Model predictive torque control device and method for permanent magnet synchronous motor, motor controller and computer readable storage medium

Abstract

The application provides a model predictive torque control device and method of a permanent magnet synchronous motor, a motor controller and a computer readable storage medium. The method comprises: establishing a model predictive torque controller based on a mathematical model of the permanent magnet synchronous motor; inputting a given torque at time k, a motor speed at time k, d-axis and q-axis voltages at time k, and d-axis and q-axis currents at time k into the model predictive torque controller to predict output d-axis and q-axis predicted voltages at time k+1; determining a reference voltage vector and a voltage vector position angle in an alpha-beta coordinate system at time k+1 based on the d-axis and q-axis predicted voltages at time k+1 and a motor potential angle at time k; determining a sector to which the reference voltage vector belongs; selecting two candidate voltage vectors from the sector; selecting a voltage vector that makes a function value of a cost function minimum as a target voltage vector through the cost function; and controlling a three-phase inverter based on the target voltage vector and acting on the motor.

Description

Technical Field

[0001] This application relates to the field of motor technology, and in particular to a model predictive torque control device and method for a permanent magnet synchronous motor, a motor controller, and a computer-readable storage medium. Background Technology

[0002] With the rapid development of the economy and technology, my country's industrialization level is constantly improving. Electric motors are a crucial tool in industrial manufacturing. Among them, permanent magnet synchronous motors (PMSMs) use permanent magnet materials such as neodymium iron boron (NdFeB) as motor materials, resulting in low cost. Furthermore, the use of permanent magnets not only reduces motor losses but also improves motor efficiency and power density. In terms of dynamic performance, PMSMs offer advantages such as a wide speed range, low moment of inertia, high stability, and strong load-bearing capacity. Based on these advantages, PMSMs are widely used in industrial production.

[0003] Permanent magnet synchronous motor (PMSM) systems are complex systems with time-varying, nonlinear, and strongly coupled characteristics. Therefore, the application of PMSMs requires suitable motor control methods. Model predictive control (MMC) primarily aims to predict the system's next state by analyzing its current state and selecting the optimal control input based on a specific cost function. MMC is easy to implement in motor control and offers advantages such as fast dynamic response, parameter-free tuning, and ease of handling nonlinear constraints. Compared to vector control, MMC exhibits better dynamic response; compared to direct torque control (DTC), MMC selects more effective voltage vectors and produces smaller torque ripple. However, MMC requires predicting torque and flux linkage under all voltage vectors, resulting in a large computational load. Furthermore, since torque and flux linkage have different dimensions in MMC, weighting coefficients need to be designed to achieve simultaneous control of torque and flux linkage. These weighting coefficients require repeated simulations and experiments to optimize. Summary of the Invention

[0004] The purpose of this application is to provide a model predictive torque control device and method for permanent magnet synchronous motors, a motor controller and a computer-readable storage medium, which can solve the problems existing in the current model predictive torque of permanent magnet synchronous motors.

[0005] One aspect of this application provides a model predictive torque control method for a permanent magnet synchronous motor. The model predictive torque control method includes:

[0006] Establish a mathematical model for the permanent magnet synchronous motor;

[0007] A model predictive torque controller is established based on the mathematical model of the permanent magnet synchronous motor.

[0008] Obtain the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k;

[0009] The given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k are input into the model predictive torque controller to predict and output the d-axis and q-axis predicted voltages at time k+1.

[0010] The reference voltage vector and voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 are determined based on the predicted voltages of the d and q axes at time k+1 and the motor potential angle at time k.

[0011] The sector to which the reference voltage vector belongs is determined based on the voltage vector position angle in the α-β coordinate system at time k+1;

[0012] Two candidate voltage vectors are selected from the sector;

[0013] Based on the reference voltage vector and the two candidate voltage vectors, a cost function is used to select the voltage vector that minimizes the function value of the cost function from the two candidate voltage vectors as the target voltage vector; and

[0014] The three-phase inverter is controlled based on the target voltage vector, which in turn controls the permanent magnet synchronous motor.

[0015] Furthermore, the mathematical model for establishing the permanent magnet synchronous motor includes:

[0016] Establish the voltage equations for the permanent magnet synchronous motor along the dq axis:

[0017]

[0018] Among them, R s For stator resistance, i d Let i be the d-axis current. q Let u be the q-axis current. d For the d-axis voltage, u q Let ψ be the q-axis voltage. d Let ψ be the d-axis flux linkage. q Let ω be the q-axis flux linkage. e This refers to the motor speed;

[0019] Establish the flux linkage equation of the permanent magnet synchronous motor on the dq axis:

[0020]

[0021] Where, ψ f For rotor flux linkage, L sFor stator inductance; and

[0022] Establish the torque equation of the permanent magnet synchronous motor:

[0023]

[0024] Among them, T e P is the torque of the permanent magnet synchronous motor. n denoted as the number of pole pairs of the permanent magnet synchronous motor.

[0025] Furthermore, the step of inputting the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k into the model predictive torque controller to predict the output d-axis and q-axis predicted voltages at time k+1 includes:

[0026] The ideal flux linkage at time k is calculated using the maximum torque-current ratio based on the given torque at time k.

