External characteristic parameter prediction method and device of motor, electronic equipment and storage medium

Abstract

The invention discloses a motor external characteristic parameter prediction method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring inherent parameters of the motor; the inherent parameters comprise permanent magnet flux linkage, direct-axis inductance, a maximum voltage limit value and a maximum current limit value; under a rectangular coordinate system with direct-axis current as the X axis and quadrature-axis current as the Y axis, the center position of a voltage limit ellipse is determined according to the permanent magnet flux linkage and the direct-axis inductance, the position relation between the center position and a current limit circle is determined, the voltage limit ellipse is determined according to the maximum voltage limit value, and the current limit circle is determined according to the current limit value. The current limit circle is determined according to the current maximum limit value; and predicting external characteristic parameters of the motor according to the position relation, the maximum voltage limit value and the maximum current limit value.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a method, device, electronic device and storage medium for predicting external characteristic parameters of a motor. Background Art

[0002] In the field of electric vehicles, the external characteristic parameters of the motor are very important parameters used to describe the performance of the motor contained in the electric vehicle. For example, they play a very important role in the design stage such as formulating the control strategy of the motor and developing the powertrain system. At present, the external characteristic parameters of the motor are usually obtained through bench calibration or vehicle testing. However, when the external characteristic parameters measured by bench calibration or vehicle testing are seriously inconsistent with the design, more repeated operations are required, such as redesign and reassembly, which will increase the manpower and material costs of the project, and in serious cases, there will be major safety hazards. Summary of the invention

[0003] The present application provides a method, device, electronic device and storage medium for predicting external characteristic parameters of a motor.

[0004] In a first aspect, the present application provides a method for predicting external characteristic parameters of a motor, comprising: obtaining inherent parameters of the motor; the inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit;

[0005] In a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, the center position of the voltage limit ellipse is determined according to the permanent magnet flux and the direct-axis inductance, and the positional relationship between the center position and the current limit circle is determined, wherein the voltage limit ellipse is determined according to the maximum voltage limit value, and the current limit circle is determined according to the current maximum limit value;

[0006] The external characteristic parameters of the motor are predicted according to the position relationship, the maximum voltage limit and the maximum current limit.

[0007] In the above solution, predicting the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit includes:

[0008] If the center position is outside the current limit circle, predict a first external characteristic parameter according to the maximum voltage limit and the maximum current limit; wherein the first external characteristic parameter includes a first sub-mapping relationship between the torque corresponding to the maximum torque current ratio MTPA control, the direct-axis current and the quadrature-axis current; and a second sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control;

[0009] If the center position is within the current limit circle, the second external characteristic parameter is predicted according to the maximum voltage limit and the maximum current limit; wherein the second external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the MTPA control; a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; and a third sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque-to-voltage ratio MTPV control.

[0010] In the above solution, the inherent parameters also include the quadrature-axis inductance and the number of pole pairs of the motor;

[0011] Obtaining the first sub-mapping relationship includes:

[0012] Obtaining a torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the number of pole pairs, and the permanent magnet flux linkage;

[0013] Under the MTPA constraint condition, a first expression with a given current as an independent variable and a direct-axis current as a dependent variable is determined according to the torque equation; a second expression with a given current and a direct-axis current as independent variables and a quadrature-axis current as a dependent variable is determined; wherein the square of the given current is equal to the sum of the square of the direct current and the square of the quadrature-axis current;

[0014] The given current is gradually increased according to a first set step length to obtain a set of target given currents; the target given current is not greater than the maximum current limit;

[0015] For each target given current, the direct-axis current and the quadrature-axis current corresponding to the target given current are obtained according to the first expression and the second expression; and the corresponding torque value is obtained according to the torque equation and each pair of the direct-axis current and the quadrature-axis current;

[0016] The first sub-mapping relationship is formed according to each pair of direct-axis current, quadrature-axis current and corresponding torque value.

[0017] In the above solution, the inherent parameter also includes the quadrature-axis inductance of the motor; and obtaining the second sub-mapping relationship includes:

[0018] Determine a first turning speed and a second turning speed of the motor according to the inherent parameters;

[0019] gradually increasing the speed of the motor from the first turning speed according to a second set step length to obtain a set of first target speeds; the first target speed is not greater than the second turning speed;

[0020] For each first target speed, a first intersection is obtained according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and a second intersection is obtained according to the voltage ellipse equation and the current limit circle equation, wherein the first intersection includes a first direct-axis current; the second intersection includes a second direct-axis current; a group of direct-axis currents between the first direct-axis current and the second direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation;

[0021] The second sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each first target speed.

[0022] In the above solution, the inherent parameter also includes the quadrature-axis inductance of the motor; obtaining the third sub-mapping relationship includes:

[0023] Determining a second turning speed under flux weakening control according to the inherent parameters;

[0024] gradually increasing the speed of the motor from the second turning speed according to a third set step length to obtain a set of second target speeds; the second target speed is not greater than a preset maximum speed;

[0025] For each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; the third intersection includes a third direct-axis current; a group of direct-axis currents between the direct-axis current corresponding to the center position and the third direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation;

[0026] The third sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each second target speed.

[0027] In the above scheme, the center position of the voltage limit circle is located on the negative half axis of the X-axis; the radius of the current limit circle is the maximum current limit value, and its center is the origin of the rectangular coordinate system; determining the positional relationship between the center position and the current limit circle includes: determining the distance value between the center position and the origin; comparing the distance value with the maximum current limit value; if the distance value is greater than the maximum current limit value, the positional relationship includes the center position being outside the current limit circle; if the distance value is less than or equal to the maximum current limit value, the positional relationship includes the center position being inside the current limit circle.

