remains confined to the traditional deviation coupling framework. The structural coupling and command interaction issues between the speed tracking target and the position synchronization target in the control loop have not been fundamentally resolved. When the system operates under highly nonlinear conditions such as driver current saturation, the mutual interference between common-mode and differential-mode regulation still exists, leading to a significant deterioration in the synchronization regulation effect.

[0006] Therefore, there is an urgent need in this field for a control strategy that can completely decouple speed tracking and position synchronization at the topology level, so as to eliminate the mutual interference between common-mode regulation and differential-mode regulation, and ensure the effectiveness of synchronous control under current saturation constraints. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of the prior art and provide a position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation. This method solves the problems of structural coupling and command interaction between speed tracking and position synchronization in traditional deviation coupling control, as well as the problem of synchronization adjustment failure under strong nonlinear conditions such as driver current saturation.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation is disclosed. The method is applied to a multi-motor system containing at least three permanent magnet synchronous motors, and the motors are synchronized using a deviation coupling topology. The method includes constructing a common-mode loop and a differential-mode loop. The common-mode loop includes a unified speed controller, and the differential-mode loop includes a nonlinear synchronization controller corresponding to each motor.

[0009] The core steps of the method include: Collect the real-time speed of each motor and real-time location And based on the rotational inertia of each motor Calculate the weighted average rotational speed as the common-mode feedback speed. Input the unified speed controller; the unified speed controller is based on the reference rotational speed. and the common-mode feedback speed Generate common-mode current reference value ; For each motor, based on the deviation coupling topology, the weighted sum of the positional deviations of that motor and the other motors is calculated and used as the synchronization deviation input for that motor. The corresponding nonlinear synchronization controller is input; the nonlinear synchronization controller inputs the synchronization deviation. By combining the adaptive nonlinear gain k and the recovery coefficient r, a differential-mode current reference value is generated. ; Wherein, the adaptive nonlinear gain k takes the first gain. Second gain The maximum value in, i.e. ,in: , ; The coefficient of recovery r is determined in the following manner: ; The common-mode current reference value Reference values ​​of differential mode current for each motor The current commands for each motor are superimposed to generate the final current commands for each motor, thereby achieving decoupled control of speed tracking and position synchronization.

[0010] Furthermore, the multi-motor system is a system of three permanent magnet synchronous motors, and the synchronization deviation input of each motor is... Calculated using the following formula: .

[0011] Furthermore, the common-mode feedback speed Calculated using the following formula: .

[0012] Furthermore, the nonlinear synchronous controller also includes an integrator and a low-pass filter; the integrator is used to eliminate the DC component in the differential-mode disturbance; the low-pass filter is used to limit the operating frequency band of the integrator to a preset low-frequency range, so that the integrator only adjusts the DC component and the extremely low-frequency component in the differential-mode disturbance.

[0013] Furthermore, the electromagnetic torque of each motor With the common-mode current reference value Sum and difference mode current reference values The following relationship exists between them: Load disturbances can be decomposed into common-mode disturbances and differential-mode disturbances that satisfy zero-sum characteristics.

[0014] Furthermore, the load disturbance of the multi-motor system Decompose into common-mode disturbances Sum and difference mode perturbations .

[0015] Furthermore, the common-mode feedback speed The dynamic process satisfies the following relationship: .

[0016] Furthermore, when the moments of inertia of the three motors are the same, that is... At that time, the second derivative of the synchronization error of motor 1 satisfies the following relationship: .

[0017] Furthermore, the preset control parameters The value is determined based on the upper limit requirement of the anti-interference frequency of the system under small deviation operating conditions; the preset recovery adjustment parameter The value of is determined based on the system's comprehensive requirements for overshoot and convergence speed during the synchronization recovery process.

[0018] Furthermore, the method is applied to multi-motor cooperative drive systems in space servo mechanisms, precision transmission devices, or CNC machine tools.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By constructing a deviation coupling control topology with common mode / differential mode separation, this invention achieves complete decoupling of the speed tracking target and the position synchronization target of a multi-motor system at the mathematical and topological levels, fundamentally eliminating the problem of command interaction and mutual interference between traditional control loops.