[0027] The predicted d-axis and q-axis currents at time k+1 are obtained based on the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k.

[0028] Based on the predicted d-axis and q-axis currents at time k+1, the predicted flux linkage at time k+1 and the predicted torque at time k+1 are obtained; and

[0029] The predicted voltages of the d and q axes at time k+1 are predicted based on the ideal flux linkage at time k, the predicted flux linkages of the d and q axes at time k+1, and the predicted torque at time k+1.

[0030] Further, the step of predicting the d-axis and q-axis currents at time k+1 based on the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k includes:

[0031] Predict the d-axis and q-axis flux linkages at time k+1, and apply the forward Euler method to equation (1) to obtain:

[0032]

[0033] Where k is the current sampling time, and k+1 is the next sampling time. The flux linkages along the d and q axes at time k are respectively. d and q axis predicted flux linkages at time k+1, respectively, and T is the prediction time period;

[0034] Substituting equation (2) into equation (4) and discretizing it with a period of T, we obtain the equations for the predicted d-axis and q-axis currents at time k+1:

[0035]

[0036] in, The d-axis and q-axis currents at time k are respectively, ω e k Let k be the motor speed at time k. The d-axis and q-axis voltages at time k are respectively. The d-axis and q-axis predicted currents at time k+1 are respectively.

[0037] Furthermore, obtaining the predicted flux linkage and predicted torque at time k+1 based on the predicted d-axis and q-axis currents at time k+1 includes:

[0038] Substituting equation (5) into the flux linkage equation (2) and the torque equation (3) of the dq axis respectively, we obtain the equations for the predicted flux linkage of the d and q axes at time k+1 and the equations for the predicted torque at time k+1:

[0039]

[0040] Where, ψ d k+1 For the predicted flux linkage along the d-axis at time k+1, ψ q k+1 For the q-axis predicted flux linkage at time k+1, T e k+1 This represents the predicted torque at time k+1.

[0041] Furthermore, the ideal flux linkage at time k is calculated using the following formula:

[0042]

[0043] in, Let be the ideal magnetic flux linkage at time k. Let k be the given torque at time k.

[0044] Further, the step of predicting the d-axis and q-axis predicted voltage at time k+1 based on the ideal flux linkage at time k, the predicted flux linkage along the d and q axes at time k+1, and the predicted torque at time k+1 includes:

[0045] By combining equations (1) and (2) and discretizing the flux linkage equation of the dq axis, the flux linkage equation at time k+2 is obtained:

[0046]

[0047] in, The predicted flux linkages along the d and q axes at time k+2 are respectively. These are the predicted voltages along the d and q axes at time k+1, respectively.

[0048] Using the concept of deadbeat-free operation, the ideal flux linkage at time k is taken as the predicted flux linkage at time k+2, and combined with formula (3), while ignoring the resistance term in formula (3), we obtain...

[0049]

[0050] Differentiating equation (3) with respect to time and discretizing it, then combining it with equation (2), we get:

[0051]

[0052] in, The predicted torque at time k+2, The predicted torque at time k+1 Predict the q-axis current at time k+2;

[0053] Substituting formula (8) into formula (10), we get:

[0054]

[0055] Using the concept of deadbeat-free timing, the given torque at time k is... The predicted torque at time k+2 Combining formulas (9) and (10), the predicted d-axis and q-axis voltages at time k+1 are obtained:

[0056]

[0057] in,

[0058]

[0059] Furthermore, the determination of the reference voltage vector in the two-phase stationary α-β coordinate system at time k+1 based on the predicted d-axis and q-axis voltages at time k+1 and the motor potential angle at time k includes:

[0060] The predicted d-axis and q-axis voltages at time k+1 are transformed by Clark into voltage components in a two-phase stationary α-β coordinate system to obtain the reference voltage vector in the α-β coordinate system at time k+1:

[0061]

[0062] Where, θ e k Let be the motor potential angle of the permanent magnet synchronous motor at time k. The predicted voltage components along the α and β axes at time k+1 are U. ref Let be the reference voltage vector in the α-β coordinate system at time k+1.

[0063] Furthermore, determining the voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 includes:

[0064] The voltage vector position angle in the α-β coordinate system at time k+1 is calculated based on the predicted voltage components along the α and β axes at time k+1.

[0065]

[0066] Where θ is the voltage vector position angle.

[0067] Furthermore, the step of selecting two candidate voltage vectors from the sector includes: based on the basic principle of direct torque control, using its stator flux linkage partitioning and voltage vector selection table, selecting the optimal non-zero voltage vector and a zero vector from the sector as the two candidate voltage vectors.

[0068] Furthermore, the model predictive torque control method further includes: obtaining the three-phase current of the permanent magnet synchronous motor at time k; and obtaining the d-axis and q-axis currents at time k based on the motor potential angle at time k and the three-phase current at time k and through coordinate transformation.

[0069] Furthermore, the model predictive torque control method further includes: obtaining the three-phase voltage at the input terminal of the three-phase inverter at time k; and obtaining the d-axis and q-axis voltages at time k based on the motor potential angle at time k and the three-phase voltage at time k, and through coordinate transformation.

