Non-cascade model-free backstepping sliding mode control method for permanent magnet synchronous motor

Abstract

The invention belongs to the technical field of motor control, discloses a non-cascade model-free backstepping sliding mode control method for a permanent magnet synchronous motor, and effectively solves the problems of current constraint, non-matching interference suppression, compensation and the like in a non-cascade architecture. By constructing a finite time disturbance observer, real-time accurate estimation of system disturbance is achieved, and it is ensured that steady-state errors converge to zero within finite time; on this basis, a backstepping sliding mode controller with switching control is developed, and the controller can effectively guarantee dynamic performance and anti-interference capability on the premise of strictly complying with current constraints. Compared with the prior art, the method has the advantages that the hyper-local model is introduced and the system transformation is performed, so that the dependence on motor parameters is eliminated, a model-free control structure independent of a motor mathematical model is constructed, and the robustness and the control precision of the system under the conditions of parameter uncertainty and external interference are improved.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, specifically to a non-cascaded, model-free backstepping sliding mode control method for permanent magnet synchronous motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) have been widely used in high-performance motion control fields such as industrial servo drives, new energy vehicles, aerospace, and precision machining due to their advantages of high power density, high torque-to-inertia ratio, high operating efficiency, and compact structure. However, a PMSM is a complex controlled object with multiple variables, strong coupling, and nonlinearity. Its mathematical model includes multiple state variables such as armature current, rotor speed, and position, and the parameters are easily affected by operating conditions such as temperature and magnetic saturation. In addition, external disturbances are unavoidable, which poses a severe challenge to the design of the controller.

[0003] In existing technologies, vector control is the mainstream solution for achieving high-performance speed regulation of PMSMs. Traditional vector control systems typically employ a cascaded control structure, with the outer loop being the speed loop and the inner loop being the current loop. This structure relies on a precise mathematical model of the motor and requires accurate parameter tuning, leading to inherent limitations such as dynamic response coupling, parameter sensitivity, and poor robustness.

[0004] To avoid dependence on precise mathematical models, the paper "Zhang Y, Jin J, Huang L. Model-free predictive current control of PMSM drives based on extended state observer using ultralocal model[J]. IEEE Transactions on Industrial Electronics, 2020, 68(2): 993-1003." proposes a model-free control method based on an ultralocal model. This method constructs a motor system model using only the inputs and outputs within the system and combines an extended state observer to design a deadbeat discrete voltage controller. Although this method avoids complex parameter identification and to some extent eliminates the influence of motor parameters, it still cannot solve the dynamic response coupling problem of cascaded systems. To overcome the above limitations, the paper "Wang Z, Dai B, Guo Z, et al. Single-Loop Current-Constrained Speed ​​Regulation for PMSM via a Switching Controller[J]. IEEE Transactions on Transportation Electrification, 2024." uses a non-cascaded architecture to design the motor controller to improve dynamic performance. However, this method introduces a new second-order system, which is a state-constrained system, and the existence of unmatched disturbances poses new requirements for the controller design. The literature “Zhang J, Ren W, Sun XM. Extended-state-observer-based nonlinear control for PMSM servo systems with current constraints and voltage saturations[J]. IEEE Transactions on Transportation Electrification, 2023, 10(2): 2713-2726” transforms the original system into an unconstrained system through a special system transformation, uses the backstepping method to design a virtual control law, stabilizes the various subsystems of the system, and achieves accurate tracking of the motor speed. However, in order to achieve accurate tracking results, the formula derivation and parameter tuning are relatively complicated. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors. This invention takes a three-phase permanent magnet synchronous motor as the directly controlled object, and its core lies in constructing a non-cascaded control architecture. On this architecture, it integrates the model-free control concept, backstepping method, and sliding mode control strategy. The aim is to solve the inherent limitations of cascaded system architectures, such as dynamic response coupling, parameter sensitivity, and poor robustness, while effectively handling challenges such as current state constraints and unmatched disturbance suppression and compensation in non-cascaded system architectures.

[0006] In this invention, firstly, the mathematical model of the permanent magnet synchronous motor is rewritten as a hyperlocal model under a non-cascaded architecture. By introducing a new set of state variables, the original system is transformed into a second-order system that is easy to analyze and design.