[0028] In the above scheme, the method is applied in the new function testing phase of the vehicle; the testing phase is before bench calibration or whole vehicle testing.

[0029] In a second aspect, the present application further provides a device for predicting external characteristic parameters of a motor, comprising:

[0030] An acquisition module, used for acquiring the inherent parameters of the motor; the inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit;

[0031] A determination module, used to determine the center position of the voltage limit ellipse according to the permanent magnet flux and the direct-axis inductance in a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, and to determine the positional relationship between the center position and the current limit circle; the voltage limit ellipse is determined according to the maximum voltage limit value; the current limit circle is determined according to the maximum current limit value;

[0032] A prediction module is used to predict the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit; the external characteristic parameters include a mapping relationship between the torque, the direct-axis current and the quadrature-axis current.

[0033] In the above scheme, the prediction module is used to predict the first external characteristic parameter according to the maximum voltage limit and the maximum current limit if the center position is outside the current limit circle; wherein the first external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the maximum torque current ratio MTPA control; and a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; if the center position is within the current limit circle, the second external characteristic parameter is predicted according to the maximum voltage limit and the maximum current limit; wherein the second external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the MTPA control; a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; and a third sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque voltage ratio MTPV control.

[0034] In the above solution, the inherent parameters also include the quadrature-axis inductance and the number of pole pairs of the motor;

[0035] The prediction module is also used to: obtain the torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the pole pair number, and the permanent magnet flux; determine a first expression with a given current as an independent variable and a direct-axis current as a dependent variable according to the torque equation under the MTPA constraint; determine a second expression with a given current and a direct-axis current as independent variables and a quadrature-axis current as a dependent variable; wherein the square of the given current is equal to the sum of the square of the direct current and the square of the quadrature-axis current; gradually increase the given current according to a first set step size to obtain a set of target given currents; the target given current is not greater than the maximum current limit; for each target given current, obtain the direct-axis current and the quadrature-axis current corresponding to the target given current according to the first expression and the second expression; and obtain the corresponding torque value according to the torque equation and each pair of direct-axis currents and quadrature-axis currents; and form the first sub-mapping relationship according to each pair of direct-axis currents, quadrature-axis currents and the corresponding torque values.

[0036] In the above scheme, the inherent parameters also include the quadrature-axis inductance of the motor; the prediction module is also used to: determine the first turning speed and the second turning speed of the motor according to the inherent parameters; gradually increase the speed of the motor from the first turning speed according to the second set step size to obtain a set of first target speeds; the first target speed is not greater than the second turning speed; for each first target speed, a first intersection is obtained according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and a second intersection is obtained according to the voltage ellipse equation and the current limit circle equation, wherein the first intersection includes a first direct-axis current; the second intersection includes a second direct-axis current; a set of direct-axis currents between the first direct-axis current and the second direct-axis current is obtained; a set of corresponding quadrature-axis currents is obtained according to the voltage ellipse equation and the obtained set of direct-axis currents; a set of corresponding torques is obtained based on the obtained set of direct-axis currents, the set of corresponding quadrature-axis currents and the torque equation; and the second sub-mapping relationship is formed according to a set of direct-axis currents, a set of corresponding quadrature-axis currents and a set of corresponding torques corresponding to each first target speed.

[0037] In the above scheme, the inherent parameters also include the cross-axis inductance of the motor; the prediction module is used to determine the second turning speed under weak magnetic control according to the inherent parameters; the speed of the motor is gradually increased from the second turning speed according to a third set step size to obtain a set of second target speeds; the second target speed is not greater than the preset maximum speed; for each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; the third intersection includes a third direct-axis current; a set of direct-axis currents corresponding to the center position and the third direct-axis current are obtained; a set of corresponding cross-axis currents are obtained according to the voltage ellipse equation and the obtained set of direct-axis currents; a set of corresponding torques are obtained based on the obtained set of direct-axis currents, the set of corresponding cross-axis currents and the torque equation; and the third sub-mapping relationship is formed according to a set of direct-axis currents, a set of corresponding cross-axis currents and a set of corresponding torques corresponding to each second target speed.

[0038] In a third aspect, the present application also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program implements the steps of any of the methods described above when executed by the processor.

[0039] In a fourth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the methods described above are implemented.

[0040] The present application provides a method, device, electronic device and storage medium for predicting the external characteristic parameters of a motor. The prediction method includes: obtaining the inherent parameters of the motor; the inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit; in a rectangular coordinate system with direct axis current as the X-axis and quadrature axis current as the Y-axis, the center position of the voltage limit ellipse is determined according to the permanent magnet flux and the direct axis inductance, and the positional relationship between the center position and the current limit circle is determined, wherein the voltage limit ellipse is determined according to the maximum voltage limit, and the current limit circle is determined according to the maximum current limit; the external characteristic parameters of the motor are predicted according to the positional relationship, the maximum voltage limit and the maximum current limit. In the present application, by obtaining the inherent parameters of the motor used, the inherent parameters and the mathematical equations of the motor are used to predict the external characteristic parameter table of the motor under MTPA control (that is, the first sub-mapping relationship), the external characteristic parameter table of the motor under weak magnetic control (that is, the second sub-mapping relationship), and the external characteristic parameter table of the motor under MTPV control (that is, the third sub-mapping relationship). In this way, the external characteristic parameters of the motor to be used can be predicted in advance, and these external characteristic parameters can be applied to the test phase of new function development of the vehicle before bench calibration or vehicle testing to complete the closed-loop test in the testing phase. This can detect problems early and make adjustments to software functions to avoid situations where actual parameters do not match design values ​​during bench calibration or vehicle testing, thereby reducing repeated operations, saving manpower and material resources, improving production efficiency, and improving vehicle safety, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The figure is a schematic flow chart of a method for predicting external characteristic parameters of a motor provided in an embodiment of the present application;

