Permanent magnet synchronous motor prediction direct speed control method considering maximum torque current ratio track operation

Abstract

The invention discloses a permanent magnet synchronous motor predictive direct speed control method considering maximum torque current ratio trajectory operation, and relates to the field of motor control, the method comprises the following steps: obtaining a load torque sliding mode observation value at the Kth moment and a motor rotating speed estimation value at the Kth moment through a sliding mode load torque disturbance observer; obtaining a motor rotating speed estimation value at the (K + 1) th moment through a permanent magnet synchronous motor mechanical model; obtaining a reference torque based on a dead-beat control principle; based on the reference torque, obtaining a dq-axis reference current of maximum torque current ratio track operation; obtaining a reference voltage vector based on a dead-beat control principle according to the dq-axis reference current; and determining an optimal voltage vector based on the reference voltage vector and the inverter candidate voltage vector, and realizing prediction direct speed control of the permanent magnet synchronous motor according to the optimal voltage vector. The control process is simplified, it is guaranteed that the stator current always runs along the maximum torque-current ratio track, and maximum torque output and high-efficiency running are achieved.

Description

Technical Field

[0001] This application relates to the field of motor control, and in particular to a predictive direct speed control method for permanent magnet synchronous motors that takes into account the maximum torque-current ratio of trajectory operation. Background Technology

[0002] Interior permanent magnet synchronous motors (IPMSMs) are widely used in various industrial and transportation fields due to their inherent advantages such as high efficiency, high power density, and compact structure. Proportional-integral (PI) control algorithms, due to their simple structure, are often used for speed and current regulation in IPMSM systems. However, the relatively low convergence speed of the PI control method limits the optimal performance of the system, especially in applications requiring high speed control accuracy.

[0003] In recent years, model predictive speed control (MRC) has attracted widespread attention due to its multi-degree-of-freedom adjustment capabilities and excellent dynamic response characteristics. It can be divided into two categories. The first is continuous control set MRC, which independently controls speed and current. The second introduces both speed and current terms into the cost function to achieve synchronous predictive control of both; this method is called finite control set MRC. Compared with continuous control set MRC, finite control set MRC can quickly select the optimal voltage vector, enabling the system to rapidly track the reference speed, with no steady-state error and no overshoot, thus achieving superior dynamic performance. Because the rotor of an embedded permanent magnet synchronous motor exhibits salient pole effect, maximum torque-to-current ratio control must be used to fully utilize its reluctance torque characteristics, achieving optimal distribution between the d-axis and q-axis currents.

[0004] However, in traditional finite control set model predictive speed control, speed tracking and maximum torque-to-current ratio control must be considered simultaneously in a single cost function. Currently, there is a lack of unified design principles for how to rationally determine weighting factors to achieve balance in multi-objective control. Summary of the Invention

[0005] The purpose of this application is to provide a predictive direct speed control method for permanent magnet synchronous motors that considers the maximum torque-to-current ratio (MTPA) trajectory. By converting multiple control objectives into a reference voltage vector, the method avoids the complex weighting factor design in traditional MPSC, simplifies the control process, and ensures that the stator current always runs along the maximum torque-to-current ratio (MTPA) trajectory, thus fully utilizing the reluctance torque characteristics of the motor and achieving maximum torque output and high-efficiency operation.

[0006] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a predictive direct speed control method for a permanent magnet synchronous motor that considers the maximum torque-current ratio during trajectory operation, including: By using the sliding mode load torque disturbance observer, the sliding mode observation value of the load torque at time K and the estimated value of the motor speed at time K are obtained. Based on the sliding mode observation of the load torque at time K and the estimated motor speed at time K, the estimated motor speed at time K+1 is obtained through the mechanical model of the permanent magnet synchronous motor. The estimated motor speed at time K+1 is used as the motor reference speed. Based on the sliding mode observation of the load torque at time K, the estimated motor speed at time K, and the motor reference speed, the reference torque is obtained according to the deadbeat control principle. Based on the reference torque, numerical optimization techniques are used to obtain the dq-axis reference current with the maximum torque current ratio for trajectory operation; Based on the dq axis reference current and the deadbeat control principle, the reference voltage vector is obtained; Based on the reference voltage vector and the inverter candidate voltage vector, a prediction cost function is used to determine the optimal voltage vector, and predictive direct speed control of the permanent magnet synchronous motor is realized according to the optimal voltage vector.

