Stepping motor model-free sliding mode rotating speed control method and system based on improved power reaching law

Abstract

The invention provides a stepping motor model-free sliding mode rotating speed control method and system based on an improved power reaching law, and the method comprises the steps: inputting the rotating speed of a stepping motor and a current under a d-q synchronous rotating coordinate system into a sliding mode disturbance observer, and obtaining an estimated system disturbance quantity; the expected reference rotating speed and the actual rotating speed of the stepping motor, the current under the d-q synchronous rotating coordinate system and the estimated system disturbance variable are input into a model-free sliding mode controller, and a q-axis current value reference value under the two-phase synchronous rotating coordinate system is obtained; and inputting the q-axis current value reference value and the d-axis current value reference value under the two-phase synchronous rotating coordinate system into a current loop controller and then carrying out inverse Park conversion to obtain the voltage of the stepping motor under the two-phase static coordinate system so as to realize the rotating speed control of the stepping motor. According to the method, the dependence of the controller on a system model can be reduced, and the method has good dynamic performance and robustness.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor drive control, and in particular relates to a model-free sliding mode speed control method and system for a stepping motor based on an improved power reaching law. Background Art

[0002] Stepper motors have been widely used in CNC machine tools, printing equipment, medical equipment, etc. due to their simple structure, precise positioning, and strong controllability. The traditional driving mode of stepper motors is open-loop control, but open-loop control is easily affected by external interference, resulting in loss of steps, overshoot, and other phenomena. If closed-loop control is adopted, the control performance can be effectively improved to obtain a more stable and smoother motion curve. However, since the stepper motor system is a nonlinear system with high-order multivariables, the traditional control method has limited anti-interference ability. For this reason, researchers have applied many control methods, such as backstepping control, fuzzy control, and sliding mode control. Among them, sliding mode control has fast response, is insensitive to parameter changes and disturbances, and is simple to implement physically, which can effectively improve the anti-interference performance of the system.

[0003] However, there are two problems with the application of sliding mode control. On the one hand, due to the existence of the sign function, the system will have a chattering problem; on the other hand, in engineering practice, due to the complex and changeable operating conditions of the motor, the motor parameters will be affected by temperature, electromagnetic and other factors and change, which will directly affect the control performance of model-based control methods such as sliding mode control. Therefore, in order to reduce the dependence of system control performance on model accuracy and effectively weaken the impact of sliding mode chattering, it is necessary to seek new control methods to achieve stable operation of the stepper motor sliding mode speed control system. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method and system for controlling the speed of a stepping motor by a model-free sliding mode based on an improved power reaching law.

[0005] In a first aspect, the present invention provides a model-free sliding mode speed control method for a stepping motor based on an improved power reaching law, comprising:

[0006] Get the speed and two-phase current of the stepper motor;

[0007] The two-phase current is transformed by Park to obtain the current of the stepper motor in the dq synchronous rotating coordinate system;

[0008] The speed of the stepper motor and the current in the dq synchronous rotating coordinate system are input into the sliding mode disturbance observer to obtain the estimated system disturbance;

[0009] The desired reference speed, actual speed, current in the dq synchronous rotating coordinate system and estimated system disturbance variables of the stepper motor are input into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system;

[0010] Obtain a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system;

[0011] The q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system are input into the current loop controller and then subjected to inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to realize the speed control of the stepper motor.

[0012] Optionally, the speed of the stepper motor and the current in the dq synchronous rotating coordinate system are input into a sliding mode disturbance observer to obtain an estimated system disturbance, including:

[0013] The estimated system disturbance is calculated according to the following formula:

[0014]

[0015] in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

[0016] Optionally, the stepper motor's desired reference speed, actual speed, current in a dq synchronous rotating coordinate system, and estimated system disturbance variables are input into a model-free sliding mode controller to obtain a reference value of the q-axis current value in a two-phase synchronous rotating coordinate system, including:

[0017] Calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula:

[0018]

[0019] Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;wd is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

[0020] In a second aspect, the present invention provides a stepping motor model-free sliding mode speed control system based on an improved power reaching law, comprising:

[0021] The first acquisition module is used to acquire the rotation speed and two-phase current of the stepper motor;