[0042] Figure 2 Shown is a schematic diagram of the running curve of the motor provided by the embodiment of the present application when the center position is outside the current limit circle;

[0043] Figure 3 Shown is a schematic diagram of an external characteristic curve of a motor provided in an embodiment of the present application;

[0044] Figure 4 Shown is a schematic diagram of an operating curve of a motor provided by an embodiment of the present application when the center position is within the current limit circle;

[0045] Figure 5 Shown is a schematic diagram of an operating curve of a motor in another case where the center position is within the current limit circle provided by an embodiment of the present application;

[0046] Figure 6 The figure is a schematic diagram of the structure of the device for predicting the external characteristic parameters of a motor provided in an embodiment of the present application;

[0047] Figure 7 Shown is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] As mentioned above, the external characteristic parameters of the motor are very important in the analysis of electric vehicles. The so-called external characteristic curve is the curve of the torque measured at full load and the change of speed, which reflects the motor characteristics. The characteristics of the external characteristics of the motor of an electric vehicle are as follows: 1) Torque characteristics: At low speeds, the motor can immediately provide the maximum torque, which is determined by its working principle. This means that the electric vehicle can obtain strong acceleration ability at the start. As the speed increases, the torque of the motor will gradually decrease until it reaches a certain value and stabilizes. 2) Power characteristics: The maximum power of the motor usually remains constant within a certain speed range. After exceeding this range, the power will decrease as the speed increases. This is because in order to protect the motor from being damaged by overload, the control system will limit the current, thereby reducing the power output. 3) Efficiency characteristics: The efficiency curve of the motor shows the change of the motor efficiency under different load conditions. Generally speaking, the motor is most efficient at medium loads, and the efficiency will decrease at low or high loads.

[0050] New energy electric vehicles use these external characteristics to optimize vehicle performance, such as improving energy efficiency through intelligent energy management systems, or adjusting the drive system to adapt to various driving needs. External characteristics are very important for understanding how the motor responds to driver commands and how to efficiently use battery power. It is one of the foundations for designers to evaluate motor performance, formulate control strategies, and develop powertrain systems.

[0051] However, during the new function software testing phase of new energy vehicles, due to differences in requirements, it is not possible to directly use the external characteristic parameters of similar motors or to obtain the external characteristic parameters of unknown motors. Based on the ASPICE software development process, function development, test verification, and actual vehicle testing are required according to requirements. Based on the V-type forward process, after the function is developed, model in loop (MIL) and hardware in loop (HIL) testing and verification are required. In the main algorithm model, the direct-axis current-cross-axis current (i d -i q) table and the corresponding external characteristic curve table will result in the inability to close the loop in MIL and HIL, and the development process cannot be smoothly promoted. If closed-loop testing cannot be performed in the test phase, if major problems are detected during bench or vehicle testing, the manpower and material costs of the project will increase, and in serious cases, there will be major safety hazards.

[0052] In order to solve the above problems, the embodiment of the present application provides a method for predicting the external characteristic parameters of a motor, by obtaining the inherent parameters of the motor in use, and using the inherent parameters and the mathematical equations of the motor to predict the external characteristic parameter table (i.e., the third sub-mapping relationship) of the motor under PV control under different motor control strategies. In this way, the external characteristic parameters of the motor in use can be predicted in advance, and such external characteristic parameters can be applied to the test phase of the vehicle's new function development before bench calibration or vehicle testing to complete the closed-loop test in the test phase, so that problems can be discovered early and adjustments to the software functions can be made.

[0053] The external characteristic parameter prediction method and related devices of the motor provided in the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0054] like Figure 1 As shown, it shows a flow chart of a method for predicting external characteristic parameters of a motor provided by an embodiment of the present application. Figure 1 In, the prediction method may include:

[0055] Step 101: Acquire the inherent parameters of the motor; the inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit;

[0056] Step 102: in a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, determining the center position of the voltage limit ellipse according to the permanent magnet flux and the direct-axis inductance, and determining the positional relationship between the center position and the current limit circle, wherein the voltage limit ellipse is determined according to the maximum voltage limit value, and the current limit circle is determined according to the maximum current limit value;

[0057] Step 103: predicting the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit.

[0058] It should be noted that the method can be applied in the new function test phase of the vehicle; the test phase is before bench calibration or vehicle testing. The motor can be a permanent magnet synchronous motor under vector control (FOC, Field-Oriented Control). The inherent parameter can refer to the permanent magnet flux linkage ψ of the permanent magnet synchronous motor. f , motor direct axis inductance L d With quadrature axis inductance Lq , pole pair number P n , Maximum current limit I s，max , Maximum voltage limit U max Etc. These inherent parameters are recorded in the motor's instruction manual or on the nameplate that comes with the motor.

[0059] After obtaining the inherent parameters of the motor, the direct axis current i d is the X-axis and quadrature-axis current i q In a rectangular coordinate system with the Y axis as the center position of the voltage limit ellipse is determined according to the permanent magnet flux and the direct axis inductance, wherein the center position is i q =0, that is, the center position of the voltage limit circle is located at the negative half axis of the X axis. The voltage limit ellipse is determined according to the maximum voltage limit value, that is, the mathematical equation of the voltage limit ellipse is as follows: Formula 1:

[0060]

[0061] Where ω is the motor speed. Voltage limit ellipse with the same center position at different speeds.