[0020] (2) The nonlinear synchronous controller designed in this invention introduces adaptive gain and recovery coefficient, which can significantly accelerate the convergence process of large-range transient deviation, thereby effectively solving the problem of synchronous regulation failure caused by the saturation limitation of the driver current in the start-up acceleration phase of the system, and greatly improving the transient response speed and anti-saturation operation capability of the system.

[0021] (3) The method provided by the present invention can adaptively extract the asymmetric part of the external load as the differential mode compensation target. Even under complex extreme working conditions with highly asymmetric load impact, it can still maintain the zero-sum characteristic of the current and suppress the position synchronization deviation between multiple motors to a very small range.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a general block diagram of a multi-motor synchronous control system provided in an embodiment of the present invention; Figure 2 This is a block diagram of the deviation coupling control based on common-mode separation in an embodiment of the present invention; Figure 3 This is a structural block diagram of the nonlinear synchronization controller in an embodiment of the present invention; Figure 4 The simulation curve of the synchronization error of the three-motor system under asymmetric load impact in the embodiment of the present invention; Figure 5 The above are simulation curves of the speed tracking performance of the three-motor system under asymmetric load impact in an embodiment of the present invention. Figure 6 This is a verification curve of the zero-sum property of the differential mode loop current of a three-motor system under asymmetric load impact in an embodiment of the present invention; Figure 7These are simulation result curves under differential mode disturbance only in this embodiment of the invention; Figure 8 The curves shown are simulation results curves under common-mode disturbance only in this embodiment of the invention. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0026] This invention provides a position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation. The method is applied to a multi-motor system containing at least three permanent magnet synchronous motors, and the motors are synchronized by a deviation coupling topology.

[0027] Example 1 This embodiment takes a cooperative drive system composed of three permanent magnet synchronous motors as an example to illustrate in detail the basic architecture and core decoupling principle of the nonlinear deviation coupling synchronous control method based on common-mode separation proposed in this invention.

[0028] 1. System Overall Architecture Figure 1 The overall block diagram of the multi-motor synchronous control system of the present invention is shown. By introducing a common-mode / differential-mode separation operator, the system decomposes the control objective into two orthogonal subspaces—speed tracking and position synchronization—at the topology level, thereby eliminating the command interaction and mutual interference between the two in traditional deviation coupling control.

[0029] The core control architecture of the system is as follows Figure 2 As shown, it consists of a common-mode circuit and multiple differential-mode circuits.

[0030] The common-mode loop includes a unified speed controller, whose input is a reference speed given by the system. and the weighted average feedback speed calculated based on the state of each motor The output is the common-mode current reference value. This common-mode current reference value After being allocated according to the ratio of the torque coefficient of each motor, the current inner loop of each motor is input as the basic drive command.

[0031] The differential-mode circuit is set up separately for each motor participating in the coordination, and includes a nonlinear synchronous controller. The input of this nonlinear synchronous controller is the synchronization deviation of each motor relative to other motors in the system, and the output is the differential-mode current reference value. Differential mode current reference value Similarly, input the corresponding motor's inner current loop and the common-mode current reference value. These components are superimposed to form the final current command.

[0032] 2. System dynamics model The simplified dynamic equations of a multi-motor synchronous system can be expressed as: (1) Where x = 1, 2, 3 represent the motor numbers, For rotational inertia, For mechanical angular velocity, For electromagnetic torque, This refers to the combined disturbance torque, which includes load and friction.

[0033] The mechanical angular position of each motor is defined as follows: .

[0034] In a multi-machine cooperative, deviation-coupled topology, the core objective of synchronous control is to minimize the positional deviation between any two motors to zero. This is due to mechanical backlash. The objective existence of this constraint requires the system's safety requirements to be met under all operating conditions: (2) in, This is the synchronization deviation input for the x-th motor. This is the preset mechanical clearance limit.

