Ship electric propulsion motor double-sliding-mode control method, device and system

Abstract

The invention relates to a double-sliding-mode control method, device and system for a ship electric propulsion motor. The method comprises the following steps: acquiring a given rotating speed and an actual rotating speed of a permanent magnet synchronous motor; and based on the given rotating speed and the actual rotating speed of the permanent magnet synchronous motor, the ship electric propulsion motor is controlled through a pre-constructed double-sliding-mode control model. In order to solve the problems that a traditional current loop PI controller is sensitive to motor parameter changes and poor in robustness, a double-sliding-mode control strategy that sliding-mode control is adopted in a current inner loop on the basis that sliding-mode control is adopted in a rotating speed outer loop is provided, and meanwhile a variable exponential reaching law sliding-mode control algorithm is introduced to design a novel controller. And when the distance is far away from the sliding mode surface, the approaching speed is increased, and when the distance is close to the sliding mode surface, the switching band of the system is reduced. According to the method, a discontinuous sign function is replaced by a continuous and smooth hyperbolic tangent function, so that the overshoot of the system is reduced, the buffeting of the system is also reduced, and the response speed and robustness of the system are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of motor control technology, and in particular to a dual sliding mode control method, device and system for a ship electric propulsion motor. Background Art

[0002] Ship electric propulsion is a propulsion method that uses a propulsion motor to directly drive the propeller to rotate, thereby propelling the ship forward. In recent years, the trend of using permanent magnet synchronous motors (PMSM) as the main propulsion power device in ship electric propulsion systems has gradually increased due to its simple structure, high efficiency, low loss and strong reliability. However, as a nonlinear, time-varying, and strongly coupled complex system, the PMSM has uncertainty in the system model. If conventional PID control is used, although it can meet the control requirements within a certain accuracy range, it is very susceptible to external disturbances and changes in internal parameters due to its reliance on the accuracy of the system model, causing the system control to deviate from the expected target. Therefore, traditional control methods are difficult to meet the requirements of permanent magnet synchronous motors operating in a stable state.

[0003] In the permanent magnet synchronous motor vector control system, sliding mode variable structure control is usually applied to the outer speed loop, while the inner current loop adopts traditional PI control. Although it speeds up the system response and enhances the robustness of the system to a certain extent, so that the motor speed can reach the specified speed faster, the current loop has a strong A series of nonlinear factors such as shaft current coupling and back electromotive force depend on the parameters and working point of the motor. It is difficult to obtain high dynamic and stable current by using traditional PI control, and it is difficult to obtain accurate and fast output torque. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the deficiencies of the prior art and to provide a method, device and system for dual sliding mode control of a ship electric propulsion motor.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: Specifically, a dual sliding mode control method for a ship electric propulsion motor is proposed, including the following: Obtain the given speed and actual speed of the permanent magnet synchronous motor; The ship electric propulsion motor is controlled based on the given speed and actual speed of the permanent magnet synchronous motor through a pre-built double sliding mode control model; Specifically, the construction principle of the pre-built dual sliding mode control model is: The traditional permanent magnet synchronous motor vector control model is improved. Its speed outer loop continues to use the original sliding mode control, while the current inner loop adopts sliding mode variable structure control to replace the PI control in the traditional permanent magnet synchronous motor vector control model.

[0006] Further, in the specific pre-built dual sliding mode control model, the construction of the speed outer loop includes: Assume that the saturation of the motor core is ignored, the eddy current and hysteresis loss in the motor are ignored, and the current in the motor is a symmetrical three-phase sine wave current. Based on this, the motor is constructed The mathematical model in the coordinate system is: (1); in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the mechanical angular velocity of the motor; is the moment of inertia; is the damping coefficient; is the load torque; is the number of motor pole pairs; Considering the surface-mounted permanent magnet synchronous motor, there is In addition, using The vector control method is used, so formula (1) is rewritten as: (2); Define the state variable of the permanent magnet synchronous motor as the given speed of the permanent magnet synchronous motor The actual speed The speed error between , the following relationship exists: (3) Can be obtained, (4) Define the sliding surface of the speed outer ring is the integral sliding surface, that is: (5) Define the reaching law of the outer speed loop for: (6) in, , ; The sliding mode control law of the speed outer loop is: (12).

