Permanent magnet linear motor sensorless speed control system based on double sliding mode structure

Abstract

The application relates to the technical field of permanent magnet linear synchronous motor control, and discloses a permanent magnet linear motor position sensorless speed control system based on a double sliding mode structure, wherein a sliding mode speed controller is adopted in a speed loop, and a cross-axis current given value is output based on a motor linear speed error; a feedback compensation loop comprises a high-order sliding mode observer and a linear speed conversion module; the high-order sliding mode observer performs online estimation based on measured voltage and measured current, calculates an electric angle estimation value and an electric angular velocity estimation value, and then converts the linear speed estimation value through the linear speed conversion module; and a current loop generates a driving signal for controlling the operation of the permanent magnet linear synchronous motor according to the cross-axis current given value and the electric angle estimation value. The application utilizes the double sliding mode structure, effectively reduces the chattering influence, improves the speed and position estimation accuracy, enhances the dynamic response and anti-disturbance robustness of the system, and solves the technical problems of low estimation accuracy and traditional sliding mode chattering in the position sensorless control.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet linear synchronous motor control technology, specifically relating to a sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure. Background Technology

[0002] Permanent magnet linear synchronous motors (PMSMs) possess advantages such as simple structure, high thrust density, fast dynamic response, high transmission efficiency, and high positioning accuracy, making them widely used in high-performance servo drives, CNC equipment, precision positioning platforms, semiconductor manufacturing equipment, and industrial automation production lines. As the requirements for operational accuracy, dynamic response speed, and disturbance rejection capabilities in high-performance motion control systems continue to increase, high-performance control technology for PMSMs is receiving increasing attention.

[0003] Existing permanent magnet linear synchronous motor control systems mostly employ position sensors to acquire mover position information, then combine this with vector control to achieve closed-loop operation. While this method offers high control accuracy, position sensors increase system hardware cost, size, and wiring complexity. Furthermore, under complex operating conditions such as high temperature, strong vibration, and electromagnetic interference, sensors are susceptible to environmental influences, reducing system reliability and engineering adaptability. Therefore, sensorless control methods have significant research and application value.

[0004] In sensorless control, online estimation of the mover position and velocity is typically required based on measurable signals such as motor terminal voltage and current. Traditional observation methods are prone to increased estimation errors, decreased dynamic performance, and insufficient robustness under low-speed operation, parameter perturbations, and load disturbances. While traditional sliding mode observers are robust, they exhibit high-frequency chattering after the system state reaches the sliding surface, leading to a decrease in back EMF and position estimation accuracy. In traditional control, the PMLSM speed loop often uses a PI controller. This method is highly reliable, simple in structure, and easy to implement, and can meet the control requirements of most situations to a certain extent. However, PI controllers often suffer from overshoot, and when the system is affected by uncertainties such as load disturbances and parameter changes, traditional PI control is insufficient to meet high-performance control requirements. Sliding mode variable structure control overcomes the dependence on models and the complex identification issues of traditional control methods through simple and unique nonlinear switching control, achieving strong robustness of the control system. Its essence is similar to achieving a high-stiffness, high-response linear servo system by using a simple direct drive method to overcome the limitations and defects of traditional indirect drive. Sliding mode variable structure control has a simple structure and strong robustness to external disturbances and parameter perturbations. By switching the control action to the sliding mode guaranteed by the maximum acceleration or maximum deceleration, the system can obtain high response and high acceleration control performance, making it very suitable for linear motor servo systems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure, so as to realize the operation control of the permanent magnet motor by adopting a sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure.

[0006] To solve the above-mentioned technical problems, the present invention provides a sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure, comprising: a speed loop, a feedback compensation loop, and a current loop;

[0007] The speed loop employs a sliding mode speed controller, which outputs a quadrature-axis current setpoint based on the speed error between the given value and the estimated value of the motor linear velocity.

[0008] The feedback compensation loop includes a high-order sliding mode observer and a linear velocity conversion module. The high-order sliding mode observer performs online estimation of the measured voltage and measured current in the two-phase stationary coordinate system, calculates and outputs the electrical angle estimate and electrical angular velocity estimate. Then, the linear velocity conversion module converts the electrical angular velocity estimate into the linear velocity estimate.

[0009] The current loop generates a drive signal to control the operation of the permanent magnet linear synchronous motor based on the given cross-axis current, the estimated electrical angle, and the measured current.