[0070] Furthermore, the model predictive torque control method also includes: calculating the motor speed at time k based on the motor potential angle at time k.

[0071] Another aspect of this application provides a model predictive torque control device for a permanent magnet synchronous motor. The model predictive torque control device includes a model predictive torque controller and a voltage sector controller. The model predictive torque controller is established based on a mathematical model of the permanent magnet synchronous motor, and is used to predict the d-axis and q-axis predicted voltages at time k+1 based on the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k as inputs. The voltage sector controller is used to determine the reference voltage vector and voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 based on the predicted voltages of the d and q axes at time k+1 and the motor potential angle at time k; determine the sector to which the reference voltage vector belongs based on the voltage vector position angle in the α-β coordinate system at time k+1; select two candidate voltage vectors from the sector; select the voltage vector that minimizes the function value of the cost function from the two candidate voltage vectors based on the reference voltage vector and the two candidate voltage vectors, and use a cost function as the target voltage vector; and control the three-phase inverter based on the target voltage vector, thereby controlling the permanent magnet synchronous motor.

[0072] Another aspect of this application provides a motor controller. The motor controller includes: a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the model predictive torque control method for a permanent magnet synchronous motor as described above.

[0073] Another aspect of this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the model predictive torque control method for a permanent magnet synchronous motor as described above.

[0074] The beneficial technical effects of the embodiments of this application are mainly reflected in the following: the reference voltage vector to be pre-applied in the next cycle is calculated by using the deadbeat prediction principle, and two candidate voltage vectors are determined according to the sector where the reference voltage vector is located, thereby reducing the number of calculations of the cost function to two, and thus reducing the amount of computation.

[0075] Furthermore, in the model predictive torque control of the permanent magnet synchronous motor in this application embodiment, the cost function is the error between the reference voltage vector and the candidate voltage vector, thereby avoiding the selection of weighting coefficients. Attached Figure Description

[0076] Figure 1 This is a flowchart of a model predictive torque control method for a permanent magnet synchronous motor according to an embodiment of this application.

[0077] Figure 2This document describes the specific steps of a model predictive torque controller in one embodiment of the present application to predict the d-axis and q-axis voltages at time k+1.

[0078] Figure 3 This is a model predictive torque control block diagram of a permanent magnet synchronous motor according to an embodiment of this application.

[0079] Figure 4 This is a schematic diagram of a voltage sector distribution.

[0080] Figure 5 This is a schematic block diagram of a motor controller according to an embodiment of this application. Detailed Implementation

[0081] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses consistent with some aspects of this application as detailed in the appended claims.

[0082] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. Unless otherwise defined, the technical or scientific terms used in the embodiments of this application should be understood in their ordinary meaning as understood by one of ordinary skill in the art to which this application pertains. The singular forms “a,” “the,” and “the” used in the specification and appended claims of this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0083] This application provides a model predictive torque control method for a permanent magnet synchronous motor. By using parameters such as torque and flux linkage at the current moment, the reference voltage vector at the next moment is predicted, which effectively improves the dynamic performance of the system and reduces torque and flux linkage pulsation.

[0084] Figure 1 A flowchart illustrating a model predictive torque control method for a permanent magnet synchronous motor according to an embodiment of this application is provided. Figure 1 As shown, a model predictive torque control method for a permanent magnet synchronous motor according to an embodiment of this application may include steps S11 to S21.

[0085] In step S11, a mathematical model of the permanent magnet synchronous motor is established.

[0086] In step S12, a model predictive torque controller is designed based on the mathematical model of the permanent magnet synchronous motor established in step S11.

[0087] In step S13, the motor potential angle at time k, the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k are obtained.

[0088] In step S14, the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k obtained in step S13 are input into the model predictive torque controller designed in step S12.

[0089] In step S15, the model predictive torque controller predicts the d-axis and q-axis predicted voltages at time k+1.

[0090] Figure 2 This application discloses the specific steps of a model predictive torque controller in one embodiment of the present application to predict the d-axis and q-axis voltages at time k+1. For example... Figure 2 As shown, in some embodiments, step S15 may further include steps S151 to S154.

[0091] In step S151, the ideal flux linkage at time k is calculated based on the given torque at time k using the maximum torque per ampere (MTPA).

[0092] In step S152, the predicted d and q axis currents at time k+1 are obtained based on the motor speed at time k, the d and q axis voltages at time k, and the d and q axis currents at time k.

[0093] In step S153, the predicted flux linkage and predicted torque at time k+1 are obtained based on the predicted d-axis and q-axis currents at time k+1 obtained in step S152.

[0094] In step S154, the predicted voltages of the d and q axes at time k+1 are predicted based on the ideal flux linkage at time k calculated in step S151, the predicted flux linkages of the d and q axes at time k+1 obtained in step S153, and the predicted torque at time k+1.

[0095] Return to continue referencing Figure 1 As shown, in step S16, the reference voltage vector and voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 are determined based on the predicted d-axis and q-axis voltages at time k+1 obtained in step S15 and the motor potential angle at time k obtained in step S13.

