Permanent magnet auxiliary synchronous reluctance motor full speed domain control method based on iteration initial point optimization

Abstract

The invention discloses a permanent magnet auxiliary synchronous reluctance motor full-speed domain control method based on iterative initial point optimization, and relates to the technical field of motor control. The invention aims to solve the problem that the operation performance of the motor is reduced due to the fact that the full-speed-domain control algorithm of the permanent magnet auxiliary synchronous reluctance motor is large in iterative calculation amount and cannot guarantee the real-time performance. An operation area and a state demarcation point are determined according to the actual rotating speed of the motor and a preset rotating speed critical value; calculating the current and torque of the state demarcation point by using a Newton-Raphson iteration method; comparing the torque of the state demarcation point in each operation area with the reference torque, and determining an operation working point in each operation area; calculating the current of the operation working point by using a Newton-Raphson iteration method; and taking the current of the operation working point as a current reference value of the motor to realize optimal control of the permanent magnet auxiliary synchronous reluctance motor.

Description

Technical Field

[0001] The invention belongs to the technical field of motor control. Background Art

[0002] Permanent magnet assisted synchronous reluctance motor has the characteristics of simple structure, low cost and good magnetic field weakening speed expansion performance. In recent years, it has received extensive attention in the fields of industrial drive and electric vehicle applications. In the motor operation area with a wide speed range, different current control methods are required at different speeds, such as maximum torque per ampere (MTPA) control at low speed and magnetic field weakening control at medium and high speeds. The optimal current control method determined based on different speeds is called the full speed domain control algorithm.

[0003] The full-speed domain control method is a method for determining the optimal operating current point. After obtaining the real-time speed and torque reference during motor operation, the optimal operating point is determined as the intersection of two specific curves. According to the expression of the two curve equations, the intersection is calculated by an iterative calculation method. The Newton-Raphson method has good convergence characteristics and a local second-order convergence rate, so it is widely used in the above-mentioned intersection solution problem. However, the permanent magnet assisted synchronous reluctance motor has a significant magnetic saturation characteristic, which causes its inductance model to be modeled as a function of the dq axis current. Compared with other motors, its curve equation is more complicated, and the table lookup calculation is added, which leads to a significant increase in the computational burden of the iterative calculation, which in turn causes a significant increase in the calculation time of the full-speed domain control algorithm.

[0004] The convergence result of the Newton-Raphson iterative method is directly related to the selection of the initial point. An unreasonable initial point of the iterative calculation can significantly increase the number of iterative calculations, thereby increasing the computational burden of the iterative calculation. The computational burden of the full-speed domain control algorithm is different under different motor operating conditions. When the computational burden is light, the full-speed domain control algorithm can be updated before the PWM output within a control cycle. When the computational burden is heavy, the update of the full-speed domain control algorithm will span multiple control cycles. The non-real-time update of the algorithm leads to a significant decrease in control performance.

[0005] At present, the full-speed domain control algorithm of permanent magnet assisted synchronous reluctance motor has the disadvantages of large iterative calculation and the inability to ensure real-time performance, which leads to the decline of motor performance. Therefore, it is of great application value to study an iterative initial point design method that reduces the iterative calculation burden and ensures the real-time performance of the algorithm. Summary of the invention

[0006] The present invention aims to solve the problem that the full-speed domain control algorithm of a permanent magnet assisted synchronous reluctance motor has a large amount of iterative calculations, the algorithm cannot guarantee real-time performance, and the motor operating performance is reduced. A full-speed domain control method for a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization is provided.

[0007] A full-speed range control method for a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization, comprising:

[0008] Constructing a mathematical model of a permanent magnet assisted synchronous reluctance motor, and describing a maximum torque current ratio curve equation, a maximum torque voltage ratio curve equation, a current limit curve equation, and a voltage limit curve equation of the permanent magnet assisted synchronous reluctance motor according to the mathematical model;

[0009] Determine the motor operation area and the state demarcation point in each operation area according to the actual speed of the permanent magnet assisted synchronous reluctance motor and the preset speed critical value;

[0010] The current at the state demarcation point of the previous control cycle is used as the initial demarcation point current of the current control cycle, the current at the state demarcation point of the current control cycle is calculated using the Newton-Raphson iteration method, and the corresponding torque is calculated according to the current at the state demarcation point of the current control cycle;

[0011] Compare the torque at the state boundary point in each operating area with the reference torque to determine the operating point in each operating area;

[0012] The initial operating point current is designed according to the similarities and differences of the reference torques in two consecutive control cycles, and the current of the operating point of this control cycle is calculated using the Newton-Raphson iteration method;

[0013] The current at the operating point of the control cycle is used as a current reference value of the permanent magnet assisted synchronous reluctance motor to achieve optimized control of the permanent magnet assisted synchronous reluctance motor.

