Motor control method, permanent magnet motor control system, device, and program product

Abstract

This application discloses a motor control method, a permanent magnet motor control system, an apparatus, and a program product. The motor control method includes: estimating the motor inductance in real time to obtain a corrected inductance; obtaining the motor voltage signal based on the corrected inductance; and, when the voltage signal indicates that the motor has entered a field-weakening control state, performing field-weakening control on the motor based on a leading current angle, so that the motor current angle changes from a first current angle to a second current angle under the same torque, wherein the difference between the second current angle and the first current angle is the leading current angle, and the motor speed under the second current angle is greater than the speed under the first current angle. The method of this application can estimate and correct the motor inductance in real time, optimize the field-weakening control performance of the motor, increase the maximum speed of the motor under the same load, and improve the stable output capability of the motor.

Description

Technical Field

[0001] This invention relates to the field of electric drive and control technology, and in particular to a motor control method, a permanent magnet motor control system, a device, and a program product. Background Technology

[0002] Permanent magnet synchronous motors are high-performance AC motors that can output torque based on stator current. They are widely used in industrial automation, electric vehicles, wind power generation and other fields. Among them, field weakening control is crucial in permanent magnet synchronous motors. It is a key technology for achieving efficient operation of the motor and expanding the speed range, and directly affects the stability, efficiency and power output capability of the motor at high speed.

[0003] Most current field weakening control technologies only perform a rough analysis of the interaction between various parameters of motor current and voltage to control motor operation, without maximizing the energy efficiency of motor operation, making it difficult to meet the motor operation requirements under more complex environmental conditions. Summary of the Invention

[0004] In view of the above problems, this application provides a motor control method that can estimate and correct the motor inductance in real time, thereby optimizing the field weakening control performance of the motor, increasing the maximum speed of the motor under the same load, and improving the stable output capability of the motor.

[0005] In a first aspect, this application provides a motor control method, which includes: estimating the inductance of the motor in real time to obtain a corrected inductance; obtaining a voltage signal of the motor based on the corrected inductance; and when the voltage signal indicates that the motor has entered a field weakening control state, performing field weakening control on the motor based on a leading current angle so that the current angle of the motor changes from a first current angle to a second current angle under the same torque, wherein the difference between the second current angle and the first current angle is the leading current angle, and the speed of the motor under the second current angle is greater than the speed under the first current angle.

[0006] In the technical solution of this application embodiment, the inductance of the motor is estimated in real time to obtain a corrected inductance, which can change with the load current. The voltage signal of the motor is obtained based on the corrected inductance, and the motor is controlled by field weakening based on the lead current angle. This allows the motor current angle to change from the first current angle to the second current angle under the same torque. This enables the motor inductance to be estimated and corrected in real time, optimizes the field weakening control performance of the motor, increases the maximum speed of the motor under the same load, and improves the stable output capability of the motor.

[0007] In some embodiments, when the voltage signal indicates that the motor has entered the field weakening control state, field weakening control of the motor is performed based on the lead current angle, including: determining the voltage error between the voltage signal and the voltage limit signal; when the voltage error is greater than a preset threshold, performing closed-loop control based on the voltage error to obtain the lead current angle; and performing field weakening control of the motor based on the lead current angle.

[0008] In the technical solution of this application embodiment, by determining the voltage error between the voltage signal and the voltage limit signal, and when the voltage error is greater than a preset threshold, closed-loop control is performed to obtain the lead current angle. Then, field weakening control is performed on the motor based on the lead current angle, so that the motor can achieve speed increase under constant torque under the stable and reliable control of the lead angle. Optimizing the field weakening control ensures that the motor can smoothly transition within a wide speed ratio range and ensures safe and reliable operation under complex working conditions.

[0009] In some embodiments, the method further includes: determining a target current angle based on a correction inductance when the voltage signal indicates that the motor is in a maximum torque-to-current ratio control state; and performing maximum torque-to-current ratio control on the motor based on the target current angle so that the motor current is reduced under the same torque, wherein the target current angle is smaller than a reference fixed current angle.

