A weak magnetic control algorithm of an interior permanent magnet synchronous motor driver

Abstract

The application discloses a kind of built-in permanent magnet synchronous motor driver's flux-weakening control algorithm, step one, model establishment, step two, work area and out-of-control analysis, step three, depth flux-weakening DFW area trajectory optimization, step four, flux-weakening control analysis, step five, fuzzy control, step six, fuzzy rule base reasoning, the present application adjusts depth flux-weakening DFW coefficient in real time according to different current operating state, so that system has better current performance during depth flux-weakening DFW, while preventing motor from out-of-control due to current regulator saturation during depth flux-weakening DFW, by setting characteristic current point, motor runs along the set current trajectory during depth flux-weakening DFW, avoid the problem of out-of-control due to current regulator saturation, then, according to the derived depth flux-weakening DFW coefficient formula, set corresponding fuzzy rule, and adjust depth flux-weakening DFW coefficient in real time by fuzzy control algorithm, the proposed algorithm has better current and voltage control performance.

Description

Technical Field

[0001] This invention relates to the field of technology, specifically to a field weakening control algorithm for a built-in permanent magnet synchronous motor driver. Background Technology

[0002] Built-in permanent magnet synchronous motors utilize the magnetic field generated by permanent magnets to replace the magnetic field generated by current excitation. They have advantages such as compact structure, small size, low loss, and high efficiency, making them one of the best choices for electric vehicle drive systems. However, traditional built-in permanent magnet synchronous motor drivers have the following disadvantages:

[0003] In the deep field weakening (DFW) control process of an embedded permanent magnet synchronous motor, the current regulator is very prone to runaway due to saturation. The current conversion coefficient is fixed or changes with the motor parameters, which will greatly affect the performance of the deep field weakening (DFW) control operation. Therefore, in deep field weakening (DFW) control, how to make the deep field weakening (DFW) region transition smoothly, avoid the current regulator runaway, and improve the stability of the control system during the deep field weakening (DFW) control process are the key parts of the research on deep field weakening (DFW) control. Summary of the Invention

[0004] The purpose of this invention is to provide a field weakening control algorithm for an embedded permanent magnet synchronous motor driver, in order to solve the problem mentioned in the background art that in the deep field weakening (DFW) control process of an embedded permanent magnet synchronous motor, the current regulator is very prone to runaway due to saturation, and the current conversion coefficient is fixed or changes with the motor parameters, which will greatly affect the performance of the deep field weakening (DFW) control operation. Therefore, in deep field weakening (DFW) control, how to make the deep field weakening (DFW) region transition smoothly, avoid the current regulator runaway, and improve the stability of the control system during the deep field weakening (DFW) control process are the key issues in the research of deep field weakening (DFW) control.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a field weakening control algorithm for a built-in permanent magnet synchronous motor driver, comprising the following steps:

[0006] Step 1: Model Establishment: Establish a mathematical model for the built-in permanent magnet synchronous motor;

[0007] Step 2, Operating Area and Runaway Analysis: When the operating speed of the built-in permanent magnet synchronous motor does not exceed ω1, its operating point is located at point A1, the intersection of the current circle and the maximum torque per ampere (MTPA) curve. At this time, the motor operates with a constant peak torque T1. According to different given torque commands, the initial operating point of the motor is located at point A2, the intersection of the output torque T2 and the maximum torque per ampere (MTPA) curve. When the built-in permanent magnet synchronous motor reaches the speed corresponding to A1 or A2, its terminal voltage has reached the maximum value of the inverter output. Therefore, it is impossible to accelerate by increasing the voltage at this time. To solve this problem, acceleration is achieved through field weakening control. Therefore, the rotational speed at this point is called the steering speed.

[0008] Step 3, Trajectory Optimization in Deep Field Weakening (DFW) Region: When the built-in permanent magnet synchronous motor is running in the deep field weakening (DFW) region, its operating point moves according to the maximum torque per voltage (MTPV) trajectory.

