Permanent magnet synchronous motor flux linkage tracking full speed domain high precision prediction current control method

Abstract

The application discloses a kind of permanent magnet synchronous motor flux tracking full-speed domain high-precision prediction current control method, comprising: sampling the phase current of permanent magnet synchronous motor, position and speed signal, obtain dq sampling current by coordinate transformation;According to the calculation of prediction current of the established tracking discrete model;Accurately consider the sinusoidal variation characteristic and its dynamic transient characteristic of resistance voltage drop in current prediction and reference voltage calculation stage, accurately characterize resistance voltage drop by the accurate feedforward compensation of prediction current and reference voltage;The driving signal of inverter is obtained by coordinate transformation and space vector modulation, realizes high-precision fast response current prediction control to permanent magnet motor full-speed domain.The application method reduces the current dynamic control error caused by model error, effectively improves the current control precision and dynamic response performance of permanent magnet synchronous motor under full-speed domain, and provides high-precision model basis for high-precision positionless control and parameter online identification.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor control technology, and in particular to a high-precision predictive current control method for permanent magnet synchronous motor flux tracking across the entire speed range. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in high-performance servo drives and high-end equipment due to their advantages such as high power density, high efficiency, and fast response. Predictive control based on motor models, such as deadbeat predictive current control, has attracted widespread attention because it combines the steady-state high accuracy of vector control with the dynamic fast response of direct torque control. However, predictive control performance is highly dependent on the motor's mathematical model, and its actual control performance often depends on the model's accuracy. Therefore, constructing a high-precision predictive model for PMSMs and achieving high-precision current control across the entire speed domain is of great significance.

[0003] The flux tracking deadbeat predictive current control avoids the coordinate transformation of the reference voltage by introducing a discrete model of the permanent magnet motor stator flux tracking, and accurately considers the digital delay effects such as rotor rotation within the control step, thus ensuring fast response current control of the permanent magnet motor in the full speed domain.

[0004] However, traditional deadbeat predictive current control based on a discrete flux tracking model typically uses an Euler linear approximation for the resistance voltage drop term, failing to accurately model the sinusoidal variation of the resistance voltage drop and the dynamic characteristics during current step changes. Model errors will significantly degrade the steady-state accuracy and dynamic response of permanent magnet synchronous motor (PMSM) current control, especially at high speeds. While traditional disturbance observers or error closed-loop methods can improve steady-state control accuracy, they are difficult to effectively suppress dynamic tracking errors due to bandwidth limitations. Furthermore, model errors that degrade control performance will further affect the estimation accuracy of positionless algorithms and online parameter identification algorithms based on the motor model, resulting in a significant decrease in the performance of positionless predictive control and parameter identification for PMSMs. These issues limit the practical application of flux tracking predictive current control in high-precision full-speed-domain drives of PMSMs. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a high-precision predictive current control method for permanent magnet synchronous motors with flux tracking across the entire speed domain. By performing amplitude and phase compensation of the resistance voltage drop across the entire speed domain based on the flux tracking current prediction model, the accuracy of the flux tracking current prediction model is improved, effectively reducing the dynamic and steady-state errors of current prediction control. This method can provide a high-precision model foundation across the entire speed domain for positionless control and online parameter identification.

[0006] This invention adopts the following technical solution: a high-precision predictive current control method for permanent magnet synchronous motor flux tracking across the entire speed range, comprising:

[0007] Step 1: Based on the differential equation of stator flux linkage in the continuous domain of the permanent magnet motor in the αβ stationary coordinate system, establish a discrete model of flux linkage tracking of the permanent magnet synchronous motor considering the sinusoidal variation characteristics of the resistance voltage drop and based on the dq coordinate system.

[0008] Step 2: Sample the phase current, position, and speed signals of the permanent magnet synchronous motor, and obtain the dq sampled current through coordinate transformation. Based on the established discrete model for flux tracking, the predicted current at the next moment is calculated. ;

[0009] Step 3: Consider the dynamic characteristics of the resistor voltage drop, based on the dq reference current. and sampling current Calculate the predicted current error compensation value plus predicted current The corrected predicted current is obtained. ;

[0010] Step 4: Based on the magnetic flux tracking discrete model, and according to the corrected predicted current... and dq reference current Calculate the reference voltage ;

[0011] Step 5: Considering the dynamic characteristics of the resistor voltage drop, calculate the reference voltage error compensation value. Adding the reference voltage, we obtain the corrected reference voltage. The inverter's drive signal is obtained through coordinate transformation and space vector modulation, enabling high-precision, fast-response current prediction control of the permanent magnet motor across the entire speed range.