[0010] In the technical solution of this application embodiment, when the motor voltage signal indicates that the motor is in the maximum torque-to-current ratio control state, the target current angle is determined according to the correction inductance, so that the target current angle is less than the reference fixed current angle under the current same torque of the motor. That is, the current vector angle is reduced according to the correction inductance parameter, and then the maximum torque-to-current ratio control of the motor is performed based on the target current angle, so that the current of the motor is reduced under the same torque, thereby more accurately suppressing the back electromotive force, reducing electromagnetic losses, and improving the stability, efficiency and power output capability of the motor operation. In addition, it improves the dynamic response and control delay caused by control through fixed inductance, and improves the control accuracy and dynamic response speed.

[0011] In some embodiments, determining the target current angle based on the modified inductance includes: obtaining an electromagnetic torque equation representing the relationship between the motor torque and the current angle based on the modified inductance, the motor current, and the motor flux linkage; and differentiating the electromagnetic torque equation by the current angle to obtain the target current angle.

[0012] In the technical solution of this application embodiment, by correcting the inductance, the motor current and the motor flux linkage, an electromagnetic torque equation representing the relationship between the motor torque and the current angle is obtained, so as to determine the current angle controlled by correcting the inductance. Then, the electromagnetic torque equation is differentiated by the current angle to obtain the target current angle, so as to control the motor with the maximum torque-current ratio based on the target current angle, reduce the motor current under the same torque, improve the dynamic response speed, effectively suppress back electromotive force and reduce electromagnetic loss.

[0013] In some embodiments, the inductance of the motor is estimated in real time to obtain a corrected inductance, including: injecting a high-frequency square wave voltage signal into the motor and acquiring the motor's response current signal; and estimating the corrected inductance based on the high-frequency square wave voltage signal and the response current signal.

[0014] In the technical solution of this application embodiment, a high-frequency square wave voltage signal is injected into the motor, and the motor's response current signal is collected to determine the motor's operating state. Based on the high-frequency square wave voltage signal and the response current signal, the corrected inductance is estimated, thereby achieving high-precision inductance parameter identification, improving dynamic response speed, and realizing precise field weakening control.

[0015] In some embodiments, the corrected inductance is estimated based on a high-frequency square wave voltage signal and a response current signal, including: estimating the corrected inductance based on the signal amplitude and signal period of the high-frequency square wave voltage signal, and the current angle and current difference between different times of the response current signal.

[0016] In the technical solution of this application embodiment, based on the signal amplitude and signal period of the high-frequency square wave voltage signal, a corresponding high-frequency square wave voltage is injected into the motor. Based on the signal amplitude and signal period, as well as the current angle of the response current signal and the current difference between different times, the corrected inductance is estimated, which reduces the current error, improves the inductance identification accuracy and dynamic response speed, and optimizes the accuracy, adaptability and reliability of field weakening control.

[0017] In some embodiments, injecting a high-frequency square wave voltage signal into the motor includes: simultaneously injecting a first high-frequency square wave voltage signal into the d-axis of the motor and injecting a second high-frequency square wave voltage signal into the q-axis of the motor, wherein the signal period of the first high-frequency square wave voltage signal is greater than the signal period of the second high-frequency square wave voltage signal.

[0018] In the technical solution of this application embodiment, a first high-frequency square wave voltage signal is injected into the d-axis of the motor, and a second high-frequency square wave voltage signal smaller than the first high-frequency square wave voltage signal is injected into the q-axis of the motor to obtain a response current. By injecting high-frequency square waves into the d-axis and q-axis for control, high-frequency square wave voltage signals of different periods can realize the smooth transition and precise control of the motor in a wide speed ratio range, and extend the system life.

[0019] In some embodiments, obtaining the motor voltage signal based on the corrected inductance includes: obtaining the motor voltage signal based on the corrected inductance, the motor current, and the motor flux linkage according to the voltage balance equation.

