Weak magnetic boundary determination method and device, electronic equipment and storage medium

Abstract

The invention provides a weak magnetic boundary determination method and device, electronic equipment and a storage medium, and the method comprises the steps: obtaining calibration test data, the calibration test data being test data of a permanent magnet synchronous motor under a weak magnetic condition, and the calibration test data comprising a motor rotating speed and a d-axis current; the calibration test data are input into a flux-weakening voltage model, target parameters are obtained, the target parameters are used for calculating the torque of the permanent magnet synchronous motor, and the flux-weakening voltage model is used for representing the linear relation between the d-axis current and the angular speed of the motor; and determining a first weak magnetic boundary curve of the permanent magnet synchronous motor based on the target parameter. According to the method provided by the invention, the weak magnetic boundary of the permanent magnet synchronous motor can be more clearly determined, and the performance of the permanent magnet synchronous motor is improved.

Description

Technical Field

[0001] This application relates to the field of permanent magnet synchronous motors, and in particular to a method, apparatus, electronic device, and storage medium for determining a weak magnetic boundary. Background Technology

[0002] As an important drive unit for electric vehicles, permanent magnet synchronous motors are crucial to the vehicle's power and comfort. Understanding the operating limits of permanent magnet synchronous motors can maximize their performance, achieve the ultimate balance between cost and performance, and enhance the vehicle's brand competitiveness.

[0003] In related technologies, commonly used methods for calibrating the field weakening boundary include the current adjustment-voltage utilization rate method, the torque adjustment-voltage utilization rate method, and the flux linkage-speed curve fitting method. These methods have low accuracy in calibrating the field weakening boundary of permanent magnet synchronous motors and cannot meet the needs of users. Summary of the Invention

[0004] This application provides a method, apparatus, electronic device, and storage medium for determining the field weakening boundary, which helps to more clearly determine the field weakening boundary of a permanent magnet synchronous motor and improve the performance of the permanent magnet synchronous motor.

[0005] In a first aspect, embodiments of this application provide a method for determining a field weakening boundary, comprising: acquiring calibration test data, wherein the calibration test data is test data of a permanent magnet synchronous motor under field weakening conditions, the calibration test data including motor speed and d-axis current; inputting the calibration test data into a field weakening voltage model to obtain target parameters, the target parameters being used to calculate the torque of the permanent magnet synchronous motor, the field weakening voltage model being used to characterize the linear relationship between the d-axis current and the motor angular velocity; and determining a first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters.

[0006] In one possible implementation, determining the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters includes: determining the value range of the d-axis current and the value range of the q-axis current based on the target parameters; determining a target d-axis current within the value range of the d-axis current and a target q-axis current within the value range of the q-axis current at each motor speed of the permanent magnet synchronous motor; constructing the first field weakening boundary curve based on the target d-axis current and the target q-axis current corresponding to each motor speed; wherein the target d-axis current and the target q-axis current at each motor speed maximize the torque at the corresponding motor speed.

[0007] In one possible implementation, the speed of each motor includes multiple speeds of the permanent magnet synchronous motor between the turning speed and the peak speed, and there is a preset step size between two adjacent motor speeds.

[0008] In one possible implementation, after determining the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters, the method further includes: dividing the first field weakening boundary curve into M points, where M is a positive integer greater than 1; selecting m points from the M points, where m is a positive integer less than M; and constructing a second field weakening boundary curve based on the m points.

[0009] In one possible implementation, the m points are determined by the curvature of the first weak magnetic boundary curve.

[0010] In one possible implementation, determining the m points by the curvature of the first weak magnetic boundary curve includes: determining the curvature of each of the M points; constructing a first sequence, the first sequence including the normalized curvature of each of the M points; determining a second sequence based on the first sequence, the second sequence including the cumulative normalized curvature corresponding to the M points; filtering the m cumulative normalized curvatures from the cumulative normalized curvatures corresponding to the M points at a preset interval, the prediction interval being the difference between two adjacent cumulative normalized curvatures among the m cumulative normalized curvatures; and finding the m corresponding points among the M points based on the m cumulative normalized curvatures.