[0010] As an improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0011] The sliding mode speed controller includes a sliding mode surface construction module, and the sliding mode surface s constructed by the sliding mode surface construction module is:

[0012]

[0013] in, The sliding surface coefficient, As the first state variable, It is the second state variable;

[0014]

[0015] in, This is an estimate of the linear velocity. The given value for the linear velocity of the motor;

[0016] Then, the quadrature-axis current setpoint is calculated using the sliding mode control law module. The method is as follows:

[0017]

[0018] Where D is the control gain coefficient. and Here, B is the sliding mode control parameter, and B is the viscosity coefficient. It is the sum of the mass of the mover and the mass of the load. It is a symbolic function.

[0019] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0020] The higher-order sliding mode observer includes a current state observation module, a higher-order sliding mode injection module, a back EMF estimation module, and a phase-locked loop module. The higher-order sliding mode injection term output by the higher-order sliding mode injection module and the measured voltage in the two-phase stationary coordinate system are used by the current state observation module to output a current estimate. The current estimate and the measured current in the two-phase stationary coordinate system are used by the higher-order sliding mode injection module to calculate and output a higher-order sliding mode injection term. The higher-order sliding mode injection term is used by the back EMF estimation module and the phase-locked loop module to calculate and output an electrical angle estimate and an electrical angular velocity estimate.

[0021] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0022] The measured voltage in the two-phase stationary coordinate system includes shaft voltage and shaft voltage The higher-order sliding mode injection term includes a first higher-order sliding mode injection term. Second higher-order sliding mode injection term ;

[0023] The calculation method of the current state observation module is as follows:

[0024]

[0025] in: , They are respectively , , They are respectively The rate of change of the shaft current estimate over time and The rate of change of the estimated shaft current over time, where R is the phase resistance of the motor. For motor phase inductance, It is a permanent magnet flux linkage.

[0026] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0027] Measured currents in a two-phase stationary coordinate system include shaft current and shaft current ;

[0028] The calculation method for the high-order sliding mode injection module is as follows:

[0029]

[0030] in, , These represent the first and second auxiliary integration states of the superspiral algorithm, respectively; k 11 k 12 k 21 and k 22 These are the gain coefficients of the first observer, the second observer, the third observer, and the fourth observer, respectively.

[0031] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0032] The calculation method of the back electromotive force estimation module is as follows:

[0033]

[0034] in, , They are respectively Shaft back electromotive force estimate and Estimated back electromotive force of the shaft.

[0035] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0036] The calculation method of the linear velocity conversion module is as follows:

[0037]

[0038] in, This is an estimated value for the electric angular velocity. This represents the polar distance.

[0039] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0040] The current loop includes a Clark transformation module, which transforms the motor stator current in the three-phase coordinate system into... shaft current and shaft current Then, together with the electrical angle estimate, it is processed by the Park transformation module to obtain the quadrature-axis current. and direct-axis current ;

[0041] quadrature axis current With cross-axis current setpoint After subtraction, the quadrature-axis voltage command is obtained by inputting it into the q-axis PI controller. Direct-axis current With direct-axis current setpoint After subtraction, the direct-axis voltage command is obtained by inputting it into the d-axis PI controller. ;

[0042] Cross-axis voltage command Direct-axis voltage command The electrical angle estimate is output along with the inverse Park transform module. shaft voltage and shaft voltage The PWM signal is then output by the vector control module as the input of the three-phase inverter, which in turn controls the operation of the permanent magnet linear synchronous motor.

[0043] As a further improvement to the sensorless speed control system for permanent magnet linear motors based on a dual sliding mode structure of the present invention:

[0044] The control algorithm of the q-axis PI controller is as follows:

[0045]

[0046] The control algorithm of the d-axis PI controller is as follows:

[0047]

[0048] in, , , , They are respectively Shaft current loop proportionality factor, Integral coefficient of shaft current loop, Shaft current loop proportionality coefficient and Integral coefficient of shaft current loop.