[0096] In step S17, the sector to which the reference voltage vector belongs is determined based on the voltage vector position angle in the α-β coordinate system at time k+1 obtained in step S16.

[0097] In step S18, two candidate voltage vectors are selected from the sectors determined in step S17.

[0098] In step S19, the reference voltage vector determined in step S16 and the two candidate voltage vectors selected in step S18 are input into the cost function.

[0099] In step S20, the voltage vector that minimizes the function value of the cost function is selected from the two candidate voltage vectors using a cost function as the target voltage vector.

[0100] In step S21, the three-phase inverter is controlled based on the target voltage vector, thereby controlling the permanent magnet synchronous motor.

[0101] Figure 3 A model predictive torque control block diagram of a permanent magnet synchronous motor according to an embodiment of this application is disclosed. The following will be combined with... Figure 3 This paper will describe in detail the specific steps of a model predictive torque control method for a permanent magnet synchronous motor according to an embodiment of this application.

[0102] 1) Establishment of the mathematical model of permanent magnet synchronous motor

[0103] Neglecting eddy current and hysteresis losses in the permanent magnet synchronous motor, and assuming the magnetic circuit is unsaturated and the permanent magnet synchronous motor is surface-mounted, the voltage equations for the permanent magnet synchronous motor along the dq axis can be established as follows:

[0104]

[0105] Among them, R s For stator resistance, i d Let i be the d-axis current. q Let u be the q-axis current. d For the d-axis voltage, u q Let ψ be the q-axis voltage. d Let ψ be the d-axis flux linkage. q Let ω be the q-axis flux linkage. e This refers to the motor speed;

[0106] Establish the flux linkage equations of the permanent magnet synchronous motor along the dq axis:

[0107]

[0108] Where, ψ f For rotor flux linkage, L s For stator inductance; and

[0109] Establish the torque equation for the permanent magnet synchronous motor:

[0110]

[0111] Among them, T e P represents the torque of the permanent magnet synchronous motor. n This represents the number of pole pairs in a permanent magnet synchronous motor.

[0112] 2) Design of Model Predictive Torque Controller

[0113] The designed model predictive torque controller can take the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k as inputs to the model. After processing by the model predictive controller, the model predictive torque controller can predict the d-axis and q-axis voltages at time k+1.

[0114] like Figure 3 As shown, in the model predictive torque control of the permanent magnet synchronous motor in this application embodiment, the motor speed at time k can be calculated based on the motor potential angle at time k.

[0115] The three-phase current of the permanent magnet synchronous motor at time k can be obtained in advance. Then, based on the three-phase current at time k and the motor potential angle at time k, the d-axis and q-axis currents at time k can be obtained through coordinate transformation.

[0116] The three-phase voltage at the input terminal of the three-phase inverter at time k can be obtained in advance. Then, based on the three-phase voltage at time k and the motor potential angle at time k, the d-axis and q-axis voltages at time k can be obtained through coordinate transformation.

[0117] The following will describe in detail how to design the model predictive torque controller of this application embodiment.

[0118] Considering that the control signal often has a one-beat delay in actual control, it needs to be compensated. The method is to predict the d-axis and q-axis flux linkages at time k+1 and apply the forward Euler method to formula (1) to obtain:

[0119]

[0120] Where k is the current sampling time, and k+1 is the next sampling time. The flux linkages along the d and q axes at time k are respectively. d and q axis predicted flux linkages at time k+1, respectively, and T is the prediction time period;

[0121] Substituting equation (2) into equation (4) and discretizing it with a period of T, we obtain the equations for the predicted d-axis and q-axis currents at time k+1:

[0122]

[0123] in, The d-axis and q-axis currents at time k are respectively, ω e k Let k be the motor speed at time k. The d-axis and q-axis voltages at time k are respectively. The d-axis and q-axis predicted currents at time k+1 are respectively.

[0124] Therefore, the predicted d-axis and q-axis currents at time k+1 can be obtained based on the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k.

[0125] Substituting equation (5) into the flux linkage equation (2) and torque equation (3) of the d and q axes respectively, we obtain the equations for the predicted flux linkage of the d and q axes at time k+1 and the equations for the predicted torque at time k+1:

[0126]

[0127] Where, ψ d k+1 Let ψ be the predicted flux linkage along the d-axis at time k+1. q k+1 For the q-axis predicted flux linkage at time k+1, T e k+1 This represents the predicted torque at time k+1.

[0128] Therefore, the predicted flux linkage and the predicted torque at time k+1 can be obtained from the predicted currents on the d and q axes at time k+1.

[0129] The ideal flux linkage at time k is calculated using the maximum torque-to-current ratio (MPTA), and the calculation formula is as follows:

[0130]

[0131] in, Let be the ideal magnetic flux at time k. Let k be the given torque at time k.

[0132] By combining equations (1) and (2) and discretizing the flux linkage equation along the dq axis, we obtain the flux linkage equation at time k+2:

[0133]

[0134] in, The predicted flux linkages along the d and q axes at time k+2 are respectively. These are the predicted voltages along the d and q axes at time k+1, respectively.