[0007] Furthermore, the approach law The stability is verified by Lyapunov function. Specifically, First, select the Lyapunov function: , when the formula satisfies When , it is considered that the sliding mode reaches the condition; The following formula is calculated: (7) It can be proved that the variable exponential reaching law satisfies the Lyapunov stability criterion and the system is asymptotic and stable.

[0008] Further, specifically, the calculation process of the sliding mode control law of the speed outer loop includes: Integral sliding surface The derivative is: (8) Combining equation (6) and equation (8), we get: (9) and , then the above formula can be expressed as: (10) (11) Then we can get: (12).

[0009] Further, in the specific pre-built dual sliding mode control model, the construction of the current inner loop includes: Building a permanent magnet synchronous motor The stator voltage equation in the coordinate system is: (13) in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the electrical angular velocity of the motor; , is the number of motor pole pairs, is the mechanical angular velocity of the motor; From formula (13), we can get: (14) Define the system state variables as: (15) In the formula, for The expected value of shaft current, It is calculated based on the outer loop of the speed, that is, the value calculated by formula (12) As The expected value of the shaft current is ; The current inner loop uses the same sliding mode surface as the speed outer loop sliding mode controller, so the sliding mode surface of the current inner loop is defined as: (16) The current inner loop adopts the same reaching law as the speed outer loop sliding mode controller, namely, equation (6); Then the sliding mode control law of the current inner loop is: (twenty four).

[0010] Furthermore, the sign function in the reaching law is Using the hyperbolic tangent function Instead, , The value determines how fast the inflection point of the hyperbolic tangent smooth function changes. The sliding mode control law of the updated speed outer loop is: (25) Update the current inner loop sliding mode control law as follows: (26).

[0011] The present invention also proposes a dual sliding mode control device for a ship electric propulsion motor, which applies the dual sliding mode control method for a ship electric propulsion motor, and comprises: A data acquisition module is used to obtain a given speed and an actual speed of the permanent magnet synchronous motor; A controller for controlling a ship electric propulsion motor based on a given speed and an actual speed of a permanent magnet synchronous motor through a pre-built double sliding mode control model.

[0012] The present invention also proposes a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the dual sliding mode control method for a ship electric propulsion motor are implemented.

[0013] The beneficial effects of the present invention are: The present invention proposes a dual sliding mode control method for a ship electric propulsion motor. First, a mathematical model is established for a permanent magnet synchronous motor, and a variable exponential reaching law speed loop vector control strategy for the permanent magnet synchronous motor is established. A sensor is used to obtain the rotor position and speed signals. Aiming at the problem that the traditional current loop PI controller is sensitive to changes in motor parameters and has weak robustness, a dual sliding mode control strategy is proposed in which sliding mode control is adopted in the current inner loop on the basis of sliding mode control in the outer speed loop. At the same time, a variable exponential reaching law sliding mode control algorithm is introduced to design a new controller. When the distance to the sliding mode surface is far, the approach speed is accelerated, and when the distance to the sliding mode surface is close, the switching band of the system is reduced, thereby reducing the jitter generated by the sliding mode control. Finally, a continuous and smooth hyperbolic tangent function is used to replace the discontinuous sign function, which reduces the overshoot of the system while also reducing the jitter of the system, thereby enhancing the response speed and robustness of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other features of the present disclosure will become more apparent by describing in detail the embodiments shown in the accompanying drawings. The same reference numerals in the accompanying drawings of the present disclosure represent the same or similar elements. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure. For those skilled in the art, other accompanying drawings can be obtained based on these accompanying drawings without creative work. In the accompanying drawings: Figure 1 Shown is a flow chart of a dual sliding mode control method for a ship electric propulsion motor according to the present invention; Figure 2 Shown is a schematic diagram of a pre-built dual sliding mode control model in the dual sliding mode control method for a ship electric propulsion motor of the present invention; Figure 3 The figure shows a comparison of the effects of the dual sliding mode control method for the ship electric propulsion motor proposed in the present invention and the traditional PI control. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other without conflict. The same reference numerals used throughout the drawings indicate the same or similar parts.