[0011] In one possible implementation, the target parameters include permanent magnet flux linkage and d-axis inductance.

[0012] Secondly, embodiments of this application provide a weak magnetic boundary determination device, including one or more functional modules, which are used to perform the weak magnetic boundary determination method as described in the first aspect.

[0013] Thirdly, embodiments of this application provide an electronic device, including: a processor and a memory, wherein the memory is used to store a computer program; and the processor is used to run the computer program to implement the weak magnetic boundary determination method as described in the first aspect.

[0014] Fourthly, embodiments of this application provide a readable storage medium storing a program that, when run on an electronic device, causes the electronic device to implement the weak magnetic boundary determination method as described in the first aspect.

[0015] Fifthly, embodiments of this application provide a program that, when run on a processor of an electronic device, causes the electronic device to perform the weak magnetic boundary determination method as described in the first aspect.

[0016] In one possible design, the program in the fifth aspect can be stored wholly or partially on a storage medium packaged with the processor, or it can be stored wholly or partially on a memory not packaged with the processor. Attached Figure Description

[0017] Figure 1 A flowchart illustrating an embodiment of the method for determining weak magnetic boundaries provided in this application; Figure 2 This is a schematic diagram of the structure of the weak magnetic boundary determination device provided in the embodiments of this application; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0018] In this embodiment of the application, unless otherwise stated, the character " / " indicates that the preceding and following objects are in an OR relationship. For example, A / B can represent A or B. "AND / OR" describes the relationship between the associated objects, indicating that three relationships can exist. For example, A AND / OR B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0019] It should be noted that the terms "first" and "second" used in the embodiments of this application are used only for distinguishing descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated, nor should they be construed as indicating or implying order.

[0020] In the embodiments of this application, "at least one" means one or more, and "more than one" means two or more. Furthermore, "at least one of the following" or similar expressions refer to any combination of these items, which may include any combination of a single item or a plurality of items. For example, at least one of A, B, or C can represent: A, B, C, A and B, A and C, B and C, or A, B, and C. Each of A, B, and C can be an element itself or a set containing one or more elements.

[0021] In this application, terms such as "exemplary," "in some embodiments," and "in another embodiment" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0022] In the embodiments of this application, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction, their meanings are consistent. Similarly, in the embodiments of this application, "communication" and "transmission" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction, their meanings are consistent. For example, transmission can include sending and / or receiving, and can be a noun or a verb.

[0023] In the embodiments of this application, the term "equal to" can be used in conjunction with "greater than" to apply to technical solutions employing the condition of "greater than", and can also be used in conjunction with "less than" to apply to technical solutions employing the condition of "less than". It should be noted that when "equal to" is used with "greater than", it cannot be used with "less than"; and when "equal to" is used with "less than", it cannot be used with "greater than".

[0024] As an important drive unit for electric vehicles, permanent magnet synchronous motors are crucial to the vehicle's power and comfort. Understanding the operating limits of permanent magnet synchronous motors can maximize their performance, achieve the ultimate balance between cost and performance, and enhance the vehicle's brand competitiveness.

[0025] In related technologies, commonly used methods for calibrating the field weakening boundary include the current adjustment-voltage utilization rate method, the torque adjustment-voltage utilization rate method, and the flux linkage-speed curve fitting method. These methods have low accuracy in calibrating the field weakening boundary of permanent magnet synchronous motors and cannot meet the needs of users.

[0026] To address the aforementioned issues, this application provides a method for determining the field weakening boundary, which helps to more clearly determine the field weakening boundary of a permanent magnet synchronous motor and improve the performance of the permanent magnet synchronous motor.