[0049] The beneficial effects of this invention are mainly reflected in:

[0050] Traditional sensorless speed control methods for permanent magnet linear synchronous motors mostly employ a control structure combining a conventional observer and a PI speed regulator. This type of method is prone to problems such as decreased position and speed estimation accuracy, slow dynamic response, and insufficient disturbance rejection under parameter perturbations, external load disturbances, and low-speed operation conditions, making it difficult to balance the system's speed, stability, and robustness. Compared with traditional sensorless speed control systems, the control method proposed in this invention, based on a high-order sliding mode observer and sliding mode speed controller, can achieve online estimation of the position and speed information of the permanent magnet linear synchronous motor without using mechanical position sensors, and improves the system's dynamic response performance and disturbance rejection capability. Its advantages are as follows:

[0051] 1. A high-order sliding mode observer is used to estimate the position and speed of the motor. By introducing an auxiliary integral state to continuously adjust the sliding mode control quantity, the chattering effect in traditional sliding mode observation can be reduced, and the accuracy of position and speed estimation can be improved.

[0052] 2. The sliding mode speed control strategy is used to generate the quadrature axis current setpoint, which can improve the system response speed, reduce overshoot, and enhance the system's robustness to parameter changes and load disturbances. Experiments show that when a sudden load disturbance is applied, the error of this system is extremely small and it can quickly recover to steady state in milliseconds (0.035s).

[0053] 3. Achieving closed-loop speed control of a permanent magnet linear synchronous motor without mechanical position sensors reduces system hardware costs and structural complexity, and has good engineering application value. Attached Figure Description

[0054] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0055] Figure 1 This is a structural block diagram of the sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure, according to the present invention.

[0056] Figure 2 This is a structural block diagram of the high-order sliding mode observer and linear velocity conversion module of the present invention;

[0057] Figure 3 This is a block diagram illustrating the principle of a sliding mode speed controller.

[0058] Figure 4 The linear velocity response curves are given under conditions of linear velocity variation and sudden load disturbance.

[0059] Figure 5 The waveform diagram shows the linear velocity estimation error under given linear velocity variation and sudden load disturbance conditions. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0061] Example 1: A sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure, comprising three parts: a speed loop, a current loop, and a feedback compensation loop. The speed loop employs a sliding mode speed controller; the current loop includes a current loop PI controller, an inverse Park transform module, a vector control module, a three-phase inverter, a Clark transform module, and a Park transform module; the feedback compensation loop includes a high-order sliding mode observer and a linear velocity conversion module.

[0062] In this embodiment, the controlled object is a permanent magnet linear synchronous motor, and its main parameters are as follows: motor phase resistance R = 9.6.

[0063] Motor phase inductance polar distance polar number The sum of the mass of the mover and the load back potential constant =102.5 V / (m·s -1 Electromagnetic thrust constant The above parameters are used to establish the voltage equation, mechanical motion equation, and electromagnetic thrust equation of the permanent magnet linear synchronous motor, and serve as the basic parameters for the design of the sliding mode speed controller and the high-order sliding mode observer.

[0064] The sensorless speed control system of the present invention relies on a microprocessor (such as a DSP digital signal processor, MCU or FPGA chip) to execute all its control and observation algorithms (including high-order sliding mode observer, sliding mode speed controller, coordinate transformation, etc.). The microprocessor collects the phase current of the permanent magnet linear motor through an A / D sampling circuit connected to a Hall current sensor, and outputs a PWM signal through a drive circuit connected to a three-phase inverter to realize the fully closed-loop sensorless control of the motor.

[0065] The block diagram of sensorless speed control for a permanent magnet linear motor based on a dual sliding mode structure is shown below. Figure 1 As shown, the details are as follows:

[0066] 1. Use direct-axis current setpoint Magnetic field orientation control methods. In the coordinate system, the electromagnetic thrust equation of the permanent magnet linear synchronous motor can be expressed as:

[0067] (1)

[0068] in: Electromagnetic thrust, It is the electromagnetic thrust constant. For extreme logarithms, For polar distance, This is the flux linkage of the permanent magnet. Therefore, the given value of the quadrature-axis current output from the velocity loop can be determined. It can achieve effective control of the thrust of permanent magnet linear motor.

[0069] 2. The sliding speed controller includes a sliding surface construction module and a sliding control law module, such as... Figure 3 As shown. The sliding surface construction module constructs the sliding surface based on the obtained speed error signal, and the sliding control law module constructs the sliding speed control law based on the motor mechanical equations and sliding control design principles, outputting the quadrature-axis current setpoint. .