[0007] Based on this, the present invention designs a finite-time disturbance observer, which can simultaneously and accurately estimate the matched and unmatched disturbances existing in the system within a finite time. Furthermore, a backstepping sliding mode controller with switching control is developed. This controller combines the stepwise design advantages of backstepping with the strong robustness of sliding mode control, and by introducing a switching mechanism, it ensures the current constraint is addressed.

[0008] The technical solution adopted in this invention is as follows: A non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors, comprising the following steps:

[0009] S1: Establish a mathematical model of the permanent magnet synchronous motor in a synchronous rotating coordinate system;

[0010] S2: Based on the established mathematical model of permanent magnet synchronous motor under the cascaded framework, sort out the control objectives under the non-cascaded framework, design new system state variables, and establish a hyperlocal model of permanent magnet synchronous motor under the non-cascaded framework.

[0011] The control objective in a non-cascaded framework is:

[0012] (1) The rotor speed can asymptotically track a given reference speed and has good anti-disturbance performance:

[0013]

[0014] in, Let be the reference rotational speed at time t;

[0015] (2) To ensure the safety of the permanent magnet synchronous motor system, the q-axis current must meet certain constraints:

[0016]

[0017] in, A pre-defined constant represents the constraint boundary of the q-axis current;

[0018] Considering a non-cascaded control framework, a first-order hyperlocal model of the permanent magnet synchronous motor is obtained:

[0019]

[0020]

[0021] in, and For the gain of the hyperlocal model to be designed, and This is the total disturbance of the system at this time;

[0022] Introducing a new set of state variables and :

[0023]

[0024] Differentiating the state variables and combining them with a non-cascaded first-order hyperlocal model, we obtain the changed system:

[0025]

[0026] in , This is a non-matching perturbation. To match the perturbation;

[0027] S3: Design a finite-time perturbation observer to estimate matched and unmatched perturbations, and to estimate the rate of change of unmatched perturbations;

[0028] Based on the following two premises: First, there are two disturbances in the system. and Both have unknown positive definite upper bounds; secondly, The second derivative and The derivatives of these derivatives are constrained by their respective known Lipschitz constants; based on these assumptions, a finite-time perturbation observer is constructed to observe both mismatched and matched perturbations:

[0029]

[0030]

[0031] in, , , , , , For observer gain; and Intermediate variables introduced for the observer; and State variables Observations and Observed values; and for and Observed values; and For observations The derivative and The derivative of , and for The derivative and The derivative of , and for The derivative and The derivative of;

[0032] S4: Combine a finite-time disturbance observer to design a non-cascaded model-free backstepping sliding mode velocity controller, including designing a novel sliding surface and switching controller to achieve disturbance rejection and current constraint.

[0033] Based on the transformed system, the motor speed tracking error is defined. and virtual control items for:

[0034]

[0035] in, This is the reference speed. The derivative of the reference rotational speed, Define the Lyapunov function as a constant greater than 0. for:

[0036]

[0037] After differentiating the above equation and combining it with the defined... and We can obtain:

[0038]

[0039] when hour, To ensure For negative fixed values, design a sliding surface:

[0040]

[0041] in, , For sliding surface gain, It is a nonlinear exponent, and the Lyapunov function is defined. for:

[0042]

[0043] right Taking the derivative, the non-cascaded model-free backstepping sliding mode controller is:

[0044]

[0045] in, , These are controller parameters, and they satisfy the following relationship:

[0046]

[0047] To achieve q-axis overcurrent protection, a switching controller is designed; the switching controller dynamically adjusts the control input based on the real-time measurement value of the q-axis current. When the q-axis current is within the safe range The controller operates normally; when the q-axis current reaches or exceeds the constraint boundary c, the controller switches to protection mode.

[0048] In step S1, the stator voltage equation and mechanical motion equation of the permanent magnet synchronous motor containing system parameter disturbances and external disturbances are constructed:

[0049]

[0050]

[0051]

[0052] in, and These are the stator currents along the d-axis and q-axis, respectively. and These are the stator voltages along the d-axis and the q-axis, respectively. and These are electric velocity and mechanical angular velocity, respectively. Stator resistance; and These are the stator inductance along the d-axis and the stator inductance along the q-axis, respectively. It is the extreme logarithm; Electromagnetic torque; It is the moment of inertia; The coefficient of friction; For permanent magnet flux; , , , , , These are the changes in motor system parameters; , , These are the external disturbances in the d-axis current loop, the q-axis current loop, and the velocity loop, respectively. , , To account for disturbances in the d-axis current loop, q-axis current loop, and velocity loop when system parameters change.

