Mtpa control method for high magnetic circuit saturation permanent magnet synchronous motor based on partial derivative compensation

Abstract

The application discloses a high-magnetic-path saturation permanent magnet synchronous motor MTPA control method based on partial derivative compensation, which comprises the following steps: obtaining the relationship between phase current and dq axis current, and obtaining corresponding dq axis current relationship based on MTPA optimization equations considering partial derivatives and MTPA optimization equations ignoring partial derivatives respectively; obtaining reference value, inductance, permanent magnet flux linkage, partial derivative and MTPA angle of i q , and obtaining dq axis current according to the MTPA optimization equation considering the partial derivative to perform motor control; wherein the MTPA angle is obtained based on the MTPA optimization equation ignoring the partial derivative and by using a difference method. The application can better track the MTPA angle of the high-magnetic-path saturation permanent magnet synchronous motor under different load conditions.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of permanent magnet synchronous motor, and particularly relates to a high magnetic circuit saturation permanent magnet synchronous motor MTPA control method based on partial derivative term compensation. BACKGROUND

[0002] Permanent magnet synchronous motor (PMSM) is widely used in numerical control machine tools, robots, advanced rail transportation equipment, new energy vehicles and other key fields due to its high power density, high efficiency, high reliability and other advantages. However, with the increasing industrial demand for power density, lightweight, small size and other requirements of permanent magnet synchronous motor, the magnetic saturation effect of the motor is more and more significant. Especially in some high-end industrial equipment, such as special vehicles, aircrafts, spacecrafts and the like, the motor is not only limited by installation space and self weight and the like, but also needs to face a series of high load tasks in extreme environments, resulting in a high saturation degree in the magnetic circuit of the motor. Compared with the traditional motor, the electromagnetic parameters of the high magnetic circuit saturation permanent magnet synchronous motor (HSPMSM) change more complexly with the saturation degree, so that the traditional maximum torque per ampere control method of permanent magnet synchronous motor is difficult to meet the performance requirements of the motor system in high-end industrial equipment. Therefore, the research on the MTPA control method of high magnetic circuit saturation permanent magnet synchronous motor has important theoretical value and practical significance for promoting the innovation and development of key field high-end industrial equipment.

[0003] Interior permanent magnet synchronous motor (PMSM) is widely used due to its high efficiency and high power density. Due to the asymmetry of the dq-axis magnetic circuit, the electromagnetic torque of the interior permanent magnet synchronous motor contains the reluctance torque. In order to make full use of the reluctance torque, the maximum torque per ampere (MTPA) control strategy is usually adopted to optimize the dq-axis current combination, so as to improve the efficiency and torque of the permanent magnet synchronous motor.

[0004] The traditional MTPA control usually regards the inductance and flux linkage of the motor as constants, and calculates the optimal current angle based on the dq mathematical model. However, in actual operation, the inductance and flux linkage of the motor and other parameters will change with the change of the load, especially for the high magnetic circuit saturation motor, the change is particularly significant. Therefore, the MTPA control method without considering the parameter change cannot truly realize the optimal distribution of the dq-axis current of the interior permanent magnet synchronous motor. In view of the problem of parameter change in MTPA control, many scholars have proposed various methods.

[0005] Some prior art uses finite element simulation to obtain motor parameters and is used for MTPA control, but there is a large deviation between the actual motor parameters and the motor parameters simulated by the finite element method, which seriously affects the effectiveness of the method. The lookup table (LUT) method or curve fitting can solve the deficiency of the finite element method. Some prior art measures the optimal dq-axis current value of the motor under different working conditions offline through experiments, and saves the data in the storage space of the controller. According to different working conditions of the permanent magnet synchronous motor, the optimal current given value is selected. Some prior art uses numerical analysis method to fit the offline measurement results into a nonlinear flux linkage model, and uses the model to calculate the optimal current angle. Some prior art is to segment the measured data for fitting, thereby improving the calculation accuracy of the optimal angle. However, whether the LUT method or the curve fitting method needs a time-consuming experimental process and a large amount of experimental data, which affects its practicability. Some prior art proposes a search method, which searches for the MTPA angle corresponding to the minimum stator current by injecting a signal online. This method does not depend on motor parameters, but is easy to cause oscillation of the current angle at the extreme value, thereby affecting the stability of the system.