[0012] As a preferred option, in step 1, the differential equation of the stator flux linkage in the continuous domain under the αβ stationary coordinate system of the permanent magnet motor is established, expressed as:

[0013] ;

[0014] Where t represents continuous time. , , These represent the stator current, voltage, and flux linkage vector at time t in the αβ coordinate system, respectively. For stator inductance, For stator resistance, It is a permanent magnet flux linkage. For rotor position, This represents a vector rotation operation.

[0015] As a preferred embodiment, in step 1, the discrete model for flux tracking of the permanent magnet synchronous motor is constructed using the following method:

[0016] Step 1.1: Calculate the voltage in the αβ coordinate system. and the back electromotive force in the dq rotating coordinate system Equivalent to a zero-order hold model, the aforementioned continuous-domain complex vector stator flux linkage differential equation is discretized using Euler, and the sinusoidal variation of the resistance voltage drop (i.e., Thus, a discrete model for flux tracking of a permanent magnet synchronous motor considering the sinusoidal variation of the resistance voltage drop is obtained:

[0017] ;

[0018] Where k represents the discrete sampling time, and Let the currents at times k and k+1 be in the discretized αβ stationary coordinate system. Let be the electric angular velocity at time k. Let be the voltage at time k in the discrete αβ stationary coordinate system. For sampling or control step size, Represents the imaginary unit. Indicates a vector rotating counterclockwise. radian.

[0019] Step 1.2: Perform a Park transformation on both sides of the discrete model equation for flux tracking described in Step 1.1, transforming it to the dq coordinate system to obtain a discrete model for flux tracking of a permanent magnet synchronous motor based on the dq coordinate system, considering the sinusoidal variation characteristics of the resistance voltage drop.

[0020] ;

[0021] in, Let be the current at time k+1 in the dq coordinate system. , These represent the stator current and voltage at time k in the dq coordinate system, respectively.

[0022] As a preferred option, in step 2, the predicted current at the next moment is calculated based on the established magnetic flux tracking discrete model. The method is as follows:

[0023] Step 2.1: Sample the current in the dq coordinate system at time k. Electric angular velocity Reference voltage after correction in the previous cycle Control cycle and motor inductance ,resistance Permanent magnet chain ;

[0024] Step 2.2: To simplify the calculation, define the coefficient matrix:

[0025] ;

[0026] in, To account for the sinusoidal variation of the resistance voltage drop, a phase compensation coefficient for the resistance voltage drop amplitude is required. This is the voltage volt-second balance factor. This is the zero-order retention coefficient of the permanent magnet flux linkage;

[0027] Step 2.3: Substitute the sampling information from Step 2.1 into the discrete model of permanent magnet synchronous motor flux tracking in Step 1.2 to predict the current at the next moment. :

[0028] ;

[0029] in, Indicates a vector rotating clockwise radian.

[0030] As a preferred embodiment, in step 3, the calculation of the predicted current error compensation value... The method is as follows:

[0031] Step 3.1: Calculate the average difference between the sampled currents at the two time points before and after the step. ;

[0032] Step 3.2: Since the current is sampled at time k+1 Since it is an unknown quantity, based on the characteristics of deadbeat current control, that is, the motor current is in two steps After reaching the reference value, further calculations yielded the following:

[0033] ;

[0034] in, This represents the reference current at time k in the dq coordinate system. This represents the unit delay operator.

[0035] Step 3.3: Combining the discrete model of permanent magnet synchronous motor flux tracking from Step 1.2, obtain the predicted current error compensation value. :

[0036] .

[0037] As a preferred embodiment, in step 4, the calculation of the reference voltage... The method is as follows:

[0038] First, combining the prediction formula in step 2.3 and the prediction current error compensation value obtained in step 3.3... Calculate the corrected predicted current :

[0039] .