[0009] Step 4, Field Weakening Control Analysis: When the d-axis stator current of the built-in permanent magnet synchronous motor reaches i... d_sat At that time, i d It is no longer possible to increase the negative value to achieve field weakening control;

[0010] Step 5, Fuzzy Control: Fuzzy control only requires quantizing the input and output and then performing simple linear operations to obtain the desired result without multiple iterations;

[0011] Step 6: Fuzzy rule base reasoning: The fuzzy rule base consists of IF-THEN rules. All control rules are represented more clearly by a 4×4 matrix, making the output smoother. The centroid method is used to defuzzify the output.

[0012] As a preferred embodiment of the present invention, the process of establishing the mathematical model in step one is as follows: the stator voltage equation of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems is: The stator flux linkage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The electromagnetic torque equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: T e =1.5p n (λ d i q -λ q i d (3), where ud and uq are the stator voltages along the d-axis and q-axis, respectively, i d and i q Let λ be the stator current along the d-axis and q-axis, respectively. d and λ qThe stator flux linkages are the d-axis and q-axis, respectively, where p is the differential operator and R is the stator flux linkage. s For the stator resistance, ω e Let λ be the rotor's electric angular velocity. f For permanent magnet flux linkage, p n For extreme logarithms, T e For electromagnetic torque, since the stator impedance of the built-in permanent magnet synchronous motor is relatively small, the voltage drop caused by the resistance is negligible when the motor is running in the deep field weakening (DFW) region. When the built-in permanent magnet synchronous motor is in steady state, the differential term of the current loop per unit period is considered zero. Therefore, the stator voltage equation of the built-in permanent magnet synchronous motor simplifies to: The operating state of an integrated permanent magnet synchronous motor is limited by its own characteristics and the inverter's output capability. These limitations include both current and voltage, with the maximum current limit set to i. smax Voltage amplitude limit is set to u max The maximum current limit is set to i. smax The constraints are as shown in formula (5): Voltage amplitude limit set to u max The constraints are as shown in formula (6): Substituting formula (4) into formula (6), the voltage limiting trajectory is expressed as i d and i q The function is expressed as shown in (7): Using the stator currents of the d-axis and q-axis as the coordinate system, formula (5) is drawn as a circle, i.e., the current-limited circular trajectory, and formula (7) is drawn as an ellipse, i.e., the voltage-limited elliptical trajectory. As the speed increases, it corresponds to a series of different voltage elliptical curves.

[0013] As a preferred embodiment of the present invention, the formula for the trajectory movement of the maximum torque MTPV per voltage in step three is specifically as follows: In i d -i q On the plane, according to formulas (3) and (7), the expression for the trajectory of the maximum torque MTPV per voltage is obtained through the Lagrange extremum theorem. The expression is: The maximum torque per voltage (MTPV) curve equation is shown in formula (8). After finding the coordinates of point B, the maximum torque per voltage (MTPV) linearization process is performed by combining the coordinates of point C, and the slope k of point BC is used as the running trajectory of the deep magnetic weakening (DFW) region. In the formula, i qB Let B be the q-axis current. The linearized trajectory equation is:

[0014] As a preferred embodiment of the present invention, the field weakening control in step four specifically involves: using Δω e As a velocity increment, i q and i d The relationship between them is as follows:

[0015]

[0016] Subtracting formula (7) from formulas (11) and (12) yields Since the d-axis and q-axis inductances of the built-in permanent magnet synchronous motor are relatively small, the square term is ignored in formula (14), thus simplifying formula (13) to (L d Δi d (L) d i d +λ f )=(L q Δi q (L) q i q (14), therefore, Δi q and Δi d The proportionality coefficient K is expressed as: In the formula, ρ is the salient pole ratio, i d and i q They are respectively and