[0020] In the technical solution of this application embodiment, after injecting high-frequency voltage, the voltage signal of the motor is obtained based on the voltage balance equation of the motor, the corrected inductance, the current of the motor, and the magnetic flux of the motor. This can accurately reflect the real-time operating status of the motor. The accuracy of the voltage signal is improved by correcting the inductance based on real-time estimation, thereby enabling precise control, reducing electromagnetic losses, and improving the efficiency and reliability of motor operation.

[0021] In some embodiments, the method further includes: inputting the motor current signal and the motor voltage signal into the sliding mode observation module for estimation to obtain the motor current angle and the motor speed.

[0022] In the technical solution of this application embodiment, by inputting the voltage signal of the motor current signal into the sliding mode observation module for estimation, the current angle and speed of the motor are obtained. The motor state can be estimated quickly and accurately under real-time operating conditions, thereby performing corresponding control and realizing sensorless control of the motor at high speed.

[0023] On the other hand, this application provides a permanent magnet motor control system, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in any of the above embodiments.

[0024] On the other hand, this application provides a motor control device, the device comprising: an estimation module for real-time estimation of the inductance of the motor to obtain a corrected inductance; an acquisition module for obtaining a voltage signal of the motor based on the corrected inductance; and a control module for performing field weakening control on the motor based on a leading current angle when the voltage signal indicates that the motor has entered a field weakening control state, so that the current angle of the motor changes from a first current angle to a second current angle under the same torque, wherein the difference between the second current angle and the first current angle is the leading current angle, and the speed of the motor under the second current angle is greater than the speed under the first current angle.

[0025] On the other hand, this application provides an electronic device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method of any of the above embodiments.

[0026] On the other hand, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method of any of the above embodiments.

[0027] On the other hand, this application provides a computer program product, including a computer program, which, when executed by a processor, implements a method for any of the above-described embodiments.

[0028] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0029] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0030] Figure 1 A flowchart of a motor control method according to an embodiment of this application is shown;

[0031] Figure 2 A schematic diagram of a high-frequency square wave injection signal according to an embodiment of this application is shown;

[0032] Figure 3 A block diagram of the modified inductance improved field weakening control section of an embodiment of this application is shown;

[0033] Figure 4 This paper shows an overall block diagram of the modified inductance-enhanced field weakening control according to an embodiment of this application;

[0034] Figure 5 This paper illustrates a schematic diagram of MTPA control under modified and fixed inductance parameters according to an embodiment of this application.

[0035] Figure 6 A schematic diagram of the field weakening control according to an embodiment of this application is shown;

[0036] Figure 7 A schematic diagram of the modified inductance-enhanced field weakening control according to an embodiment of this application is shown;

[0037] Figure 8 A partial block diagram of the sliding mode observation module implementation according to an embodiment of this application is shown;

[0038] Figure 9 A partial block diagram of the phase-locked loop implementation according to an embodiment of this application is shown;

[0039] Figure 10 A block diagram of a permanent magnet motor control system according to an embodiment of this application is shown;

[0040] Figure 11A block diagram of a motor control device according to an embodiment of this application is shown. Detailed Implementation

[0041] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0043] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related 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. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0046] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0047] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0048] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0049] Permanent magnet synchronous motors are high-performance AC motors that can output torque based on stator current. They are widely used in industrial automation, electric vehicles, wind power generation and other fields. Among them, field weakening control is crucial in permanent magnet synchronous motors. It is a key technology for achieving efficient operation of the motor and expanding the speed range, and directly affects the stability, efficiency and power output capability of the motor at high speed.

[0050] Most current field weakening control technologies only perform a rough analysis of the interaction between various parameters of motor current and voltage to control motor operation, without maximizing the energy efficiency of motor operation, making it difficult to meet the motor operation requirements under more complex environmental conditions.