[0040] Then, based on the reference current Corrected predicted current Electric angular velocity ,resistance ,inductance and magnetic chain By combining the discrete model of permanent magnet synchronous motor flux tracking, the reference voltage is derived. :

[0041] .

[0042] As a preferred embodiment, in step 5, the calculation of the reference voltage error compensation value... The method is as follows:

[0043] Step 5.1: Calculate the average current difference between the two moments before and after the current step. ;

[0044] Step 5.2: Since the current is sampled at time k+2 Since it is an unknown quantity, based on the characteristics of deadbeat current control, the motor current is in two steps. After reaching the reference value, the following calculations were performed:

[0045] ;

[0046] in, The sampled current is at time k+2.

[0047] Step 5.3: Using the reference voltage calculation formula, obtain the reference voltage error compensation value. :

[0048] .

[0049] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0050] 1. This invention effectively suppresses the influence of discrete modeling errors on the steady-state accuracy of current control by modeling the sinusoidal variation characteristics of the resistance voltage drop, thereby improving the steady-state accuracy of the current control of permanent magnet synchronous motor.

[0051] 2. When the current jumps and rapid operating conditions change, this invention proposes a predictive current and reference voltage feedforward compensation method, which can accurately characterize the dynamic changes of the resistor voltage drop within the control cycle, significantly reduce the transient deviation of the current, and improve the dynamic response performance of the current control of the permanent magnet synchronous motor.

[0052] 3. By improving the accuracy of the current prediction model and weakening the coupling effect between model discrete error and parameter mismatch error, it can provide a reliable current response basis for positionless control and online parameter identification based on the motor discrete model, thereby improving the accuracy of position estimation and parameter identification.

[0053] 4. The method of the present invention is simple to implement and applicable to full-speed-range operating conditions. It does not require the addition of complex observer structures or significant increase in control frequency. It can be implemented under the conventional deadbeat predictive current control framework and has good engineering application value for full-speed-range drive systems of permanent magnet synchronous motors. Attached Figure Description

[0054] Figure 1 This is a general block diagram of the high-precision predictive control method for full-speed domain magnetic flux tracking of permanent magnet synchronous motors according to the present invention;

[0055] Figure 2 This is a block diagram illustrating the specific implementation of the high-precision predictive control for full-speed domain magnetic flux tracking of the permanent magnet synchronous motor of the present invention.

[0056] Figure 3 This is a comparison chart of the current control performance of the present invention and existing magnetic flux tracking predictive current control methods at low speeds;

[0057] Figure 4 This is a comparison chart showing the current control performance of the present invention and existing magnetic flux tracking predictive current control methods at high speeds. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the application will be further described in detail below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments involved in this invention. All non-innovative embodiments based on these embodiments by other researchers in the art are within the protection scope of this invention. Furthermore, the step numbers in the embodiments of this invention are only set for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0059] In one embodiment of the present invention, a high-precision predictive current control method for full-speed domain flux tracking of a permanent magnet synchronous motor is proposed, and the overall control block diagram is as follows: Figure 1 As shown:

[0060] Electric angular velocity and phase current at sampling time k According to the rotor position The dq current is obtained by transforming the coordinates to the dq coordinate system. The speed outer loop controller or the directly given dq-axis reference current The input flux linkage tracking full-speed domain high-precision predictive current controller calculates the next current prediction value and predictive current error compensation, then performs reference voltage calculation and reference voltage error compensation, and finally outputs the corrected stator reference voltage. Finally, after dq-αβ coordinate transformation and space vector modulation, the output switching signal S is obtained. a S b S c The inverter enables high-precision, fast-response, deadbeat-free predictive current control of the permanent magnet synchronous motor (PMSM) across the entire speed range.

[0061] The specific implementation process of the high-precision predictive control of permanent magnet synchronous motor flux tracking across the entire speed domain in this invention is as follows: Figure 2 As shown, the specific implementation steps are as follows:

[0062] S1. Calculate the predicted current for the next step.