[0022] A conversion module is used to obtain the current of the stepper motor in a dq synchronous rotating coordinate system by Park transformation of the two-phase current;

[0023] The first input module is used to input the speed of the stepper motor and the current in the dq synchronous rotating coordinate system into the sliding mode disturbance observer to obtain an estimated system disturbance;

[0024] The second input module is used to input the desired reference speed of the stepper motor, the actual speed, the current in the dq synchronous rotating coordinate system and the estimated system disturbance variable into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system;

[0025] The second acquisition module is used to obtain a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system;

[0026] The third input module is used to input the q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system into the current loop controller and then perform inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to achieve speed control of the stepper motor.

[0027] Optionally, the first input module includes:

[0028] The first calculation unit is used to calculate the estimated system disturbance according to the following formula:

[0029]

[0030] in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

[0031] Optionally, the second input module includes:

[0032] The second calculation unit is used to calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula:

[0033]

[0034] Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;w d is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

[0035] In a third aspect, the present invention provides a computer device comprising a processor and a memory; wherein, when the processor executes a computer program stored in the memory, it implements the steps of the model-free sliding mode speed control method for a stepper motor based on an improved power reaching law as described in the first aspect.

[0036] In a fourth aspect, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the model-free sliding mode speed control method for a stepper motor based on an improved power reaching law as described in the first aspect are implemented.

[0037] In a fifth aspect, the present invention provides a computer program product, comprising computer executable instructions or a computer program. When the computer executable instructions or the computer program are executed by a processor, the steps of the model-free sliding mode speed control method of a stepper motor based on the improved power reaching law as described in the first aspect are implemented.

[0038] The present invention provides a model-free sliding mode speed control method and system for a stepping motor based on an improved power reaching law. In the method, in order to weaken the chattering problem of sliding mode control, an improved reaching law method is adopted to improve the power reaching law, and the reaching rate is adaptively adjusted in combination with the system state variables. In order to reduce the controller's dependence on the system model, the sliding mode control is combined with the model-free theory, and a disturbance observer is adopted to estimate the unknown quantities of the system, which ultimately speeds up the response time of the system and improves the dynamic performance and robustness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A schematic flow chart of a method for model-free sliding mode speed control of a stepping motor based on an improved power reaching law provided by an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the structure of a control system provided by an embodiment of the present invention;

[0042] Figure 3 A speed tracking curve diagram under speed change conditions provided by an embodiment of the present invention;

[0043] Figure 4 A speed tracking curve diagram under load mutation conditions provided by an embodiment of the present invention;

[0044] Figure 5 A controller output curve diagram provided by an embodiment of the present invention;

[0045] Figure 6 A schematic structural diagram of a model-free sliding mode speed control system for a stepping motor based on an improved power reaching law provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, this embodiment provides a model-free sliding mode speed control method for a stepping motor based on an improved power reaching law, comprising:

[0049] Step 101, obtaining the rotation speed and two-phase current of the stepper motor.

[0050] The rotating transformer is used to detect the speed and position information of the stepper motor during operation, and the actual speed and position of the motor are obtained after decoding. The two-phase current of the stepper motor is collected through the Hall current sensor.

[0051] Step 102, the two-phase currents are subjected to Park transformation to obtain the current of the stepper motor in a dq synchronous rotating coordinate system.

[0052] The obtained two-phase current and the detected motor position are transformed into coordinates, and the current i of the stepper motor in the two-phase synchronous rotating coordinate system is obtained according to the principle of two-phase stationary coordinate transformation to two-phase synchronous rotating coordinate transformation. d and i q .

[0053] The mathematical model of the two-phase stepper motor in the dq synchronous rotating coordinate system is as follows:

[0054]

[0055] Among them, U d and U q are d-axis voltage and q-axis voltage respectively; L d and L q The d-axis inductance and q-axis inductance are respectively; w e is the electrical angular velocity of the stepper motor rotor; R s is the stator resistance of the stepper motor; M sr is the stator-rotor mutual inductance coefficient; I mis the excitation equivalent current; T e is the output electromagnetic torque; N r is the number of rotor teeth; J is the moment of inertia; w is the mechanical angular velocity; T L is the load torque; B is the viscous friction coefficient.

