A finite set model predictive current control method for permanent magnet synchronous motors

Abstract

The present invention relates to the field of motor control technology, and specifically provides a finite set model predictive current control method for a permanent magnet synchronous motor. The method first establishes a mathematical model of the permanent magnet synchronous motor including parameter mismatch, then designs a sliding mode disturbance observer based on the motor model, performs delay compensation based on the current estimate output by the sliding mode disturbance observer, extracts the inductance offset from the disturbance estimate output by the sliding mode disturbance observer, and performs inductance mismatch compensation. The method also utilizes a model reference adaptive method to compensate for flux linkage parameter mismatch. The present invention improves the delay compensation link and performs parameter compensation on the discrete model of the permanent magnet synchronous motor in the model predictive current control, effectively solving the current harmonic distortion problem caused by motor parameter mismatch and improving system robustness.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and in particular relates to a current control method for a permanent magnet synchronous motor using a finite set model. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in robotics, automotive drive systems, and intelligent manufacturing due to their significant advantages, including high efficiency, high energy density, and easy maintenance. With the rapid development of related manufacturing industries, PMSMs are placing higher demands on efficient and reliable control strategies. Model predictive current control (MPC) is increasingly considered a viable alternative for power electronics and motor drive applications, offering advantages such as strong dynamic performance, ease of implementation, and the ability to add constraints. MPC uses a discrete model of the PMSM and its current state to predict future current states. It then uses a pre-designed cost function to select the optimal voltage vector from eight candidate vectors. However, this process requires extensive computation and can result in significant time delays. Furthermore, the accuracy of the output vector is critically dependent on the precision of the motor model parameters, compromising the robustness of the control system. Summary of the Invention

[0003] In view of this, the present invention aims to provide a finite set model predictive current control method for a permanent magnet synchronous motor, which can significantly improve the robustness of the control system to motor parameter mismatch and reduce the current ripple caused by the time delay in the voltage selection process, thereby reducing the total harmonic distortion of the system current.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] The present invention provides a method for predicting current control of a permanent magnet synchronous motor using a finite set model, comprising:

[0006] Establish a mathematical model of permanent magnet synchronous motor including disturbance;

[0007] A sliding mode disturbance observer is designed based on the mathematical model of the permanent magnet synchronous motor. The current estimation and disturbance estimation obtained by the sliding mode disturbance observer are then compensated for the delay of the current estimation.

[0008] Extract inductance offset based on disturbance estimation and perform inductance mismatch compensation;

[0009] Based on the voltage equation of permanent magnet synchronous motor, the model reference adaptive method is used to compensate for the flux parameter mismatch.

[0010] Preferably, the mathematical model of the permanent magnet synchronous motor including disturbance is:

[0011] ;

[0012] in, represents the nominal resistance of the motor, represents the nominal flux linkage of the motor, represents the nominal inductance, represents the d-axis stator voltage of the motor, represents the q-axis stator voltage of the motor, represents the d-axis stator current of the motor, represents the q-axis stator current of the motor, represents the derivative of the motor's d-axis stator current, represents the derivative of the motor's q-axis stator current, represents the motor electrical angular velocity, represents the d-axis disturbance caused by parameter mismatch, represents the q-axis disturbance caused by parameter mismatch, represents the rate of change of the d-axis disturbance caused by parameter mismatch, which is equal to The derivative of represents the rate of change of the q-axis disturbance caused by parameter mismatch, which is equal to The derivative of .

[0013] Preferably, the calculation formulas for the d-axis disturbance and the q-axis disturbance are:

[0014] ;

[0015] in, Indicates the offset value of the inductance, Indicates the offset value of the resistor, Indicates the offset value of the magnetic flux.

[0016] Preferably, the sliding mode disturbance observer is:

[0017] ;

[0018] in, represents the d-axis current estimate, represents the q-axis current estimate, represents the derivative of the d-axis current estimate, represents the derivative of the q-axis current estimate, represents the d-axis perturbation estimate, represents the q-axis disturbance estimate, represents the derivative of the d-axis perturbation estimate, represents the derivative of the q-axis disturbance estimate, represents the d-axis sliding mode function, represents the q-axis sliding mode function, represents the d-axis sliding mode control gain, represents the q-axis sliding mode control gain.