[0035] If the synchronization deviation exceeds this constraint, a mechanical collision will occur, generating a transient impact force. Traditional linear control strategies often struggle to balance steady-state accuracy and dynamic collision avoidance capability when dealing with such nonlinear systems with hard constraints.

[0036] 3. Proof of common-mode / differential-mode separation and decoupling To eliminate command interference between velocity tracking and position synchronization, this invention introduces a common-mode / differential-mode separation operator.

[0037] Taking a three-motor system as an example, the common-mode disturbance of the system is defined. The arithmetic mean of all motor load disturbances, differential mode disturbance. This represents the deviation of the individual load from the average load.

[0038] Based on the superposition principle, the load disturbance of each motor It can be decomposed into the sum of common-mode disturbance and differential-mode disturbance: (3) (4) To satisfy the zero-sum characteristic of the differential mode component of the system, differential mode disturbance Defined as: (5) Similarly, the electromagnetic torque of each motor It can be expressed as the sum of the common-mode torque component and the differential-mode torque component: (6) in, This is the motor torque coefficient. Let be the transfer function of the current loop. In order to drive all motors to track the common-mode torque at a given speed, The differential mode torque, which is responsible for synchronous correction, also satisfies the zero-sum characteristic.

[0039] In the deviation coupling topology, the synchronous deviation input of motor x Defined as the weighted sum of the positional deviations of this motor from all other motors: (7) Define the weighted average velocity of the system as the common-mode feedback velocity. : (8) Differentiate equation (8) and substitute equations (1), (3), and (6) into it: (9) Utilizing the zero-sum property of differential modulus components and Equation (9) simplifies to: (10) Equation (10) shows that the common-mode feedback speed The dynamic process is only affected by common-mode instructions. and common-mode disturbance The effect is independent of each differential modulus component.

[0040] Furthermore, the second derivative of the synchronization error between motor 1 and motor 2 is calculated: (11) Substituting equations (1), (3), and (6) into equation (11), and assuming that the inertia of the three machines is consistent... have to: (12) Equation (12) does not contain any common-mode components. and This proves that the synchronization performance of the three-motor system is driven only by differential-mode torque and differential-mode disturbance, achieving complete decoupling from the speed tracking target.

[0041] In summary, by constructing a common-mode / differential-mode decoupling framework, the dynamic model of the three-motor system was successfully transformed into two orthogonal subspaces. The common-mode loop was then used for weighted averaging of the speeds. The system's overall motion state is characterized by its dynamic performance, which depends solely on the common-mode instruction. and total system load The differential mode circuit, on the other hand, characterizes the transient position deviation between the motors, and its evolution is only affected by the differential mode component. Differential mode disturbance Driven by this, the decoupling in the topology not only eliminates the command interaction interference between the speed loop and the synchronization loop at the source, but also provides an independent theoretical basis for the subsequent design of high-performance nonlinear controllers for asymmetric load impact and current saturation conditions.

[0042] Example 2 Based on the common-mode / differential-mode separation architecture of Example 1, the speed loop is responsible for the overall speed tracking performance of the system, while the synchronization performance depends entirely on the adjustment capability of the differential-mode loop. This example designs a nonlinear synchronization controller, the block diagram of which is shown below. Figure 3 As shown.

[0043] 1. Overall structure of the controller The controller mainly consists of three parts: an integrator, a low-pass filter, and a nonlinear function.

[0044] The integrator is used to eliminate the DC component in differential-mode disturbances in order to reduce steady-state error; A low-pass filter limits the operating frequency band of the integrator to the low-frequency region, so that it is only responsible for regulating the DC and very low-frequency components in differential-mode disturbances. Nonlinear function: responsible for handling high-frequency AC components and transient response, it is the core part of the controller.