[0006] At the same time, some scholars also propose to calculate the optimal current angle by using the changing parameters through online parameter estimation. Some prior art uses a signal processing technology based on virtual high-frequency signal injection to obtain inductance in real time. Some prior art uses a rotating high-frequency voltage injection method to identify inductance, and performs normalization processing on the parameters. In addition, some literatures use intelligent algorithms to obtain parameters under different loads, such as genetic algorithm, model reference adaptive algorithm, neural network algorithm, etc. However, this kind of method often ignores the change trend of inductance and permanent magnet flux linkage in the operation process, that is, the partial derivative of the parameter. Therefore, there is still a deviation between the calculated optimal current angle and the actual optimal current angle, thereby affecting the final optimization effect. SUMMARY

[0007] In view of the technical problems existing in the prior art, the present application provides a high magnetic circuit saturation permanent magnet synchronous motor MTPA control method based on partial derivative compensation with precise control.

[0008] To solve the above technical problems, the technical solution provided by the present application is:

[0009] A high magnetic circuit saturation permanent magnet synchronous motor MTPA control method based on partial derivative compensation, comprising the steps of:

[0010] Obtaining the relationship between the phase current and the dq-axis current, and obtaining the corresponding dq-axis current relationship based on the MTPA optimization equation considering the partial derivative and the MTPA optimization equation ignoring the partial derivative, respectively;

[0011] Obtaining i qreference value, inductance, permanent magnet flux linkage, partial derivative term and MTPA angle, and then obtains the dq-axis current according to the MTPA optimization equation considering the partial derivative term to control the motor; wherein the MTPA angle is obtained based on the MTPA optimization equation ignoring the partial derivative term and by using the difference method.

[0012] Preferably, the relationship between the phase current and the dq-axis current is specifically:

[0013]

[0014] wherein i d , i q are the d-axis and q-axis currents respectively; i s is the phase current vector; β is the included angle between i s and the q-axis, also known as the current angle.

[0015] Preferably, the MTPA optimization equation considering the partial derivative term is:

[0016]

[0017] F(β) is the sum of the partial derivative terms; the flux linkage ψ f generated by the permanent magnet under load is decomposed into a d-axis component of the permanent magnet flux linkage ψ fd (id,iq) and a q-axis component of the permanent magnet flux linkage ψ fq (id,iq) ; in the dq-axis coordinate system, the inductance is divided into a d-axis inductance L d (id,iq) and a q-axis inductance L q (id,iq) ; L Δ (id,iq) = L d (id,iq) - L q (id,iq) ;

[0018] The MTPA optimization equation ignoring the partial derivative term is:

[0019]

[0020] Preferably, the dq-axis current relationship considering the partial derivative term is:

[0021]

[0022] wherein

[0023] The dq-axis current relationship ignoring the partial derivative term is:

[0024]

[0025] Preferably, the permanent magnet flux linkage is obtained according to the following voltage equation, specifically:

[0026]

[0027] wherein V d and V q are dq-axis voltages; R s is resistance; ω e is electrical angular velocity.

[0028] Preferably, the specific process of obtaining the MTPA angle based on the MTPA optimization equation considering the partial derivative and using the difference method is as follows:

[0029] Firstly, the dq-axis current relationship formula ignoring the partial derivative is rewritten as:

[0030]

[0031] wherein i b is a compensation value of i d , and the initial value is zero; under a certain load, increasing or decreasing i b will cause β to decrease or increase;

[0032] After the MTPA angle is obtained by using the rewritten dq-axis current relationship formula ignoring the partial derivative, i b is adjusted, and the size of i s before and after adjustment is compared to determine whether Δβ is constantly greater than or less than zero;

[0033] Then, i b is adjusted again, the current angle will gradually approach the actual MTPA angle, and i s satisfies the preset requirement;

[0034] Finally, the partial derivative of each parameter is calculated using the difference method for compensation.