[0062] Here, the current limit circle is determined according to the maximum current limit, that is, in the aforementioned rectangular coordinate system, with I s，max The current limit circle has a radius of , and the origin is the center of the circle, that is, the radius of the current limit circle is the maximum current limit value, and the center of the circle is the origin of the rectangular coordinate system.

[0063] After obtaining the center position of the voltage limit ellipse and the current limit circle, the positional relationship between the center position and the current limit circle can be determined. In some embodiments, the determination of the positional relationship between the center position and the current limit circle can include: determining the distance value between the center position and the origin; comparing the distance value with the maximum current limit value; if the distance value is greater than the maximum current limit value, the positional relationship includes that the center position is outside the current limit circle; if the distance value is less than or equal to the maximum current limit value, the positional relationship includes that the center position is within the current limit circle.

[0064] That is, determine the distance value With the maximum current limit I s，max If the size between Greater than I s，max , then the positional relationship includes the center position being outside the current limit circle; if Less than I s，max , then the positional relationship includes the center position being within the current limit circle.

[0065] After determining the positional relationship of the center position between the current limit circles, in some embodiments, predicting the external characteristic parameters of the motor according to the positional relationship, the maximum voltage limit, and the maximum current limit may include:

[0066] If the center position is outside the current limit circle, predict a first external characteristic parameter according to the maximum voltage limit and the maximum current limit; wherein the first external characteristic parameter includes a first sub-mapping relationship between the torque corresponding to the maximum torque current ratio MTPA control, the direct-axis current and the quadrature-axis current; and a second sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control;

[0067] If the center position is within the current limit circle, the second external characteristic parameter is predicted according to the maximum voltage limit and the maximum current limit; wherein the second external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the MTPA control; a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; and a third sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque-to-voltage ratio MTPV control.

[0068] That is, the positional relationship between the center position and the current limit circle is different, and the external characteristic parameters of the motor to be predicted are also different. Specifically, when the center position is outside the current limit circle, the motor only has a constant torque operation area (that is, the maximum torque current ratio (MTPA) control operation area) and a flux weakening control operation area. At this time, there is a maximum theoretical speed ω max0 . At this time, the external characteristic parameters required to be predicted include the first external characteristic parameters, that is, including: the first sub-mapping relationship between the torque corresponding to the maximum torque current ratio MTPA control, the direct-axis current and the quadrature-axis current; and the second sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control. When the center position is within the current limit circle, the maximum speed of the motor is no longer subject to the voltage limit, and theoretically can reach infinity. At this time, in addition to the MTPA control operation area and the weak magnetic control operation area, it also includes the maximum torque voltage ratio (MTPV) control operation area. At this time, the external characteristic parameters required to be predicted include the second external characteristic parameters, that is, including: the first sub-mapping relationship between the torque corresponding to the MTPA control, the direct-axis current and the quadrature-axis current; the second sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control, and the third sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque voltage ratio MTPV control.

[0069] It should be noted that, no matter the center position is inside or outside the current limit circle, the first sub-mapping relationship and the second sub-mapping relationship may be determined in the same manner, and only the determination of the first sub-mapping relationship, the second sub-mapping relationship and the third sub-mapping relationship is described in detail below.

[0070] Specifically, in some embodiments, the inherent parameters further include the quadrature-axis inductance and the number of pole pairs of the motor; then, obtaining the first sub-mapping relationship may include:

[0071] Obtaining a torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the number of pole pairs, and the permanent magnet flux linkage;

[0072] Under the MTPA constraint condition, a first expression with a given current as an independent variable and a direct-axis current as a dependent variable is determined according to the torque equation; a second expression with a given current and a direct-axis current as independent variables and a quadrature-axis current as a dependent variable is determined; wherein the square of the given current is equal to the sum of the square of the direct current and the square of the quadrature-axis current;

[0073] The given current is gradually increased according to a first set step length to obtain a set of target given currents; the target given current is not greater than the maximum current limit;

[0074] For each target given current, the direct-axis current and the quadrature-axis current corresponding to the target given current are obtained according to the first expression and the second expression; and the corresponding torque value is obtained according to the torque equation and each pair of the direct-axis current and the quadrature-axis current;

[0075] The first sub-mapping relationship is formed according to each pair of direct-axis current, quadrature-axis current and corresponding torque value.

[0076] It should be noted that the first sub-mapping relationship here is the external characteristic parameter of the motor under MTPA control. The process of obtaining the first sub-mapping relationship can refer to Figure 2 The details are as follows:

[0077] The first step is to obtain the torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the pole pair number, and the permanent magnet flux linkage. The mathematical equation is as follows:

[0078]

[0079] Where T is the torque.

[0080] The second step is to transform the above torque equation into i under the MTPA constraint condition. d Take the derivative of the independent variable and let To obtain the first expression with the given current as the independent variable and the direct-axis current as the dependent variable, that is, under the MTPA constraint condition, the first expression with the given current as the independent variable and the direct-axis current as the dependent variable is determined according to the torque equation.

[0081] The first expression is expressed as follows:

[0082]

[0083] Among them, I s For a given current.

[0084] Also because Therefore, according to formula (3), the second expression can be obtained as follows:

[0085]

[0086] The third step is to take the given current I s The first set step length is gradually increased to obtain a set of target given currents; the target given current is not greater than the maximum current limit. For example, according to 5 amperes as the first set step length, the given current is gradually increased to obtain a set of target given currents. According to formula (3) and formula (4), a set of i corresponding to each target given current is obtained. d -i q ; After that, each group i d -i q , substituted into formula (2) to obtain each group i d -i q The corresponding torque.