[0045] 2. Adaptive Nonlinear Gain Design When analyzing the nonlinear components, the DC component in the integrator and differential-mode disturbances can be ignored. The single-machine differential-mode current command output by the nonlinear controller is denoted as... The corresponding torque it produces Represented as: (13) in, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage.

[0046] In a three-motor cooperative system, synchronization deviation Constrained by mechanical clearance Within this range. To prevent mechanical collisions under extreme conditions, it is essential to ensure that the differential mode compensation torque generated by the controller can dissipate the deviation kinetic energy caused by synchronization failure. At any deviation position... Based on the current relative speed Including the angular margin from the mechanical boundary, the necessary condition for no collision can be expressed as the following energy integral equation: (14) in, This represents the maximum moment of inertia among the three motors. For differential mode compensation torque; This is the differential mode disturbance torque.

[0047] Define the relationship between differential mode compensation torque and nonlinear gain k as follows: Substituting this proportional relationship into equation (14), and assuming that the instantaneous correction torque is much greater than the load disturbance, the first gain (adaptive nonlinear gain) applicable to the three-motor system is derived by solving the integral term. : (15) These are time-varying parameters based on real-time mechanical clearance, current position deviation, and their first derivatives.

[0048] when deviation Approaching the boundary When the denominator approaches zero, the gain surges exponentially, forcing the generation of a reverse torque sufficient to prevent the deviation from expanding.

[0049] To further improve the upper limit of the system's anti-interference frequency under small deviation conditions, a second gain (constant gain coefficient) is introduced. .in, These are preset control parameters, which can be determined based on the upper limit requirement of the anti-interference frequency of the system under small deviation operating conditions.

[0050] Ultimately, the gain k of the nonlinear function is set to the maximum of both values ​​to balance safety margins and tracking accuracy. (16) 3. Design of the coefficient of recovery To address the recovery requirements of a three-motor system after an impact and transient collision, this invention introduces a recovery coefficient *r* to dynamically scale the differential mode command. Its definition is based on the polarity determination of the deviation and its rate of change. (17) in, Input for synchronization deviation rate of change, The preset recovery adjustment parameters can be determined based on the system's comprehensive requirements for overshoot and convergence speed during the synchronous recovery process.

[0051] This coefficient was introduced to optimize the energy consumption process after a collision.

[0052] During the deviation amplification phase r=1 ensures that the controller performs correction at full gain k, thus suppressing position deviation to the greatest extent. During the bias regression phase The compensation strength is adjusted through exponential decay. Because r will increase with... The power is gradually increased by decreasing the power and increasing it gradually, so as to ensure that the compensation power is always slightly greater than the disturbance power throughout the convergence process. This ensures a rapid return to the synchronization point and suppresses overshoot and secondary oscillation that may be caused by excessive gain by adjusting the damping characteristics, thus ensuring the stability of the three-motor system.

[0053] 4. Differential mode current reference value generation Based on the above design, the nonlinear synchronization controller is based on the synchronization deviation input. By combining the adaptive nonlinear gain k and the recovery coefficient r, a differential mode current reference value is generated. Finally, the common-mode current reference value will be... Reference values ​​of differential mode current corresponding to each motor The current commands for each motor are superimposed to generate the final current commands for each motor, thereby achieving decoupled control of speed tracking and position synchronization.

[0054] Example 3 To verify the effectiveness of the proposed synchronous control strategy, a simulation model of a three-motor system was built on the MATLAB / Simulink platform. The rated speed of all three motors is 200 rpm.

[0055] 1. Simulation parameter settings In the simulation, common-mode and differential-mode loads were applied simultaneously to the three motors. The common-mode load was a constant of 1 Nm. To simulate the complexity of actual working conditions and to demonstrate the disturbance rejection capability of the designed nonlinear controller, the differential-mode load included three sinusoidal components with different amplitudes and frequencies, and two triangular wave components with different amplitudes and frequencies, as shown in Table 1.