[0035] Preferably, when Δβ is constantly less than zero, i b is decreased; when i s is greater than the value of the last adjustment, the partial derivative is calculated;

[0036] When Δβ is constantly greater than zero, i b is increased; when i s is less than the value of the last adjustment, the partial derivative is calculated.

[0037] Preferably, the partial derivative of each parameter is calculated using the difference method according to the following formula, specifically:

[0038]

[0039] wherein subscript k represents the adjustment of i bThe number of times.

[0040] The application also discloses a computer readable storage medium, which stores a computer program, and the computer program executes the steps of the method when being run by a processor.

[0041] The application further discloses a high-magnetic-path-saturation permanent magnet synchronous motor MTPA control system based on partial derivative compensation, which comprises a memory and a processor connected with each other, and the memory stores a computer program, and the computer program executes the steps of the method when being run by the processor.

[0042] Compared with the prior art, the application has the advantages that:

[0043] The MTPA control method of the permanent magnet synchronous motor based on parameter partial derivative compensation of the application deduces the MTPA optimization equation suitable for the high-magnetic-path-saturation permanent magnet synchronous motor by analyzing the change of the parameters; the relationship between the MTPA curves obtained by the two methods considering and ignoring the partial derivative is compared and analyzed, and on this basis, the error caused by ignoring the partial derivative in the MTPA optimization process is compensated by using the difference method. The simulation and experimental results show that the method proposed in the application can better track the MTPA angle of the high-magnetic-path-saturation permanent magnet synchronous motor under different load conditions, and the effectiveness and accuracy of the method are verified. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The figure is the relationship between the torque and the current angle of the application.

[0045] Figure 2 The figure is the permanent magnet flux linkage offset d-axis direction schematic diagram of the application.

[0046] Figure 3 The figure is the influence of the dq-axis current of the application on the permanent magnet flux linkage dq-axis component; (a) is the influence of the id on the permanent magnet flux linkage dq-axis component; (b) is the influence of the iq on the permanent magnet flux linkage dq-axis component. q The figure is the influence of the permanent magnet flux linkage dq-axis component on the id. d The figure is the influence of the permanent magnet flux linkage dq-axis component on the iq.

[0047] Figure 4 The figure is the relationship between the torque and the current angle when the parameter change is considered in the application.

[0048] Figure 5 The figure is the curve relationship between the id and β in the application. s The figure is the curve relationship between the id and β in the application.

[0049] Figure 6 The figure is the partial derivative compensation flowchart in the application.

[0050] Figure 7 The figure is the control block diagram of the application.

[0051] Figure 8 Figure for motor model in the present application.

[0052] Figure 9 Figure for stator tooth flux density in the present application.

[0053] Figure 10 Figure for parameter identification in the present application.

[0054] Figure 11 Figure for MTPA control under different methods.

[0055] Figure 12 Figure for torque and MTPA curves in the rated current range of the present application.

[0056] Figure 13 Figure for torque waveform in the present application.

[0057] Figure 14 Figure for test results in the present application; (a) is a MTPA curve figure; (b) is a MTPA angle comparison figure. DETAILED DESCRIPTION

[0058] The present application is further described below in conjunction with the accompanying drawings and specific examples.

[0059] Now, the traditional mathematical model and MTPA control method are described as follows:

[0060] In the traditional dq-axis model of permanent magnet synchronous motor, the flux linkage equation of dq-axis is expressed as:

[0061]

[0062] In the formula, ψ d and ψ q are total flux linkages on dq-axis; L d and L q are dq-axis inductances; i d and i q are dq-axis currents; and ψ f is the flux linkage generated by permanent magnet at no load.

[0063] At the same time, the relationship between phase current and dq-axis current can be expressed as:

[0064]

[0065] In the formula, i s is phase current vector; β is the included angle between i s and q-axis, also known as current angle.