[0014] Furthermore, the mathematical model of the permanent magnet assisted synchronous reluctance motor includes a voltage equation and a torque equation;

[0015] The voltage equation is expressed as:

[0016]

[0017] Among them, R s is the stator resistance, ω e is the electrical angular velocity, u d and u q are the voltages of the d-axis and q-axis respectively, i d and i q are the currents of the d-axis and q-axis respectively, and are the magnetic flux along the d-axis and q-axis respectively.

[0018] The torque equation is expressed as:

[0019]

[0020] Among them, T e is the motor torque, P n is the number of motor pole pairs.

[0021] Furthermore, the expression of the maximum torque current ratio curve equation is:

[0022]

[0023] The expression of the maximum torque voltage ratio curve equation is:

[0024]

[0025] The expression of the current limit curve equation is:

[0026]

[0027] Among them, I lim is the current limit value;

[0028] The voltage limit curve equation is expressed as:

[0029]

[0030] Furthermore, the above-mentioned determining the motor operation area according to the actual speed of the permanent magnet assisted synchronous reluctance motor and the preset speed critical value includes:

[0031] When n≤n M When , the operating area is I;

[0032] When n M <n≤n N , the operating area is II;

[0033] When n N <n≤n O When , the operating area is III;

[0034] When n O When <n, the operation area is IV;

[0035] Where n is the actual speed, n M is the motor base speed, n N and n O There are two different critical speeds.

[0036] Furthermore, the method for determining the state demarcation points in each operating area is as follows:

[0037] The state demarcation point in the operating area I is the intersection of the maximum torque current ratio curve and the current limit curve;

[0038] The state demarcation points in the operation area II are the intersection points of the voltage limit curve and the current limit curve and the intersection points of the voltage limit curve and the maximum torque current ratio curve;

[0039] The state demarcation points in the operation area III are the intersection points of the voltage limit curve and the maximum torque voltage ratio curve and the intersection points of the voltage limit curve and the maximum torque current ratio curve;

[0040] The state dividing point within the operating area IV is the intersection of the voltage limit curve and the maximum torque voltage ratio curve.

[0041] Furthermore, the current at the state demarcation point of the previous control cycle is used as the initial demarcation point current of the current control cycle by the following formula:

[0042]

[0043] in, and are the d-axis and q-axis currents at the initial demarcation point in the m control cycle, and are the d-axis and q-axis currents at the state boundary points in the m-1 control cycle respectively;

[0044] When m=1, the initial demarcation point current is randomly selected in the region where the state demarcation point is located.

[0045] Furthermore, the above-mentioned Newton-Raphson iteration method is used to calculate the current of the state boundary point of this control cycle, including:

[0046]

[0047] Among them, f 1 () and f 2 () represent the iterative curve equations to be calculated according to the rotation speed, k represents the number of iterations, and are the d-axis and q-axis reference currents, respectively, and J(k) is the Jacobian matrix at the kth iteration;

[0048] The convergence conditions are:

[0049]

[0050] Among them, ε is the iteration accuracy.

[0051] Furthermore, the above-mentioned comparison of the torque of the state demarcation point in each operating area with the reference torque value to determine the operating point in each operating area includes:

[0052] In operating area I, when When the operating point is the intersection of the maximum torque current ratio curve and the current limit curve, When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve;

[0053] In operating region II, when When , the operating point is the intersection of the voltage limit curve and the current limit curve; when When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve; when When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve;

[0054] In operating region III, when When the operating point is the intersection of the voltage limit curve and the maximum torque voltage ratio curve, When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve is When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve;

[0055] In operating region IV, when When the operating point is the intersection of the voltage limit curve and the maximum torque voltage ratio curve, When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve;

[0056] in, is the reference torque, T e,M is the torque at the intersection point M, T e,A is the torque at the intersection point A, T e,B is the torque at the intersection point B, T e,C is the torque at the intersection point C, T e,D is the torque at the intersection point D, T e,E is the torque at the intersection point E;

[0057] The intersection point M is the intersection point of the maximum torque current ratio curve and the current limit curve in the operating area I.