[0135] Using the concept of deadbeat-free operation, the ideal flux linkage at time k is taken as the predicted flux linkage at time k+2, and combined with formula (3), while ignoring the resistance term in formula (3), we obtain...

[0136]

[0137] Differentiating equation (3) with respect to time and discretizing it, then combining it with equation (2), we get:

[0138]

[0139] in, The predicted torque at time k+2, The predicted torque at time k+1 Predict the q-axis current at time k+2;

[0140] Substituting formula (8) into formula (10), we get:

[0141]

[0142] Using the concept of deadbeat-free timing, the given torque at time k is... The predicted torque at time k+2 Combining formulas (9) and (10), the predicted d-axis and q-axis voltages at time k+1 are obtained:

[0143]

[0144] in,

[0145]

[0146] Therefore, the predicted voltages on the d and q axes at time k+1 can be predicted based on the ideal flux linkage at time k, the predicted flux linkages on the d and q axes at time k+1, and the predicted torque at time k+1.

[0147] 3) Design of voltage sector controller

[0148] The predicted d-axis and q-axis voltages at time k+1 are transformed by Clark into voltage components in a two-phase stationary α-β coordinate system to obtain the reference voltage vector in the α-β coordinate system at time k+1:

[0149]

[0150] Where, θ e k Let be the motor potential angle of the permanent magnet synchronous motor at time k. The predicted voltage components along the α and β axes at time k+1 are U. ref Let be the reference voltage vector in the α-β coordinate system at time k+1.

[0151] Therefore, the reference voltage vector in the two-phase stationary α-β coordinate system at time k+1 can be determined based on the predicted voltages of the d and q axes at time k+1 and the motor potential angle at time k.

[0152] The voltage vector position angle in the α-β coordinate system at time k+1 is calculated based on the predicted voltage components along the α and β axes at time k+1.

[0153]

[0154] Where θ is the voltage vector position angle.

[0155] The reference voltage vector U is determined based on the voltage vector position angle θ calculated using formula (15). ref The sector in which it is located. Figure 4 A schematic diagram of voltage sector distribution is shown. For example, when the calculated voltage vector position angle θ = π / 3, the reference voltage vector U can be determined. ref Located in sector 2.

[0156] In some embodiments, based on the fundamental principles of direct torque control, the stator flux linkage partitioning and voltage vector selection table are used to select the optimal non-zero voltage vector and one zero vector from the sectors as two candidate voltage vectors. For example, when the reference voltage vector U is determined... ref When located in sector 2, u2 can be selected as the optimal non-zero voltage vector.

[0157] Then, the cost is calculated using the cost function:

[0158] g=|U ref -U i | (16)

[0159] Among them, U i These are two candidate voltage vectors located in the sector where the voltage vector position angle θ lies.

[0160] Substitute the two candidate voltage vectors into formula (16) to calculate the corresponding cost function value g, sort the cost function values ​​g, and select the candidate voltage vector that minimizes the cost function value g as the target voltage vector. The target voltage vector acts as the switching control signal of the three-phase inverter and then acts on the permanent magnet synchronous motor through the three-phase inverter.

[0161] The beneficial technical effects of the model predictive torque control method for permanent magnet synchronous motors in this application are mainly reflected in the following: the reference voltage vector to be pre-applied in the next cycle is calculated using the deadbeat prediction principle, and two candidate voltage vectors are determined according to the sector where the reference voltage vector is located, thereby reducing the number of calculations of the cost function to two, and thus reducing the amount of computation.

[0162] Furthermore, in the model predictive torque control method for permanent magnet synchronous motors in this application embodiment, the cost function is the error between the reference voltage vector and the candidate voltage vector, thereby avoiding the selection of weighting coefficients.

[0163] This application also provides a model predictive torque control device 200 for a permanent magnet synchronous motor. For example... Figure 3 As shown, a model predictive torque control device 200 for a permanent magnet synchronous motor according to one embodiment of this application may include a model predictive torque controller 210 and a voltage sector controller 220.

[0164] The model predictive torque controller 210 is established based on the mathematical model of the permanent magnet synchronous motor 100. The model predictive torque controller 210 can predict the torque based on the given torque at time k. Motor speed at time k d-axis and q-axis voltages at time k and the d-axis and q-axis currents at time k Used as input to predict the d-axis and q-axis predicted voltages at time k+1.

[0165] The voltage sector controller 220 can predict the voltage based on the d and q axes at time k+1. and the motor potential angle θ at time k e k Determine the reference voltage vector U in the two-phase stationary α-β coordinate system at time k+1. ref The voltage vector position angle θ is used to determine the sector to which the reference voltage vector belongs based on the voltage vector position angle θ in the α-β coordinate system at time k+1. Two candidate voltage vectors are selected from the sector. Based on the reference voltage vector and the two candidate voltage vectors, the voltage vector that minimizes the function value of the cost function is selected from the two candidate voltage vectors as the target voltage vector through a cost function. The three-phase inverter is controlled based on the target voltage vector, thereby realizing the control of the permanent magnet synchronous motor.