[0056] Table 1

[0057] In real-world complex operating conditions, external loads often exhibit asymmetry. To test the extreme robustness of the controller, the combined disturbances shown in Table 1 were injected into the system in an asymmetric manner during the simulation: the loads on motors 1 and 2 were the sum of the common-mode load and the differential-mode load, while the load on motor 3 was the difference between the common-mode load and the differential-mode load.

[0058] 2. Verification of Synchronization Performance under Asymmetric Load Impact Figure 4 The position synchronization error curves between each pair of motors in the three-motor system under this asymmetric load impact are shown. It can be seen that after entering steady state, all position differences are controlled within 0.02 rad, indicating good synchronization.

[0059] Figure 5 The speed response curves of the three motors are shown. It can be seen that the speeds of all three motors stabilize around 200 rpm after reaching steady state, demonstrating excellent speed tracking performance.

[0060] Figure 6 The waveform of the sum of the differential-mode currents of the three motors is shown. The results show that even under asymmetrical input load conditions, the sum of the differential-mode currents remains stable near 0.

[0061] The above results verify the effectiveness of the common-mode separation algorithm: the system can adaptively extract the asymmetric part of the load as the differential-mode compensation target, while the overall mean is handled by the common-mode loop. Simultaneously, it verifies that the designed nonlinear deviation coupling controller has forced balancing capability and can automatically compensate for the risk of synchronization failure caused by asymmetric disturbances.

[0062] 3. Verification of common-mode / differential-mode decoupling effect Figure 7 The system simulation results are shown under differential-mode disturbance only (common-mode disturbance is set to zero). Since the common-mode disturbance is zero, it can be seen from the figure that the output of the unified speed loop in steady state (i.e., the common-mode current setting) is 0, and the synchronization regulation of the system is entirely undertaken by the differential-mode loop.

[0063] Figure 8 The waveforms of the three-motor system under common-mode load alone are shown. The results show that even with asymmetrical input load, the sum of differential-mode currents remains stable near 0.

[0064] The above results further validate the effectiveness of the common-mode separation architecture: the system can adaptively extract the asymmetric portion of the load as the differential-mode compensation target, while the overall mean is handled by the common-mode loop. Simultaneously, it verifies that the designed nonlinear deviation coupling controller has a forced balancing capability and can automatically compensate for the synchronous failure risk caused by asymmetric disturbances.

[0065] 4. Parameter Influence Analysis In the above simulation verification process, the parameters in the coefficient of restitution r were further examined. Impact on system dynamic performance. When taking respectively For smaller (5), intermediate (20), and larger (50) values, the synchronization error convergence curves of the system exhibit different dynamic characteristics. This results in a slower decay of the recovery coefficient, faster convergence, but may lead to slight overshoot; a larger... Excessive damping slows down the convergence process; an intermediate value usually strikes a good balance between speed and stability. Therefore, in practical engineering applications, those skilled in the art can select appropriate values ​​using conventional parameter tuning methods based on the specific system's inertia, mechanical backlash, and dynamic response requirements. value.