[0016] Reference Figure 1 as well as Figure 2 , Embodiment 1, the present invention proposes a dual sliding mode control method for a ship electric propulsion motor, comprising the following: Step 110, obtaining a given speed and an actual speed of the permanent magnet synchronous motor; Step 120: Control the ship electric propulsion motor through a pre-built dual sliding mode control model based on the given speed and actual speed of the permanent magnet synchronous motor; Specifically, the construction principle of the pre-built dual sliding mode control model is: The traditional permanent magnet synchronous motor vector control model is improved. Its speed outer loop continues to use the original sliding mode control, while the current inner loop adopts sliding mode variable structure control to replace the PI control in the traditional permanent magnet synchronous motor vector control model.

[0017] In this embodiment 1, the traditional PI controller in the current inner loop is improved to use sliding mode variable structure control to control the current inner loop, so as to obtain highly dynamic and stable current, ensure the response speed of the system, and improve the anti-interference ability. At the same time, the speed loop also adopts sliding mode variable structure control to improve the dynamic stability of the control system, thereby forming a dual sliding mode control system to further enhance the robustness of the system. Based on this, a dual sliding mode control model is pre-constructed to control the ship's electric propulsion motor, which can achieve the above advantages.

[0018] As a preferred embodiment of the present invention, specifically, in the pre-constructed dual sliding mode control model, the construction of the speed outer loop includes: In order to simplify the analysis and not affect the establishment of the mathematical model, the following assumptions are made: the saturation of the motor core is ignored, the eddy current and hysteresis loss in the motor are not considered, and the current in the motor is a symmetrical three-phase sinusoidal current. The mathematical model in the coordinate system is: (1); in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the mechanical angular velocity of the motor; is the moment of inertia; is the damping coefficient; is the load torque; is the number of motor pole pairs; Considering the surface-mounted permanent magnet synchronous motor, there is In addition, using The vector control method is used, so formula (1) is rewritten as: (2); Define the state variable of the permanent magnet synchronous motor as the given speed of the permanent magnet synchronous motor The actual speed The speed error between , the following relationship exists: (3) Can be obtained, (4) Define the sliding surface of the speed outer ring is the integral sliding surface, that is: (5) Here, considering that the traditional differential sliding surface design requires the differentiation of the command signal and the tracked signal, it is easy to cause high-frequency components that are not considered in the system modeling, thus causing the system to oscillate or even collapse, so the sliding surface is defined The integral sliding surface design can eliminate the steady-state error of the system variables and improve the control accuracy. At the same time, it makes the differential term absent in the control rate equation, thereby enhancing the stability of the controller.

[0019] Define the reaching law of the outer speed loop for: (6) in, , ; Here, compared with the traditional exponential reaching law, the constant speed term is increased with the state variable of the system The product of the approach speed and the system state variable associated; When the system state point is far away from the sliding surface ( is larger), that is, the system state variable When it is larger, the approach speed of the system state point to the sliding surface is changed from the variable speed approach term and exponential approach They work together, so they have a faster convergence speed than the traditional exponential convergence law.

[0020] When the system state point is near the sliding surface ( is small), that is, the system state variable When is small, the exponential approaches is approximately equal to 0, and the variable speed approach term plays a leading role. At this time, the approach speed is , under the action of the sliding mode control law, the system state variable Move towards the equilibrium point, Approaching 0, the approaching speed As the switching band of the system becomes narrower, the amplitude of the vibration when the system approaches the sliding surface is greatly reduced. Therefore, this reaching law can dynamically adapt to the changes between the sliding surface and the system state, thereby obtaining better control performance.

[0021] The sliding mode control law of the speed outer loop is: (12).

[0022] As a preferred embodiment of the present invention, the convergence law The stability is verified by Lyapunov function. Specifically, First, select the Lyapunov function: , when the formula satisfies When , it is considered that the sliding mode reaches the condition; The following formula is calculated: (7) It can be proved that the variable exponential reaching law satisfies the Lyapunov stability criterion and the system is asymptotic and stable.

[0023] In this preferred embodiment, by selecting a Lyapunov function verifier to verify the stability of the reaching law, the stability of the reaching law can be accurately verified.

[0024] As a preferred embodiment of the present invention, specifically, the calculation process of the sliding mode control law of the speed outer loop includes: Integral sliding surface The derivative is: (8) Combining equation (6) and equation (8), we get: (9) and , then the above formula can be expressed as: (10) (11) Then we can get: (12).