[0166] In some embodiments, the model predictive torque controller 210 may include a maximum torque-to-current ratio (MPTA) control module 211, a one-step delay compensation module 212, a torque and flux prediction module 213, and a voltage reference vector prediction module 214.

[0167] The maximum torque-to-current ratio control module 211 can control the maximum torque-to-current ratio based on the given torque at time k. The ideal flux linkage at time k is obtained by calculating the maximum torque-current ratio.

[0168] The one-beat delay compensation module 212 can adjust the motor speed ω at time k. e k d-axis and q-axis voltages at time k and the d-axis and q-axis currents at time k To predict the d-axis and q-axis currents at time k+1.

[0169] Torque and flux prediction module 213 can predict the current based on the d and q axes at time k+1. To obtain the predicted flux linkage ψ along the d and q axes at time k+1 d k+1 ψ q k+1 and the predicted torque T at time k+1 e k+1 .

[0170] The voltage reference vector prediction module 214 can predict the ideal magnetic flux at time k. The predicted flux linkage ψ along the d and q axes at time k+1 d k+1 ψ q k+1 and the predicted torque T at time k+1 e k+1 To predict the d-axis and q-axis predicted voltages at time k+1.

[0171] In some embodiments, the voltage reference vector prediction module 214 of this application can predict the predicted flux linkage at time k+2, and using the idea of ​​deadbeat-free prediction, predict the ideal flux linkage at time k. As the predicted flux linkage at time k+2 and the given torque at time k As the predicted torque at time k+2, and based on the d and q axes at time k+1, the flux linkage ψ is predicted. d k+1 ψ q k+1 and the predicted torque T at time k+1 e k+1 To predict the d-axis and q-axis voltages at time k+1.

[0172] In some embodiments, the voltage sector controller 220 can directly control the basic principle of torque by using its stator flux linkage partitioning and voltage vector selection table to select the optimal non-zero voltage vector and a zero vector from the sector as two candidate voltage vectors.

[0173] The model predictive torque control device 200 in this embodiment further includes a Park and Clark conversion module 230. The Park and Clark conversion module 230 can be based on the motor potential angle θ of the permanent magnet synchronous motor at time k. e k and the three-phase current at time k The d-axis and q-axis currents at time k are obtained through coordinate transformation.

[0174] The model predictive torque control device 200 in this embodiment further includes a voltage measurement and coordinate transformation module 240. The voltage measurement and coordinate transformation module 240 can obtain the three-phase voltage at the input terminal of the three-phase inverter at time k, and based on the three-phase voltage at time k and the motor potential angle θ at time k... e k The d-axis and q-axis voltages at time k are obtained through coordinate transformation.

[0175] The model predictive torque control device 200 in this embodiment further includes a speed calculation module 250. The speed calculation module 250 can calculate the speed based on the motor potential angle θ of the permanent magnet synchronous motor at time k. e k The motor speed ω at time k is calculated. e k .

[0176] The model predictive torque control device 200 in this embodiment further includes a PI controller 260. The PI controller 260 can adjust the motor speed ω of the permanent magnet synchronous motor at time k. e k and the given motor speed ω * The difference between them and the given torque at time k are given.

[0177] This application also provides a motor controller 400. Figure 5 A schematic block diagram of a motor controller 400 according to one embodiment of this application is shown. Figure 5 As shown, a motor controller 400 of one embodiment of this application includes a memory 401, a processor 402, and a program stored in the memory 401 and executable on the processor 402. When the processor 402 executes the program, it can implement the model predictive torque control method for permanent magnet synchronous motors as described above.

[0178] This application also provides a computer-readable storage medium storing a computer program thereon. When executed by processor 402, the program implements the model predictive torque control method for a permanent magnet synchronous motor as described above.

[0179] The foregoing has provided a detailed description of the model predictive torque control device and method, motor controller, and computer-readable storage medium for permanent magnet synchronous motors provided in the embodiments of this application. Specific examples have been used to illustrate the model predictive torque control device and method, motor controller, and computer-readable storage medium for permanent magnet synchronous motors in the embodiments of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of this application and are not intended to limit this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the spirit and principles of this application, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A model predictive torque control method for a permanent magnet synchronous motor, characterized in that: include: Establish a mathematical model for the permanent magnet synchronous motor; A model predictive torque controller is designed based on the mathematical model of the permanent magnet synchronous motor. Obtain the motor potential angle, the given torque, the motor speed, the d-axis and q-axis voltages, and the d-axis and q-axis currents at time k. The given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k are input into the model predictive torque controller to predict the output d-axis and q-axis predicted voltages at time k+1, specifically including: The ideal flux linkage at time k is calculated using the maximum torque-current ratio based on the given torque at time k. The predicted d-axis and q-axis currents at time k+1 are obtained based on the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k. Based on the predicted d-axis and q-axis currents at time k+1, the predicted flux linkage at time k+1 and the predicted torque at time k+1 are obtained; and The predicted flux linkage at time k+2 is predicted using the idea of ​​no deadbeat. The ideal flux linkage at time k is used as the predicted flux linkage at time k+2, and the given torque at time k is used as the predicted torque at time k+2. Based on the ideal flux linkage at time k, the predicted flux linkages of the d and q axes at time k+1, and the predicted torque at time k+1, the predicted voltages of the d and q axes at time k+1 are predicted. The reference voltage vector and voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 are determined based on the predicted voltages of the d and q axes at time k+1 and the motor potential angle at time k. The sector to which the reference voltage vector belongs is determined based on the voltage vector position angle in the α-β coordinate system at time k+1; Two candidate voltage vectors are selected from the sector, including an optimal non-zero voltage vector and a zero vector; Based on the reference voltage vector and the two candidate voltage vectors, a cost function is used to select the voltage vector that minimizes the function value of the cost function from the two candidate voltage vectors as the target voltage vector. The cost function is the error between the reference voltage vector and the candidate voltage vectors and does not include weighting coefficients. The three-phase inverter is controlled based on the target voltage vector, which in turn controls the permanent magnet synchronous motor.