[0019] Preferably, both the d-axis and the q-axis adopt a uniform approach rate to design the sliding mode surface, and the dynamic behavior of the sliding mode surface of the sliding mode disturbance observer is expressed as follows:

[0020] ;

[0021] in, Represents a positive number, represents the sliding surface, represents the derivative of the sliding surface;

[0022] For the motor d-axis, its sliding surface ,in, represents the error between the estimated and actual current of the d-axis;

[0023] For the motor q axis, its sliding surface ,in, It represents the error between the estimated current and the actual current of the q-axis;

[0024] The sliding stability condition of the sliding mode disturbance observer is:

[0025] ;

[0026] in, represents the error between the d-axis disturbance estimate and the actual disturbance, , represents the error between the q-axis disturbance estimate and the actual disturbance, .

[0027] Preferably, performing delay compensation by a sliding mode disturbance observer includes:

[0028] The sliding mode disturbance observer is discretized, and the discretized sliding mode disturbance observer is obtained as follows:

[0029] ;

[0030] in, is the coefficient, , Indicates the sampling period of motor A system, represents the d-axis current at the kth moment, represents the q-axis current at the kth moment, represents the d-axis voltage at the kth moment, represents the q-axis voltage at the kth moment, represents the d-axis current estimation at the kth moment, represents the q-axis current estimation at the kth moment, represents the d-axis current estimation at the k+1th moment, represents the q-axis current estimation at the k+1th moment, represents the d-axis disturbance estimate at the kth moment, represents the q-axis disturbance estimate at the kth moment, represents the d-axis disturbance estimate at the k+1th moment, represents the q-axis disturbance estimate at time k+1;

[0031] The d-axis and q-axis currents at the k+1th moment are estimated using the output of the sliding mode disturbance observer. and Update the d-axis and q-axis currents at the kth moment in the mathematical model of the discretized permanent magnet synchronous motor without considering disturbances and , the update calculation formula for delay compensation is:

[0032] ;

[0033] in, represents the d-axis current at the k+2th moment, represents the q-axis current at the k+2th moment.

[0034] Preferably, the process of inductance mismatch compensation includes:

[0035] The difference between the d-axis disturbance estimate and the expected disturbance based on the output of the sliding mode disturbance observer at the kth moment , then Perform low-pass filtering and calculate the inductance offset. Add the inductance offset to the nominal inductance to obtain the compensated inductance value. The calculation formula for the compensated inductance value is:

[0036] ;

[0037] in, express The result after low-pass filtering is represents the inductance offset, represents the inductance value after compensation, and s represents the complex parameter variable in the Laplace transform.

[0038] Preferably, the voltage equation of the permanent magnet synchronous motor is:

[0039] .

[0040] Preferably, the reference model in the model reference adaptive method based on the voltage equation of the permanent magnet synchronous motor is:

[0041] ;

[0042] in, , , , , , ;

[0043] The adjustable model in the model reference adaptive method is established as:

[0044] ;

[0045] in, represents the estimated value of the corresponding parameter;

[0046] The state error vector can be obtained from the reference model and the adjustable model The derivative of for:

[0047] ;

[0048] in, , , , .

[0049] Preferably, the parameter adaptation rule designed based on the model reference adaptation method is:

[0050] ;

[0051] in, Indicates adjustable parameters The initial value of Indicates adjustable parameters The initial value of represents the state error vector The component on the d-axis, represents the state error vector The component on the q-axis, , Respectively express the 、 The proportional parameter corresponding to the proportional-integral controller used when , Respectively express the 、 The integral parameter corresponding to the proportional-integral controller used when

[0052] By adjustable parameters and adjustable parameters Obtain the estimated flux linkage after parameter mismatch compensation for:

[0053] .