[0056] Step 103: input the rotation speed of the stepper motor and the current in the dq synchronous rotating coordinate system into a sliding mode disturbance observer to obtain an estimated system disturbance.

[0057] Exemplarily, the estimated system disturbance is calculated according to the following formula:

[0058]

[0059] in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

[0060] Step 104 , input the desired reference speed of the stepper motor, the actual speed, the current in the dq synchronous rotating coordinate system and the estimated system disturbance variable into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system.

[0061] Combining the mathematical model of the two-phase stepper motor and considering the influence of load disturbance and motor parameter perturbation in actual working conditions, the state equation of the stepper motor speed loop can be expressed as:

[0062]

[0063] Among them, Δδ1, Δδ2 and Δδ3 all represent the parameter change values ​​during the operation of the stepper motor; f represents the disturbance caused by the load and parameter perturbation;

[0064] Constructing a local model of the speed loop in a two-phase stepper motor control system:

[0065]

[0066] Among them, α w is the current gain; β w is the speed gain.

[0067] A model-free sliding mode controller based on the improved power reaching law is designed for the speed loop. The state error of the model-free sliding mode controller is e=w d -w; Improve the power approach law for

[0068] Calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula:

[0069]

[0070] Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;w d is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

[0071] To verify the stability of the system, construct the Lyapunov function The derivative is:

[0072]

[0073] in, According to Lyapunov stability theory, the sliding mode controller designed in this embodiment is asymptotically stable.

[0074] Step 105, obtaining a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system.

[0075] Step 106, inputting the q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system into the current loop controller and performing inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to achieve speed control of the stepper motor.

[0076] In order to verify the effectiveness of the stepper motor model-free sliding mode speed control method provided in this embodiment, the following is established: Figure 2 The system simulation model shown in the figure gives the basic parameters of the system: two-phase winding coil resistance R = 0.38Ω; two-phase winding coil resistance L = 1.75mh; stepper motor rotor tooth pair number N r =50; moment of inertia J = 480 g·cm 2 ; Rotor flux The method described in this embodiment (IPMFSMC) is compared with the PI controller and the traditional model-free sliding mode control (MFSMC) for simulation.

[0077] Case 1: Set the initial motor speed to 300rpm, add a load of 0.05N·m at 0.3s, and then suddenly change to 0N·m at 0.6s. The simulation waveform is as follows: Figure 3 shown.

[0078] Case 2: Set the initial motor speed to 300rpm, then suddenly increase to 400rpm at 0.3s, and suddenly increase to 200rpm at 0.6s. The simulation waveform is as follows: Figure 4 shown.

[0079] Case 3: Set the motor speed to 300rpm, the output simulation waveforms of different speed controllers are as follows: Figure 5 shown.

[0080] From the simulation results, we can see that:

[0081] In case 1, the motor controlled by PI has overshoot in the startup phase, while the motors controlled by MFSMC and IPMFSMC have no obvious overshoot, and the IPMFSMC method can reach the given speed faster. When the load changes suddenly, the speed fluctuation of PI control is large, while the speed fluctuation of MFSMC and IPMFSMC methods is significantly smaller, and the speed fluctuation of IPMFSMC is the smallest and the adjustment time is the shortest. The above analysis shows that the IPMFSMC method has better dynamic performance and stronger robustness.

[0082] In case 2, when the speed changes suddenly, the motor speed controlled by the IPMFSMC method responds faster and can still achieve tracking without overshoot.

[0083] In case 3, the output jitter amplitude of the IPMFSMC controller is significantly lower than that of the MFSMC controller, indicating that the IPMFSMC method can effectively suppress the sliding mode chattering.

[0084] In summary, the model-free sliding mode speed control method for a stepper motor based on the improved power reaching law provided in this embodiment adopts the method of improving the reaching law to weaken the chattering problem of the sliding mode control, improves the power reaching law, and realizes adaptive adjustment of the reaching rate by combining the system state variables; in order to reduce the controller's dependence on the system model, the sliding mode control is combined with the model-free theory, and the disturbance observer is used to estimate the unknown quantities of the system, which ultimately speeds up the response time of the system and improves the dynamic performance and robustness of the system.