[0007] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a predictive direct speed control (MDS) method for permanent magnet synchronous motors (PMSMs) that considers the maximum torque-current ratio (MTPA) trajectory. By converting multiple control objectives into a reference voltage vector, it avoids the complex weighting factor design in traditional MPSCs, simplifying the control process. Combined with the deadbeat control principle, it achieves fast speed response and small overshoot, improving the dynamic performance of this application. Simultaneously, this application ensures that the stator current always runs along the MTPA trajectory, fully utilizing the reluctance torque characteristics of the PMSM to achieve maximum torque output and high-efficiency operation. Furthermore, the numerical optimization mechanism enhances the robustness of this application to parameter uncertainties and external disturbances. While maintaining excellent control performance, the computational load is moderate, making it suitable for motor drive systems with high real-time requirements. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1A flowchart of a predictive direct speed control method for a permanent magnet synchronous motor considering the maximum torque-current ratio trajectory operation is provided in one embodiment of this application; Figure 2 This is an overall control block diagram of a permanent magnet synchronous motor considering the maximum torque-to-current ratio trajectory operation, provided as an embodiment of this application; Figure 3 This refers to the speed tracking performance at a reference rotational speed of 600 r / min. Figure 4 (a) Speed ​​tracking performance at a reference speed of 1500 r / min; (b) Stator A-phase current performance at a reference speed of 1500 r / min; Figure 5 (a) Speed ​​tracking performance when a step load occurs; (b) Stator A-phase current performance when a step load occurs; Figure 6 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0011] To make the objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] In one exemplary embodiment, such as Figure 1 As shown, a predictive direct speed control method for a permanent magnet synchronous motor considering the maximum torque-current ratio trajectory operation is provided. This method is executed by a computer device, specifically by a terminal or server alone, or by both a terminal and a server. In this embodiment, it includes the following steps 101 to 106. Wherein: Step 101: Obtain the sliding mode observation value of the load torque and the estimated value of the motor speed at time K using the sliding mode load torque disturbance observer.

[0013] Step 102: Based on the sliding mode observation of the load torque at time K and the estimated value of the motor speed at time K, the estimated value of the motor speed at time K+1 is obtained through the mechanical model of the permanent magnet synchronous motor.

[0014] Step 103: The estimated motor speed at time K+1 is used as the motor reference speed. Based on the sliding mode observation of the load torque at time K, the estimated motor speed at time K, and the motor reference speed, the reference torque is obtained based on the deadbeat control principle.

[0015] Step 104: Based on the reference torque, numerical optimization techniques are used to obtain the dq-axis reference current with the maximum torque current ratio for trajectory operation.

[0016] Step 105: Based on the dq axis reference current and the deadbeat control principle, obtain the reference voltage vector.

[0017] Step 106: Based on the reference voltage vector and the inverter candidate voltage vector, a prediction cost function is used to determine the optimal voltage vector, and predictive direct speed control of the permanent magnet synchronous motor is realized according to the optimal voltage vector.

[0018] Implementing steps 101 to 106 above avoids the complex weight factor design in traditional MPSC and simplifies the control process.

[0019] In another exemplary embodiment of this application, in step 101, the expression for the sliding mode load torque disturbance observer is: .

[0020] in, This is an estimated value for the motor speed. The load torque is the sliding mode observation value. The electromagnetic torque of the permanent magnet synchronous traction motor. This refers to the rotational inertia of the permanent magnet synchronous traction motor. For time, This is the constant velocity sliding mode reaching law. For sliding mode gain, , Here, the term represents the isotropic approach term, and sign is the switching function. This refers to the speed of the permanent magnet synchronous traction motor.

[0021] In another exemplary embodiment of this application, in step 102, the expression for the mechanical model of the permanent magnet synchronous motor is: .

[0022] in, This is the estimated motor speed at time K+1. This is the estimated motor speed at time K. This refers to the rotational inertia of the permanent magnet synchronous traction motor. The sampling step size, Let be the electromagnetic torque of the permanent magnet synchronous traction motor at time K. Let K be the sliding mode observation of the load torque at time K, where K is the index of the sampling time.

[0023] In another exemplary embodiment of this application, in step 103, the expression for the reference torque is: .

[0024] in, This is the reference torque for the permanent magnet synchronous traction motor. This refers to the rotational inertia of the permanent magnet synchronous traction motor. The sampling step size, This is the reference speed for the motor. This is the estimated motor speed at time K. The load torque sliding mode observation value at time K is given.

[0025] In another exemplary embodiment of this application, step 104 specifically includes steps 201 to 204.

[0026] Step 201: Establish the discrete-time current equations for the permanent magnet synchronous motor.

[0027] Step 202: Based on the reference torque, establish the optimization equation.

[0028] Step 203: Based on the optimization equation, the objective optimization function is obtained using the Lagrange multiplier method.

[0029] Step 204: Based on the objective optimization function, the Gauss-Newton method is used to obtain the dq-axis reference current for the maximum torque current ratio trajectory operation.

[0030] In another exemplary embodiment of this application, in step 201, the expression for the discrete-time current equation of the permanent magnet synchronous motor is: .