[0054] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0055] The present invention effectively solves the impact of motor parameter mismatch and time delay by combining a sliding mode disturbance observer with model reference adaptive control, and makes innovative improvements to the traditional delay compensation link. The d-axis and q-axis current estimates at the next moment obtained by the sliding mode disturbance observer replace the current d-axis and q-axis currents in the traditional discrete permanent magnet synchronous motor mathematical model that does not consider disturbances. The present invention uses a sliding mode disturbance observer to replace the traditional single-step delay compensation, which can effectively reduce the current ripple caused by the delay in the voltage selection process and improve the accuracy of the predicted current.

[0056] The present invention extracts the inductance offset by using the disturbance estimation obtained by the sliding mode disturbance observer and performs compensation, thereby significantly reducing the influence of current harmonics caused by inductance mismatch.

[0057] The present invention adopts a model reference adaptive method to identify the permanent magnet flux parameters of a permanent magnet synchronous motor, and performs system design based on the Popov hyperstability theory. Through an adaptive law in the form of proportional-integral control, the state error is converged to zero, preventing the adjustment effect from weakening due to the state error approaching zero, effectively ensuring the global stability of the adaptive control, and calculating the required flux estimation value after parameter mismatch compensation based on the obtained adjustable parameters, thereby effectively suppressing the current harmonics caused by the flux mismatch. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0059] Figure 1 This is a structural block diagram of a finite set model predictive current control for a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0060] Figure 2 3. This is a comparison diagram of the effects of using a sliding mode observer single-step delay compensation and traditional single-step compensation according to an embodiment of the present invention;

[0061] Figure 3 This is a current response effect diagram of a conventional finite set model predicting current control when the inductance of a permanent magnet synchronous motor undergoes a sudden change under a load of 5 N·m and the motor speed is 500 r / min according to an embodiment of the present invention;

[0062] Figure 4 This is a current response effect diagram of a permanent magnet synchronous motor under a load of 5 N·m and a motor speed of 500 r / min, provided by an embodiment of the present invention, where the inductance of the permanent magnet synchronous motor undergoes a sudden change using a traditional finite set model predictive current control and a model reference adaptive method for parameter compensation;

[0063] Figure 5This is a current response effect diagram of parameter compensation performed by the method of the present invention when the inductance of a permanent magnet synchronous motor undergoes a sudden change under a load of 5 N·m and the motor speed is 500 r / min according to an embodiment of the present invention;

[0064] Figure 6 This is a current response effect diagram of a conventional finite set model predictive current control of a permanent magnet synchronous motor with a sudden change in flux linkage under a load of 5 N·m and a motor speed of 500 r / min according to an embodiment of the present invention;

[0065] Figure 7 This is a current response effect diagram of a permanent magnet synchronous motor with a sudden change in flux linkage under a load of 5 N·m and a motor speed of 500 r / min provided by an embodiment of the present invention, using a model reference adaptive method for parameter compensation under conventional finite set model predictive current control;

[0066] Figure 8 This is a current response effect diagram of parameter compensation using the method of the present invention when a sudden change in flux linkage occurs in a permanent magnet synchronous motor under a load of 5 N·m and the motor speed is 500 r / min according to an embodiment of the present invention. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0068] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0069] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0070] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0071] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0072] In one embodiment of the present invention, a method for predicting current control of a permanent magnet synchronous motor using a finite set model is provided, which is specifically applied to Figure 1 In the permanent magnet synchronous motor current control structure shown in FIG,

[0073] PI controller is used to adjust the speed according to the given The actual speed of the motor The difference between the two values ​​is regulated by PI to generate a regulation signal and adjust the current reference value. and , ensuring that the motor speed stably tracks the reference speed.

[0074] The cost function is mainly based on the d-axis and q-axis current reference values and And predict the current value, evaluate the control effect of different voltage vectors, and select the optimal voltage vector , to minimize the current error. The goal of the finite set model predictive current control is to select the optimal solution from the eight voltage vectors, so the cost function in the figure can be expressed as:

[0075] (1)

[0076] in, and denote the d-axis and q-axis reference currents, respectively, and is set to 0, and Determined by the output of the proportional-integral controller in the speed loop.