[0017] As a preferred embodiment of the present invention, the fuzzy rule base in step six is ​​composed of IF-THEN rules, and all control rules are more clearly represented by a 4×4 matrix. The inference block is based on the input fuzzy set. and Summarize all IF-THEN rules and their weighting factors. The weighting factor for each rule, i.e., w... i,j It is obtained through product operations and is represented as: μ represents the membership degree of the fuzzy set in fuzzy control. To make the output smoother, the centroid method is used to defuzzify the output, i.e.: In the formula, u i,j It is the determined value corresponding to the output fuzzy set of each control rule. Since the triangular membership function is used, the denominator in equation (17) is transformed into the formula: Combining equations (16), (17), and (18), the output can be rewritten as: To verify the differences between the proposed fuzzy control algorithm and the formulaic method, characteristic surfaces of the input and output variables were plotted.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The deep field weakening (DFW) coefficient is adjusted in real time according to different current operating states to improve the current performance of the system during deep field weakening (DFW) and prevent the motor from going out of control due to current regulator saturation. First, by setting a characteristic current point, the motor runs along a set current trajectory during deep field weakening (DFW), avoiding the problem of going out of control due to current regulator saturation. Then, based on the derived formula for deep field weakening (DFW) coefficient, corresponding fuzzy rules are set, and the deep field weakening (DFW) coefficient is adjusted in real time through a fuzzy control algorithm. The proposed algorithm has better current and voltage control performance. Attached Figure Description

[0020] Figure 1 These are diagrams of the current-limiting circular trajectory and the voltage-limiting elliptical trajectory of the present invention.

[0021] Figure 2 This is a trajectory diagram of the weak magnetic region of the present invention;

[0022] Figure 3 This is an optimized weak magnetic field trajectory diagram for the present invention;

[0023] Figure 4 This is the control block diagram of the fuzzy coefficient q-axis current increment field weakening control algorithm of the present invention;

[0024] Figure 5 This is a graph of the member functions of the present invention;

[0025] Figure 6 This is a feature surface diagram of the fuzzy coefficients of the present invention;

[0026] Figure 7 This is a flowchart of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1-7This invention provides a field weakening control algorithm for a built-in permanent magnet synchronous motor driver, comprising the following steps:

[0029] Step 1: Model Establishment: Establish a mathematical model for the built-in permanent magnet synchronous motor;

[0030] Step 2, Operating Area and Runaway Analysis: When the operating speed of the built-in permanent magnet synchronous motor does not exceed ω1, its operating point is located at point A1, the intersection of the current circle and the maximum torque per ampere (MTPA) curve. At this time, the motor operates with a constant peak torque T1. According to different given torque commands, the initial operating point of the motor is located at point A2, the intersection of the output torque T2 and the maximum torque per ampere (MTPA) curve. When the built-in permanent magnet synchronous motor reaches the speed corresponding to A1 or A2, its terminal voltage has reached the maximum value of the inverter output. Therefore, it is impossible to accelerate by increasing the voltage at this time. To solve this problem, acceleration is achieved through field weakening control. Therefore, the rotational speed at this point is called the steering speed.

[0031] Step 3, Trajectory Optimization in Deep Field Weakening (DFW) Region: When the built-in permanent magnet synchronous motor is running in the deep field weakening (DFW) region, its operating point moves according to the maximum torque per voltage (MTPV) trajectory.

[0032] Step 4, Field Weakening Control Analysis: When the d-axis stator current of the built-in permanent magnet synchronous motor reaches i... d_sat At that time, i d It is no longer possible to increase the negative value to achieve field weakening control;

[0033] Step 5, Fuzzy Control: Fuzzy control only requires quantizing the input and output and then performing simple linear operations to obtain the desired result without multiple iterations;

[0034] Step 6: Fuzzy rule base reasoning: The fuzzy rule base consists of IF-THEN rules. All control rules are represented more clearly by a 4×4 matrix, making the output smoother. The centroid method is used to defuzzify the output.