[0058] Intersection point A is the intersection of the voltage limit curve and the current limit curve in operation area II.

[0059] Intersection point B is the intersection of the voltage limit curve and the maximum torque current ratio curve in operating area II.

[0060] The intersection point C is the intersection point of the voltage limit curve and the maximum torque voltage ratio curve in the operating area III.

[0061] The intersection point D is the intersection point of the voltage limit curve and the maximum torque current ratio curve in the operating area III.

[0062] The intersection point E is the intersection point of the voltage limit curve and the maximum torque voltage ratio curve in the operating region IV.

[0063] Furthermore, the initial operating point current is designed according to the similarities and differences of the reference torques in two consecutive control cycles, including:

[0064] When the reference torques in two consecutive control cycles are the same, the current of the operating point in the previous control cycle is used as the initial operating point current in the current control cycle;

[0065] When the reference torque in two consecutive control cycles is different, the design is as follows:

[0066] When the operating point is the intersection of the maximum torque current ratio curve and the current limit curve, the intersection of the voltage limit curve and the current limit curve, or the intersection of the voltage limit curve and the maximum torque voltage ratio curve, the current of the operating point is directly obtained;

[0067] When the operating point is the voltage limit curve and the torque value is T e * When the constant torque curve of the initial working point is at the intersection, the initial working point current is:

[0068]

[0069] in, and are the d-axis and q-axis currents of the initial working point of this control cycle, y represents the state demarcation point on the right side of the voltage limit curve, z represents the state demarcation point on the left side of the voltage limit curve, T e,y and T e,z are the torques at point y and point z respectively, i d,y and i d,z are the d-axis currents at points y and z, respectively, i q,y and i q,z are the q-axis currents at points y and z respectively;

[0070] When the operating point is the maximum torque current ratio curve and the torque value is When the constant torque curve of the initial working point is at the intersection, the initial working point current is:

[0071]

[0072] Among them, i d,M and i q,M are the d-axis and q-axis currents at the intersection M respectively.

[0073] Furthermore, the torque value is The constant torque curve equation is:

[0074] Among them, P n is the number of motor pole pairs, and are the magnetic flux of d-axis and q-axis respectively, i d and i q are the currents of the d-axis and q-axis respectively.

[0075] The present invention adopts the MTPA equation and MTPV equation that consider magnetic saturation. The two equations not only consider the change of inductance with current, but also include the partial differential term of inductance to current in the standard solution, fully considering the magnetic saturation characteristics of the permanent magnet assisted synchronous reluctance motor. The MTPA and MTPV equations more accurately describe the optimal curve of the motor in the full speed range, providing a basis for the high-performance operation of the motor in the full speed range.

[0076] The present invention provides a process for determining the optimal operating point of the motor during full-speed control, determines the working partitions of the motor based on the operating speed, and provides a selection scheme for the optimal current working point in each partition. The optimization process adopted ensures the stability of the motor operation process and the smoothness of the switching process between different speed regions.

[0077] The iterative initial point design method proposed in the present invention is based on the local convergence characteristics of the Newton-Raphson iterative method. This method ensures the approximation of the iterative initial point and the final convergence point, ensuring that the present invention can reduce the computational burden. At the same time, the iterative initial point design method is not only aimed at the iterative solution of the operating point, but also considers the iterative solution of the state demarcation point. This takes into account the possibility of solving all intersection points, ensuring the low burden of the entire algorithm calculation process.

[0078] The present invention provides an iterative initial point design method for full-speed domain control of a permanent magnet assisted synchronous reluctance motor. The method does not require additional signal injection and complex controller design, has a simple principle and is easy to implement. The proposed method significantly reduces the online calculation time of the full-speed domain control algorithm of the permanent magnet assisted synchronous reluctance motor, ensures the real-time operation of the full-speed domain control algorithm, and improves the full-speed domain operation performance of the permanent magnet assisted synchronous reluctance motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1Schematic diagram of two intersecting curves determined under different torque references in different operating regions of the motor, wherein (a) operating region I, (b) operating region II, (c) operating region III, and (d) operating region IV;

[0080] Figure 2 It is a flowchart of iterative calculation based on Newton-Raphson iterative calculation;

[0081] Figure 3 Determine the flow chart for the operating point

[0082] Figure 4 is a schematic diagram of the initial iteration point of the operating point and its corresponding iterative convergence process when the torque reference changes; where (a) is the intersection point (b) The intersection point is

[0083] Figure 5 The experimental waveform diagram of the full-speed control strategy, where (a) the speed is constant and the torque reference increases in steps; (b) the torque reference is constant and the speed increases linearly.