[0085] Example 2

[0086] Based on the same inventive concept as Example 1, this embodiment provides a model-free sliding mode speed control system for a stepper motor based on an improved power reaching law. Since the principle of solving the problem by this system is similar to the aforementioned model-free sliding mode speed control method for a stepper motor based on an improved power reaching law, the implementation of this system can refer to the implementation of the model-free sliding mode speed control method for a stepper motor based on an improved power reaching law.

[0087] like Figure 6 As shown, the stepper motor model-free sliding mode speed control system based on the improved power reaching law includes:

[0088] The first acquisition module 10 is used to acquire the rotation speed and two-phase current of the stepper motor.

[0089] The conversion module 20 is used to obtain the current of the stepping motor in the dq synchronous rotating coordinate system by Park transformation of the two-phase current.

[0090] The first input module 30 is used to input the rotation speed of the stepper motor and the current in the dq synchronous rotating coordinate system into the sliding mode disturbance observer to obtain an estimated system disturbance.

[0091] The second input module 40 is used to input the desired reference speed, actual speed, current in the dq synchronous rotating coordinate system and estimated system disturbance variables of the stepper motor into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system.

[0092] The second acquisition module 50 is used to acquire a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system.

[0093] The third input module 60 is used to input the q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system into the current loop controller and then perform inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to achieve speed control of the stepper motor.

[0094] Exemplarily, the first input module includes:

[0095] The first calculation unit is used to calculate the estimated system disturbance according to the following formula:

[0096]

[0097] in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

[0098] Exemplarily, the second input module includes:

[0099] The second calculation unit is used to calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula:

[0100]

[0101] Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;w d is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

[0102] For more specific working processes of the above modules, please refer to the corresponding contents disclosed in Example 1, which will not be repeated here.

[0103] Example 3

[0104] This embodiment provides a computer device, including a processor and a memory; wherein, when the processor executes the computer program stored in the memory, the steps of the model-free sliding mode speed control method for a stepping motor based on an improved power reaching law described in Embodiment 1 are implemented.

[0105] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 1, which will not be repeated here.

[0106] Example 4

[0107] This embodiment provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the model-free sliding mode speed control method for a stepping motor based on an improved power reaching law described in Embodiment 1 are implemented.

[0108] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 1, which will not be repeated here.

[0109] Example 5

[0110] This embodiment provides a computer program product, including computer executable instructions or a computer program. When the computer executable instructions or the computer program are executed by a processor, the steps of the model-free sliding mode speed control method for a stepper motor based on an improved power reaching law described in Embodiment 1 are implemented.

[0111] For more specific details of the above method, please refer to the corresponding contents disclosed in Example 1, which will not be repeated here.

[0112] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the systems, devices, storage media, and computer program products disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0113] Those skilled in the art can clearly understand that the technology in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution in the embodiments of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention or some parts of the embodiments.

[0114] In some embodiments, computer executable instructions may be in the form of a program, software, software module, script or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine or other unit suitable for use in a computing environment.

[0115] As an example, computer-executable instructions may, but need not, correspond to a file in a file system, may be stored as part of a file that stores other programs or data, such as in one or more scripts in a HyperText Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files storing one or more modules, subroutines, or code portions).

[0116] As an example, computer executable instructions may be deployed to be executed on one electronic device, or on multiple electronic devices located at one site, or on multiple electronic devices distributed at multiple sites and interconnected by a communication network.

[0117] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A model-free sliding mode speed control method for a stepping motor based on an improved power reaching law, characterized in that: include: Get the speed and two-phase current of the stepper motor; The two-phase current is transformed by Park to obtain the current of the stepper motor in the dq synchronous rotating coordinate system; The speed of the stepper motor and the current in the dq synchronous rotating coordinate system are input into the sliding mode disturbance observer to obtain the estimated system disturbance; The desired reference speed, actual speed, current in the dq synchronous rotating coordinate system and estimated system disturbance variables of the stepper motor are input into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system; Obtain a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system; The q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system are input into the current loop controller and then subjected to inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to realize the speed control of the stepper motor.