[0066] In addition, the torque of permanent magnet synchronous motor under dq-axis coordinate system can be expressed as:

[0067]

[0068] where p is the pole pairs; Te is the electromagnetic torque.

[0069] Substitute equation (1) into equation (3), equation (4) can be obtained by simplifying:

[0070]

[0071] where L Δ is the difference of inductance in dq axis, i.e. L Δ = L d - L q .

[0072] Substitute equation (2) into equation (4), the torque equation can be rewritten as:

[0073]

[0074] From equation (5), it can be seen that when i s , L Δ and ψ f are constant, there is an optimal current angle in a certain angle range that can make Te maximum, as shown in Fig. 1. Figure 1

[0075] When i s changes, the optimal current angle will also change. By connecting the maximum torque points under different i s , the MTPA curve can be obtained. In order to obtain the optimal current angle, the partial derivative of equation (5) with respect to β is:

[0076]

[0077] Let equation (6) equal to zero, i.e.:

[0078]

[0079] Since the inductance and the permanent magnet flux linkage do not change with the current in the traditional MTPA control method, the partial derivative term of the permanent magnet flux linkage and the inductance difference with respect to the current angle in equation (7) is zero. By solving, the expression of the current angle can be obtained as:

[0080]

[0081] ​However, in practice, the permanent magnet flux linkage and inductance will vary with the dq-axis currents, resulting in a large error between the MTPA angle calculated by equation (8) and the actual MTPA angle. In addition, in the conventional dq-axis mathematical model, the q-axis component of the permanent magnet flux linkage due to saturation effect is not considered, so equation (8) is not applicable to high magnetic circuit saturation permanent magnet synchronous machines.

[0082] The variation of the permanent magnet flux linkage with the dq-axis currents is analyzed as follows:

[0083] When the motor operates in motor mode, with the increase of the core saturation level, the permanent magnet flux linkage originally in the d-axis direction will gradually shift to the negative direction of the q-axis, with the shift angle γ, as shown in Figure 2 .

[0084] At this time, ψ f can be decomposed into a permanent magnet flux linkage d-axis component ψ fd (id,iq) in the positive direction of the d-axis, and a permanent magnet flux linkage q-axis component ψ fq (id,iq) , which is in the negative direction of the q-axis, and can be represented as:

[0085]

[0086] The influence of the dq-axis currents on ψ f can be analyzed from the following two points respectively:

[0087] (1) When i q increases, the saturation level of the core increases, the shift angle γ of ψ f to the negative direction of the q-axis also increases, resulting in the decrease of ψ fd (id,iq) and the increase of ψ fq (id,iq) along the negative direction of the q-axis, as shown in (a) of Figure 3 .

[0088] (2) When i d decreases, the d-axis direction will experience desaturation, which reduces the saturation level of the core and the shift angle γ, thereby resulting in the increase of ψ fd (id,iq) and the decrease of ψ fq (id,iq) along the negative direction of the q-axis, as shown in (b) of Figure 3 . Among them, the data in (b) is obtained by finite element simulation. Figure 3

[0089] At the same time, the inductance will also change with the change of the current. The dq-axis inductance will change with i q ​It decreases as i increases, and decreases as i increases. d The inverse of the current increases. Therefore, in the flux linkage equation of a high magnetic circuit saturated permanent magnet synchronous motor, it is necessary to consider the changes in inductance and permanent magnet flux linkage with the dq axis current. Thus, equation (1) should be rewritten as:

[0090]

[0091] In the dq-axis coordinate system, the inductance is divided into d-axis inductance L. d (id,iq) and q-axis inductance L q (id,iq) In the formula, the superscript (i) d i q The ) represents the real-time value of the corresponding parameter as the dq-axis current changes.