[0051] Currently, some technologies have made corresponding improvements to address the shortcomings of weak magnetic field control, for example:

[0052] (1) Regarding the current response, the influence of the d-axis current on the q-axis current when working on the current limit circle was analyzed. With the current tracking error and the dq control voltage increment as optimization targets, the optimization problem was solved in real time to output the control voltage, which improved the robustness of the field weakening control current response.

[0053] (2) A cascaded model predicts speed and current control method, which sets different sampling frequencies for the two control loops for MTPA and field weakening control, thereby improving the dynamic drive performance of the motor.

[0054] (3) Construct a torque closed loop, estimate the torque by collecting motor magnetic field information, and combine the voltage and current loops to achieve adaptive control so that the motor runs at the optimal operating point.

[0055] (4) The difference in amplitude between the command voltage and the voltage limit is used to form a voltage feedback section to improve the tracking accuracy of the weak magnetic current.

[0056] (5) An improved sliding mode control method is proposed, which proposes a new adaptive terminal sliding mode control technology and effectively solves the problem of motor chattering under high speed in field weakening control.

[0057] However, the above-mentioned technical methods all have certain problems. First, existing online inductance identification methods lack tracking of changes in motor inductance parameters as current changes, and are often designed for fixed parameters, mostly implemented under position sensor control. Second, current research on field weakening control to improve inductance parameters is often based on a general trend description of the interaction between various parameters, with little quantitative analysis of the improvement effect based on mathematical models and actual inductance change trends. Finally, for field weakening control improvement, existing research focuses on directly compensating and optimizing motor current and voltage, and the improvement results are mostly stability-related, lacking performance optimization under field weakening control.

[0058] In view of this, this application proposes a motor control method that can estimate and correct the motor inductance in real time, thereby optimizing the field weakening control performance of the motor, increasing the maximum speed of the motor under the same load, and improving the stable output capability of the motor.

[0059] In the technical solution of this application embodiment, the inductance of the motor is estimated in real time to obtain a corrected inductance, which can change with the load current. The voltage signal of the motor is obtained based on the corrected inductance, and the motor is controlled by field weakening based on the lead current angle. This allows the motor current angle to change from the first current angle to the second current angle under the same torque. This enables the motor inductance to be estimated and corrected in real time, optimizes the field weakening control performance of the motor, increases the maximum speed of the motor under the same load, and improves the stable output capability of the motor.

[0060] Figure 1 A flowchart of a motor control method according to an embodiment of this application is shown.

[0061] like Figure 1 As shown, the motor control method 100 provided in this application includes steps S110 to S130.

[0062] Step S110: The inductance of the motor is estimated in real time to obtain the corrected inductance.

[0063] For example, the motor may be a built-in permanent magnet synchronous motor, and the inductance of the motor may include quadrature-axis inductance and direct-axis inductance. Real-time estimation of the motor inductance may be performed, for example, by injecting a high-frequency voltage signal into the motor under the same torque and estimating the inductance in real time based on the high-frequency response current of the motor, thereby obtaining the quadrature-axis corrected inductance and the direct-axis corrected inductance of the motor, thus obtaining the combined corrected inductance of the two axes. The corrected inductance may be used as a corrected inductance identification parameter, which can change with the load current of the motor, thereby enabling real-time monitoring of the motor's operating status.

[0064] Step S120: Based on the corrected inductance, obtain the voltage signal of the motor.

[0065] For example, the built-in permanent magnet synchronous motor has the characteristics of a salient-pole machine, meaning that the variation range of the quadrature-axis inductance reference value is higher than that of the direct-axis inductance reference value. The inductance reference value can be regarded as the corrected inductance of the quadrature-axis or direct-axis. There is a preset relationship between the corrected inductance and the motor's voltage signal. The corrected inductance can be input into the preset relationship to obtain the motor's voltage signal. For example, it can be the voltage signal under the current motor operating state, which is estimated in real time based on the salient-pole machine characteristics of the motor and the current torque.