[0077] The inverter switches according to the selected control signal , converting DC power into three-phase AC power to drive the permanent magnet synchronous motor.

[0078] The encoder is used to collect the motor speed.

[0079] The prediction model mainly predicts the d-axis and q-axis currents at the next moment based on the current control input and motor parameters, such as inductance and magnetic flux, and provides the predicted current for the value function.

[0080] Since the prediction model needs to use motor parameters when predicting current, but the mismatch problem of motor parameters will introduce disturbances, resulting in increased total harmonic distortion of current, the embodiment of the present invention designs a sliding mode disturbance observer, which uses the current estimation and disturbance estimation of the sliding mode disturbance observer to perform delay compensation, inductance offset extraction, and flux extraction using model reference adaptation, thereby compensating for the above-mentioned mismatched parameters. Specifically, the permanent magnet synchronous motor finite set model prediction current control method includes the following steps:

[0081] S1: First, establish the voltage equation of the permanent magnet synchronous motor, which can be expressed as:

[0082] (2)

[0083] This formula does not take into account the permanent magnet synchronous motor parameter mismatch, where: represents the nominal resistance of the permanent magnet synchronous motor, represents the nominal flux linkage of the permanent magnet synchronous motor, Indicates the nominal inductance. Since the d-axis and q-axis inductances of the surface-mounted permanent magnet synchronous motor are consistent, express, represents the d-axis stator voltage of the motor, represents the q-axis stator voltage of the motor, represents the d-axis stator current of the motor, represents the q-axis stator current of the motor, represents the derivative of the d-axis stator current of the motor, represents the derivative of the motor's q-axis stator current, Indicates the motor electrical angular velocity.

[0084] Based on the voltage equation of the permanent magnet synchronous motor shown in formula (2), considering the disturbance introduced by parameter mismatch, a mathematical model of the permanent magnet synchronous motor including disturbance is established, or it is called the dq-axis voltage model of the permanent magnet synchronous motor including disturbance. The expression of this model is as follows:

[0085] (3)

[0086] in, represents the d-axis disturbance caused by parameter mismatch, represents the q-axis disturbance caused by parameter mismatch, represents the rate of change of the d-axis disturbance caused by parameter mismatch, which is equal to The derivative of represents the rate of change of the q-axis disturbance caused by parameter mismatch, which is equal to The derivative of .

[0087] For the perturbation in formula (3) and , the calculation formulas for d-axis perturbation and q-axis perturbation are defined as:

[0088] (4)

[0089] in, Indicates the offset value of the inductance, Indicates the offset value of the resistor, Indicates the offset value of the magnetic flux.

[0090] S2: Based on the mathematical model of the permanent magnet synchronous motor with disturbance shown in equation (3), a sliding mode disturbance observer about the dq axis is designed and expressed as:

[0091] (5)

[0092] in, represents the d-axis current estimate, represents the q-axis current estimate, represents the derivative of the d-axis current estimate, represents the derivative of the q-axis current estimate, represents the d-axis perturbation estimate, represents the q-axis disturbance estimate, represents the derivative of the d-axis perturbation estimate, represents the derivative of the q-axis disturbance estimate, represents the d-axis sliding mode function, represents the q-axis sliding mode function, represents the d-axis sliding mode control gain, represents the q-axis sliding mode control gain.

[0093] In order to improve the accuracy of the sliding mode disturbance observer and its ability to track high-frequency disturbances, the present invention uses a uniform approach rate to design the sliding mode surface for both the motor's d-axis and q-axis. The design of the uniform approach rate can avoid system jitter or slow response caused by the sliding mode surface reaching too fast or too slow, thereby improving the observer's ability to track high-frequency disturbances. The expression of the designed sliding mode surface dynamic behavior is:

[0094] (6)

[0095] in, Represents a positive number, represents the selected sliding surface, represents the derivative of the sliding surface.