2. The stepping motor model-free sliding mode speed control method according to claim 1, characterized in that: The speed of the stepper motor and the current in the dq synchronous rotating coordinate system are input into the sliding mode disturbance observer to obtain an estimated system disturbance, including: The estimated system disturbance is calculated according to the following formula: in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

3. The stepping motor model-free sliding mode speed control method according to claim 1, characterized in that: The stepper motor's desired reference speed, actual speed, current in the dq synchronous rotating coordinate system, and estimated system disturbance variables are input into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system, including: Calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula: Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;w d is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

4. A model-free sliding mode speed control system for a stepping motor based on an improved power reaching law, characterized in that: include: The first acquisition module is used to acquire the rotation speed and two-phase current of the stepper motor; A conversion module is used to obtain the current of the stepper motor in a dq synchronous rotating coordinate system by Park transformation of the two-phase current; The first input module is used to input the speed of the stepper motor and the current in the dq synchronous rotating coordinate system into the sliding mode disturbance observer to obtain an estimated system disturbance; The second input module is used to input the desired reference speed of the stepper motor, the actual speed, the current in the dq synchronous rotating coordinate system and the estimated system disturbance variable into the model-free sliding mode controller to obtain a reference value of the q-axis current value in the two-phase synchronous rotating coordinate system; The second acquisition module is used to obtain a reference value of the d-axis current value in a two-phase synchronous rotating coordinate system; The third input module is used to input the q-axis current value reference value and the d-axis current value reference value in the two-phase synchronous rotating coordinate system into the current loop controller and then perform inverse Park transformation to obtain the voltage of the stepper motor in the two-phase stationary coordinate system to achieve speed control of the stepper motor.

5. The stepping motor model-free sliding mode speed control system according to claim 4, characterized in that: The first input module comprises: The first calculation unit is used to calculate the estimated system disturbance according to the following formula: in, is the estimated system disturbance f w The derivative of; h is the gain of the sliding mode disturbance observer; u smo is the sliding mode control law; β w is the speed gain; s1 is the first sliding surface, is the estimated value of the mechanical angular velocity w of the stepper motor; and are the gains of the sliding mode disturbance observer to be designed; sgn(·) is the sign function; t is the time.

6. The stepper motor model-free sliding mode speed control system according to claim 4, characterized in that: The second input module comprises: The second calculation unit is used to calculate the reference value of the q-axis current value in the two-phase synchronous rotating coordinate system according to the following formula: Among them, α w is the current gain; β w is the speed gain; k1 is the first parameter to be set for the reaching law, k1>0; sgn(·) is the sign function; s2 is the second sliding surface, s2=e+c∫edt; e is the state error of the model-free sliding mode controller, e=w d -w;w d is the preset speed; c is the preset coefficient; w is the mechanical angular velocity of the stepper motor; k2 is the second parameter of the reaching law to be set, k2>0; μ is the third parameter of the reaching law to be set, μ>1; k is the fourth parameter of the reaching law to be set, k>0; is the speed loop super local model; β w is the speed gain; is the estimated system disturbance; λ is the fifth parameter of the reaching law to be set, 0<λ<1; γ is the sixth parameter of the reaching law to be set, γ>0; ε is the sixth parameter of the reaching law to be set, 0<ε<1; tanh(·) is the hyperbolic tangent function; σ is the seventh parameter of the reaching law to be set, σ>0; x is the system state variable; t is the time; i q is the q-axis current; f w is the estimated system disturbance; f w Observed value of .

7. A computer device, characterized in that: It comprises a processor and a memory; wherein, when the processor executes the computer program stored in the memory, it implements the steps of the model-free sliding mode speed control method of a stepping motor based on an improved power reaching law as described in any one of claims 1 to 3.

8. A computer-readable storage medium, characterized in that: Used to store computer programs; when the computer programs are executed by the processor, the steps of the model-free sliding mode speed control method for a stepping motor based on an improved power reaching law as described in any one of claims 1 to 3 are implemented.

9. A computer program product, characterized in that It includes computer executable instructions or computer programs. When the computer executable instructions or computer programs are executed by a processor, the steps of the model-free sliding mode speed control method of a stepping motor based on an improved power reaching law as described in any one of claims 1 to 3 are implemented.

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