[0084] Figure 6 Based on Figure 5 Schematic diagram of the recorded waveform and the operating results mapped to the dq-axis current plane. DETAILED DESCRIPTION

[0085] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0086] Reference Figures 1 to 6 Specifically describing this embodiment, a permanent magnet assisted synchronous reluctance motor full speed range control method based on iterative initial point optimization described in this embodiment includes:

[0087] Step 1: Establish a mathematical model of the permanent magnet assisted synchronous reluctance motor to describe the voltage equation and torque equation of the motor.

[0088] The specific expression of the voltage equation is:

[0089]

[0090] Among them, R s is the stator resistance, ω e is the electrical angular velocity, ud and u q are the voltages of the d-axis and q-axis respectively, i d and i q are the currents of the d-axis and q-axis respectively, and are the magnetic flux along the d-axis and q-axis respectively.

[0091] The specific expression of the torque equation is:

[0092]

[0093] Among them, T e is the motor torque, P n is the number of motor pole pairs.

[0094] Step 2: According to the voltage equation and torque equation described in step 1, solve the maximum torque per ampere (MTPA) curve equation and the maximum torque per voltage (MTPV) curve equation of the motor operation:

[0095] The MTPA trajectory curve of the motor operation is solved according to the mathematical model, where the mathematical description of the MTPA problem is:

[0096]

[0097] Among them, f 1 Optimize the objective function for MTPA, I lim is the current limit, and the Lagrange multiplier method is used to solve the above optimization problem. The solution equation established is:

[0098]

[0099] Among them, λ 1 is the Langrange multiplier of the MTPA problem, and the equation of the MTPA curve obtained by solving it is:

[0100]

[0101] The MTPV trajectory curve of the motor operation is solved according to the mathematical model, where the mathematical description of the MTPV problem is:

[0102]

[0103] Among them, f 2 Optimize the objective function for MTPV, u lim is the voltage limit, and the Lagrange multiplier method is also used to solve the above optimization problem. The solution equation established is:

[0104]

[0105] Among them, λ 2 is the Langrange multiplier of the MTPV problem, and the equation of the MTPV curve obtained by solving it is:

[0106]

[0107] Step 3: According to the voltage limit value u of the motor operation lim and the current limit value I lim , determine the equations of the voltage limit curve and the current limit curve.

[0108] The voltage limit curve equation is expressed as:

[0109]

[0110] The expression of the current limit curve equation is:

[0111]

[0112] In this embodiment, the rated voltage of the 5.5kW permanent magnet assisted synchronous reluctance motor is 380V and the rated current is 14.7A, so the motor voltage limit is determined to be 311V and the motor current limit is determined to be 20.78A. The voltage limit equation and current limit equation determined thereby are:

[0113]

[0114]

[0115] Step 4: According to the actual speed n of the motor and the three speed critical values ​​n M 、n N 、n O Determine the area in which the motor will operate.

[0116] When n≤n M When , the operating area is I;

[0117] When n M <n≤n N , the operating area is II;

[0118] When n N <n≤n O When , the operating area is III;

[0119] When n O When <n, the operation area is IV;

[0120] Among them, n M is the motor base speed, n N and nO There are two different critical speeds.

[0121] In this embodiment, the motor base speed n M is 3270rpm, critical speed n N is 7650rpm, critical speed n O is 15000rpm.

[0122] Step 5, determine the state dividing points of each area, design the current information at the iterative initial point when calculating each state dividing point, calculate the current information of the state dividing point by the Newton-Raphson iterative method, and then calculate the corresponding torque based on the torque equation of step 1.

[0123] For the operation area I, there is a state dividing point M (the intersection of the maximum torque current ratio curve and the current limit curve, expressed as C MTPA ∩C CL ).

[0124] For operation area II, there are two state dividing points A (the intersection of the voltage limit curve and the current limit curve, represented by C VL ∩C CL ) and B (the intersection of the voltage limit curve and the maximum torque current ratio curve, expressed as C VL ∩C MTPA ).