[0031] in, Let be the stator dq-axis current at time K+1. It is the identity matrix. This is the first coefficient matrix. This is the second coefficient matrix. This is the third coefficient matrix. For the current sampling period, Let be the stator dq-axis current at time K. Let be the stator dq-axis voltage at time K.

[0032] , , .

[0033] in, For stator resistance, For d-axis inductance, It is the q-axis inductance. It is a permanent magnet flux chain. ω is the electric angular velocity.

[0034] In another exemplary embodiment of this application, in step 202, the expression of the optimization equation is: .

[0035] in, For stator dq-axis current, This is the reference torque for the permanent magnet synchronous traction motor. For the stator q-axis current, For stator d-axis current, For q-axis flux linkage, For d-axis flux linkage, This represents the number of pole pairs of the motor.

[0036] In another exemplary embodiment of this application, step 203 specifically includes steps 301 to 304: Step 301: Transform the optimization equation in step 202 using the Lagrange multiplier method to obtain the transformed equation: .

[0037] in, Represents the Lagrange function, Represents the Lagrange multiplier.

[0038] Step 302, taking the partial derivative of the transformation equation, we obtain the partial derivative equation: .

[0039] Step 303, eliminating the Lagrange multipliers in the partial derivative equations, yields: .

[0040] Step 304, let The objective function in least squares form can be obtained as follows: .in, Let be the objective function. For the residual vector, As the first constraint term, This is the second constraint term. This represents the number of pole pairs of the motor. For q-axis flux linkage, For the d-axis flux linkage, For stator dq-axis current, This is the reference torque for the permanent magnet synchronous traction motor. For the stator q-axis current, This represents the stator d-axis current.

[0041] In another exemplary embodiment of this application, in step 204, the optimal value of the objective function in step 203 is found using the Gauss-Newton method. The iterative formula in the Gauss-Newton method is: .

[0042] .

[0043] in, The iteration step size, In the direction of descent, Let dq be the reference current at time K+1. Let be the dq-axis reference current at time K. For a positive value, The Jacobian matrix of the objective function is to optimize the function. It is the identity matrix. Let K be the residual vector, and K be the index of the sampling time.

[0044] In another exemplary embodiment of this application, as derived from step 201, the expression for the reference voltage vector in step 105 is: .

[0045] in, For the reference voltage vector, This is the first coefficient matrix. This is the second coefficient matrix. This is the third coefficient matrix. This is the reference current for the dq axis. For the current sampling period, Let be the stator dq-axis current at time K.

[0046] In another exemplary embodiment of this application, in step 106, a prediction cost function is designed, the reference voltage vector is used as a control variable, and the optimal voltage vector at time K is directly selected through predictive control technology and directly applied to the traction inverter at time K+1, thereby realizing predictive direct speed control and precise maximum torque-current ratio trajectory operation of the permanent magnet synchronous motor.

[0047] The prediction cost function is: .in, This represents the candidate voltage vector for the inverter. This is the index of the inverter candidate voltage vector.

[0048] In another exemplary embodiment of this application, the following embodiments are proposed and verified by simulation experiments based on MATLAB to verify the validity of this application: This embodiment considers the speed control of a permanent magnet synchronous motor model while simultaneously satisfying the maximum torque-to-current ratio trajectory. The selected permanent magnet synchronous motor parameters are as follows: rated power 2.3kW, rated voltage 220V, rated current 7.5A, d-axis inductance 2.06mH, q-axis inductance 3.97mH, number of pole pairs 4, permanent magnet flux linkage 0.2858Wb, and moment of inertia 0.009 kg. m^2, DC bus voltage is 380V, PWM switching frequency is 10KHz, and speed sampling period is 0.001s.

[0049] Simulation verification of the proposed predictive direct speed control strategy for permanent magnet synchronous motors with maximum torque-to-current ratio trajectory operation yields the results. Figure 3 , Figure 4 and Figure 5 .in, Figure 3 Speed ​​tracking performance at a reference speed of 600 r / min; Figure 4 The control performance is shown at a reference speed of 1500 r / min. (a) Speed ​​tracking performance; (b) Stator A-phase current performance; Figure 5 The control performance under step load conditions is shown. (a) Speed ​​tracking performance; (b) Stator A-phase current performance. Simulation results are presented. Figure 3 , Figure 4 and Figure 5 It can be concluded that this application enables a permanent magnet synchronous motor to operate at the maximum torque-to-current ratio trajectory while tracking speed, exhibiting superior dynamic performance. The blue line represents the method of this application, while the yellow line represents the traditional method. In particular, this application overcomes the problem of complex weighting factor design required by the traditional method.

[0050] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 6As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data for the permanent magnet synchronous traction motor. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a predictive direct speed control method for a permanent magnet synchronous motor that considers the maximum torque-to-current ratio trajectory operation.