[0092] Next, consider the MTPA control method for the partial derivative of the parameters:

[0093] Substituting equation (10) into equation (3), the expression for torque can be rewritten as:

[0094]

[0095] In the formula, L Δ (id,iq) =L d (id,iq) -L q (id,iq) Te' represents the electromagnetic torque considering parameter variations; substituting equation (2) into equation (11), the expression for the torque can be expressed using i s And β are represented as:

[0096]

[0097] when i s At a given time, the relationship between Te' and β is as follows: Figure 4 As shown.

[0098] from Figure 4 As can be seen, within the range of 0° < β < 90°, the electromagnetic torque waveform still maintains the characteristic of having only one peak. Therefore, for MTPA control considering parameter changes, the MTPA angle can also be obtained by taking the partial derivative with respect to the current angle. The partial derivative of equation (12) with respect to β is:

[0099]

[0100] Let equation (13) equal zero, that is:

[0101]

[0102] According to equation (14), each term in the equation is related to the change of the parameters. However, most of the improved MTPA formula methods ignore the rate of change of the parameters, i.e. the partial derivative, although they consider the change of the parameters.

[0103] Therefore, in order to further analyze the relationship between the MTPA curves obtained by the two methods when considering and ignoring the partial derivative, the partial derivative in equation (14) is extracted to construct a function and simplified, and the following equation is obtained:

[0104]

[0105] In the equation, F(β) is the sum of the partial derivatives; α is an auxiliary angle, i.e.

[0106]

[0107] When the leakage inductance is not considered, ψ fd (id,iq) can be equivalent to:

[0108]

[0109] In the equation, i f is the equivalent excitation current; and the total flux linkage equation of the d-axis can be equivalent to:

[0110]

[0111] Since ψ d (id,iq) and L d (id,iq) are greater than zero, i f +i d >0; equation (18) is substituted into equation (16) to obtain:

[0112]

[0113] Qualitative analysis of equation (19) shows that when β increases, L d (id,iq) and L q (id,iq) increase at the same time, and according to equation (18), i f +i d >0, so equation (18) is greater than zero. In addition, when i d increases in the opposite direction, i q decreases, ψ fq (id,iq) will increase, i.e. will increase with the increase of β angle, so it can be obtained that:

[0114]

[0115] Substituting formula (20) into formula (16) can obtain 0° < a < 90°, and 0° < β + a < 180°; in combination with formula (15), it can be known that F(β) > 0.

[0116] In order to better illustrate the conclusion, the MTPA optimization equations considering and ignoring the partial derivative term are respectively referred to as method 1 and method 2, that is:

[0117] Method 1:

[0118] Method 2:

[0119] Based on the above analysis, it can be concluded that: since F(β) is always greater than zero, when the load is constant, the MTPA angles obtained by method 1 and method 2 are always not equal. In other words, there is no intersection between the MTPA curves obtained by the two methods, that is, the angle error Δβ of method 2 is always greater than zero or less than zero, as shown in formula (13). Figure 5

[0120] Therefore, in order to accurately obtain the distribution relationship of the dq-axis current on the MTPA curve, in addition to obtaining the size of the inductance and the permanent magnet flux linkage in real time, the corresponding partial derivative term also needs to be obtained.

[0121] Since formula (21) and formula (22) are difficult to be simplified into an analytical expression of β, the two equations cannot be directly used to complete the MTPA control, but need to be converted. Substituting formula (2) into formula (21) and formula (22) can obtain the dq-axis current relationship of method 1 and method 2 as formula (23) and formula (24):

[0122]

[0123]

[0124] In vector control, the reference value of iq can be obtained by the PI integral of the speed loop, the inductance can be obtained by parameter identification, and the permanent magnet flux linkage can be obtained according to the voltage equation, that is:

[0125]

[0126] In the formula, V d and V q are the dq-axis voltages; R s is the resistance; ω e is the electrical angular velocity; wherein, the dq-axis inductance and the resistance are obtained by parameter identification method.

[0127] In order to obtain the partial derivative term in formula (23), the difference method can be used on the basis of method 2, and the specific method is as follows: ​

[0128] Firstly, formula (24) is rewritten as:

[0129]

[0130] where i b is the compensation value of i d , and the initial value is zero. Under certain load, adjusting i b to increase or decrease will cause β to decrease or increase.