[0053] The switching controller is specifically:

[0054]

[0055] in, , It is a constant. Indicates disturbance The upper boundary.

[0056] The beneficial effects of this invention are as follows:

[0057] The non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors proposed in this invention first establishes a hyperlocal model of the permanent magnet synchronous motor under a non-cascaded framework. Then, it integrates the changes in internal motor parameters, model uncertainties, and external unknown disturbances into two total disturbance terms, introduces a new set of state variables, and performs system transformation. The resulting second-order system is completely independent of any specific motor parameters in form, thereby fundamentally reducing the system's dependence on parameter accuracy and improving the system's robustness and anti-interference ability.

[0058] Secondly, in order to ensure stable system operation and achieve superior dynamic speed response performance and tracking accuracy, this invention designs a backstepping sliding mode controller with switching control, which ensures that the motor speed can be directly and accurately controlled, while ensuring dynamic response performance and steady-state accuracy.

[0059] Furthermore, this invention designs a finite-time disturbance controller to estimate matched and unmatched disturbances in real time and accurately, ensuring that the steady-state error converges to zero within a finite time, thereby further improving the system's anti-interference capability.

[0060] This invention targets three-phase permanent magnet synchronous motors. The proposed control method not only improves the dynamic response speed and steady-state accuracy of the permanent magnet synchronous motor, but also significantly enhances the robustness and reliability of the system under complex working conditions. The control scheme has the advantages of high universality, simple structure and easy engineering implementation. Attached Figure Description

[0061] Figure 1This is a control block diagram of a permanent magnet synchronous motor using the non-cascaded model-free backstepping sliding mode control method of the present invention;

[0062] Figure 2 This is a schematic diagram of the specific scheme of the backstepping sliding mode control with switching control of the present invention;

[0063] Figure 3 These are the speed curves and q-axis current curves of the permanent magnet synchronous motor before and after sudden load increase and decrease on three different sliding surfaces when it starts at the desired speed of 1000 r / min in Example 1; (a) is the speed change curve; (b) is the q-axis current change curve.

[0064] Figure 4 The following are the speed curves and q-axis current curves of the permanent magnet synchronous motor in Example 1 when it starts at the desired speed of 1000 r / min, with and without a switching controller; (a) is the speed change curve; (b) is the q-axis current change curve.

[0065] Figure 5 The following are the speed curves and q-axis current curves of the permanent magnet synchronous motor before and after sudden load increase and decrease when starting at a desired speed of 1000 r / min in Example 2: (a) is the speed change curve; (b)-(d) are the q-axis current curves of the three control strategies respectively; (e) is the locally magnified curve of the q-axis current during the start-up phase of the three control strategies.

[0066] Figure 6 The following are the speed curves and q-axis current curves of the three control strategies when the permanent magnet synchronous motor starts at the desired speed of 1000 r / min in Example 2 and the motor parameters change: (a) is the speed change curve; (b)-(d) are the q-axis current curves of the three control strategies respectively; (e) is the locally magnified curve of the q-axis current during the start-up phase of the three control strategies. Detailed Implementation

[0067] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0068] Figure 1This diagram illustrates an overall system block diagram for implementing the motor control method provided in the embodiments of the present invention, employing a speed-current single-loop control structure instead of the traditional cascaded control. The control system mainly comprises a d-axis PI voltage controller, a q-axis single-loop backstepping sliding mode controller, a Clark / Park transformation module, a permanent magnet synchronous motor module, an SVPWM model, and a three-phase voltage inverter. During actual operation, the three-phase current of the permanent magnet synchronous motor is detected by a current sensor and converted into d-axis and q-axis current components in a rotating coordinate system via Clark and Park transformations. Simultaneously, a speed sensor provides real-time speed and rotor position signals. In the control structure of this invention, the q-axis current and speed signal are jointly input to the designed single-loop backstepping sliding mode controller to obtain the q-axis reference voltage; the d-axis uses... The control strategy ensures a constant magnetic flux and simplifies the control structure.

[0069] Figure 2 The overall architecture of the backstepping sliding mode control method with switching control proposed in this invention is shown. It aims to effectively address issues such as q-axis current constraints and non-matching disturbance suppression in non-cascaded architectures, thereby improving the dynamic performance and robustness of the motor control system.