[0125] For operation area III, there are two state dividing points C (the intersection of the voltage limit curve and the maximum torque voltage ratio curve, denoted as C VL ∩C MTPV ) and D (the intersection of the voltage limit curve and the maximum torque current ratio curve, expressed as C VL ∩C MTPA );

[0126] For operation area IV, there is a state dividing point E (the intersection of the voltage limit curve and the maximum torque voltage ratio curve, expressed as C VL ∩C MTPV ).

[0127] Among them, C MTPA is the MTPA curve, C MTPV is the MTPV curve, C VL is the voltage limit curve, C CL is the current limit curve.

[0128] The schematic diagram of the state boundary points in different speed operation areas is as follows Figure 1 shown.

[0129] The initial demarcation point of the above state demarcation point is designed as follows, that is, the current of the state demarcation point of the previous control cycle is used as the initial demarcation point current of this control cycle:

[0130]

[0131] Among them, among them, and are the d-axis and q-axis currents at the initial demarcation point in the m control cycle, and They are the d-axis and q-axis currents of the state boundary points in the m-1 control cycle, respectively, x=M,A,B,C,D,E.

[0132] When m=1, the initial demarcation point current is randomly selected in the region where the state demarcation point is located.

[0133] The current at the state boundary point of this control cycle is calculated using the Newton-Raphson iterative method:

[0134]

[0135] Among them, f 1 () and f 2 () represent the iterative curve equations to be calculated according to the rotation speed, k represents the number of iterations, and The d-axis and q-axis reference currents respectively.

[0136] The Jacobian matrix J(k) at the kth iteration is described as:

[0137]

[0138] The convergence condition of iterative calculation is:

[0139]

[0140] In this embodiment, the iteration accuracy ε is selected to be 0.04.

[0141] When the iteration meets the above convergence conditions, the dq current of the state boundary point is obtained, and then the corresponding torque is calculated based on the torque equation in step 1.

[0142] The flowchart of the Newton-Raphson iterative calculation process is as follows Figure 2 shown.

[0143] Step 6, according to the state demarcation point and torque determined in step 5, determine the two intersecting curves where the motor operating point is located, design the iterative initial point of the operating point, and calculate the coordinates of the operating point by the Newton-Raphson iterative method.

[0144] In operating area I, when When the maximum torque current ratio curve intersects with the current limit curve, the operating point is represented by C MTPA ∩C CL ;when When the maximum torque current ratio curve and torque value are The constant torque curve intersects, and the operating point is expressed as

[0145] In operating region II, when When the voltage limit curve intersects with the current limit curve, the operating point is represented by C VL ∩C CL ;when When the voltage limit curve and torque value are The constant torque curve intersects, and the operating point is expressed as when When the maximum torque current ratio curve and torque value are The constant torque curve intersects, and the operating point is expressed as

[0146] In operating region III, when When the voltage limit curve intersects with the maximum torque voltage ratio curve, the operating point is represented by C VL ∩C MTPV ;when When the voltage limit curve and torque value are The constant torque curve intersects, and the operating point is expressed as when When the maximum torque current ratio curve and torque value are The constant torque curve intersects, and the operating point is expressed as

[0147] In operating region IV, when When the voltage limit curve intersects with the maximum torque voltage ratio curve, the operating point is represented by C VL ∩C MTPV ;when When the voltage limit curve and torque value are The constant torque curve intersects, and the operating point is expressed as

[0148] Among them, T e,M is the torque at the state boundary point M, T e,A is the torque at the state boundary point A, T e,B is the torque at the state boundary point B, T e,C is the torque at the state boundary point C, T e,D is the torque at the state boundary point D, Te,E is the torque at the state boundary point E.

[0149] The expression of the constant torque curve equation is:

[0150]

[0151] The operating points of different regions are determined as follows: Figure 3 Flowchart shown.

[0152] In this embodiment, the initial operating point current design needs to first determine whether the reference torque changes in two consecutive control cycles:

[0153] A. When the reference torque in two consecutive control cycles is the same, the current of the operating point in the previous control cycle is used as the initial operating point current in this control cycle:

[0154]

[0155] in, and are the d-axis and q-axis currents of the initial operating point in the m control cycle, and They are the d-axis and q-axis currents of the operating point in the m-1 control cycle respectively.

[0156] When m=1, the initial operating point current is randomly selected in the region where the operating point is located.

[0157] B.