[0131] After obtaining the MTPA angle by using formula (26), i b is adjusted, and the size of i s before and after adjustment is compared to determine whether Δβ of method 2 is always greater than or always less than zero. Taking the case of always less than zero as an example, i b is continuously decreased. At this time, according to the analysis, the current angle will gradually approach the actual MTPA angle and i s will gradually decrease until i s is greater than the value at the last adjustment. Assuming that the phase current and the current angle at this moment are i s(k+1) and β (k+1) , respectively, and the phase current and the current angle at the last adjustment are i s(k) and β (k) , respectively, then the actual MTPA angle is between β (k+1) and β (k) . Within a smaller range, the rate of change of the parameter with β can be regarded as a constant value, that is, the partial derivative is constant.

[0132] Finally, the partial derivative of each parameter is calculated by using the difference method according to formula (27) and is brought into method 1 for compensation. The specific process is shown in Figure 6 , and the overall control block diagram is shown in Figure 7 .

[0133]

[0134] where subscript (k) represents the number of adjustments of i b .

[0135] Figure 7 where θ e is the electrical angle of the rotor; ω m is the speed; i dh and i qh are high-frequency dq-axis currents injected for parameter identification; and subscript ref is the corresponding reference value.

[0136] The application establishes a HSPMSM mathematical model on the basis of a conventional PMSM mathematical model, proposes a MTPA control optimization equation of the HSPMSM, and analyzes variation of parameters in the optimization equation and non-ignorability of partial derivatives of the parameters to a current angle in the optimization equation; in order to simultaneously consider influences of the variation of the parameters and the partial derivatives, the application invents a MTPA control method based on partial derivative compensation, acquires partial derivatives of the parameters by using a finite difference method on the basis of considering the variation of the parameters, and compensates the partial derivatives in the optimization equation; finally, simulation and experiment verify that the conventional MTPA control method is not applicable to the HSPMSM, and the method proposed by the application can accurately track an optimal current angle.

[0137] Specifically, in order to verify effectiveness of the method, the application establishes a high magnetic circuit saturation permanent magnet synchronous motor finite element model, as shown in Figure 8 Table 1 lists main parameters of the model, including dq-axis inductances when dq-axis currents are zero and a permanent magnet flux linkage.

[0138] Table 1 Motor parameters

[0139]

[0140] For the high magnetic circuit saturation permanent magnet synchronous motor under different load conditions, a stator core is usually in a high saturation state, and especially maximum magnetic density of a stator tooth part is usually greater than 1.8T. In order to verify the saturation degree of the stator tooth part, a motor speed is set as a rated speed. Then, the stator tooth part magnetic density is simulated under different load conditions, as shown in Figure 9

[0141] It can be known from Figure 9 that the stator tooth part magnetic density exceeds 1.8T within a range of 78% of a rated current. At the same time, when i d =-275A and i q =605A, the motor can operate at a rated torque with minimum current, and the stator tooth part magnetic density is 2.05T. Therefore, the saturation degree of the permanent magnet synchronous motor is high. And from the previous analysis, it can be known that the inductance and the permanent magnet flux linkage of the high magnetic circuit saturation permanent magnet synchronous motor will change nonlinearly with load, so parameters under different loads need to be identified, taking the MTPA trajectory (OA) as an example, as shown in Figure 10

[0142] It can be known from Figure 10 that the identified value and the simulation value are close, verifying effectiveness of the parameter identification method. Then, according to the control block diagram of Figure 7 , the proposed method is used for MTPA control, and in order to better illustrate importance of the variation of the parameters and the partial derivatives in the MTPA optimization process, different methods are used for comparison, as shown in​​Figure 11 As shown. Among them, Method 1 is the method proposed in this invention; Method 2 considers the change of parameters but ignores the partial derivative term; Method 3 is the traditional MTPA control, which ignores the change of parameters and the partial derivative term.