[0070] Combination Figure 1 and Figure 2 The present invention provides a non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors, comprising the following steps:

[0071] S1: Establish a mathematical model of the permanent magnet synchronous motor in a synchronous rotating coordinate system;

[0072] Construct the stator voltage equations and mechanical motion equations of a permanent magnet synchronous motor containing system parameter disturbances and external disturbances:

[0073] (1)

[0074] (2)

[0075] (3)

[0076] in, and These are the stator currents along the d-axis and q-axis, respectively. and These are the stator voltages along the d-axis and the q-axis, respectively. and These are electric velocity and mechanical angular velocity, respectively. Stator resistance; and These are the stator inductance along the d-axis and the stator inductance along the q-axis, respectively. It is the extreme logarithm; Electromagnetic torque; It is the moment of inertia; The coefficient of friction; For permanent magnet flux; , , , , , These are the changes in motor system parameters; , , These are the disturbances in the d-axis current loop, the q-axis current loop, and the velocity loop, respectively. , , To account for disturbances in the d-axis current loop, q-axis current loop, and velocity loop when system parameters change;

[0077] S2: Based on the established PMSM mathematical model under the cascaded framework, sort out the control objectives under the non-cascaded framework, design new system state variables, and establish a hyperlocal model of permanent magnet synchronous motor under the non-cascaded framework.

[0078] The control objective in a non-cascaded framework is:

[0079] (1) The rotor speed can asymptotically track a given reference speed and has good anti-disturbance performance:

[0080] (4)

[0081] in, Let be the reference rotational speed at time t;

[0082] (2) To ensure the safety of the permanent magnet synchronous motor system, the q-axis current must meet certain constraints:

[0083] (5)

[0084] in A pre-defined constant represents the constraint boundary of the q-axis current;

[0085] Considering a non-cascaded control framework, a first-order hyperlocal model of the permanent magnet synchronous motor is obtained:

[0086] (6)

[0087] (7)

[0088] in, and For the model-free control gain to be designed, and This is the total disturbance of the system at this time;

[0089] Introducing a new set of state variables and :

[0090] (8)

[0091] Differentiating the state variables and combining them with a non-cascaded first-order hyperlocal model, we obtain the changed system:

[0092] (9)

[0093] in , This is a non-matching perturbation. To match the perturbation;

[0094] S3: Design a finite-time perturbation observer to estimate matched and unmatched perturbations, and to estimate the rate of change of unmatched perturbations;

[0095] Based on the following two premises: First, there are two disturbances in the system. and There is an unknown positive definite upper bound; secondly, The second derivative and The derivatives of these derivatives are constrained by their respective known Lipschitz constants; based on the aforementioned assumptions, a finite-time perturbation observer is constructed to observe both mismatched and matched perturbations:

[0096] (10)

[0097] (11)

[0098] in, , , , , , For observer gain; and Intermediate variables introduced for the observer; and State variables Observations and Observed values; and for and Observed values; and For observations The derivative and The derivative of , and for The derivative and The derivative of , and for The derivative and The derivative of;

[0099] S4: Combine a finite-time disturbance observer to design a non-cascaded model-free backstepping sliding mode velocity controller, including designing a sliding surface and a switching controller, to achieve disturbance rejection and current constraint;

[0100] Based on the transformed system, the motor speed tracking error is defined. and virtual control items for:

[0101] (12)

[0102] in, This is the reference speed. The derivative of the reference rotational speed, Define the Lyapunov function as a constant greater than 0. for:

[0103] (13)

[0104] After differentiating the above equation and combining it with the defined... and have to:

[0105] (14)

[0106] when hour, In order to ensure For negative fixed values, design a sliding surface:

[0107] (15)

[0108] in, , For sliding surface gain, It is a nonlinear exponent, and the Lyapunov function is defined. for:

[0109] (16)

[0110] right Taking the derivative, the non-cascaded model-free backstepping sliding mode controller is:

[0111] (17)

[0112] in, , These are controller parameters, and they satisfy the following relationship:

[0113] (18)

[0114] To implement q-axis overcurrent protection, a switching controller is designed:

[0115] (19)

[0116] in, , It is a constant. Indicates disturbance The upper bound;

[0117] The switching controller dynamically adjusts the control input based on the real-time measurement of the q-axis current. When the q-axis current is within the safe range The controller operates normally within the specified range; when the q-axis current reaches or exceeds the constraint boundary c, the controller switches to [a specific mode / function]. model.