[0035] The specific process of establishing the mathematical model in step one is as follows: The stator voltage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are: The stator flux linkage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The electromagnetic torque equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: T e =1.5p n (λ d i q -λ q i d(3), where u d and u q The stator voltages along the d-axis and q-axis are respectively, i d and i q Let λ be the stator current along the d-axis and q-axis, respectively. d and λ q The stator flux linkages are the d-axis and q-axis, respectively, where p is the differential operator and R is the stator flux linkage. s For the stator resistance, ω e Let λ be the rotor's electric angular velocity. f For permanent magnet flux linkage, p n For extreme logarithms, T e For electromagnetic torque, since the stator impedance of the built-in permanent magnet synchronous motor is relatively small, the voltage drop caused by the resistance is negligible when the motor is running in the deep field weakening (DFW) region. When the built-in permanent magnet synchronous motor is in steady state, the differential term of the current loop per unit period is considered zero. Therefore, the stator voltage equation of the built-in permanent magnet synchronous motor simplifies to: The operating state of an integrated permanent magnet synchronous motor is limited by its own characteristics and the inverter's output capability. These limitations include both current and voltage, with the maximum current limit set to i. smax Voltage amplitude limit is set to u max The maximum current limit is set to i. smax The constraints are as shown in formula (5): Voltage amplitude limit set to u max The constraints are as shown in formula (6): Substituting formula (4) into formula (6), the voltage limiting trajectory is expressed as i d and i q The function is expressed as shown in (7): Using the stator currents of the d-axis and q-axis as the coordinate system, formula (5) is drawn as a circle, i.e., the current-limited circular trajectory, and formula (7) is drawn as an ellipse, i.e., the voltage-limited elliptical trajectory. As the speed increases, it corresponds to a series of different voltage elliptical curves.

[0036] The specific formula for the maximum torque MTPV trajectory movement per voltage in step three is as follows: In i d -i q On the plane, according to formulas (3) and (7), the expression for the trajectory of the maximum torque MTPV per voltage is obtained through the Lagrange extremum theorem. The expression is: The maximum torque per voltage (MTPV) curve equation is shown in formula (8). After finding the coordinates of point B, the maximum torque per voltage (MTPV) linearization process is performed by combining the coordinates of point C, and the slope k of point BC is used as the running trajectory of the deep magnetic weakening (DFW) region. In the formula, i qB Let B be the q-axis current. The linearized trajectory equation is:

[0037] The specific field weakening control in step four is as follows: using Δω e As a velocity increment, i q and i d The relationship between them is as follows:

[0038] Subtracting formula (7) from formulas (11) and (12) yields Since the d-axis and q-axis inductances of the built-in permanent magnet synchronous motor are relatively small, the square term is ignored in formula (14), thus simplifying formula (13) to (L d Δi d (L) d i d +λ f )=(L q Δi q (L) q i q (14), therefore, Δi q and Δi d The proportionality coefficient K is expressed as: In the formula, ρ is the salient pole ratio, i d and i q They are respectively and

[0039] Step six: The fuzzy rule base consists of IF-THEN rules. All control rules are represented more clearly using a 4×4 matrix. The inference block is based on the input fuzzy set. and Summarize all IF-THEN rules and their weighting factors. The weighting factor for each rule, i.e., w... i,j It is obtained through product operations and is represented as: μ represents the membership degree of the fuzzy set in fuzzy control. To make the output smoother, the centroid method is used to defuzzify the output, i.e.: In the formula, ui,j It is the determined value corresponding to the output fuzzy set of each control rule. Since the triangular membership function is used, the denominator in equation (17) is transformed into the formula: Combining equations (16), (17), and (18), the output can be rewritten as: To verify the differences between the proposed fuzzy control algorithm and the formulaic method, characteristic surfaces of the input and output variables were plotted.