2. The model predictive torque control method as described in claim 1, characterized in that: The mathematical model for establishing the permanent magnet synchronous motor includes: Establish the voltage equations for the permanent magnet synchronous motor along the dq axis: （1） in, For stator resistance, For d-axis current, For q-axis current, The voltage along the d-axis. This is the q-axis voltage. For the d-axis flux linkage, For q-axis flux linkage, This refers to the motor speed; Establish the flux linkage equation of the permanent magnet synchronous motor on the dq axis: （2） in, For rotor flux linkage, For stator inductance; and Establish the torque equation of the permanent magnet synchronous motor: （3） in, The torque of the permanent magnet synchronous motor is... denoted as the number of pole pairs of the permanent magnet synchronous motor.

3. The model predictive torque control method as described in claim 1, characterized in that: The step of predicting the d-axis and q-axis currents at time k+1 based on the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k includes: Predict the d-axis and q-axis flux linkages at time k+1, and apply the forward Euler method to equation (1) to obtain: （4） Where k is the current sampling time, and k+1 is the next sampling time. , The flux linkages along the d and q axes at time k are respectively. , d and q axis predicted flux linkages at time k+1, respectively, and T is the prediction time period; Substituting equation (2) into equation (4) and discretizing it with a period of T, we obtain the equations for the predicted d-axis and q-axis currents at time k+1: （5） in, , Let be the d-axis and q-axis currents at time k, respectively. Let k be the motor speed at time k. , The d-axis and q-axis voltages at time k are respectively. , The d-axis and q-axis predicted currents at time k+1 are respectively.

4. The model predictive torque control method as described in claim 3, characterized in that: The process of obtaining the predicted flux linkage and predicted torque at time k+1 based on the predicted d-axis and q-axis currents at time k+1 includes: Substituting equation (5) into the flux linkage equation (2) and the torque equation (3) of the dq axis respectively, we obtain the equations for the predicted flux linkage of the d and q axes at time k+1 and the equations for the predicted torque at time k+1: （6） in, Predict the flux linkage along the d-axis at time k+1. Predict the flux linkage along the q-axis at time k+1. This represents the predicted torque at time k+1.

5. The model predictive torque control method as described in claim 1, characterized in that: The ideal flux linkage at time k is calculated using the following formula: （7） in, Let be the ideal magnetic flux linkage at time k. Let k be the given torque at time k.

6. The model predictive torque control method as described in claim 1, characterized in that: The step of predicting the d-axis and q-axis predicted voltage at time k+1 based on the ideal flux linkage at time k, the predicted flux linkage along the d and q axes at time k+1, and the predicted torque at time k+1 includes: By combining equations (1) and (2) and discretizing the flux linkage equation of the dq axis, the flux linkage equation at time k+2 is obtained: （8） in, , The predicted flux linkages along the d and q axes at time k+2 are respectively. , These are the predicted voltages along the d and q axes at time k+1, respectively. Using the concept of deadbeat-free operation, the ideal flux linkage at time k is taken as the predicted flux linkage at time k+2, and combined with formula (3), while ignoring the resistance term in formula (3), we obtain... （9） Differentiating equation (3) with respect to time and discretizing it, and combining it with equation (2), we get: （10） in, The predicted torque at time k+2, The predicted torque at time k+1 Predict the q-axis current at time k+2; Substituting formula (8) into formula (10), we get: （11） Using the concept of deadbeat-free timing, the given torque at time k is... The predicted torque at time k+2 Combining formulas (9) and (10), the predicted d-axis and q-axis voltages at time k+1 are obtained: （12） in, （13）。 7. The model predictive torque control method as described in claim 1, characterized in that: The determination of the reference voltage vector in the two-phase stationary α-β coordinate system at time k+1 based on the predicted voltages of the d and q axes at time k+1 and the motor potential angle at time k includes: The predicted d-axis and q-axis voltages at time k+1 are transformed by Clark into voltage components in a two-phase stationary α-β coordinate system to obtain the reference voltage vector in the α-β coordinate system at time k+1: （14） in, Let be the motor potential angle of the permanent magnet synchronous motor at time k. , These are the predicted voltage components along the α and β axes at time k+1, respectively. Let be the reference voltage vector in the α-β coordinate system at time k+1.