[0143] from Figure 11 It can be seen that the traditional method has the largest error, while method 2, although reducing the error compared to the traditional method, still deviates from the optimal angle due to neglecting the partial derivative term, and the error increases with the load. Compared with other methods, the method proposed in this invention is closer to the actual MTPA curve, verifying the effectiveness of the analysis and proposed method of this invention.

[0144] To further verify the method proposed in this invention, relevant experiments were conducted. A 300kW built-in permanent magnet synchronous motor prototype was fabricated, and the design model and parameters of this prototype are as follows: Figure 8 As shown in Table 1, an 800kW induction motor with a rated speed of 3000rpm was used to drive the prototype in the experiment. Water cooling was employed, with 30℃ cooling water flowing into the water jacket of the prototype at a rate of 60L / min to prevent excessive temperature rise. To ensure the accuracy of torque measurement, a torque sensor (ATESTEO:DF3) with a rated torque of 2kNm and an accuracy of ±0.04% was installed. Simultaneously, a high-speed recorder from HiTechnologies was used to observe the data in real time, and the data was exported via PC software.

[0145] First, torque measurements were performed on the prototype to find the actual MTPA curve. (Set i) d The prototype was run under no-load conditions; then, the load was gradually increased, and the torque and dq-axis current were measured and recorded under different load conditions; finally, the i-axis current was gradually decreased. d And repeat the previous steps; the torque obtained within the rated current range is as follows Figure 12 As shown, the actual MTPA trajectory (OB) is plotted.

[0146] Due to certain technical and assembly errors during prototype manufacturing, the actual torque values ​​differ from the simulated values ​​under different load conditions. For example, the minimum current under rated torque differs from the simulated value. When the prototype operates under rated torque, the dq-axis currents are i... d =-350A and i q =580A, torque waveform as follows Figure 13 As shown.

[0147] Next, according to Figure 7 The control block diagram was used, and experiments were conducted using different methods. The resulting MTPA curves are shown below. Figure 14The MTPA angles under different loads are extracted and compared under the corresponding method, as shown in Figure 14 As shown in (b).

[0148] Figure 14 It is shown that, in the rated load range, the maximum error of the MTPA angle is-2.8° when the method 2 is used, and the main reason for the error is that the partial derivative in the MTPA optimization control is not considered. When the method 3 is used, the maximum error of the MTPA angle is 9.1°, and the main reason for the error is that the parameter change is not considered. In addition, due to the certain difference between the simulation model and the actual prototype, the maximum error of the MTPA angle between the simulation result and the test result is 6.1°. The MTPA angle error of the method proposed in the application is relatively stable, and the maximum error is 1.3°. Compared with other methods, the method can obtain better precision, and the effectiveness and accuracy of the method are verified.

[0149] The MTPA control method of the permanent magnet synchronous motor based on the parameter partial derivative compensation provided by the application can derive the MTPA optimization equation suitable for the high magnetic saturation permanent magnet synchronous motor by analyzing the parameter change, compare and analyze the relationship between the MTPA curves obtained by the two methods considering and ignoring the partial derivative, and on this basis, the differential method is used to make up for the error caused by ignoring the partial derivative in the MTPA optimization process. The simulation and experimental results show that the method proposed in the application can better track the MTPA angle of the high magnetic saturation permanent magnet synchronous motor under different load conditions, and the effectiveness and accuracy of the method are verified.

[0150] The application further discloses a computer readable storage medium, which stores a computer program, and the computer program executes the steps of the method when being run by a processor. The application further discloses a high magnetic saturation permanent magnet synchronous motor MTPA control system based on partial derivative compensation, which comprises a memory and a processor connected with each other, and the memory stores a computer program, and the computer program executes the steps of the method when being run by the processor. The medium and the system of the application correspond to the above method, and have the advantages of the above method.

[0151] The present application can realize all or part of the processes in the above-mentioned embodiment methods, and can also be completed by computer program instruction related hardware. The computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned method embodiment can be realized. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable storage medium includes any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc. The memory is used to store computer programs and / or modules. The processor realizes various functions by running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory. The memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage device, etc.