[0118] To verify the performance advantages of this invention, a single-loop model-free backstepping sliding mode controller designed in this invention was built in Matlab / Simulink, and the performance evaluation was analyzed covering two comparative scenarios and three different control methods.

[0119] Example 1: Comparison of anti-interference and current constraint performance

[0120] like Figure 3 and Figure 4 The figures show the speed response curves and q-axis current variation curves of the non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors proposed in this invention, under the starting condition with a desired speed set at 1000 r / min, using three different controllers, and the influence of switching controllers on the speed and q-axis current. Controller 1, Controller 2, and Controller 3 correspond to the use of linear sliding surfaces. Nonlinear sliding surface With integral sliding surface Three different control strategies were designed.

[0121] like Figure 3As shown in the speed response curves, controller 1 (using a linear sliding surface), controller 2 (using a nonlinear sliding surface), and controller 3 (using an integral sliding surface) all exhibit fast response speeds. Regarding steady-state accuracy, controller 1 has a steady-state error of 4.43, controller 3 has a steady-state error of 2.51, while controller 2 maintains a stable steady-state error of 0.8, demonstrating significantly better tracking accuracy. In terms of disturbance rejection capability, under disturbance conditions of a sudden load increase of 0.2s and a sudden load decrease of 0.3s, controller 2 exhibits a smaller speed drop and a shorter recovery time compared to controllers 1 and 3, verifying its superior dynamic disturbance rejection performance.

[0122] Figure 4 The changes in system performance after introducing the switching controller are further demonstrated. With a high-gain switching controller, the system's disturbance rejection performance remained largely maintained, but a certain amount of overshoot appeared in the speed response. With a low-gain switching controller, the speed response curve changed little, but its disturbance rejection performance decreased significantly, and the recovery process was slow. It is worth noting that after introducing the switching control, the q-axis current was effectively limited within a preset range, enhancing the protection capability of key actuators in the control system and improving the system's operational safety. Overall, while effectively constraining the q-axis current, the impact of the switching controller on the system's dynamic performance remained within an acceptable range.

[0123] Example 2: Comparison with methods proposed in recent years.

[0124] like Figure 5 and Figure 6The figures show the speed curves and q-axis current change curves of the non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors proposed in this invention under the starting condition with a desired speed set at 1000 r / min, using three different control methods, as well as the performance comparison of various control methods when the motor parameters change. The control methods compared include: ISMC-DDO, an integral sliding mode control method with a dual disturbance observer proposed in the literature “Li T, Liu X. Model-free non-cascade integral sliding mode control of permanent magnet synchronous motordrive with a fast reaching law[J]. Symmetry, 2021, 13(9): 1680.”; DOB-CC, a current-constrained control method based on a disturbance observer proposed in the literature “Dai C, Guo T, Yang J, et al. Adisturbance observer-based current-constrained controller for speedregulation of PMSM systems subject to unmatched disturbances[J]. IEEETransactions on Industrial Electronics, 2020, 68(1): 767-775.”; and RBSMC, a backstepping sliding mode control method with a switching controller proposed in this paper.

[0125] Given that the motor parameters are precisely known, from Figure 5 It can be seen that the three control methods do not differ significantly in terms of load disturbance resistance performance, and all can achieve relatively smooth speed recovery. However, in terms of q-axis current control, the three methods show obvious differences: the ISMC-DDO method does not consider current constraints, resulting in a large peak value in the q-axis current response, which may adversely affect the motor drive system; although the DOB-CC method has current constraint capability, its q-axis current ripple is more significant, which can easily cause increased output torque pulsation and thus affect the quality of the three-phase current waveform. In comparison, the RBSMC method proposed in this invention can obtain a q-axis current response with smaller ripple and smoother waveform while strictly ensuring current constraints, which helps to improve the steady-state performance and output quality of the system.

[0126] exist , and Under the condition of changes in motor parameters (where , and (For the changed motor parameters), from Figure 6 It can be seen that the ISMC-DDO method exhibits a certain speed tracking error after load is applied, significantly affecting the system's recovery capability. While the DOB-CC method can achieve speed recovery, its adjustment process suffers from continuous fluctuations and poor dynamic stability. In contrast, the RBSMC control method proposed in this invention can recover the reference speed more smoothly and quickly, and its dynamic performance is improved to some extent under changes in motor parameters. Regarding q-axis current control, the proposed RBSMC control method is less affected by changes in motor parameters, and while strictly adhering to current constraints, it can still output a q-axis current response curve with low ripple and a smooth waveform. In comparison, although the ISMC-DDO method shows little change in current response when parameters change, its overall performance is limited by model dependence, making it difficult to maintain good comprehensive performance under parameter mismatch conditions. The DOB-CC method is more sensitive to parameter changes, further increasing q-axis ripple, leading to a decrease in torque output quality and affecting the stable operation of the system.