8. The model predictive torque control method as described in claim 7, characterized in that: Determining the voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 includes: The voltage vector position angle in the α-β coordinate system at time k+1 is calculated based on the predicted voltage components along the α and β axes at time k+1. （15） in, The voltage vector position angle.

9. The model predictive torque control method as described in claim 1, characterized in that: The step of selecting two candidate voltage vectors from the sector includes: Based on the fundamental principle of direct torque control, the stator flux linkage partitioning and voltage vector selection table are used to select the optimal non-zero voltage vector and a zero vector from the sector as the two candidate voltage vectors.

10. The model predictive torque control method as described in claim 1, characterized in that: Also includes: Obtain the three-phase current of the permanent magnet synchronous motor at time k; and Based on the motor potential angle and the three-phase current at time k, and after coordinate transformation, the d-axis and q-axis currents at time k are obtained.

11. The model predictive torque control method as described in claim 1, characterized in that: Also includes: Obtain the three-phase voltage at time k at the input terminal of the three-phase inverter; and Based on the motor potential angle and the three-phase voltage at time k, the d-axis and q-axis voltages at time k are obtained through coordinate transformation.

12. The model predictive torque control method as described in claim 1, characterized in that: Also includes: The motor speed at time k is calculated based on the motor potential angle at time k.

13. A model predictive torque control device for a permanent magnet synchronous motor, characterized in that, The device employs the model predictive torque control method for permanent magnet synchronous motors according to any one of claims 1-12, comprising: A model predictive torque controller, designed based on an established mathematical model of a permanent magnet synchronous motor, is used to predict the output d-axis and q-axis voltages at time k+1 based on the given torque at time k, the motor speed at time k, the d-axis and q-axis voltages at time k, and the d-axis and q-axis currents at time k as inputs. A voltage sector controller is used to determine the reference voltage vector and voltage vector position angle in the two-phase stationary α-β coordinate system at time k+1 based on the predicted d-axis and q-axis voltages at time k+1 and the motor potential angle at time k; determine the sector to which the reference voltage vector belongs based on the voltage vector position angle in the α-β coordinate system at time k+1; select two candidate voltage vectors from the sector; select the voltage vector that minimizes the function value of the cost function from the two candidate voltage vectors based on the reference voltage vector and the two candidate voltage vectors, and use a cost function as the target voltage vector; and control the three-phase inverter based on the target voltage vector, thereby controlling the permanent magnet synchronous motor.

14. The model predictive torque control device as described in claim 13, characterized in that: The model predictive torque controller includes: The maximum torque-to-current ratio control module is used to calculate the ideal flux linkage at time k based on the given torque at time k using the maximum torque-to-current ratio. The one-step delay compensation module is used to predict the d and q axis currents at time k+1 based on the motor speed at time k, the d and q axis voltages at time k, and the d and q axis currents at time k. A torque and flux linkage prediction module is used to obtain the predicted flux linkage and predicted torque at time k+1 based on the predicted d-axis and q-axis currents at time k+1. The voltage reference vector prediction module is used to predict the d-axis and q-axis predicted voltage at time k+1 based on the ideal flux linkage at time k, the predicted flux linkages along the d and q axes at time k+1, and the predicted torque at time k+1.

15. The model predictive torque control device as described in claim 14, characterized in that: The voltage reference vector prediction module is used to predict the predicted flux linkage at time k+2. Using the idea of ​​no deadbeat, the ideal flux linkage at time k is used as the predicted flux linkage at time k+2, and the given torque at time k is used as the predicted torque at time k+2. Based on the predicted flux linkages of the d and q axes at time k+1 and the predicted torque at time k+1, the predicted voltages of the d and q axes at time k+1 are predicted.

16. The model predictive torque control device as described in claim 13, characterized in that: The basic principle of the voltage sector controller for direct torque control is to use its stator flux linkage partitioning and voltage vector selection table to select the optimal non-zero voltage vector and a zero vector from the sector as the two candidate voltage vectors.

17. The model predictive torque control device as described in claim 13, characterized in that: Also includes: The Park and Clark transformation modules are used to obtain the d-axis and q-axis currents at time k based on the motor potential angle and the three-phase current at time k of the permanent magnet synchronous motor through coordinate transformation.

18. The model predictive torque control device as described in claim 13, characterized in that: Also includes: The voltage measurement and coordinate transformation module is used to obtain the three-phase voltage at the input terminal of the three-phase inverter at time k, and to obtain the d-axis and q-axis voltages at time k based on the three-phase voltage at time k and the motor potential angle at time k through coordinate transformation.

19. The model predictive torque control device as described in claim 13, characterized in that: Also includes: The speed calculation module is used to calculate the motor speed at time k based on the motor potential angle of the permanent magnet synchronous motor at time k.

20. A motor controller, characterized in that: include: A memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the model predictive torque control method for a permanent magnet synchronous motor as described in any one of claims 1-12.

21. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the model predictive torque control method for permanent magnet synchronous motors as described in any one of claims 1-12.

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