[0087] In the fourth step, the first sub-mapping relationship is formed according to each pair of direct-axis current, quadrature-axis current and corresponding torque value.

[0088] That is, based on the above formulas (2), (3) and (4), appropriate step lengths are taken to gradually increase the given current, and different I s Next d 、i q The value is then calculated using the torque formula to obtain the corresponding torque value T, and the operating point in the constant torque operation area is obtained.

[0089] At this point, the motor speed ω at point A can be calculated b , which is the motor base speed. The calculation formula (5) is as follows:

[0090]

[0091] Among them, ω b is the motor base speed.

[0092] The second sub-mapping relationship is the external characteristic parameter corresponding to the motor under magnetic field weakening control. In some embodiments, the inherent parameter further includes the quadrature-axis inductance of the motor. The second sub-mapping relationship may include:

[0093] Determine a first turning speed and a second turning speed of the motor according to the inherent parameters;

[0094] gradually increasing the speed of the motor from the first turning speed according to a second set step length to obtain a set of first target speeds; the first target speed is not greater than the second turning speed;

[0095] For each first target speed, a first intersection is obtained according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and a second intersection is obtained according to the voltage ellipse equation and the current limit circle equation, wherein the first intersection includes a first direct-axis current; the second intersection includes a second direct-axis current; a group of direct-axis currents between the first direct-axis current and the second direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation;

[0096] The second sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each first target speed.

[0097] It should be noted that the first turning speed mentioned here can be the motor base speed obtained by the previous calculation. The second turning speed can refer to the maximum theoretical speed ω mentioned above. max0 .Depend on Figure 2 As shown, the speed of point B is ω max0 The coordinates of point B are i d =-I s ,i q =0.ω max0 The calculation formula can be as follows (7):

[0098]

[0099] Under this weak magnetic control, the external characteristic curve of the motor is as follows: Figure 3 As shown, the constant torque operation area has been obtained by the first sub-mapping relationship calculated above, and the operating point under the current demand curve AB is obtained. Figure 3 middle,

[0100] Specifically, the process of obtaining the second sub-mapping relationship is as follows:

[0101] The first step is to obtain the first turning speed and the second turning speed, which have been described above and will not be repeated here.

[0102] In the second step, the motor speed is gradually increased from the first turning speed according to a second set step length to obtain a set of first target speeds; the first target speed is not greater than the second turning speed. b to max0 The first target speed is obtained by gradually increasing the speed of the curve AB by 100 revolutions per minute (rpm). The first target speeds of this group are not greater than the second turning speed.

[0103] Step 3: For each first target speed, obtain the first intersection point according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and obtain the second intersection point according to the voltage ellipse equation and the current limit circle equation; obtain a set of direct-axis currents between the first direct-axis current and the second direct-axis current; obtain a set of corresponding quadrature-axis currents according to the voltage ellipse equation and the obtained set of direct-axis currents; obtain a set of corresponding torques based on the obtained set of direct-axis currents, the corresponding set of quadrature-axis currents and the torque equation. In other words, the AB segment of the curve is cut at a step size of 100 rpm, and the points on each straight line are the operating points at the speed, combined with the following Figure 4 As shown, first move along the MTPA curve to the first intersection with the voltage ellipse at the speed, and then move along the voltage ellipse at the speed to the second intersection with the current limit circle; at different speeds, by interpolating i between the first intersection and the second intersection d , we can find i q The value is then calculated using the torque formula to determine the corresponding torque value T, and the operating point in the weak magnetic control operation area is obtained.

[0104] The fourth step is to form the second sub-mapping relationship according to a set of direct-axis currents, a set of corresponding quadrature-axis currents and a set of corresponding torques corresponding to each first target speed. That is, the obtained set of direct-axis currents, a set of corresponding quadrature-axis currents and a set of corresponding torques form the second sub-mapping relationship.

[0105] For example, Figure 4 As shown, it shows that when the speed is ω 1 ,ω 2 The moving trajectory of the operating point. Figure 4 In the case of a rotational speed of ω 1 When 1 The MTPA curve equation and the voltage circle equation at this speed are solved together to obtain:

[0106] Intersection B 1By solving the voltage circle equation and the current limit circle equation at this speed, we can get:

[0107]

[0108] Among them, A1 is the first intersection point; B1 is the second intersection point.

[0109] Then, at the speed ω 1 When a set of i can be obtained based on the intersection A1 and the intersection B1 d According to this group i d Get a group i q ; Then, we get a corresponding set of torques. Similarly, when the motor speed is ω 2 The same method can also be used to obtain a set of i d According to this group d Get a group i q Then, a corresponding set of torques is obtained. By analogy, the external characteristic parameters under weak magnetic control can be obtained, which is the second sub-mapping relationship.

[0110] For the third sub-mapping relationship, it is a constant power operation area, that is, an external characteristic parameter under MTPV control. In some embodiments, the inherent parameter also includes the quadrature axis inductance of the motor; obtaining the third sub-mapping relationship may include:

[0111] Determining a second turning speed under flux weakening control according to the inherent parameters;

[0112] gradually increasing the speed of the motor from the second turning speed according to a third set step length to obtain a set of second target speeds; the second target speed is not greater than a preset maximum speed;

[0113] For each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; the third intersection includes a third direct-axis current; a group of direct-axis currents between the direct-axis current corresponding to the center position and the third direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation;

[0114] The third sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each second target speed.