[0152] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that some improvements and refinements made by ordinary skilled persons in the art without departing from the principles of the present application shall be considered as falling within the protection scope of the present application.

Claims

1. A method for MTPA control of a high-magnetic-path saturation permanent magnet synchronous motor based on partial derivative compensation, characterized in that, The steps include: obtaining the relationship between the phase currents and dq the axis currents, and obtaining the corresponding dq axis current relationships based on the MTPA optimization equation considering the partial derivative and the MTPA optimization equation ignoring the partial derivative, respectively. acquisition i q reference value, inductance, permanent magnet flux linkage, partial derivative term and MTPA angle, and then according to the MTPA optimization equation considering the partial derivative term dq axis current for motor control; Wherein the MTPA angle is based on the MTPA optimization equation ignoring the partial derivative and is obtained by using the difference method; Phase current and dq The specific relationship between the shaft currents is as follows: wherein i d , i q are respectively d、q axis current; i s is a phase current vector; is i s and q the angle between the axes, also called the current angle; The MTPA optimization equation considering the partial derivative is: F (β) is the sum of the partial derivatives; flux generated by the permanent magnet when loaded decomposed into permanent magnet flux d axial component , and permanent magnet flux q axial component ; In dq In the axis coordinate system, the inductance is divided into d Axis inductance L d (id,iq) and q Axis inductance L q (id,iq) ; = L d (id,iq) - L q (id,iq) ; The MTPA optimization equation ignoring the partial derivative is: ； Wherein the specific process of the MTPA angle based on the MTPA optimization equation considering the partial derivative and obtained by using the difference method is: First, the partial derivative of the bias will be ignored dq The axial current relationship is rewritten as: wherein i b is the compensation value, and the initial value is zero. Under certain load, adjusting i d the compensation value will cause β to decrease or increase. i b or decrease, will cause β to decrease or increase. When using the rewritten method that ignores partial derivatives dq After obtaining the MTPA angle from the shaft current relationship, adjust... i b And by comparing and adjusting before and after time i s Judging by size It is either always greater than or always less than zero; Next, the current angle is adjusted again i b , the current angle will gradually approach the actual MTPA angle and i s satisfy the preset requirement; Finally, the partial derivative of each parameter is calculated by using the difference method for compensation.

2. The MTPA control method for high-magnetic-path saturation permanent magnet synchronous motor based on partial derivative compensation according to claim 1, characterized in that, considering the partial derivative dq The shaft current relationship is: wherein ; ; ignoring the partial derivatives dq The axial current relationship is: 。 3. The MTPA control method of a high-magnetic-path saturation permanent magnet synchronous motor based on partial derivative compensation according to claim 2, characterized in that, The permanent magnet flux linkage is obtained according to the following voltage equation, specifically: wherein V d and V q is dq shaft voltage; R s is resistance; ω e is electrical angular velocity.

4. The MTPA control method of a high-magnetic-path saturation permanent magnet synchronous motor based on partial derivative compensation according to claim 3, characterized in that, In When constant is less than zero, decrease i b When i s When greater than the value from the last adjustment, calculate the partial derivative In When constant is greater than zero, increase i b When i s When less than the value of the last adjustment, calculate the partial derivative.

5. The MTPA control method of a high-magnetic-path saturation permanent magnet synchronous motor based on partial derivative compensation according to claim 3, characterized in that, The partial derivative of each parameter is calculated by using the difference method according to the following formula, specifically: wherein the subscript k represents the number of times of adjustment i b .

6. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program, when executed by a processor, performs the steps of the method of any one of claims 1-5.

7. A high magnetic path saturation permanent magnet synchronous motor (MTPA) control system based on partial derivative compensation, comprising a memory and a processor connected to each other, and the memory has a computer program stored thereon, characterized in that, The computer program, when executed by a processor, performs the steps of the method of any one of claims 1-5.

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