[0040] In this invention, in conjunction with the appendix to the specification... Figure 1 The stator voltage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The stator flux linkage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The electromagnetic torque equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are: T e =1.5p n (λ d i q -λ q i d (3), where ud and uq are the stator voltages along the d-axis and q-axis, respectively, i d and i q Let λ be the stator current along the d-axis and q-axis, respectively. d and λ q The stator flux linkages are the d-axis and q-axis, respectively, where p is the differential operator and R is the stator flux linkage. s For the stator resistance, ω e Let λ be the rotor's electric angular velocity. f For permanent magnet flux linkage, p n For extreme logarithms, T e For electromagnetic torque, since the stator impedance of the built-in permanent magnet synchronous motor is relatively small, the voltage drop caused by the resistance is negligible when the motor is running in the deep field weakening (DFW) region. When the built-in permanent magnet synchronous motor is in steady state, the differential term of the current loop per unit period is considered zero. Therefore, the stator voltage equation of the built-in permanent magnet synchronous motor simplifies to: The operating state of an integrated permanent magnet synchronous motor is limited by its own characteristics and the inverter's output capability. These limitations include both current and voltage, with the maximum current limit set to i. smax Voltage amplitude limit is set to u max The maximum current limit is set to i. smax The constraints are as shown in formula (5): Voltage amplitude limit set to u maxThe constraints are as shown in formula (6): Substituting formula (4) into formula (6), the voltage limiting trajectory is expressed as i d and i q The function is expressed as shown in (7): Using the stator currents of the d-axis and q-axis as the coordinate system, formula (5) is drawn as a circle, i.e., the current-limited circle trajectory, and formula (7) is drawn as an ellipse, i.e., the voltage-limited elliptical trajectory. As the speed increases, it corresponds to a series of different voltage elliptical curves. When the running speed of the built-in permanent magnet synchronous motor does not exceed ω1, its operating point is located at the intersection point A1 of the current circle and the maximum torque per ampere (MTPA) curve. At this time, the motor runs with a constant peak torque T1. According to different given torque commands, the initial operating point of the motor is located at the intersection point A2 of the output torque T2 and the maximum torque per ampere (MTPA) curve. When the built-in permanent magnet synchronous motor reaches the speed corresponding to A1 or A2, its terminal voltage has reached the maximum value of the inverter output. Therefore, it is impossible to accelerate by increasing the voltage at this time. In order to solve this problem, acceleration is achieved by field weakening control. Therefore, the rotational speed at this point is called the steering speed. Figure 2 When the rotational speed reaches the turning speed A1, the motor's working trajectory moves along the direction A1→B. This belongs to the constant power field weakening in the ordinary field weakening region. Depending on the torque command, when the speed reaches the turning speed A2, the motor's working trajectory moves along the direction A2→B. This belongs to the constant torque field weakening in the ordinary field weakening region. When the built-in permanent magnet synchronous motor reaches point B, its speed is ω2. If the rotational speed increases from ω2 to ω3, it will move along the direction B→D or B→C. However, the contraction trend in the B→D direction is opposite to the contraction trend of the voltage ellipse, which easily leads to current regulator saturation and runaway. If the built-in permanent magnet synchronous motor continues to reduce i... d Acceleration can easily lead to loss of control. To avoid this, when the motor speed reaches point B, the current trajectory needs to be rationally planned. Therefore, based on the electromagnetic torque equation and voltage constraints of the built-in permanent magnet synchronous motor, the maximum torque per voltage is obtained, and then a maximum torque per voltage MTPV curve is acquired. When the current moves along the maximum torque per voltage MTPV curve, the current trajectory on the curve is consistent with the contraction trend of the voltage ellipse, which greatly avoids the probability of the current regulator losing control. Therefore, in order to make the rotational speed stably increase from ω2 to ω3, the current trajectory is B→C. However, the mathematical expression of the current trajectory B→C is complex and difficult to apply in engineering. Therefore, it is necessary to optimize the algorithm in the deep field weakening (DFW) region. d -i qOn the plane, according to formulas (3) and (7), the expression for the trajectory of the maximum torque MTPV per voltage is obtained through the Lagrange extremum theorem. The expression is: The maximum torque per voltage (MTPV) curve equation is shown in formula (8). After finding the coordinates of point B, the maximum torque per voltage (MTPV) linearization process is performed by combining the coordinates of point C, and the slope k of point BC is used as the running trajectory of the deep magnetic weakening (DFW) region. In the formula, i qB Let B be the q-axis current. The linearized trajectory equation is: Although this method linearizes the maximum torque per voltage (MTPV) curve, it calculates the q-axis current i at point B. qB It remains quite complex and difficult to apply to different motors. Formulas (8) to (10) are only theoretical expressions and are not applicable to engineering practice. In practice, engineers usually calibrate the points of the maximum torque per voltage (MTPV) curve to replace the theoretical expressions. However, the calibration working area is affected by motor parameters and DC bus voltage. (See attached manual for details.) Figure 3 Therefore, the coordinates of point C are (-λ) f / L d The x-coordinate value of (,0) is used as the lower limit of the d-axis current, i.e., i d_sat =-λ f / L d Also known as the characteristic current point, it occurs when the d-axis stator current of a built-in permanent magnet synchronous motor reaches the i-axis. d_sat At that time, i d Limited, then by reducing i q To achieve deep field weakening (DFW), the operating point trajectory of the built-in permanent magnet synchronous motor is shown in the attached figure. Figure 3 As shown, specifically A2→E2→F2 or A1→E1→F2, refer to the instruction manual appendix. Figure 4 When the d-axis stator current of the built-in permanent magnet synchronous motor reaches i d_sat At that time, i d We cannot continue to increase the negative value to achieve field weakening control. At this point, in order to satisfy the voltage equation, we need to decrease i. q To achieve deep field weakening DFW control, a deep field weakening DFW control algorithm was designed based on this theory. This algorithm achieves a smooth transition from the constant torque region to the constant power region, with Δω e As a velocity increment, i q and i d The relationship between them is as follows:

[0041]

[0042] Subtracting formula (7) from formulas (11) and (12) yields Since the d-axis and q-axis inductances of the built-in permanent magnet synchronous motor are relatively small, the square term is ignored in formula (14), thus simplifying formula (13) to (L d Δi d (L) d i d +λ f )=(L q Δi q (L) q i q (14), therefore, Δi q and Δi d The proportionality coefficient K is expressed as: In the formula, ρ is the salient pole ratio, i d and i q They are respectively and When using the formula to calculate the incremental current of the q-axis, this method is applied to both built-in permanent magnet synchronous motors and surface-mounted permanent magnet synchronous motors. However, due to changes in motor operating conditions and magnetic circuit saturation, the accuracy of coefficient K will be affected. In order to ensure the stability of the field weakening control system and improve the accuracy of the conversion coefficient K, fuzzy control is used to perform fuzzy processing on the conversion coefficient K based on formula (15). The conversion coefficient K is determined only by using current as an input parameter. Therefore, the calculation of the coefficient does not require motor parameters, thus improving the stability of the system. Fuzzy control only needs to quantize the input and output and perform simple linear operations to obtain the required result without multiple iterations. At the same time, the trend of the entire coefficient change is obtained according to the formula. Therefore, it is only necessary to set the rules according to experience to achieve the control requirements well. According to the formula, i d and i q As the input variable of the fuzzy controller, and the transformation coefficient K as the output variable of the fuzzy controller, the analysis of formula (15) shows that when the built-in permanent magnet synchronous motor has not reached the characteristic current, K has no effect. Therefore, K is set to zero. d K begins to function when the characteristic current is reached and exceeded, and as i... d and i q It varies with differences; on the one hand, when i d Reaching the characteristic current point and i q When i is large, the value of K is small; on the other hand, when i is large... d Reaching the characteristic current point and i q When i is small, the value of K is large; when i is small, the value of K is large. q When they are the same, if i d The norm of i is relatively large, i.e., id The greater the degree to which the current exceeds the characteristic current, the larger the value of K. Based on this theory, the fuzzy rules for K are obtained, as shown in Table 1:

[0043] Table 1 Fuzzy Rule Base

[0044]