[0115] It should be noted that the MTPV control principle is: under a given voltage U, there is an optimal i d 、i q The maximum torque can also be set The curve formula (8) is:

[0116] Here, the second turning speed is also the aforementioned ω max0 MTPV control is a motor control method after weak magnetic control. Under this MTPV control, the motor speed can increase from the second turning speed upwards. Theoretically, the speed can be infinite, but according to the actual hardware of the motor or other factors, the motor speed is still limited. The motor speed cannot be greater than the preset maximum speed ω max1 Between the second turning speed and the preset maximum speed, a set of second target speeds can be obtained by gradually increasing according to the third set step length, and each second target speed is not greater than the preset maximum speed. At each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; a set of i can be obtained between the center position and the third intersection. d According to this group i d Get a group i q ; Then, a corresponding set of torques is obtained. Then, the torques at different speeds are obtained. d- i q- The third sub-mapping relationship of torque.

[0117] like Figure 5 As shown, it shows that when the speed is ω 3 The moving trajectory of the operating point. Figure 5 Middle, curve BO max Indicates the constant power operation area, on curve BO max segment, that is, the speed changes from ω max0 to max1 Between, it can be cut in 100rpm steps to obtain a set of second target speeds. At each second target speed, for example, ω b1 When , the intersection point B can be obtained by solving the MTPV equation and the current limit circle equation simultaneously. Then, at the speed ω b1 Next, by interpolating i d According to the above formula (8), a set of i q value; and then a set of torques is obtained according to the torque equation. Similarly, at the speed ω 3 When 3 , and then a set of i at different speeds can be calculated d , the corresponding set i q And a corresponding set of torques T, and so on, to obtain the aforementioned third sub-mapping relationship.

[0118] It should be noted that in Figure 2 , Figure 4 as well as Figure 5In the curve OA section, the motor adopts MTPA control; in the curve AB section, the motor adopts weak magnetic control; in the curve BO max MTPV control is adopted. In addition, Figure 2 and Figure 5 In the diagram, it shows the distribution diagram of the motor's operating conditions when the center position and the current limit circle have different position relationships. It should be understood that although based on Figure 2 and Figure 5 The first sub-mapping relationship and the second sub-mapping relationship can be predicted, but based on Figure 2 The predicted first sub-mapping relationship and the second sub-mapping relationship are based on Figure 5 The predicted first sub-mapping relationship and the predicted second sub-mapping relationship contain different values.

[0119] The technical solution provided in the embodiment of the present application obtains the inherent parameters of the motor used, and uses the inherent parameters and the mathematical equations of the motor to predict the external characteristic parameter table of the motor under MTPA control (i.e., the first sub-mapping relationship), the external characteristic parameter table of the motor under weak magnetic control (i.e., the second sub-mapping relationship), and the external characteristic parameter table of the motor under MTPV control (i.e., the third sub-mapping relationship). In this way, the external characteristic parameters of the motor used can be predicted in advance, and such external characteristic parameters can be applied to the test phase of the new function development of the vehicle before bench calibration or vehicle testing to complete the closed-loop test in the testing phase, so that problems can be discovered early and adjustments can be made to the software functions to avoid the situation where the actual parameters do not match the design values ​​during bench calibration or vehicle testing, thereby reducing repeated operations, saving manpower and material resources, improving production efficiency, and improving vehicle safety, etc.

[0120] like Figure 6 As shown, the present application also provides a motor external characteristic parameter prediction device 600, which may include:

[0121] An acquisition module 601 is used to acquire the inherent parameters of the motor; the inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit;

[0122] A determination module 602 is used to determine the center position of a voltage limit ellipse according to the permanent magnet flux and the direct-axis inductance in a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, and to determine the positional relationship between the center position and the current limit circle; the voltage limit ellipse is determined according to the maximum voltage limit value; and the current limit circle is determined according to the maximum current limit value;

[0123] The prediction module 603 is used to predict the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit; the external characteristic parameters include the mapping relationship between the torque, the direct-axis current and the quadrature-axis current.

[0124] In some embodiments, the prediction module is used to predict a first external characteristic parameter according to the maximum voltage limit and the maximum current limit if the center position is outside the current limit circle; wherein the first external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the maximum torque current ratio MTPA control; and a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; if the center position is within the current limit circle, predict a second external characteristic parameter according to the maximum voltage limit and the maximum current limit; wherein the second external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the MTPA control; a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; and a third sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque voltage ratio MTPV control.

[0125] In some embodiments, the inherent parameters further include the quadrature-axis inductance and the number of pole pairs of the motor;

[0126] The prediction module is also used to: obtain the torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the pole pair number, and the permanent magnet flux; determine a first expression with a given current as an independent variable and a direct-axis current as a dependent variable according to the torque equation under the MTPA constraint; determine a second expression with a given current and a direct-axis current as independent variables and a quadrature-axis current as a dependent variable; wherein the square of the given current is equal to the sum of the square of the direct current and the square of the quadrature-axis current; gradually increase the given current according to a first set step size to obtain a set of target given currents; the target given current is not greater than the maximum current limit; for each target given current, obtain the direct-axis current and the quadrature-axis current corresponding to the target given current according to the first expression and the second expression; and obtain the corresponding torque value according to the torque equation and each pair of direct-axis currents and quadrature-axis currents; and form the first sub-mapping relationship according to each pair of direct-axis currents, quadrature-axis currents and the corresponding torque values.