[0027] Figure 1 A flowchart illustrating an embodiment of the weak magnetic boundary determination method provided in this application includes the following steps: Step 101: Obtain calibration test data. The calibration test data is the test data of the permanent magnet synchronous motor under weak magnetic field conditions. The calibration test data includes the motor speed and d-axis current Id.

[0028] Specifically, when the permanent magnet synchronous motor is in a weak magnetic environment, calibration test data of the permanent magnet synchronous motor under weak magnetic boundary conditions can be obtained.

[0029] The calibration test data may include multiple sets of scatter data consisting of motor speed and d-axis current Id.

[0030] For example, a permanent magnet synchronous motor can be controlled to enter a current control operation mode, and the d-axis current Id and q-axis current Iq can be changed at various speeds under rated voltage to maximize torque. Thus, multiple combinations of speed and d-axis current Id can be found under the condition of maximum torque.

[0031] For example, Table 1 shows the calibration test data.

[0032] Table 1 Referring to Table 1, the calibration test data can include n sets of data, where n is a positive integer greater than 1. Each set of data can include a speed value, a d-axis current Id value, and a q-axis current Iq value. It is understood that the value of each set of data in the n sets maximizes the torque. For example, at a permanent magnet synchronous motor speed V1, adjusting the d-axis current Id to Id1 and the q-axis current Iq1 can obtain the maximum torque at speed V1; or, at a permanent magnet synchronous motor speed V2, adjusting the d-axis current Id to Id2 and the q-axis current Iq2 can obtain the maximum torque at speed V2.

[0033] Step 102: Input the calibration test data into the field weakening voltage model to obtain the target parameters. These target parameters are used to calculate the torque of the permanent magnet synchronous motor. The field weakening voltage model is used to characterize the linear relationship between the d-axis current Id and the motor angular velocity ω.

[0034] Specifically, under steady-state conditions, the voltage equation of the permanent magnet synchronous motor on the dq axis can be simplified to the following formula: ; (1) ; (2) Where Ud is the d-axis voltage, ω is the motor angular velocity, Lq is the q-axis inductance, Uq is the q-axis voltage, Ld is the d-axis inductance, and Ψ is the permanent magnet flux linkage.

[0035] Furthermore, the voltage limit circle equation of a permanent magnet synchronous motor operating at a field weakening boundary can be characterized by the following formula: ; (3) ; (4) Where Udc is the DC voltage.

[0036] Using the above formulas (1)-(4), we can obtain the following formula: ; (5) Understandably, in the deep magnetic weakening region, the contribution of the q-axis inductance Lq is relatively small. Simultaneously, under this condition, the q-axis current is forced to decrease to maintain the voltage circle. In this case, Lq... The value of Iq can be ignored, so formula (5) can be simplified to the following formula: ; (6) It should be noted that in commonly used control quadrants, the value of the d-axis current Id is generally negative. Therefore, formula (6) can be simplified to the following formula: ; (7) As can be seen from formula (7), the d-axis current Id and the reciprocal of the motor angular velocity ω have a linear relationship. For example, this linear relationship can be understood as Id = k1 + k2 1 / ω, where k1=-(Ψ / Ld), k2=±(Umax / Ld).

[0037] It is understandable that formula (7) can be used as a field weakening voltage model for permanent magnet synchronous motors.

[0038] Next, the calibration test data can be input into the above-mentioned weak magnetic voltage model to obtain the target parameters, which may include the permanent magnet flux linkage Ψ and the d-axis inductance Ld.

[0039] It is understood that the target parameters can be obtained by using linear least squares to fit the relevant data to a straight line, or the target parameters can be obtained by other algorithms. This application does not impose any special limitations on this.

[0040] Step 103: Determine the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters.

[0041] Specifically, the torque of a permanent magnet synchronous motor can be characterized by the following formula: ; (8) Where Te is the torque of the permanent magnet synchronous motor, and p is the number of pole pairs.