[0025] As a preferred embodiment of the present invention, specifically, in the pre-built dual sliding mode control model, the construction of the current inner loop includes: Building a permanent magnet synchronous motor The stator voltage equation in the coordinate system is: (13) in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the electrical angular velocity of the motor; , is the number of motor pole pairs, is the mechanical angular velocity of the motor; From formula (13), we can get: (14) Define the system state variables as: (15) In the formula, for The expected value of shaft current, It is calculated based on the outer loop of the speed, that is, the value calculated by formula (12) As The expected value of the shaft current is ; The current inner loop uses the same sliding mode surface as the speed outer loop sliding mode controller, so the sliding mode surface of the current inner loop is defined as: (16) The current inner loop adopts the same reaching law as the speed outer loop sliding mode controller, namely, equation (6); Then the sliding mode control law of the current inner loop is: (twenty four).

[0026] In this preferred embodiment, the specific derivation process of the sliding mode control law of the current inner loop is as follows: Derivation of the sliding surface, i.e., equation (16), yields: (17) From formula (14), we can know that: (18) Combining equations (14) and (18) we get: (19) Transform the above formula to get: (20) make , , , ; , , , ,in is regarded as a disturbance term, which requires the current loop controller to have strong anti-disturbance capability and robustness. Then equation (20) can be simplified as: (twenty one) Combining equations (17) and (21) yields: (twenty two) Select the sliding mode reaching law of equation (6), and combine equations (6) and (22) to obtain: (twenty three) Then the current loop sliding mode control law can be obtained as: (twenty four).

[0027] As a preferred embodiment of the present invention, the speed outer loop and the current inner loop are connected, and the sign function in the reaching law is Using the hyperbolic tangent function Instead, , The value determines how fast the inflection point of the hyperbolic tangent smooth function changes. The sliding mode control law of the updated speed outer loop is: (25) Update the current inner loop sliding mode control law as follows: (26).

[0028] In this preferred embodiment, in order to reduce the chattering caused by the sliding mode variable structure control, the sign function in the reaching law is Using the hyperbolic tangent function Since the hyperbolic tangent function is continuous and smooth, using the hyperbolic tangent function instead of the discontinuous sign function can effectively reduce the chattering in the sliding mode control.

[0029] When applying, refer to Figure 3 The experimental comparison between the improved controller and the traditional PI control is shown in the figure. The black line is the torque under dual sliding mode control, and the blue line is the torque under traditional PI control. It can be seen from the image that compared with the traditional PI control, the improved controller has better anti-disturbance ability in the initial stage of ship propulsion motor startup, and reduces the torque pulsation and system overshoot in subsequent operation.

[0030] The present invention also proposes a dual sliding mode control device for a ship electric propulsion motor, which applies the dual sliding mode control method for a ship electric propulsion motor, and comprises: A data acquisition module is used to obtain a given speed and an actual speed of the permanent magnet synchronous motor; A controller for controlling a ship electric propulsion motor based on a given speed and an actual speed of a permanent magnet synchronous motor through a pre-built double sliding mode control model.

[0031] The present invention also proposes a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the dual sliding mode control method for a ship electric propulsion motor are implemented.

[0032] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

[0033] In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of software functional modules.

[0034] If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or system that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0035] Although the description of the present invention has been quite detailed and specifically describes several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be regarded as providing a broad possible interpretation of these claims by reference to the attached claims in view of the prior art, thereby effectively covering the intended scope of the present invention. In addition, the above description of the present invention is based on the embodiments that can be foreseen by the implementer, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that have not yet been foreseen may still represent equivalent changes to the present invention.

[0036] The above is only a preferred embodiment of the present invention. The present invention is not limited to the above implementation. As long as the technical effect of the present invention is achieved by the same means, it should belong to the protection scope of the present invention. Within the protection scope of the present invention, its technical scheme and / or implementation method can have various modifications and changes.

Claims

1. A dual sliding mode control method for a ship electric propulsion motor, characterized in that: Includes the following: Get the given speed and actual speed of the permanent magnet synchronous motor; The ship electric propulsion motor is controlled based on the given speed and actual speed of the permanent magnet synchronous motor through a pre-built double sliding mode control model; Specifically, the construction principle of the pre-built dual sliding mode control model is: The traditional permanent magnet synchronous motor vector control model is improved. Its speed outer loop continues to use the original sliding mode control, while the current inner loop adopts sliding mode variable structure control to replace the PI control in the traditional permanent magnet synchronous motor vector control model.