[0096] For the motor d-axis, its sliding surface ,in, It represents the error between the estimated d-axis current and the actual current.

[0097] For the motor q axis, its sliding surface ,in, It represents the error between the estimated current and the actual current of the q-axis.

[0098] Furthermore, by subtracting Equation (3) from Equation (5), we can obtain the dynamic equation of the observer's estimation error for the system disturbance, and substitute it into Equation (6) to solve the condition that the parameter C needs to satisfy when the system reaches the stable condition.

[0099] In order to achieve sliding mode, stability conditions need to be achieved , at this time need to meet:

[0100] (7)

[0101] in, represents the error between the d-axis disturbance estimate and the actual disturbance, , represents the error between the q-axis disturbance estimate and the actual disturbance, .

[0102] In the sliding mode, the value of the sliding surface can gradually approach zero, which enables the system state to slide along the sliding surface and achieve dynamic compensation effect for disturbances.

[0103] The sliding mode disturbance observer is discretized, and the discretized sliding mode disturbance observer is obtained as follows:

[0104] (8)

[0105] in, is the coefficient, , represents the motor system sampling period, represents the d-axis current at the kth moment, represents the q-axis current at the kth moment, represents the d-axis voltage at the kth moment, represents the q-axis voltage at the kth moment, represents the d-axis current estimation at the kth moment, represents the q-axis current estimation at the kth moment, represents the d-axis current estimation at the k+1th moment, represents the q-axis current estimation at the k+1th moment, represents the d-axis disturbance estimate at the kth moment, represents the q-axis disturbance estimate at the kth moment, represents the d-axis disturbance estimate at the k+1th moment, represents the q-axis disturbance estimate at the k+1th moment.

[0106] After the sliding mode disturbance observer is discretized, the estimated value of the system disturbance is updated in each sampling period. As can be seen from Equation (8), the sliding mode disturbance observer can dynamically compensate for the current at the next moment, thereby reducing the impact of parameter mismatch and external interference on the system, reducing current ripple, and improving the accuracy of current control and system stability.

[0107] The present invention uses the k+1th moment d-axis and q-axis currents output by the sliding mode observer to estimate and Update the d-axis and q-axis currents at the kth moment in the mathematical model of the discretized permanent magnet synchronous motor without considering disturbances and In the traditional finite set model predictive control, in order to select the optimal inverter voltage vector, the voltage equation of the permanent magnet synchronous motor represented by formula (2) is discretized and then a prediction model is established. The mathematical model obtained after discretization is expressed as:

[0108] (9)

[0109] The embodiment of the present invention uses the sliding mode observer output at the k+1th moment d-axis and q-axis current estimation and Substitute the formula (9) and , to replace the traditional single-step compensation method, the delay compensation update calculation formula of the embodiment of the present invention is:

[0110] (10)

[0111] in, represents the d-axis current at the k+2th moment, represents the q-axis current at the k+2th moment.

[0112] S3: For inductance mismatch compensation, the present invention designs an inductance extraction method by d-axis perturbation. It can be found that the d-axis disturbance contains the inductance offset In addition, since the motor adopts field oriented control (FOC), , so consider the d-axis disturbance estimate output from the sliding mode disturbance observer at the kth moment Specifically, the difference between the d-axis disturbance estimate output by the sliding mode disturbance observer at the kth moment and the expected disturbance is After low-pass filtering, the extracted inductance offset value is more accurate and can effectively reflect the difference between the actual inductance and the nominal inductance. After low-pass filtering, the difference is used to calculate the inductance offset, and the inductance offset is added to the nominal inductance to obtain the compensated inductance value. In summary, the calculation formula for the compensated inductance value is:

[0113] (11)

[0114] in, express The result after low-pass filtering is represents the inductance offset, represents the inductance value after compensation, and s represents the complex parameter variable in the Laplace transform.