[0042] As can be seen from the above formula (8), the torque Te of the permanent magnet synchronous motor is related to the permanent magnet flux linkage Ψ, d-axis inductance Ld, q-axis inductance Lq, d-axis current Id, and q-axis current Iq.

[0043] It is understood that the permanent magnet flux linkage Ψ and the d-axis inductance Ld have been obtained through step 102, and the q-axis inductance Lq can be input by the user. The q-axis inductance Lq input by the user can be an empirical value, or the q-axis inductance Lq input by the user can be determined according to actual needs. This application does not impose any special limitations on this.

[0044] In this case, the field weakening boundary data of the permanent magnet synchronous motor can be obtained simply by selecting the corresponding d-axis current Id and q-axis current Iq on the voltage limit circle and selecting the maximum torque at each speed.

[0045] For example, formula (5) in the voltage limit circle equation can be simplified to the following formula: (9) Understandably, in electric mode, the d-axis current Id can be positive, while in generator mode, the d-axis current Id can be negative.

[0046] Furthermore, to ensure that the value under the square root in formula (9) is greater than 0, the following expression can be obtained: ; (10) Through expression (10), the range of values ​​for the d-axis current Id can be obtained as follows: Idmin = (-Ψ-Umax / ω) / Ld; Idmax = (-Ψ+Umax / ω) / Ld.

[0047] Where Idmin is the minimum value of the d-axis current Id, and Idmax is the maximum value of the d-axis current Id.

[0048] It is understandable that, according to formula (9), the range of values ​​for the q-axis current Iq can be determined by the range of values ​​for the d-axis current Id. Once the range of values ​​for the d-axis current Id is determined, the range of values ​​for the q-axis current Iq can be determined accordingly. For example, Idmin can be substituted into formula (9) to obtain the corresponding Iqmax, and Idmax can be substituted into formula (9) to obtain the corresponding Iqmin. Here, Iqmin is the minimum value of the q-axis current Iq, and Iqmax is the maximum value of the q-axis current Iq.

[0049] By using the above-described curve selection method, the optimal combination of d-axis current Id and q-axis current Iq at each motor speed can be obtained to maximize torque. In this case, the embodiments of this application can traverse from the turning point speed to the peak speed by a preset step size, thereby obtaining the first field weakening boundary curve within the range from the turning point speed to the peak speed. This first field weakening boundary curve is a smooth curve that closely reflects the actual operating state of the motor.

[0050] In this embodiment, the automatic point selection method significantly reduces the manpower and time costs of data processing compared to the existing manual point selection method, thereby improving work efficiency and reducing data risks caused by human error. Furthermore, this embodiment can generate a field weakening boundary curve based on the actual characteristics of the motor, avoiding the incomplete utilization of the motor's external characteristics due to conservative and simplistic linear calibration. The generated field weakening boundary curve is also closer to the actual operating curve of the motor, preventing system oscillations caused by boundary fluctuations and thus preventing torque runaway.

[0051] In some alternative embodiments, after step 103, the following steps may also be included: Step 104: Select m points from the first magnetic weakening boundary curve and construct a second magnetic weakening boundary curve based on the m points. The m points are determined by the curvature of the first magnetic weakening boundary curve.

[0052] Specifically, after obtaining the first magnetic weakening boundary curve, the points in the first magnetic weakening boundary curve can be filtered to select the optimal m points, so that the optimal m points constitute the second magnetic weakening boundary curve, thereby improving the accuracy of the magnetic weakening boundary curve, where m is a positive integer greater than 1.

[0053] In some alternative embodiments, the m points can be determined by the curvature in the first weak magnetic boundary curve.

[0054] For example, the first weak magnetic boundary curve can be divided into M points, where M is a positive integer greater than 1 and M>m. The curvature of each of the M points is calculated using a relevant curvature function, the curve of the M points is normalized, and a first sequence is constructed based on the M points, where each point in the first sequence contains the corresponding normalized curvature.

[0055] Table 2 illustrates the first sequence as an example.