[0070] Motor linear velocity setpoint The linear velocity estimate of the motor mover output by the higher-order sliding mode observer By comparison, the speed error is obtained. As input to the sliding mode speed controller:

[0071] (2)

[0072] Define the first state variable Second state variable :

[0073] (3)

[0074] in, This is an estimate of the linear velocity. First state variable The first derivative.

[0075] In this embodiment, the sliding surface is defined as:

[0076] (4)

[0077] in, The sliding surface coefficient is set to in this embodiment. .

[0078] Based on the mechanical equations of the motor and the exponential reaching law, a sliding mode speed control law is derived using the sliding surface to calculate the quadrature-axis current setpoint:

[0079] (5)

[0080] Where D is the control gain coefficient. and These are sliding mode control parameters, and and In this embodiment, it is set to... and B is the viscosity coefficient, which is set to 0.001 in this embodiment. For symbolic functions, the definition is:

[0081] (6)

[0082] 3. The current loop PI controller includes a q-axis PI controller and a d-axis PI controller. The quadrature-axis current output by the Park transform module... With cross-axis current setpoint Comparison to obtain quadrature axis current error ( The quadrature-axis current error is processed by the q-axis PI controller to generate a quadrature-axis voltage command. The direct-axis current output by the Park converter module. With direct-axis current setpoint The direct-axis current error was obtained by comparison. The direct-axis current error is processed by the d-axis PI controller to generate a direct-axis voltage command. In this embodiment, the permanent magnet linear synchronous motor adopts vector control, and the direct-axis current setpoint is set as follows: .

[0083] The control algorithm of the q-axis PI controller is as follows:

[0084] (7-1)

[0085] The control algorithm of the d-axis PI controller is as follows:

[0086] (7-2)

[0087] in, , , , They are respectively Shaft current loop proportionality factor, Integral coefficient of shaft current loop, Shaft current loop proportionality coefficient and The integral coefficient of the shaft current loop is preferably, in this embodiment, [missing information]. , .

[0088] 4. Quadrature axis voltage command and direct axis voltage command The output after the inverse Park transformation module is in two-phase stationary coordinate systems. shaft voltage and shaft voltage The vector control module is based on shaft voltage and shaft voltage The system outputs six PWM signals with corresponding pulse widths as inputs to the three-phase inverter. The PWM signals control the switching of the three-phase inverter transistors, thereby controlling the operation of the permanent magnet linear synchronous motor.

[0089] 5. Obtain the stator current of the permanent magnet linear motor in the three-phase coordinate system by acquiring current signals using a Hall current sensor. , and Motor stator current , and Obtained via Clark Transformation Module shaft current and shaft current ,Then shaft current and shaft current With electrical angle estimate The quadrature-axis current is obtained by passing the Park transformation module together. and direct-axis current and the quadrature axis current and direct-axis current Feedback is sent to the q-axis PI controller and the d-axis PI controller to achieve closed-loop control.

[0090] The Park conversion module, vector control module, three-phase inverter, Clark conversion module, and inverse Park conversion module involved in this invention are all existing technologies in traditional permanent magnet synchronous motor servo control systems. This is a concise textual description of the invention, and the specific implementation structure and principle will not be described further.

[0091] 6. The high-order sliding mode observer includes a current state observation module, a high-order sliding mode injection module, a back EMF estimation module, and a phase-locked loop module. It is based on the measured voltage in the two-phase stationary coordinate system output by the inverse Park transformation module. shaft voltage and shaft voltage ), the measured current in the two-phase stationary coordinate system output by the Clark transformation module ( shaft current and shaft current ), calculate and output the electrical angle estimate. and estimated electric angular velocity ,like Figure 2 As shown, the details are as follows:

[0092] 6.1 Current State Observation Module

[0093] The current state observation module receives data in a two-phase stationary coordinate system. shaft voltage and shaft voltage Simultaneously, it receives the first higher-order sliding mode injection item fed back from the higher-order sliding mode injection module. Second higher-order sliding mode injection term Calculate and output the two-phase stationary coordinate system. shaft current estimate and shaft current estimate .

[0094] The current state observation module is designed as follows:

[0095] (8)

[0096] in: , They are respectively , and They are respectively The rate of change of the shaft current estimate over time and Rate of change of the shaft current estimate over time.