[0051] Those skilled in the art will understand that Figure 6 The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0052] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A predictive direct speed control method for a permanent magnet synchronous motor considering the maximum torque-current ratio trajectory operation, characterized in that, The method includes: By using the sliding mode load torque disturbance observer, the sliding mode observation value of the load torque at time K and the estimated value of the motor speed at time K are obtained. Based on the sliding mode observation of the load torque at time K and the estimated motor speed at time K, the estimated motor speed at time K+1 is obtained through the mechanical model of the permanent magnet synchronous motor. The estimated motor speed at time K+1 is used as the motor reference speed. Based on the sliding mode observation of the load torque at time K, the estimated motor speed at time K, and the motor reference speed, the reference torque is obtained according to the deadbeat control principle. Based on the reference torque, numerical optimization techniques are used to obtain the dq-axis reference current with the maximum torque current ratio for trajectory operation; Based on the dq axis reference current and the deadbeat control principle, the reference voltage vector is obtained; Based on the reference voltage vector and the inverter candidate voltage vector, a prediction cost function is used to determine the optimal voltage vector, and predictive direct speed control of the permanent magnet synchronous motor is realized according to the optimal voltage vector.

2. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation as described in claim 1, characterized in that, The expression for the sliding mode load torque disturbance observer is: ； in, This is an estimated value for the motor speed. The load torque is the sliding mode observation value. The electromagnetic torque of the permanent magnet synchronous traction motor. This refers to the rotational inertia of the permanent magnet synchronous traction motor. For time, This is the constant velocity sliding mode reaching law. This is the sliding mode gain.

3. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation as described in claim 1, characterized in that, The expression for the mechanical model of the permanent magnet synchronous motor is: ； in, This is the estimated motor speed at time K+1. This is the estimated motor speed at time K. This refers to the rotational inertia of the permanent magnet synchronous traction motor. The sampling step size, Let be the electromagnetic torque of the permanent magnet synchronous traction motor at time K. Let K be the sliding mode observation of the load torque at time K, where K is the index of the sampling time.

4. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation as described in claim 1, characterized in that, The expression for the reference torque is: ； in, This is the reference torque for the permanent magnet synchronous traction motor. This refers to the rotational inertia of the permanent magnet synchronous traction motor. The sampling step size, This is the reference speed for the motor. This is the estimated motor speed at time K. Let K be the sliding mode observation of the load torque at time K, where K is the index of the sampling time.

5. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation according to claim 1, characterized in that, Based on the reference torque, numerical optimization techniques are used to obtain the dq-axis reference current with the maximum torque current ratio during trajectory operation, specifically including: Based on the reference torque, an optimization equation is established; Based on the optimization equation, the objective optimization function is obtained through the Lagrange multiplier method; Based on the objective optimization function, the Gauss-Newton method is used to obtain the dq-axis reference current for the maximum torque current ratio of the trajectory operation.

6. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation according to claim 5, characterized in that, The expression for the optimization equation is: ； in, For stator dq-axis current, This is the reference torque for the permanent magnet synchronous traction motor. For the stator q-axis current, For stator d-axis current, For q-axis flux linkage, For d-axis flux linkage, This represents the number of pole pairs of the motor.

7. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation according to claim 5, characterized in that, The expression for the objective function is: ； ； ； in, Let be the objective function. For the residual vector, As the first constraint term, This is the second constraint term. This represents the number of pole pairs of the motor. For q-axis flux linkage, For d-axis flux linkage, For stator dq-axis current, This is the reference torque for the permanent magnet synchronous traction motor. For the stator q-axis current, This represents the stator d-axis current.

8. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation according to claim 5, characterized in that, The iterative formula in the Gauss-Newton method is: ； ； in, The iteration step size, In the direction of descent, Let dq be the reference current at time K+1. Let be the dq-axis reference current at time K. For a positive value, The Jacobian matrix of the objective function is to optimize the function. It is the identity matrix. Let K be the residual vector, and K be the index of the sampling time.

9. The predictive direct speed control method for permanent magnet synchronous motors considering maximum torque-current ratio trajectory operation according to claim 1, characterized in that, The expression for the reference voltage vector is: ； in, For the reference voltage vector, This is the first coefficient matrix. This is the second coefficient matrix. This is the third coefficient matrix. This is the reference current for the dq axis. For the current sampling period, Let K be the stator dq-axis current at time K, where K is the index of the sampling time.

10. The predictive direct speed control method for a permanent magnet synchronous motor considering maximum torque-current ratio trajectory operation according to claim 1, characterized in that, The expression for the prediction cost function is: ； in, For the reference voltage vector, This is the candidate voltage vector for the inverter. This is the index of the inverter candidate voltage vector.

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