[0127] In some embodiments, the inherent parameters also include the quadrature-axis inductance of the motor; the prediction module is also used to: determine the first turning speed and the second turning speed of the motor according to the inherent parameters; gradually increase the speed of the motor from the first turning speed according to a second set step size to obtain a set of first target speeds; the first target speed is not greater than the second turning speed; for each first target speed, a first intersection is obtained according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and a second intersection is obtained according to the voltage ellipse equation and the current limit circle equation, wherein the first intersection includes a first direct-axis current; the second intersection includes a second direct-axis current; a set of direct-axis currents between the first direct-axis current and the second direct-axis current is obtained; a set of corresponding quadrature-axis currents is obtained according to the voltage ellipse equation and the obtained set of direct-axis currents; a set of corresponding torques is obtained based on the obtained set of direct-axis currents, the set of corresponding quadrature-axis currents and the torque equation; and the second sub-mapping relationship is formed according to a set of direct-axis currents, a set of corresponding quadrature-axis currents and a set of corresponding torques corresponding to each first target speed.

[0128] In some embodiments, the inherent parameters also include the cross-axis inductance of the motor; the prediction module is used to determine the second turning speed under weak magnetic control according to the inherent parameters; the speed of the motor is gradually increased from the second turning speed according to a third set step size to obtain a set of second target speeds; the second target speed is not greater than the preset maximum speed; for each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; the third intersection includes a third direct-axis current; a set of direct-axis currents corresponding to the center position and the third direct-axis current are obtained; a set of corresponding cross-axis currents are obtained according to the voltage ellipse equation and the obtained set of direct-axis currents; a set of corresponding torques are obtained based on the obtained set of direct-axis currents, the set of corresponding cross-axis currents and the torque equation; and the third sub-mapping relationship is formed according to a set of direct-axis currents, a set of corresponding cross-axis currents and a set of corresponding torques corresponding to each second target speed.

[0129] It should be noted that the prediction device described above has the same technical features as the prediction method described above. Therefore, the terms appearing here and how to implement them have been described in detail above. You can refer to the above description for understanding and will not repeat them here.

[0130] The present application also provides an electronic device, comprising a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program implements the steps of any of the above methods when executed by the processor.

[0131] The present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0132] Figure 7 It is a schematic block diagram of a device 700 according to an embodiment of the present application. Figure 7 The device 700 shown includes a memory 701, a processor 702, a communication interface 703 and a bus 704. The memory 701, the processor 702 and the communication interface 703 are connected to each other through the bus 704.

[0133] The memory 701 may be a graphics processing unit (GPU) storage system, a read-only memory (ROM), a static storage device, a dynamic storage device and / or a random access memory (RAM). The memory 701 may store programs. When the programs stored in the memory 701 are executed by the processor 702, the processor 702 is used to execute the various steps of the method of the embodiment of the present application. For example, the aforementioned Figure 1 etc. are the steps of the embodiments shown.

[0134] The processor 702 can adopt a graphics processing unit (GPU), a neural network processing unit (NPU), a microprocessor, an application specific integrated circuit (ASIC), and / or one or more integrated circuits to execute relevant programs to implement the method of the method embodiment of the present application.

[0135] The processor 702 may also be an integrated circuit chip with signal processing capability. In the implementation process, each step of the method of the embodiment of the present application may be completed by hardware integrated logic circuits in the processor 1202 and / or software instructions.

[0136] The processor 702 may also be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit, a field programmable gate array (FPGA), and / or other programmable logic devices, discrete gates and / or transistor logic devices, and discrete hardware components. The disclosed methods, steps, and logic block diagrams in the embodiments of the present application may be implemented and / or executed. The general purpose processor may be a microprocessor and / or the processor may also be any conventional processor, etc.

[0137] The steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware decoding processor, and / or being executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory and / or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 701, and the processor 702 reads the information in the memory 701, and combines its hardware to complete the functions required to be executed by the units included in the embodiments of the present application, and / or execute the methods of the various method embodiments in the present application, for example, it can execute Figure 1 etc. The various steps / functions of the embodiments shown.

[0138] The communication interface 703 may use, but is not limited to, a transceiver or other transceiver device to implement communication between the device 700 and other devices or a communication network.

[0139] The bus 704 may include a path for transmitting information between various components of the device 700 (eg, the memory 701 , the processor 1202 , and the communication interface 703 ).

[0140] It should be understood that the device 700 shown in the embodiment of the present application may be a processor or a chip for executing the method described in the embodiment of the present application.

[0141] It should be understood that in the embodiment of the present application, the processor may be a graphics processing unit (GPU), and the processor may also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) and / or other programmable logic devices, discrete component gate circuits and / or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor and / or the processor may also be any conventional processor, etc.

[0142] It should be understood that in the embodiment of the present application, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0143] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0144] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0145] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined and / or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0146] The units described as separate components may and / or may not be physically separated, and the components shown as units may and / or may not be physical units, that is, they may be located in one place and / or may be distributed on multiple network units. Some and / or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0147] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0148] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware and / or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, and / or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, and / or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL, Digital Subscriber Line)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can read and / or a data storage device such as a server, data center, etc. that contains one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a digital versatile disk (DVD)) and / or a semiconductor medium (e.g., a solid state drive (SSD)), etc.

[0149] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for predicting external characteristic parameters of a motor, characterized in that: include: Acquiring intrinsic parameters of the motor; The inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit; In a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, the center position of the voltage limit ellipse is determined according to the permanent magnet flux and the direct-axis inductance, and the positional relationship between the center position and the current limit circle is determined, wherein the voltage limit ellipse is determined according to the maximum voltage limit value, and the current limit circle is determined according to the current maximum limit value; The external characteristic parameters of the motor are predicted according to the position relationship, the maximum voltage limit and the maximum current limit.