[0063] Based on the dq-axis current at sampling time k electric angular velocity Reference voltage after correction in the previous cycle Control cycle and motor inductance ,resistance Permanent magnet chain And other relevant information to predict the next current. for:

[0064] ;

[0065] Wherein, the coefficient matrix is .

[0066] S2. Calculate the error compensation amount for the predicted current.

[0067] The reference current at time k Delay and sampling current Take the difference and divide by 2, then multiply by the coefficient. The predicted current compensation amount is obtained. :

[0068] ;

[0069] S3. Calculate the corrected predicted current.

[0070] The next step in step S1 is to predict the current. And the predicted current compensation amount in step S2 The corrected predicted current is obtained by adding them together. .

[0071] S4. Calculate the reference voltage.

[0072] Based on reference current Corrected predicted current Electric angular velocity Control cycle and motor inductance ,resistance Permanent magnet chain Calculate the reference voltage using relevant information. .

[0073] ;

[0074] S5. Calculate the reference voltage error compensation. .

[0075] Reference current and the corrected predicted current Take the difference and divide by 2, then multiply by the coefficient. The reference voltage compensation amount is obtained. :

[0076] .

[0077] S6. Calculate the corrected reference voltage.

[0078] The reference voltage in step S4 and the reference voltage compensation amount in step S5 Add them together to obtain the corrected reference voltage. .

[0079] Furthermore, the current control performance comparison results of the method of the present invention with that of the existing magnetic flux tracking predictive current control method at low speed (3,000 r / min, carrier ratio of 100) and high speed (30,000 r / min, carrier ratio of 10) are as follows: Figure 3 and Figure 4 As shown. Among them, Figure 3 (a) and Figure 4 (a) in the figure represents the control result of this invention. Figure 3 (b) and Figure 4 (b) in the figure represents the existing flux tracking predictive current control result.

[0080] A comparison of the steady-state current control errors before and after a step change in the reference current shows that the method of this invention exhibits smaller steady-state current errors at both low and high speeds, while existing methods show significantly increased control errors at high speeds. Furthermore, when a step change occurs in the reference current, the motor current controlled by the method of this invention can track the reference value more quickly, with a significantly lower dynamic current tracking error than existing methods, and maintains excellent control performance across the entire speed range.

[0081] The above results demonstrate that the present invention effectively improves the control accuracy of flux linkage tracking predictive control across the entire speed domain by accurately modeling the sinusoidal variation characteristics and dynamic transient characteristics of the resistance voltage drop and by accurately feeding forward compensation.