[0066] Step S130: When the voltage signal indicates that the motor has entered the field weakening control state, the motor is subjected to field weakening control based on the lead current angle so that the motor current angle changes from the first current angle to the second current angle under the same torque. The difference between the second current angle and the first current angle is the lead current angle, and the speed of the motor under the second current angle is greater than the speed under the first current angle.

[0067] For example, when the current voltage signal of the motor (e.g., the combined effective value of the output voltages of the quadrature axis and direct axis of the motor) exceeds a preset voltage limit, it indicates that the motor enters a field weakening control state. At this time, the motor is field weakened based on the lead current angle, so that the current angle of the motor changes from the first current angle to the second current angle under the same torque. The lead current angle can be the difference between the second current angle and the first current angle. Under the control of the lead current angle, the speed of the motor at the second current angle is greater than the speed at the first current angle. The first current angle and the second current angle can be, for example, the current vector angle of the motor operation (the angle between the current vector and the reference axis, such as the quadrature axis).

[0068] In the technical solution of this application embodiment, the inductance of the motor is estimated in real time to obtain a corrected inductance, which can change with the load current. The voltage signal of the motor is obtained based on the corrected inductance, and the motor is controlled by field weakening based on the lead current angle. This allows the motor current angle to change from the first current angle to the second current angle under the same torque. This enables the motor inductance to be estimated and corrected in real time, optimizes the field weakening control performance of the motor, increases the maximum speed of the motor under the same load, and improves the stable output capability of the motor.

[0069] In one example, field weakening control of the motor is mainly based on the estimated corrected inductance (corrected inductance identification parameters). The corrected inductance can reduce the current vector angle under the same torque, thereby reducing the stator current, increasing the maximum speed that the motor can reach under the same load, and optimizing the performance of the motor field weakening control. The following describes in detail how to obtain the corrected inductance.

[0070] For example, the inductance of the motor is estimated in real time to obtain the corrected inductance. For instance, a high-frequency square wave voltage signal is first injected into the motor, and the motor's response current signal is collected; then, the corrected inductance is estimated based on the high-frequency square wave voltage signal and the response current signal.

[0071] For example, a high-frequency square wave voltage signal can be injected into the motor based on its voltage equation and flux linkage equation to obtain a corrected inductance and achieve high-precision inductance identification. The voltage equation of a permanent magnet synchronous motor (motor) is a fundamental mathematical model describing the motor's operating state, reflecting the relationship between the motor's voltage, current, resistance, inductance, and electromotive force. By inputting a voltage u to the motor's d-axis... d q-axis input voltage u q Each generates a current i d and i q A d-axis voltage drop Ri is generated across resistor R. d and q-axis pressure drop Ri q A changing electric field generates a magnetic field, which in turn generates a voltage. and voltage The motor generates a q-axis back electromotive force ω at the same time as it rotates. e Ψ q and d-axis back electromotive force ω e Ψ d The voltage equation of an ideal permanent magnet synchronous motor is: resistance voltage drop + magnetic field voltage drop + back electromotive force. The voltage equation of a permanent magnet synchronous motor is shown in formula (1):

[0072]

[0073] Where R is the resistance (stator resistance), u d For the d-axis voltage, u q Let i be the q-axis voltage.d Let i be the d-axis current. q For the q-axis current, Ψ d Ψ is the d-axis flux linkage. q Let ω be the q-axis flux linkage. e It represents the electric angular velocity.

[0074] The flux linkage equation of the motor is given by formula (2):

[0075]

[0076] Among them, Ψ f For permanent magnet flux linkage (rotor), L d Let L be the inductance along the d-axis. q The inductance along the q-axis (corrected inductance).

[0077] Therefore, combined Figure 2 This describes an example of injecting a high-frequency square wave voltage signal into a motor.

[0078] Figure 2 A schematic diagram of a high-frequency square wave injection signal according to an embodiment of this application is shown.