2. The dual sliding mode control method for ship electric propulsion motor according to claim 1, characterized in that: Specifically, in the pre-built dual sliding mode control model, the construction of the speed outer loop includes: Assume that the saturation of the motor core is ignored, the eddy current and hysteresis loss in the motor are ignored, and the current in the motor is a symmetrical three-phase sine wave current. Based on this, the motor is constructed The mathematical model in the coordinate system is: （1）； in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the mechanical angular velocity of the motor; is the moment of inertia; is the damping coefficient; is the load torque; is the number of motor pole pairs; Considering the surface-mounted permanent magnet synchronous motor, there is In addition, using The vector control method is used, so formula (1) is rewritten as: （2）； Define the state variable of the permanent magnet synchronous motor as the given speed of the permanent magnet synchronous motor The actual speed The speed error between , there is the following relationship: （3）； Can be obtained, （4）； Define the sliding surface of the speed outer ring is the integral sliding surface, that is: （5）； Define the reaching law of the outer speed loop for: （6）； in, , , is the approaching speed of the isokinetic term, is the exponential term approach coefficient, is the coefficient of the exponential function, is the adjustable parameter of the reaching law; The sliding mode control law of the speed outer loop is: （12）。 3. The dual sliding mode control method for ship electric propulsion motor according to claim 2, characterized in that: Convergence Law The stability is verified by Lyapunov function. Specifically, First, select the Lyapunov function: , when the formula satisfies When , it is considered that the sliding mode reaches the condition; The following formula is calculated: （7）； It can be proved that the variable exponential reaching law satisfies the Lyapunov stability criterion and the system is asymptotic and stable.

4. The dual sliding mode control method for ship electric propulsion motor according to claim 2, characterized in that: Specifically, the calculation process of the sliding mode control law of the speed outer loop includes: Integral sliding surface The derivative is: （8）； Combining equation (6) and equation (8), we get: （9）； and , then the above formula can be expressed as: （10）； （11）； Then we can get: （12）。 5. The dual sliding mode control method for ship electric propulsion motor according to claim 2, characterized in that: Specifically, in the pre-built dual sliding mode control model, the construction of the current inner loop includes: Building a permanent magnet synchronous motor The stator voltage equation in the coordinate system is: （13）； in, The stator voltage is Axis component; The stator current is Axis component; They are The inductance component of the shaft; is the resistance of the stator; represents the flux linkage of the permanent magnet; is the electrical angular velocity of the motor; , is the number of motor pole pairs, is the mechanical angular velocity of the motor; From formula (13), we can get: （14）； Define the system state variables as: （15）； In the formula, for The expected value of shaft current, It is calculated based on the outer loop of the speed, that is, the value calculated by formula (12) As The expected value of the shaft current is ; The current inner loop uses the same sliding mode surface as the speed outer loop sliding mode controller, so the sliding mode surface of the current inner loop is defined as: （16）； in, is the sliding surface integral coefficient, The current inner loop adopts the same reaching law as the speed outer loop sliding mode controller, namely, equation (6); Then the sliding mode control law of the inner current loop is: （24）； in, , , , ; , , , .

6. The dual sliding mode control method for ship electric propulsion motor according to claim 5, characterized in that: In the outer loop of speed and the inner loop of current, the sign function in the reaching law Using the hyperbolic tangent function Instead, , The value determines how fast the inflection point of the hyperbolic tangent smooth function changes. The sliding mode control law of the updated speed outer loop is: （25）； Update the current inner loop sliding mode control law as follows: （26）。 7. A dual sliding mode control device for a ship electric propulsion motor, characterized in that: The dual sliding mode control method for a ship electric propulsion motor according to any one of claims 1 to 6 is applied, comprising: A data acquisition module is used to obtain a given speed and an actual speed of the permanent magnet synchronous motor; A controller for controlling a ship electric propulsion motor based on a given speed and an actual speed of a permanent magnet synchronous motor through a pre-built double sliding mode control model.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

Images