[0056] Table 2 Referring to Table 2, the first sequence contains M points, for example, the M points are 1 to M points, where the normalized curve of the first point is A1, the normalized curvature of the second point is A2, and so on, with the normalized curvature of the Mth point being AM.

[0057] Next, a second sequence is determined based on the first sequence, wherein each point in the second sequence includes the cumulative curvature.

[0058] Table 3 illustrates the second sequence as an example.

[0059] Table 3 Referring to Table 3, the second sequence contains M points, which are points 1 to M. Each of these M points contains a cumulative curvature. For example, the normalized cumulative curvature of the first point is itself, i.e., A1; the normalized cumulative curvature of the second point is the sum of the curvatures of the first and second points, and so on. The normalized cumulative curvature of the Mth point is the sum of the curvatures of the first to the Mth points.

[0060] Then, starting with the cumulative curvature value of the first point in the second sequence and ending with the cumulative curvature value of the Mth point, the second sequence is traversed at equal intervals t to obtain m values, where the interval t is the cumulative curvature difference between two adjacent values ​​among the m values.

[0061] For example, the m values ​​include B1, B2, ..., B m B m -B m-1 =t.

[0062] Once the m values ​​are determined, the corresponding points can be found in the second sequence based on these m values, and the second weak magnetic boundary curve can be constructed based on these m corresponding points.

[0063] Figure 2 This is a schematic diagram of the structure of the weak magnetic boundary determination device provided in the embodiments of this application, as shown below. Figure 2 As shown, the aforementioned weak magnetic boundary determination device 20 may include: an acquisition module 21, a calculation module 22, and a construction module 23; wherein, The acquisition module 21 is used to acquire calibration test data, which is the test data of the permanent magnet synchronous motor under weak magnetic field conditions. The calibration test data includes motor speed and d-axis current. The calculation module 22 is used to input the calibration test data into the field weakening voltage model to obtain target parameters. The target parameters are used to calculate the torque of the permanent magnet synchronous motor. The field weakening voltage model is used to characterize the linear relationship between the d-axis current and the motor angular velocity. Module 23 is used to determine the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters.

[0064] In one possible implementation, the construction module 23 is further configured to determine the range of values ​​for the d-axis current and the q-axis current based on the target parameters. At each motor speed of the permanent magnet synchronous motor, a target d-axis current is determined within the range of the d-axis current, and a target q-axis current is determined within the range of the q-axis current. A first field weakening boundary curve is constructed based on the target d-axis current and the target q-axis current corresponding to each motor speed; Among them, the target d-axis current and the target q-axis current at each motor speed maximize the torque at the corresponding motor speed.

[0065] In one possible implementation, the speed of each motor includes multiple speeds of the permanent magnet synchronous motor between the turning speed and the peak speed, and there is a preset step size between two adjacent motor speeds. In one possible implementation, the construction module 23 is further configured to divide the first weak magnetic boundary curve into M points, where M is a positive integer greater than 1; Select m points from the M points, where m is a positive integer less than M; The second weak magnetic boundary curve is constructed based on the m points.

[0066] In one possible implementation, the m points are determined by the curvature of the first weak magnetic boundary curve. In one possible implementation, the construction module 23 is further configured to determine the curvature of each of the M points; Construct a first sequence, the first sequence including the normalized curvature of each of the M points; A second sequence is determined based on the first sequence, the second sequence including the cumulative normalized curvature corresponding to the M points; According to a preset interval, the m cumulative normalized curvatures corresponding to the M points are selected, and the prediction interval is the difference between two adjacent cumulative normalized curvatures among the m cumulative normalized curvatures. Based on the m cumulative normalized curvatures, the m corresponding points are found among the M points. In one possible implementation, the target parameters include permanent magnet flux linkage and d-axis inductance. Figure 2 The weak magnetic boundary determination device 20 provided in the illustrated embodiment can be used to execute the technical solution of the method embodiment shown in this application. Its implementation principle and technical effect can be further referred to the relevant description in the method embodiment.