[0079] For example, such as Figure 2 As shown, the horizontal axis represents time, and the vertical axis represents... To inject a high-frequency square wave voltage signal along the d-axis (direct axis), To inject a high-frequency square wave voltage signal along the q-axis, V h -V h Let ΔT be the amplitude of the high-frequency square wave voltage signal injected within one cycle. d For half a cycle of injecting a high-frequency square wave voltage signal into the d-axis, 2ΔT d The waveform above represents one complete cycle of a high-frequency square wave voltage signal injected along the d-axis, ΔT. q Inject half a cycle of a square wave into the q-axis (cross axis), 2ΔT q A complete cycle of a square wave is injected into the q-axis. The waveform diagram below shows the high-frequency square wave voltage injected into the q-axis. High-frequency square wave voltage signals can be injected into the motor simultaneously. For example, a first high-frequency square wave voltage signal can be injected into the d-axis of the motor, and a second high-frequency square wave voltage signal can be injected into the q-axis of the motor. The signal period of the first high-frequency square wave voltage signal is longer than the signal period of the second high-frequency square wave voltage signal.

[0080] Specifically, please refer to Figure 2 The high-frequency square wave voltage injected into the motor is as shown in formula (3):

[0081]

[0082] Simultaneously injecting a period of 2ΔT into the d-axisd The voltage signal range is V h ~-V h The high-frequency square wave voltage signal (the first high-frequency square wave voltage signal), and simultaneously injected into the q-axis with a period of 2ΔT q (ΔT d >ΔT q The voltage signal range is V. h ~-V h The high-frequency square wave voltage signal (second high-frequency square wave voltage signal), in equation (3), To inject a high-frequency square wave voltage along the d-axis, To inject a high-frequency square wave voltage along the q-axis, V h -V represents the maximum amplitude of a high-frequency square wave voltage signal injected into the d-axis or q-axis within one cycle. h ΔT represents the minimum amplitude of a high-frequency square wave voltage signal injected into the d-axis or q-axis within one cycle. d For half a cycle of injecting a high-frequency square wave voltage signal into the d-axis, ΔT q Half a cycle of injecting a high-frequency square wave voltage signal into the q-axis.

[0083] In the technical solution of this application embodiment, a first high-frequency square wave voltage signal is injected into the d-axis of the motor, and a second high-frequency square wave voltage signal smaller than the first high-frequency square wave voltage signal is injected into the q-axis of the motor to obtain a response current. By injecting high-frequency square waves into the d-axis and q-axis for control, high-frequency square wave voltage signals of different periods can realize the smooth transition and precise control of the motor in a wide speed ratio range, and extend the system life.

[0084] The high-frequency square wave injection method can measure the change in response current by injecting a high-frequency voltage signal into the motor, thereby estimating and extracting inductance information, improving dynamic response speed, and achieving high-precision inductance parameter identification. The following is a detailed explanation.

[0085] For example, the corrected inductance is estimated based on the high-frequency square wave voltage signal and the response current signal. For instance, the corrected inductance is estimated based on the signal amplitude and signal period of the high-frequency square wave voltage signal, and the current angle and current difference between different times of the response current signal.

[0086] Specifically, the relationship between the response current under a high-frequency square wave voltage injected into the motor and the injected voltage signal is shown in formula (4):

[0087]

[0088] in, For the injection impedance matrix, i dh Let i be the response current along the d-axis. qh Let be the q-axis response current.

[0089] In the stationary two-phase coordinate system (α-β), equation (4) is transformed into equation (5):

[0090]

[0091] Where 2r / 2s represents the transformation from the two-phase rotating coordinate system 2r to the two-phase stationary coordinate system 2s, 2s / 2r represents the transformation from the two-phase stationary coordinate system 2s to the two-phase rotating coordinate system 2r, θ represents the estimated current angle, Δθ represents the error between the estimated current angle at the previous moment and the current moment, and T represents the transformation matrix.