[0158] When the reference torque in two consecutive control cycles is different, the design is as follows:

[0159] When the operating point is C MTPA ∩C CL , C VL ∩C CL and C VL ∩C MTPV When the operating point has been calculated a priori, the current at the operating point is known, and there is no need to design the initial operating point, and the current at the operating point can be directly obtained.

[0160] The operating point is When the initial operating point current is designed to be:

[0161]

[0162] in, and are the d-axis and q-axis currents of the initial working point of this control cycle, y represents the state demarcation point on the right side of the voltage limit curve, z represents the state demarcation point on the left side of the voltage limit curve, Te,y and T e,z are the torques at point y and point z respectively, i d,y and i d,z are the d-axis currents at points y and z, respectively, i q,y and i q,z are the q-axis currents at point y and point z respectively.

[0163] The operating point is When the initial operating point current is designed to be:

[0164]

[0165] Among them, i d,M and i q,M They are the d-axis and q-axis currents at point M respectively.

[0166] In this example, the Newton-Raphson iterative algorithm is used to obtain the dq current coordinates of the operating point, which is the same as the calculation process of the state boundary point in step 5, and the convergence conditions are also the same. The convergence process of the proposed iterative method is as follows Figure 5 shown. Figure 6 The experimental waveform of the entire algorithm implementation is given.

[0167] Finally, the current information of the operating point under the online calculation is used as the current reference value of the permanent magnet assisted synchronous reluctance motor to achieve optimized control of the permanent magnet assisted synchronous reluctance motor.

[0168] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A full-speed range control method for a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization, characterized in that: include: Constructing a mathematical model of a permanent magnet assisted synchronous reluctance motor, and describing a maximum torque current ratio curve equation, a maximum torque voltage ratio curve equation, a current limit curve equation, and a voltage limit curve equation of the permanent magnet assisted synchronous reluctance motor according to the mathematical model; Determine the motor operation area and the state demarcation point in each operation area according to the actual speed of the permanent magnet assisted synchronous reluctance motor and the preset speed critical value; The current at the state demarcation point of the previous control cycle is used as the initial demarcation point current of the current control cycle, the current at the state demarcation point of the current control cycle is calculated using the Newton-Raphson iteration method, and the corresponding torque is calculated according to the current at the state demarcation point of the current control cycle; Compare the torque at the state boundary point in each operating area with the reference torque to determine the operating point in each operating area; The initial operating point current is designed according to the similarities and differences of the reference torques in two consecutive control cycles, and the current of the operating point of this control cycle is calculated using the Newton-Raphson iteration method; The current at the operating point of the control cycle is used as a current reference value of the permanent magnet assisted synchronous reluctance motor to achieve optimized control of the permanent magnet assisted synchronous reluctance motor.

2. A permanent magnet assisted synchronous reluctance motor full speed range control method based on iterative initial point optimization according to claim 1, characterized in that: The mathematical model of the permanent magnet assisted synchronous reluctance motor includes a voltage equation and a torque equation; The voltage equation is expressed as: Among them, R s is the stator resistance, ω e is the electrical angular velocity, u d and u q are the voltages of the d-axis and q-axis respectively, i d and i q are the currents of the d-axis and q-axis respectively, and are the magnetic flux along the d-axis and q-axis respectively. The torque equation is expressed as: Among them, T e is the motor torque, P n is the number of motor pole pairs.

3. A permanent magnet assisted synchronous reluctance motor full speed range control method based on iterative initial point optimization according to claim 2, characterized in that: The expression of the maximum torque current ratio curve equation is: The expression of the maximum torque voltage ratio curve equation is: The expression of the current limit curve equation is: Among them, I lim is the current limit value; The voltage limit curve equation is expressed as:

4. The method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 1, characterized in that: Determining the motor operation area according to the actual speed of the permanent magnet assisted synchronous reluctance motor and a preset speed critical value includes: When n≤n M When , the operating area is I; When n M <n≤n N , the operating area is II; When n N <n≤n O When , the operating area is III; When n O When <n, the operation area is IV; Where n is the actual speed, n M is the motor base speed, n N and n O There are two different critical speeds.

5. The method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 4, characterized in that: The method for determining the state demarcation points in each operating area is: The state demarcation point in the operating area I is the intersection of the maximum torque current ratio curve and the current limit curve; The state demarcation points in the operation area II are the intersection points of the voltage limit curve and the current limit curve and the intersection points of the voltage limit curve and the maximum torque current ratio curve; The state demarcation points in the operation area III are the intersection points of the voltage limit curve and the maximum torque voltage ratio curve and the intersection points of the voltage limit curve and the maximum torque current ratio curve; The state dividing point within the operating area IV is the intersection of the voltage limit curve and the maximum torque voltage ratio curve.