[0097] 6.2 Advanced Sliding Mode Injection Module

[0098] Will With Clark Transform Module Output shaft current and shaft current By comparing and subtracting, the current error signal is obtained. ), ( The data is fed into the higher-order sliding mode injection module; the higher-order sliding mode injection module calculates and outputs the higher-order sliding mode injection term based on the superspiral sliding mode control law, which is as follows:

[0099] (9)

[0100] in: , These represent the first and second auxiliary integration states of the superspiral algorithm, respectively; k 11 k 12 k 21 and k 22 These are the gain coefficients of the first observer, the second observer, the third observer, and the fourth observer, respectively. In this embodiment, k is preferred. 11 =k 21 =50,k 12 =k22 =25000.

[0101] , The feedback is sent to the current state observation module to form a closed loop, and at the same time, it is output to the next-level back EMF estimation module.

[0102] 6.3 Back EMF Estimation Module

[0103] The back EMF estimation module receives the first higher-order sliding mode injection term after the sliding surface has reached a stable state. Second higher-order sliding mode injection term Extracted Shaft back electromotive force estimate and Shaft back electromotive force estimate :

[0104] (10)

[0105] 6.4 Phase-Locked Loop Module

[0106] back electromotive force estimate , The input phase-locked loop (PLL) module performs phase tracking on the input signal and outputs an electrical angle estimate. (This value is fed back to the Park transform module and the inverse Park transform module) and the estimated electric angular velocity. .

[0107] 7. Linear velocity conversion module

[0108] Electric angular velocity of motor With linear velocity The following conditions must be met:

[0109] (11)

[0110] Based on the conversion relationship between the electric angular velocity and linear velocity of the motor, the estimated value of the linear velocity of the permanent magnet linear synchronous motor is obtained:

[0111] (12)

[0112] This enables online estimation of the position and speed of a permanent magnet linear synchronous motor without the need for mechanical position sensors, and provides feedback signals for speed closed-loop control.

[0113] experiment:

[0114] To verify the effectiveness of the sensorless speed control system for permanent magnet linear synchronous motors based on a high-order sliding mode observer according to the present invention, verification was conducted on a permanent magnet linear synchronous motor experimental platform. The experimental platform included: a host computer, a three-phase inverter, a servo controller, a power supply, a permanent magnet linear synchronous motor, a speed sensor, and a thrust sensor; the test power supply was AC 380V at a frequency of 50Hz. After the host computer issued commands, the servo controller, with a DSP as its core, executed the sensorless speed control method for permanent magnet linear synchronous motors based on a high-order sliding mode observer according to Embodiment 1 of the present invention, accurately calculated the PWM signal, and drove the three-phase inverter to control the permanent magnet linear synchronous motor. Data throughout the process could be monitored and recorded in real time by the host computer.

[0115] The system initially operates in a closed-loop configuration at 50 mm / s. The speed command begins to increase linearly at 0.2 s, reaching 80 mm / s at 0.4 s, and a 50 N load disturbance is applied at 0.5 s. (See attached diagram) Figure 4 and attached Figure 5 The velocity response curves and velocity estimation error waveforms under varying linear velocity conditions are presented respectively. It should be noted that... Figure 4 The target value is equivalent to the given value of the motor linear velocity proposed in Example 1. The estimated speed is equivalent to the estimated linear velocity of the motor mover proposed in Example 1. The actual speed is measured by a high-precision optical grating ruler (or magnetic grating ruler). This actual speed signal is only used for comparison and verification and does not participate in the closed-loop control of the system.

[0116] From the appendix Figure 4 and attached Figure 5 It can be seen that the motor starts at a speed of 50 mm / s. When the target speed is 50 mm / s, the error between the estimated speed of the high-order sliding mode observer and the actual speed of the motor is 0.05 mm / s. When the target speed increases to 80 mm / s, the error between the estimated speed and the actual speed of the motor is 0.08 mm / s. During speed switching, the maximum speed estimation error is 0.2 mm / s. Under the condition of sudden load disturbance, the maximum speed estimation error is 0.3 mm / s, and the system recovers to the steady state of 80 mm / s after 0.035 s. The results show that the high-order sliding mode observer can achieve relatively accurate speed and position information estimation. Under the conditions of speed change and load disturbance, the high-order sliding mode observer can still maintain high estimation accuracy, indicating that it has good dynamic tracking performance and a certain degree of disturbance rejection capability.