[0115] S4: The q-axis current prediction error of a permanent magnet synchronous motor is usually caused by permanent magnet flux mismatch, which directly affects torque control, increases ripple interference, and even reduces system stability. Therefore, the present invention uses a model reference adaptive method to identify and compensate for the permanent magnet flux parameters. Specifically, based on the voltage equation of the permanent magnet synchronous motor shown in equation (2), the reference model in the model reference adaptive method is derived as follows:

[0116] (12)

[0117] in, , , , , , .

[0118] Formula (12) is the reference model for parameter identification. 、 express 、 The estimated value of 、 and As motor parameters 、 and Therefore, the adjustable model in the model reference adaptive method is:

[0119] (13)

[0120] in, denotes the estimated value of the corresponding parameter.

[0121] The state error vector can be obtained by subtracting the adjustable model represented by equation (13) from the reference model represented by equation (12). The derivative of for:

[0122] (14)

[0123] in, , , , .

[0124] Considering the complexity of controller design and stability proof in model reference adaptation, the embodiment of the present invention adopts Popov's hyperstability theory for system design, which is conducive to ensuring the global stability of the adaptive control system. According to Popov's stability theory, the conditions for system stability are as follows:

[0125] (1) The transfer function matrix of the linear forward block must be a strictly positive real number;

[0126] (2) The nonlinear feedback block must satisfy the Popov integral inequality.

[0127] For condition (1), we can use Prove that, is the unit matrix, and s represents the complex parameter in the Laplace transform.

[0128] For condition (2), the following inequality needs to be satisfied:

[0129] (15)

[0130] in Represents the input vector of the system The transpose of represents the output vector, represents the stability limit constant, and represent the lower and upper bounds of the integration time, respectively.

[0131] Based on the adaptive control theory, in the stable state of the system, the state error vector is guaranteed by adopting a specific adaptive law adjustable parameter model. Converges to zero. In order to prevent the adjustment effect from increasing with the state error As it approaches zero, it becomes weaker. The adaptive law is usually designed as a proportional integral control form. The specific parameter adaptive law can be expressed as:

[0132] (16)

[0133] (17)

[0134] in, Indicates adjustable parameters The initial value of Indicates adjustable parameters The initial value of , , , is the proportional integral term to be determined, represents the integration variable.

[0135] Substitute equations (16) and (17) into equation (15), and replace the and Substitute into formula (14) and , from this we can get the parameter adaptation law:

[0136] (18)

[0137] Solving Equation (18), the parameter adaptation rule finally designed is:

[0138] (19)

[0139] Furthermore, the adjustable parameters and adjustable parameters Obtain the estimated flux linkage after parameter mismatch compensation for:

[0140] (20)

[0141] Among them, the adjustable parameters and Adaptively update the model parameters. When the system is stable, the estimated This can indicate accurate magnetic flux identification results.

[0142] In order to verify the effectiveness and progress of the method of the present invention, a simulation comparison experiment was carried out, and the following results were obtained:

[0143] For the delay compensation scheme, all other processes and conditions except delay compensation in the experiment are kept the same, and the sliding mode disturbance observer single-step compensation method of the present invention and the traditional single-step compensation method are used to control the motor. The three-phase current of the motor is measured to obtain the following Figure 2 The total harmonic distortion (THD) value of the current is shown. Figure 2 It can be seen that regardless of whether parameter mismatch occurs, the total harmonic distortion (THD) of the current measured using the sliding mode disturbance observer instead of the single-step delay compensation method decreases. This demonstrates that the present invention, based on the sliding mode disturbance observer, can better perform single-step delay compensation, reduce current harmonics, and improve the accuracy of current prediction.