[0082] In summary, this invention proposes a high-precision predictive current control method for permanent magnet synchronous motors with flux tracking across the entire speed domain. It accurately considers the sinusoidal variation characteristics and dynamic transient characteristics of the resistance voltage drop during the current prediction and reference voltage calculation stages. Through precise feedforward compensation of the predicted current and reference voltage, it achieves accurate characterization of the resistance voltage drop, significantly reducing the current dynamic steady-state control error caused by model errors. This effectively improves the current control accuracy and dynamic response performance of the permanent magnet synchronous motor across the entire speed domain, and provides a high-precision model foundation for high-precision positionless control and online parameter identification.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-precision predictive current control method for permanent magnet synchronous motor with flux tracking across the entire speed range, characterized in that, include: Step 1: Based on the differential equation of stator flux linkage in the continuous domain of the permanent magnet motor in the αβ stationary coordinate system, establish a discrete model of flux linkage tracking of the permanent magnet synchronous motor considering the sinusoidal variation characteristics of the resistance voltage drop and based on the dq coordinate system. Step 2: Sample the phase current, position, and speed signals of the permanent magnet synchronous motor, and obtain the dq sampled current through coordinate transformation. Based on the established discrete model for flux tracking, the predicted current at the next moment is calculated. ; Step 3: Consider the dynamic characteristics of the resistor voltage drop, based on the dq reference current. and sampling current Calculate the predicted current error compensation value plus predicted current The corrected predicted current is obtained. ; Step 4: Based on the magnetic flux tracking discrete model, and according to the corrected predicted current... and dq reference current Calculate the reference voltage ; Step 5: Considering the dynamic characteristics of the resistor voltage drop, calculate the reference voltage error compensation value. Adding the reference voltage, we obtain the corrected reference voltage. The drive signal of the inverter is obtained through coordinate transformation and space vector modulation, thereby realizing high-precision and fast-response current prediction control of the permanent magnet motor across the entire speed range. In step 1, the discrete model for flux tracking of the permanent magnet synchronous motor is constructed as follows: Step 1.1: Calculate the voltage in the αβ coordinate system. and the back electromotive force in the dq rotating coordinate system Equivalent to a zero-order hold model, the Euler discretization of the complex vector stator flux linkage differential equation in the continuous domain is performed, and the sinusoidal variation of the resistance voltage drop is considered, resulting in a discrete model for flux linkage tracking of a permanent magnet synchronous motor that takes into account the sinusoidal variation of the resistance voltage drop: ； in, For stator inductance, For stator resistance, It is a permanent magnet flux linkage. For rotor position, This represents a vector rotation operation; k represents a discrete sampling time. and Let K be the stator current at times k and k+1 in the discretized αβ stationary coordinate system. Let be the voltage at time k in the discrete αβ stationary coordinate system. Let be the electric angular velocity at time k. For sampling or control step size, Represents the imaginary unit. Indicates a vector rotating counterclockwise. radian; Step 1.2: Perform Park transformation on both sides of the discrete model equation for flux tracking to the dq coordinate system to obtain a discrete model for flux tracking of a permanent magnet synchronous motor based on the dq coordinate system, considering the sinusoidal variation characteristics of the resistance voltage drop. ； in, Let be the current at time k+1 in the dq coordinate system. , These are the stator current and voltage at time k in the dq coordinate system, respectively; In step 3, the calculation of the predicted current error compensation value... The method is as follows: Step 3.1: Calculate the average difference between the sampled currents at the two time points before and after the step. ; Step 3.2: Based on the characteristics of deadbeat current control, the motor current is in two beats. After reaching the reference value, the following calculations were performed: ； in, This represents the reference current at time k in the dq coordinate system. Indicates the unit delay operator; Step 3.3: Combining the discrete model of permanent magnet synchronous motor flux tracking from Step 1.2, obtain the predicted current error compensation value. : ； in, The voltage drop amplitude-phase compensation coefficient is used to account for the sinusoidal variation characteristics of the voltage drop. In step 5, the calculation of the reference voltage error compensation value The method is as follows: Step 5.1: Calculate the average current difference between the two moments before and after the current step. ,in, The sampling current is at time k+2; Step 5.2: Based on the characteristics of deadbeat current control, the motor current is in two beats. After reaching the reference value, the following calculations were performed: ； Step 5.3: Using the reference voltage calculation formula, obtain the reference voltage error compensation value. : ； in, This is the voltage-volt-second balance coefficient.

2. The predictive current control method according to claim 1, characterized in that, In step 1, the differential equation of the stator flux linkage in the continuous domain under the αβ stationary coordinate system of the permanent magnet motor is expressed as: ； in, Indicates continuous time. , , These represent the stator current, voltage, and flux linkage vector at time t in the αβ coordinate system, respectively.

3. The predictive current control method according to claim 2, characterized in that, In step 2, the predicted current for the next moment is calculated based on the established discrete model for magnetic flux tracking. The method is as follows: Step 2.1: Sample the current in the dq coordinate system at time k. Electric angular velocity Reference voltage after correction in the previous cycle Control cycle and motor inductance ,resistance Permanent magnet chain ; Step 2.2, Define the coefficient matrix: ； in, To account for the sinusoidal variation of the resistance voltage drop, a phase compensation coefficient for the resistance voltage drop amplitude is required. This is the voltage volt-second balance factor. This is the zero-order retention coefficient of the permanent magnet flux linkage; Step 2.3: Substitute the sampled information into the discrete model of permanent magnet synchronous motor flux tracking in Step 1.2 to predict the current at the next moment. : ； in, Indicates a vector rotating clockwise radian.

4. The predictive current control method according to claim 3, characterized in that, In step 4, the calculation of the reference voltage The method is as follows: Based on reference current Corrected predicted current Electric angular velocity ,resistance ,inductance and permanent magnet chain By combining the discrete model of permanent magnet synchronous motor flux tracking, the reference voltage is derived. : 。

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