[0067] It should be understood that the division of the various modules in the above-described weak magnetic boundary determination device 20 is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, these modules can be implemented entirely in software via processing element calls; they can be fully implemented in hardware; or some modules can be implemented in software via processing element calls, while others are implemented in hardware. For example, the detection module can be a separate processing element, or it can be integrated into a chip in the terminal device. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. During implementation, each step of the above method or each of the above modules can be completed through integrated logic circuits in the hardware of the processor element or through software instructions.

[0068] For example, these modules can be one or more integrated circuits configured to implement the above methods, such as one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs). Alternatively, these modules can be integrated together as a system-on-a-chip (SOC).

[0069] Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device 300 may include: at least one processor; and at least one memory communicatively connected to the processor. The memory stores program instructions executable by the processor. The processor in the electronic device 300 can execute the actions performed in the magnetic field weakening boundary determination method provided in this embodiment by calling the program instructions.

[0070] like Figure 3 As shown, the electronic device 300 is presented in the form of a general-purpose computing device. The components of the electronic device 300 may include, but are not limited to: one or more processors 310, memory 320, communication bus 340 connecting different system components (including memory 320 and processor 310), and communication interface 330.

[0071] Communication bus 340 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, Industry Standard Architecture (ISA) buses, Micro Channel Architecture (MAC) buses, Enhanced ISA buses, Video Electronics Standards Association (VESA) local buses, and Peripheral Component Interconnect (PCI) buses.

[0072] Electronic device 300 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by an end device, including volatile and non-volatile media, removable and non-removable media.

[0073] Memory 320 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. The terminal device may further include other removable / non-removable, volatile / non-volatile computer system storage media. Although Figure 3 As not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disc drive for reading and writing to a removable non-volatile optical disc (e.g., a compact disc read-only memory (CD-ROM), a digital video disc read-only memory (DVD-ROM), or other optical media) may be provided. In these cases, each drive may be connected to the communication bus 340 via one or more data media interfaces. The memory 320 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of this application.

[0074] A program / utility having a set (at least one) of program modules can be stored in memory 320. Such program modules include—but are not limited to—an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. The program modules typically perform the functions and / or methods described in the embodiments of this application.

[0075] Electronic device 300 can also communicate with one or more external devices (e.g., keyboard, pointing device, display, etc.), and with one or more devices that enable a user to interact with the terminal device, and / or with any device that enables the terminal device to communicate with one or more other computing devices (e.g., network card, modem, etc.). This communication can be performed through communication interface 330. Furthermore, electronic device 300 can also communicate through a network adapter (… Figure 3 (Not shown) communicates with one or more networks (e.g., Local Area Network (LAN), Wide Area Network (WAN), and / or public networks, such as the Internet). The aforementioned network adapter can communicate with other modules of the terminal device via the communication bus 340. It should be understood that, although... Figure 3 As not shown, other hardware and / or software modules may be used in conjunction with electronic device 300, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, Redundant Arrays of Independent Drives (RAID) systems, tape drives, and data backup storage systems.

[0076] The processor 310 executes various functional applications and data processing by running programs stored in the memory 320, such as implementing the methods provided in the embodiments of this application.

[0077] It is understood that the interface connection relationships between the modules illustrated in the embodiments of this application are merely illustrative and do not constitute a structural limitation on the electronic device 300. In other embodiments of this application, the electronic device 300 may also employ different interface connection methods or combinations of multiple interface connection methods as described in the above embodiments.

[0078] In the above embodiments, the processor may include, for example, a CPU, DSP, microcontroller, or digital signal processor, and may also include a GPU, embedded neural network processing unit (NPU), and image signal processor (ISP). The processor may also include necessary hardware accelerators or logic processing hardware circuits, such as an ASIC, or one or more integrated circuits for controlling the execution of the program in this application. Furthermore, the processor may have the function of operating one or more software programs, which may be stored in a storage medium.