[0144] For inductor mismatch compensation, such as Figure 3 、 Figure 4 and Figure 5 The figures show the current response of the conventional finite set model predictive current control, the combined conventional finite set model predictive current control and model reference adaptive method, and the invented method, respectively, when the inductance of a permanent magnet synchronous motor undergoes a sudden change at a motor speed of 500 r / min and a load of 5 N·m. For convenience, these three methods are referred to below as the conventional method, the comparative method, and the invented method, respectively. and Respectively represent the actual inductance value and nominal inductance value of the motor. From the comparison of the three figures, it can be found that when When , the dq axis current harmonics of all three methods will be reduced. Compared with the other two methods, the method of the present invention further reduces the current harmonics thanks to the sliding mode disturbance observer. When , there is a slight difference in the dq axis current harmonics between the comparison method and the traditional method. However, the invented method effectively reduces the total harmonic distortion value of the current from 7.82% to 6.8%. When the dq axis current ripple in the traditional MPCC is large, and the reference current offset may cause motion speed deviation. The comparison method can eliminate the reference current offset and reduce the total harmonic distortion value of the current from 18.2% to 14.82%. The method further reduces the total harmonic distortion value of the current to 12.1% based on eliminating the reference current offset. Therefore, it can be concluded that the method of the present invention can significantly reduce the harmonic impact of the current caused by inductance mismatch.

[0145] For flux parameter mismatch compensation, such as Figure 6 、 Figure 7 and Figure 8 As shown, they respectively represent the current response effect diagrams of traditional finite set model predictive current control, traditional finite set model predictive current control combined with model reference adaptive method, and the method of the present invention when the motor speed is 500r / min and the permanent magnet synchronous motor flux linkage suddenly changes under a load of 5N·m. and Represent the actual inductance value and the nominal inductance value of the motor respectively. From the comparison of the three figures, it can be found that when the permanent magnet flux of the permanent magnet synchronous motor is mismatched, the traditional method will not only increase the q-axis current harmonics, but also cause the q-axis reference current to shift, resulting in the output current being unable to track the reference current well. Although the comparison method can eliminate the offset of the q-axis reference current, the q-axis current will also produce harmonics when facing a flux mismatch, but the total harmonic distortion value of the current is lower than that of the traditional method. The method of the present invention can significantly reduce the current harmonics and eliminate the offset of the q-axis reference current in a steady state. This shows that the method of the present invention can achieve better performance when the motor flux parameters are mismatched.

[0146] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification shall be included in the scope of protection of this specification.

[0147] The systems, devices, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0148] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0149] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0150] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A method for predicting current control of a permanent magnet synchronous motor using a finite set model, characterized in that: include: Establish a mathematical model of permanent magnet synchronous motor including disturbance; A sliding mode disturbance observer is designed based on the mathematical model of the permanent magnet synchronous motor. The current estimation and disturbance estimation obtained by the sliding mode disturbance observer are then subjected to delay compensation for the current estimation. The sliding mode disturbance observer is: ； in, represents the d-axis current estimate, represents the q-axis current estimate, represents the derivative of the d-axis current estimate, represents the derivative of the q-axis current estimate, represents the d-axis perturbation estimate, represents the q-axis disturbance estimate, represents the derivative of the d-axis perturbation estimate, represents the derivative of the q-axis disturbance estimate, represents the d-axis sliding mode function, represents the q-axis sliding mode function, represents the d-axis sliding mode control gain, represents the q-axis sliding mode control gain, represents the d-axis stator current of the motor, represents the q-axis stator current of the motor, represents the d-axis stator voltage of the motor, represents the q-axis stator voltage of the motor, represents the nominal resistance of the motor, represents the nominal flux linkage of the motor, represents the nominal inductance, Indicates the motor electrical angular velocity; Performing delay compensation by the sliding mode disturbance observer includes: The sliding mode disturbance observer is discretized to obtain the discretized sliding mode disturbance observer: ； in, is the coefficient, , Indicates the sampling period of motor A system, represents the d-axis current at the kth moment, represents the q-axis current at the kth moment, represents the d-axis voltage at the kth moment, represents the q-axis voltage at the kth moment, represents the d-axis current estimation at the kth moment, represents the q-axis current estimation at the kth moment, represents the d-axis current estimation at the k+1th moment, represents the q-axis current estimation at the k+1th moment, represents the d-axis disturbance estimate at the kth moment, represents the q-axis disturbance estimate at the kth moment, represents the d-axis disturbance estimate at the k+1th moment, represents the q-axis disturbance estimate at time k+1; The d-axis and q-axis currents at the k+1th moment output by the sliding mode disturbance observer are estimated. and Update the d-axis and q-axis currents at the kth moment in the mathematical model of the discretized permanent magnet synchronous motor without considering disturbances and , the update calculation formula for delay compensation is: ； in, represents the d-axis current at the k+2th moment, represents the q-axis current at the k+2th moment; Extract the inductance offset based on the disturbance estimation and perform inductance mismatch compensation; The difference between the d-axis disturbance estimation output by the sliding mode disturbance observer at the kth moment and the expected disturbance , then Perform low-pass filtering and calculate the inductance offset. Add the inductance offset to the nominal inductance to obtain the compensated inductance value. The calculation formula for the compensated inductance value is: ； in, express The result after low-pass filtering is represents the inductance offset, represents the inductance value after compensation, and s represents the complex parameter variable in Laplace transform; Based on the voltage equation of permanent magnet synchronous motor, the model reference adaptive method is used to compensate for the flux parameter mismatch.

2. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 1, wherein: The mathematical model of the permanent magnet synchronous motor including disturbance is: ； in, represents the nominal resistance of the motor, represents the nominal flux linkage of the motor, represents the nominal inductance, represents the d-axis stator voltage of the motor, represents the q-axis stator voltage of the motor, represents the d-axis stator current of the motor, represents the q-axis stator current of the motor, represents the derivative of the motor's d-axis stator current, represents the derivative of the motor's q-axis stator current, represents the motor electrical angular velocity, represents the d-axis disturbance caused by parameter mismatch, represents the q-axis disturbance caused by parameter mismatch, represents the rate of change of the d-axis disturbance caused by parameter mismatch, which is equal to The derivative of represents the rate of change of the q-axis disturbance caused by parameter mismatch, which is equal to The derivative of .

3. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 2, wherein: The calculation formulas for d-axis disturbance and q-axis disturbance are: ； in, Indicates the offset value of the inductance, Indicates the offset value of the resistor, Indicates the offset value of the magnetic flux.

4. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 1, wherein: The sliding surface of both the d-axis and the q-axis is designed using a uniform approach rate. The dynamic behavior of the sliding surface of the sliding mode disturbance observer is expressed as follows: ； in, Represents a positive number, represents the sliding surface, represents the derivative of the sliding surface; For the motor d-axis, its sliding surface ,in, represents the error between the estimated and actual current of the d-axis; For the motor q axis, its sliding surface ,in, It represents the error between the estimated current and the actual current of the q-axis; The sliding stability condition of the sliding mode disturbance observer is: ； in, represents the error between the d-axis disturbance estimate and the actual disturbance, , represents the error between the q-axis disturbance estimate and the actual disturbance, .

5. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 2, wherein: The voltage equation of the permanent magnet synchronous motor is: 。 6. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 5, characterized in that: The reference model in the model reference adaptive method based on the voltage equation of the permanent magnet synchronous motor is: ； in, , , , , , ; The adjustable model in the model reference adaptive method is established as: ； in, represents the estimated value of the corresponding parameter; The state error vector can be obtained from the reference model and the adjustable model The derivative of for: ； in, , , , .

7. The method for predicting current control of a permanent magnet synchronous motor using a finite set model according to claim 6, wherein: The parameter adaptation rule designed based on the model reference adaptive method is: ； in, Indicates adjustable parameters The initial value of Indicates adjustable parameters The initial value of represents the state error vector The component on the d-axis, represents the state error vector The component on the q-axis, , Respectively express the 、 The proportional parameter corresponding to the proportional-integral controller used when , Respectively express the 、 The integral parameter corresponding to the proportional-integral controller used when By adjustable parameters and adjustable parameters Obtain the estimated flux linkage after parameter mismatch compensation for: 。

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