6. The method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 1, characterized in that: The current at the state demarcation point of the previous control cycle is used as the initial demarcation point current of this control cycle through the following formula: in, and are the d-axis and q-axis currents at the initial demarcation point in the m control cycle, and are the d-axis and q-axis currents at the state boundary points in the m-1 control cycle respectively; When m=1, the initial demarcation point current is randomly selected in the region where the state demarcation point is located.

7. The method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 1, characterized in that: The method of calculating the current of the state demarcation point of the control cycle by using the Newton-Raphson iteration method includes: Wherein, f1() and f2() represent the iterative curve equations to be calculated according to the rotation speed, k represents the number of iterations, and are the d-axis and q-axis reference currents, respectively, and J(k) is the Jacobian matrix at the kth iteration; The convergence conditions are: Among them, ε is the iteration accuracy.

8. The method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 5, characterized in that: The step of comparing the torque of the state demarcation point in each operating area with the reference torque value to determine the operating point in each operating area includes: In operating area I, when When the operating point is the intersection of the maximum torque current ratio curve and the current limit curve, When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve; In operating region II, when When , the operating point is the intersection of the voltage limit curve and the current limit curve; when When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve; when When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve; In operating region III, when When the operating point is the intersection of the voltage limit curve and the maximum torque voltage ratio curve, When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve is When the operating point is the maximum torque current ratio curve and the torque value is The intersection of the constant torque curve; In operating region IV, when When the operating point is the intersection of the voltage limit curve and the maximum torque voltage ratio curve, When the operating point is the voltage limit curve and the torque value is The intersection of the constant torque curve; in, is the reference torque, T e,M is the torque at the intersection point M, T e,A is the torque at the intersection point A, T e,B is the torque at the intersection point B, T e,C is the torque at the intersection point C, T e,D is the torque at the intersection point D, T e,E is the torque at the intersection point E; The intersection point M is the intersection point of the maximum torque current ratio curve and the current limit curve in the operating area I. Intersection point A is the intersection of the voltage limit curve and the current limit curve in operation area II. Intersection point B is the intersection of the voltage limit curve and the maximum torque current ratio curve in operating area II. The intersection point C is the intersection point of the voltage limit curve and the maximum torque voltage ratio curve in the operating area III. The intersection point D is the intersection point of the voltage limit curve and the maximum torque current ratio curve in the operating area III. The intersection point E is the intersection point of the voltage limit curve and the maximum torque voltage ratio curve in the operating region IV.

9. A permanent magnet assisted synchronous reluctance motor full speed range control method based on iterative initial point optimization according to claim 8, characterized in that: The initial operating point current is designed according to the similarities and differences of the reference torques in two consecutive control cycles, including: When the reference torques in two consecutive control cycles are the same, the current of the operating point in the previous control cycle is used as the initial operating point current in the current control cycle; When the reference torque in two consecutive control cycles is different, the design is as follows: When the operating point is the intersection of the maximum torque current ratio curve and the current limit curve, the intersection of the voltage limit curve and the current limit curve, or the intersection of the voltage limit curve and the maximum torque voltage ratio curve, the current of the operating point is directly obtained; When the operating point is the voltage limit curve and the torque value is When the constant torque curve of the initial working point is at the intersection, the initial working point current is: in, and are the d-axis and q-axis currents of the initial working point of this control cycle, y represents the state demarcation point on the right side of the voltage limit curve, z represents the state demarcation point on the left side of the voltage limit curve, T e,y and T e,z are the torques at point y and point z respectively, i d,y and i d,z are the d-axis currents at points y and z, respectively, i q,y and i q,z are the q-axis currents at points y and z respectively; When the operating point is the maximum torque current ratio curve and the torque value is When the constant torque curve of the initial working point is at the intersection, the initial working point current is: Among them, i d,M and i q,M are the d-axis and q-axis currents at the intersection M respectively.

10. According to the method for full-speed control of a permanent magnet assisted synchronous reluctance motor based on iterative initial point optimization according to claim 9, the torque value is The constant torque curve equation is: in, P n is the number of motor pole pairs, and are the magnetic flux of d-axis and q-axis respectively, i d and i q are the currents of the d-axis and q-axis respectively.

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