[0045] Refer to the instruction manual. Figure 5 Several language labels are labeled using a fuzzy set with two inputs and one output: NVB represents negative very large, NB represents negative large, NM represents negative medium, NS represents negative small, Z represents zero, PS represents positive small, PM represents positive medium, PB represents positive large, and PVB represents positive very large. The fuzzy domain is set to [-3, 0], and the fuzzy subset is set to {Z, NS, NM, NB}. The actual domain and quantization factor are determined based on the actual motor parameters; the value at the characteristic current is set as the point with a domain value of 0; when point A changes in the negative direction of the characteristic current, the domain value tends towards -3. The fuzzy domain is set to [0,3], and the fuzzy subset is set to {Z,PS,PM,PB}. The actual domain and quantization factor are determined based on the actual motor parameters. The value at that point is set to the value of 0 in the domain. The more the current changes in the positive direction, the closer the threshold value tends to 3. The output variable of the fuzzy controller is the transformation coefficient K. The fuzzy domain is set to [-5, 0], and the fuzzy subset is set to {Z, NVS, NS, NM, NB, NVB}. The actual K is quantized based on the actual control effect. To simplify calculations, both input and output variables follow the trigonometric membership distribution curves. (See attached instruction manual.) Figure 5 The input and output membership functions are shown based on experimental results. These membership functions map the sharp values ​​of the input and output to the membership degree μ of each fuzzy set. Due to their high computational efficiency, the input... Both the output K and the trigonometric membership function are used, as detailed in the instruction manual. Figure 6 The fuzzy rule base consists of IF-THEN rules, and all control rules are more clearly represented by a 4×4 matrix. The inference block is based on the input fuzzy set. and Summarize all IF-THEN rules and their weighting factors. The weighting factor for each rule, i.e., w... i,j It is obtained through product operations and is represented as: μ represents the membership degree of the fuzzy set in fuzzy control. To make the output smoother, the centroid method is used to defuzzify the output, i.e.: In the formula, u i,j It is the determined value corresponding to the output fuzzy set of each control rule. Since the triangular membership function is used, the denominator in equation (17) is transformed into the formula: Combining equations (16), (17), and (18), the output can be rewritten as: To verify the differences between the proposed fuzzy control algorithm and the formulaic method, characteristic surfaces of the input and output variables were plotted, as shown in the figure. Figure 6 As shown in the figure, by observing this figure, it can be found that when the input and output variables change within the domain range, the trend of the output variable K is consistent with the previous theoretical analysis results.

[0046] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A field weakening control algorithm for a built-in permanent magnet synchronous motor driver, characterized in that, Includes the following steps: Step 1: Model Establishment: Establish a mathematical model for the built-in permanent magnet synchronous motor; Step 2, Operating Area and Runaway Analysis: When the operating speed of the built-in permanent magnet synchronous motor does not exceed ω1, its operating point is located at point A1, the intersection of the current circle and the maximum torque per ampere (MTPA) curve. At this time, the motor operates with a constant peak torque T1. According to different given torque commands, the initial operating point of the motor is located at point A2, the intersection of the output torque T2 and the maximum torque per ampere (MTPA) curve. When the built-in permanent magnet synchronous motor reaches the speed corresponding to A1 or A2, its terminal voltage has reached the maximum value of the inverter output. Therefore, it is impossible to accelerate by increasing the voltage at this time. To solve this problem, acceleration is achieved through field weakening control. Therefore, the rotational speed at this point is called the steering speed. Step 3, Trajectory Optimization in Deep Field Weakening (DFW) Region: When the built-in permanent magnet synchronous motor is running in the deep field weakening (DFW) region, its operating point moves according to the maximum torque per voltage (MTPV) trajectory. Step 4, Field Weakening Control Analysis: When the d-axis stator current of the built-in permanent magnet synchronous motor reaches i... d_sat At that time, i d It is no longer possible to increase the negative value to achieve field weakening control; Step 5, Fuzzy Control: Fuzzy control only requires quantizing the input and output and then performing simple linear operations to obtain the desired result without multiple iterations; Step 6: Fuzzy rule base reasoning: The fuzzy rule base consists of IF-THEN rules. All control rules are represented more clearly by a 4×4 matrix, making the output smoother. The centroid method is used to defuzzify the output.