[0079] This application also provides a readable storage medium storing a program that, when run on a system, causes the system to execute the method provided in the embodiments shown in this application.

[0080] This application also provides a program product, which includes a program that, when run on a system, causes the system to execute the method provided in the embodiments shown in this application.

[0081] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0082] Those skilled in the art will recognize that the units and algorithm steps described in the embodiments disclosed herein can be implemented using electronic hardware, computer software, or a combination of electronic hardware and software. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0083] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0084] In the several embodiments provided in this application, any function, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0085] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for determining a weak magnetic boundary, characterized in that, The method includes: Obtain calibration test data, which is the test data of the permanent magnet synchronous motor under weak magnetic field conditions, including motor speed and d-axis current; The calibration test data is input into the field weakening voltage model to obtain the target parameters. The target parameters are used to calculate the torque of the permanent magnet synchronous motor. The field weakening voltage model is used to characterize the linear relationship between the d-axis current and the motor angular velocity. The first field weakening boundary curve of the permanent magnet synchronous motor is determined based on the target parameters.

2. The method according to claim 1, characterized in that, The determination of the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters includes: The range of values ​​for the d-axis current and the q-axis current are determined based on the target parameters. At each motor speed of the permanent magnet synchronous motor, a target d-axis current is determined within the range of the d-axis current, and a target q-axis current is determined within the range of the q-axis current. A first field weakening boundary curve is constructed based on the target d-axis current and the target q-axis current corresponding to each motor speed; Among them, the target d-axis current and the target q-axis current at each motor speed maximize the torque at the corresponding motor speed.

3. The method according to claim 2, characterized in that, The speed of each motor includes multiple speeds of the permanent magnet synchronous motor between the turning speed and the peak speed, and there is a preset step size between two adjacent motor speeds.

4. The method according to any one of claims 1-3, characterized in that, After determining the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters, the method further includes: The first weak magnetic boundary curve is divided into M points, where M is a positive integer greater than 1; Select m points from the M points, where m is a positive integer less than M; The second weak magnetic boundary curve is constructed based on the m points.

5. The method according to claim 4, characterized in that, The m points are determined by the curvature of the first weak magnetic boundary curve.

6. The method according to claim 5, characterized in that, The m points are determined by the curvature of the first weak magnetic boundary curve, including: Determine the curvature of each of the M points; Construct a first sequence, the first sequence including the normalized curvature of each of the M points; A second sequence is determined based on the first sequence, the second sequence including the cumulative normalized curvature corresponding to the M points; According to a preset interval, the m cumulative normalized curvatures corresponding to the M points are selected, and the prediction interval is the difference between two adjacent cumulative normalized curvatures among the m cumulative normalized curvatures. Based on the m cumulative normalized curvatures, the m corresponding points are found among the M points.

7. The method according to claim 1, characterized in that, The target parameters include permanent magnet flux linkage and d-axis inductance.

8. A device for determining a weak magnetic boundary, characterized in that, The device includes: The acquisition module is used to acquire calibration test data, which is the test data of the permanent magnet synchronous motor under weak magnetic field conditions. The calibration test data includes motor speed and d-axis current. The calculation module is used to input the calibration test data into the field weakening voltage model to obtain target parameters. The target parameters are used to calculate the torque of the permanent magnet synchronous motor. The field weakening voltage model is used to characterize the linear relationship between the d-axis current and the motor angular velocity. A construction module is used to determine the first field weakening boundary curve of the permanent magnet synchronous motor based on the target parameters.

9. An electronic device, characterized in that, include: A processor and a memory, wherein the memory is used to store a program; the processor is used to run the program to implement the weak magnetic boundary determination method as described in any one of claims 1-7.

10. A readable storage medium, characterized in that, The readable storage medium stores a program that, when run on an electronic device, implements the weak magnetic boundary determination method as described in any one of claims 1-7.

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