[0117] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure, characterized in that: Includes speed loop, feedback compensation loop, and current loop; The speed loop employs a sliding mode speed controller, which outputs a quadrature-axis current setpoint based on the speed error between the given value and the estimated value of the motor linear velocity. The feedback compensation loop includes a high-order sliding mode observer and a linear velocity conversion module. The high-order sliding mode observer performs online estimation of the measured voltage and measured current in the two-phase stationary coordinate system, calculates and outputs the electrical angle estimate and electrical angular velocity estimate. Then, the linear velocity conversion module converts the electrical angular velocity estimate into the linear velocity estimate. The current loop generates a drive signal to control the operation of the permanent magnet linear synchronous motor based on the given cross-axis current, the estimated electrical angle, and the measured current.

2. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 1, characterized in that: The sliding mode speed controller includes a sliding mode surface construction module, and the sliding mode surface s constructed by the sliding mode surface construction module is: in, The sliding surface coefficient, As the first state variable, It is the second state variable; in, This is an estimate of the linear velocity. The given value for the linear velocity of the motor; Then, the quadrature-axis current setpoint is calculated using the sliding mode control law module. The method is as follows: Where D is the control gain coefficient. and Here, B is the sliding mode control parameter, and B is the viscosity coefficient. It is the sum of the mass of the mover and the mass of the load. It is a symbolic function.

3. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 2, characterized in that: The higher-order sliding mode observer includes a current state observation module, a higher-order sliding mode injection module, a back EMF estimation module, and a phase-locked loop module. The higher-order sliding mode injection term output by the higher-order sliding mode injection module and the measured voltage in the two-phase stationary coordinate system are used by the current state observation module to output a current estimate. The current estimate and the measured current in the two-phase stationary coordinate system are used by the higher-order sliding mode injection module to calculate and output a higher-order sliding mode injection term. The higher-order sliding mode injection term is used by the back EMF estimation module and the phase-locked loop module to calculate and output an electrical angle estimate and an electrical angular velocity estimate.

4. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 3, characterized in that: The measured voltage in the two-phase stationary coordinate system includes shaft voltage and shaft voltage The higher-order sliding mode injection term includes a first higher-order sliding mode injection term. Second higher-order sliding mode injection term ; The calculation method of the current state observation module is as follows: in: , They are respectively , , They are respectively The rate of change of the shaft current estimate over time and The rate of change of the estimated shaft current over time, where R is the phase resistance of the motor. For motor phase inductance, It is a permanent magnet flux linkage.

5. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 4, characterized in that: Measured currents in a two-phase stationary coordinate system include shaft current and shaft current ; The calculation method for the high-order sliding mode injection module is as follows: in, , These represent the first and second auxiliary integration states of the superspiral algorithm, respectively; k 11 k 12 k 21 and k 22 These are the gain coefficients of the first observer, the second observer, the third observer, and the fourth observer, respectively.

6. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 5, characterized in that: The calculation method of the back electromotive force estimation module is as follows: in, , They are respectively Shaft back electromotive force estimate and Estimated back electromotive force of the shaft.

7. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 6, characterized in that: The calculation method of the linear velocity conversion module is as follows: in, This is an estimated value for the electric angular velocity. This represents the polar distance.

8. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 7, characterized in that: The current loop includes a Clark transformation module, which transforms the motor stator current in the three-phase coordinate system into... shaft current and shaft current Then, together with the electrical angle estimate, it is processed by the Park transformation module to obtain the quadrature-axis current. and direct-axis current ; quadrature axis current With cross-axis current setpoint After subtraction, the quadrature-axis voltage command is obtained by inputting it into the q-axis PI controller. Direct-axis current With direct-axis current setpoint After subtraction, the direct-axis voltage command is obtained by inputting it into the d-axis PI controller. ; Cross-axis voltage command Direct-axis voltage command The electrical angle estimate is output along with the inverse Park transform module. shaft voltage and shaft voltage The PWM signal is then output by the vector control module as the input of the three-phase inverter, which in turn controls the operation of the permanent magnet linear synchronous motor.

9. The sensorless speed control system for a permanent magnet linear motor based on a dual sliding mode structure according to claim 8, characterized in that: The control algorithm of the q-axis PI controller is as follows: The control algorithm of the d-axis PI controller is as follows: in, , , , They are respectively Shaft current loop proportionality factor, Integral coefficient of shaft current loop, Shaft current loop proportionality coefficient and Integral coefficient of shaft current loop.

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