[0066] Furthermore, although the above embodiments are described in detail using a three-motor system as an example, the core architecture of this invention (decoupling control based on common-mode / differential-mode separation) can be naturally extended to systems containing any number of motors. For a system containing n motors, the common-mode disturbance is defined as the arithmetic mean of the load disturbances of all motors, and the differential-mode disturbance of each motor is defined as the difference between its individual load disturbance and the arithmetic mean, with the sum of all differential-mode disturbances satisfying a zero-sum characteristic; the common-mode feedback speed is defined as the weighted average of the rotational speeds of each motor, weighted by its moment of inertia; the synchronization deviation input of each motor is calculated by the weighted sum of the positional deviations of that motor and the other motors, according to the generalization principle of the deviation coupling topology. The remaining control structures, including the unified speed controller, the nonlinear synchronization controller independently set for each motor, and the final current command synthesis method, are completely consistent with the three-motor system. The corresponding dynamic decoupling proof can also be similarly extended to the n-dimensional case. Therefore, the scope of protection of this invention is not limited to the specific number of motors described in the embodiments.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for position synchronization control of multiple permanent magnet synchronous motors based on common-mode separation, the method being applied to a multi-motor system comprising at least three permanent magnet synchronous motors, wherein the motors are synchronized using a deviation-coupled topology, the method comprising constructing a common-mode loop and a differential-mode loop, wherein the common-mode loop comprises a unified speed controller, and the differential-mode loop comprises a nonlinear synchronization controller corresponding one-to-one with each motor, characterized in that: Collect the real-time speed of each motor and real-time location And based on the rotational inertia of each motor Calculate the weighted average rotational speed as the common-mode feedback speed. Input the unified speed controller; the unified speed controller is based on the reference rotational speed. and the common-mode feedback speed Generate common-mode current reference value ; For each motor, based on the deviation coupling topology, the weighted sum of the positional deviations of that motor and the other motors is calculated and used as the synchronization deviation input for that motor. The corresponding nonlinear synchronization controller is input; the nonlinear synchronization controller inputs the synchronization deviation. By combining the adaptive nonlinear gain k and the recovery coefficient r, a differential-mode current reference value is generated. ; Wherein, the adaptive nonlinear gain k takes the first gain. Second gain The maximum value in, i.e. ,in: in, This is the synchronization deviation input for the x-th motor. The preset mechanical clearance limit, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage. Preset control parameters; The coefficient of recovery r is determined in the following manner: in, Input the synchronization deviation rate of change, Preset recovery adjustment parameters; The common-mode current reference value Reference values ​​for differential mode current corresponding to each motor The current commands for each motor are superimposed to generate the final current commands for each motor, thereby achieving decoupled control of speed tracking and position synchronization.

2. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, The multi-motor system consists of three permanent magnet synchronous motors, with synchronization deviation input for each motor. Calculated using the following formula: in, and These are the mechanical angular positions of the x-th and j-th motors, respectively.

3. The position synchronization control method for multiple permanent magnet synchronous motors based on common-differential mode separation according to claim 1, characterized in that, The common-mode feedback speed Calculated using the following formula: in, These are the moments of inertia of the three motors, , , These are the real-time speeds of the three motors.

4. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, The nonlinear synchronous controller further includes an integrator and a low-pass filter; the integrator is used to eliminate the DC component in the differential-mode disturbance; the low-pass filter is used to limit the operating frequency band of the integrator to a preset low-frequency range, so that the integrator only adjusts the DC component and the extremely low-frequency component in the differential-mode disturbance.

5. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, Electromagnetic torque of each motor With the common-mode current reference value Sum and difference mode current reference values The following relationship exists between them: in, This is the motor torque coefficient. The current loop transfer function, This is the common-mode component of the electromagnetic torque. This is the differential-mode component of the electromagnetic torque.

6. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, Load disturbance of the multi-motor system Decompose into common-mode disturbances Sum and difference mode perturbations And satisfy: 。 7. The position synchronization control method for multiple permanent magnet synchronous motors based on common-differential mode separation according to claim 1, characterized in that, The common-mode feedback speed The dynamic process satisfies the following relationship: in, This is the common-mode component of the electromagnetic torque. This represents the common-mode component of the load disturbance.

8. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, When the moments of inertia of the three motors are the same, that is At that time, the second derivative of the synchronization error of motor 1 satisfies the following relationship: in, These are the differential-mode components of the electromagnetic torque of the three motors. These are the differential mode components of the load disturbances of the three motors, respectively.

9. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to claim 1, characterized in that, The preset control parameters The value is determined based on the upper limit requirement of the anti-interference frequency of the system under small deviation operating conditions; The preset recovery adjustment parameters The value of is determined based on the system's comprehensive requirements for overshoot and convergence speed during the synchronization recovery process.

10. The position synchronization control method for multiple permanent magnet synchronous motors based on common-mode separation according to any one of claims 1 to 9, characterized in that, The method is applied to multi-motor cooperative drive systems in space servo mechanisms, precision transmission devices, or CNC machine tools.

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