2. The method according to claim 1, characterized in that The predicting of the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit includes: If the center position is outside the current limit circle, predict a first external characteristic parameter according to the maximum voltage limit and the maximum current limit; wherein the first external characteristic parameter includes a first sub-mapping relationship between the torque corresponding to the maximum torque current ratio MTPA control, the direct-axis current and the quadrature-axis current; and a second sub-mapping relationship between the torque, speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; If the center position is within the current limit circle, the second external characteristic parameter is predicted according to the maximum voltage limit and the maximum current limit; wherein the second external characteristic parameter includes a first sub-mapping relationship between the torque, the direct-axis current and the quadrature-axis current corresponding to the MTPA control; a second sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the weak magnetic control; and a third sub-mapping relationship between the torque, the speed, the direct-axis current and the quadrature-axis current corresponding to the maximum torque-to-voltage ratio MTPV control.

3. The method according to claim 2, characterized in that The inherent parameters also include the quadrature-axis inductance and the number of pole pairs of the motor; Obtaining the first sub-mapping relationship includes: Obtaining a torque equation of the motor according to the direct-axis inductance, the quadrature-axis inductance, the number of pole pairs, and the permanent magnet flux linkage; Under the MTPA constraint condition, a first expression with a given current as an independent variable and a direct-axis current as a dependent variable is determined according to the torque equation; a second expression with a given current and a direct-axis current as independent variables and a quadrature-axis current as a dependent variable is determined; wherein the square of the given current is equal to the sum of the square of the direct current and the square of the quadrature-axis current; The given current is gradually increased according to a first set step length to obtain a set of target given currents; the target given current is not greater than the maximum current limit; For each target given current, the direct-axis current and the quadrature-axis current corresponding to the target given current are obtained according to the first expression and the second expression; and the corresponding torque value is obtained according to the torque equation and each pair of the direct-axis current and the quadrature-axis current; The first sub-mapping relationship is formed according to each pair of direct-axis current, quadrature-axis current and corresponding torque value.

4. The method according to claim 2, characterized in that: The inherent parameter also includes the quadrature-axis inductance of the motor; obtaining the second sub-mapping relationship includes: Determine a first turning speed and a second turning speed of the motor according to the inherent parameters; The rotation speed of the motor is gradually increased from the first turning speed according to a second set step length to obtain a set of first target rotation speeds; the first target rotation speed is not greater than the second turning speed; For each first target speed, a first intersection is obtained according to the voltage ellipse equation and the MTPA curve equation at the first target speed; and a second intersection is obtained according to the voltage ellipse equation and the current limit circle equation, wherein the first intersection includes a first direct-axis current; the second intersection includes a second direct-axis current; a group of direct-axis currents between the first direct-axis current and the second direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation; The second sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each first target speed.

5. The method according to claim 2, characterized in that: The inherent parameters also include the quadrature-axis inductance of the motor; obtaining the third sub-mapping relationship includes: Determining a second turning speed under flux weakening control according to the inherent parameters; gradually increasing the speed of the motor from the second turning speed according to a third set step length to obtain a set of second target speeds; the second target speed is not greater than a preset maximum speed; For each second target speed, a third intersection is obtained according to the voltage ellipse equation and the MTPV curve equation at the second target speed; the third intersection includes a third direct-axis current; a group of direct-axis currents between the direct-axis current corresponding to the center position and the third direct-axis current are obtained; a group of corresponding quadrature-axis currents are obtained according to the voltage ellipse equation and the obtained group of direct-axis currents; a group of corresponding torques are obtained based on the obtained group of direct-axis currents, the corresponding group of quadrature-axis currents and the torque equation; The third sub-mapping relationship is formed according to a group of direct-axis currents, a group of corresponding quadrature-axis currents and a group of corresponding torques corresponding to each second target speed.

6. The method according to claim 1, characterized in that The center position of the voltage limit circle is located on the negative half axis of the X-axis; the radius of the current limit circle is the maximum current limit value, and the center of the circle is the origin of the rectangular coordinate system; determining the positional relationship between the center position and the current limit circle includes: determining the distance value between the center position and the origin; comparing the distance value with the maximum current limit value; if the distance value is greater than the maximum current limit value, the positional relationship includes that the center position is outside the current limit circle; if the distance value is less than or equal to the maximum current limit value, the positional relationship includes that the center position is inside the current limit circle.

7. The method according to any one of claims 1 to 6, characterized in that: The method is applied in a new function test phase of a vehicle; the test phase is before bench calibration or whole vehicle testing.

8. A device for predicting external characteristic parameters of a motor, characterized in that: include: An acquisition module, used for acquiring the intrinsic parameters of the motor; The inherent parameters include permanent magnet flux, direct axis inductance, maximum voltage limit, and maximum current limit; A determination module, used to determine the center position of the voltage limit ellipse according to the permanent magnet flux and the direct-axis inductance in a rectangular coordinate system with the direct-axis current as the X-axis and the quadrature-axis current as the Y-axis, and to determine the positional relationship between the center position and the current limit circle; The voltage limit ellipse is determined according to the maximum voltage limit value; the current limit circle is determined according to the maximum current limit value; A prediction module is used to predict the external characteristic parameters of the motor according to the position relationship, the maximum voltage limit and the maximum current limit; the external characteristic parameters include a mapping relationship between the torque, the direct-axis current and the quadrature-axis current.

9. An electronic device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and capable of running on the processor, wherein the computer program implements the steps of the method according to any one of claims 1 to 6 when executed by the processor.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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