2. The field weakening control algorithm for a built-in permanent magnet synchronous motor driver according to claim 1, characterized in that: The specific process of establishing the mathematical model in step one is as follows: The stator voltage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The stator flux linkage equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: The electromagnetic torque equations of the built-in permanent magnet synchronous motor in the d-axis and q-axis coordinate systems are as follows: T e =1.5p n (λ d i q -λ q i d (3), where u d and u q The stator voltages along the d-axis and q-axis are respectively, i d and i q Let λ be the stator current along the d-axis and q-axis, respectively. d and λ q The stator flux linkages are the d-axis and q-axis, respectively, where p is the differential operator and R is the stator flux linkage. s For the stator resistance, ω e Let λ be the rotor's electric angular velocity. f For permanent magnet flux linkage, p n For extreme logarithms, T e For electromagnetic torque, Because the stator impedance of the built-in permanent magnet synchronous motor is relatively small, the voltage drop caused by the resistance is negligible when the motor is running in the deep field weakening (DFW) region. When the built-in permanent magnet synchronous motor is in steady state, the differential term of the current loop per unit period is considered zero. Therefore, the stator voltage equation of the built-in permanent magnet synchronous motor simplifies to: The operating state of an integrated permanent magnet synchronous motor is limited by its own characteristics and the inverter's output capability. These limitations include both current and voltage, with the maximum current limit set to i. smax Voltage amplitude limit is set to u max The maximum current limit is set to i. smax The constraints are as shown in formula (5): Voltage amplitude limit set to u max The constraints are as shown in formula (6): Substituting formula (4) into formula (6), the voltage limiting trajectory is expressed as i d and i q The function, Its expression is shown in (7): Using the stator currents of the d-axis and q-axis as the coordinate system, formula (5) is drawn as a circle, i.e., the current-limited circular trajectory, and formula (7) is drawn as an ellipse, i.e., the voltage-limited elliptical trajectory. As the speed increases, it corresponds to a series of different voltage elliptical curves.

3. The field weakening control algorithm for a built-in permanent magnet synchronous motor driver according to claim 1, characterized in that: The formula for the maximum torque MTPV trajectory movement per voltage in step three is as follows: In i d -i q On the plane, according to formulas (3) and (7), the expression for the trajectory of the maximum torque MTPV per voltage is obtained through the Lagrange extremum theorem. The expression is: The maximum torque per voltage (MTPV) curve equation is shown in formula (8). After finding the coordinates of point B, the maximum torque per voltage (MTPV) linearization process is performed by combining the coordinates of point C, and the slope k of point BC is used as the running trajectory of the deep magnetic weakening (DFW) region. In the formula, i qB Let B be the q-axis current. The linearized trajectory equation is:

4. The field weakening control algorithm for a built-in permanent magnet synchronous motor driver according to claim 1, characterized in that: The field weakening control in step four specifically involves: using Δω e As a velocity increment, i q and i d The relationship between them is as follows: Subtracting formula (7) from formulas (11) and (12) yields: Since the d-axis and q-axis inductances of the built-in permanent magnet synchronous motor are relatively small, the square term is ignored in formula (14), thus simplifying formula (13) to: (L d Δi d )(L d the d +λ f )=(L q Δi q )(L q the q )(14), Therefore, Δi q and Δi d The proportionality coefficient K is expressed as: In the formula, ρ is the salient pole ratio, i d and i q They are respectively and 5. The field weakening control algorithm for a built-in permanent magnet synchronous motor driver according to claim 1, characterized in that: The fuzzy rule base in step six consists of IF-THEN rules. All control rules are represented more clearly using a 4×4 matrix. The inference block is based on the input fuzzy set. and Summarize all IF-THEN rules and their weighting factors. The weighting factor for each rule, i.e., w... i,j It is obtained through product operations and is represented as: μ represents the membership degree of the fuzzy set in fuzzy control. To make the output smoother, the centroid method is used to deblur the output, that is: In the formula, u i,j It is the determined value corresponding to the output fuzzy set of each control rule. Since the triangular membership function is used, the denominator in equation (17) is transformed into the formula: Combining equations (16), (17), and (18), the output can be rewritten as: To verify the differences between the proposed fuzzy control algorithm and the formulaic method, characteristic surfaces of the input and output variables were plotted.

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