Claims

1. A non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors, characterized in that, Includes the following steps: S1: Establish a mathematical model of the permanent magnet synchronous motor in a synchronous rotating coordinate system; S2: Based on the established mathematical model of permanent magnet synchronous motor under the cascaded framework, sort out the control objectives under the non-cascaded framework, design new system state variables, and establish a hyperlocal model of permanent magnet synchronous motor under the non-cascaded framework. The control objective in a non-cascaded framework is: (1) The rotor speed can asymptotically track a given reference speed and has good anti-disturbance performance: ； in, Let be the reference rotational speed at time t; (2) To ensure the safety of the permanent magnet synchronous motor system, the q-axis current must meet certain constraints: ； in, A pre-defined constant represents the constraint boundary of the q-axis current; Considering a non-cascaded control framework, a first-order hyperlocal model of the permanent magnet synchronous motor is obtained: ； ； in, and For the gain of the hyperlocal model to be designed, and This is the total disturbance of the system at this time; Introducing a new set of state variables and : ； Differentiating the state variables and combining them with a non-cascaded first-order hyperlocal model, we obtain the changed system: ； in , This is a non-matching perturbation. To match the perturbation; S3: Design a finite-time perturbation observer to estimate matched and unmatched perturbations, and to estimate the rate of change of unmatched perturbations; Based on the following two premises: First, there are two disturbances in the system. and Both have unknown positive definite upper bounds; secondly, The second derivative and The derivatives of these derivatives are constrained by their respective known Lipschitz constants; based on these assumptions, a finite-time perturbation observer is constructed to observe both mismatched and matched perturbations: ； ； in, , , , , , For observer gain; and Intermediate variables introduced for the observer; and State variables Observations and Observed values; and for and Observed values; and For observations The derivative and The derivative of , and for The derivative and The derivative of , and for The derivative and The derivative of; S4: Combine a finite-time disturbance observer to design a non-cascaded model-free backstepping sliding mode velocity controller, including designing a novel sliding surface and switching controller to achieve disturbance rejection and current constraint. Based on the transformed system, the motor speed tracking error is defined. and virtual control items for: ； in, This is the reference speed. The derivative of the reference rotational speed, Define the Lyapunov function as a constant greater than 0. for: ； After differentiating the above equation and combining it with the defined... and We can obtain: ； when hour, To ensure For negative fixed values, design a sliding surface: in, , For sliding surface gain, It is a nonlinear exponent, and the Lyapunov function is defined. for: ； right Taking the derivative, the non-cascaded model-free backstepping sliding mode controller is: in, , These are controller parameters, and they satisfy the following relationship: ； To achieve q-axis overcurrent protection, a switching controller is designed; the switching controller dynamically adjusts the control input based on the real-time measurement value of the q-axis current. When the q-axis current is within the safe range The controller operates normally; when the q-axis current reaches or exceeds the constraint boundary c, the controller switches to protection mode.

2. The non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors according to claim 1, characterized in that, In step S1, the stator voltage equation and mechanical motion equation of the permanent magnet synchronous motor containing system parameter disturbances and external disturbances are constructed: ； ； ； in, and These are the stator currents along the d-axis and q-axis, respectively. and These are the stator voltages along the d-axis and the q-axis, respectively. and These are electric velocity and mechanical angular velocity, respectively. Stator resistance; and These are the stator inductance along the d-axis and the stator inductance along the q-axis, respectively. It is the extreme logarithm; Electromagnetic torque; It is the moment of inertia; The coefficient of friction; For permanent magnet flux; , , , , , These are the changes in motor system parameters; , , These are the external disturbances in the d-axis current loop, the q-axis current loop, and the velocity loop, respectively. , , To account for disturbances in the d-axis current loop, q-axis current loop, and velocity loop when system parameters change.

3. The non-cascaded model-free backstepping sliding mode control method for permanent magnet synchronous motors according to claim 1, characterized in that, The switching controller is specifically: ； in, , It is a constant. Indicates disturbance The upper boundary.

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