[0092] Under high-frequency square wave signal injection, ignoring the effects of resistance (stator resistance) and back electromotive force, the injection impedance matrix is ​​as shown in formula (6):

[0093]

[0094] Where R is resistance, ω e L d For the back electromotive force, ω e Let ω be the electric angular velocity. h L is the frequency of the injected high-frequency square wave. d Let L be the inductance along the d-axis. q The inductance is the q-axis inductance.

[0095] Then, in the stationary two-phase coordinate system (α-β), the response current error is derived from the above formulas (1)-(6) as shown in formula (7):

[0096]

[0097] in, The error between the response current at the previous and current moments under high-frequency injection is ΔT, where ΔT is half a cycle of the high-frequency square wave injected into the d-axis or q-axis (e.g., ΔT). d ΔT q ), where θ is the estimated current angle, and Δθ is the error between the estimated current angle at the previous moment and the current moment.

[0098] Treating the estimated angle error Δθ as a constant, i.e., Δθ = θ c Based on formula (7), the estimated value of the d-axis inductance L can be derived. d And the estimated value of q-axis inductance L q As in formula (8):

[0099]

[0100] When θ c When = 0, the high-frequency square wave is actually injected into the d-axis, and the d-axis inductance is as shown in formula (9):

[0101]

[0102] When θ c When π / 2, the high-frequency square wave is actually injected into the q-axis, and the q-axis inductance is as shown in formula (10):

[0103]

[0104] When high-frequency square wave voltage signals are injected into the d-axis and q-axis simultaneously, the d-axis inductance and q-axis inductance (d-axis corrected inductance and q-axis corrected inductance) can be estimated simultaneously by combining formulas (9) and (10) as shown in formula (11):

[0105]

[0106] Among them, L d The inductance along the d-axis; L q The inductance along the q-axis (corrected inductance); Δi αd-h , Δi βd-h In a stationary two-phase coordinate system (α-β), the current error (current difference between different times) of the high-frequency injected response current along the d-axis at the previous and current moments is given; Δi αq-h , Δi βq-h In a stationary two-phase coordinate system (α-β), the current error (current difference between different times) of the q-axis high-frequency injected response current at the previous and current moments is given; θ is the estimated current angle; ΔT d For half a cycle of the high-frequency square wave injected along the d-axis; ΔT q This is half a cycle of the high-frequency square wave injected along the q-axis.

[0107] In the technical solution of this application embodiment, based on the signal amplitude and signal period of the high-frequency square wave voltage signal, a corresponding high-frequency square wave voltage is injected into the motor. Based on the signal amplitude and signal period, as well as the current angle of the response current signal and the current difference between different times, the corrected inductance is estimated, which reduces the current error, improves the inductance identification accuracy and dynamic response speed, and optimizes the accuracy, adaptability and reliability of field weakening control.

[0108] In the technical solution of this application embodiment, a high-frequency square wave voltage signal is injected into the motor, and the motor's response current signal is collected to determine the motor's operating state. Based on the high-frequency square wave voltage signal and the response current signal, the corrected inductance is estimated, thereby achieving high-precision inductance parameter identification, improving dynamic response speed, and realizing precise field weakening control.

[0109] Based on the corrected inductance estimated from the current operating state of the motor, the real-time output voltage (voltage signal) of the motor can be obtained. Then, according to the different ranges of the output voltage, corresponding control strategies can be implemented to ensure that the motor speed is increased under the same torque. The following is a detailed introduction.

[0110] First, we will introduce how to obtain the motor voltage signal based on the corrected inductance.

[0111] For example, the voltage signal of the motor is obtained based on the corrected inductance, for instance, by using the voltage balance equation to obtain the voltage signal of the motor based on the corrected inductance, the motor current, and the motor flux linkage.

[0112] For example, a corrected inductance is obtained by injecting a high-frequency voltage into the motor. The corrected inductance and the voltage signal of the motor satisfy a preset relationship, which includes a voltage balance equation. The voltage balance equation is shown in formula (12):

[0113]

[0114] Among them, u s The voltage of the motor (stator); ω e The electric angular velocity (rotor speed); ρ = L q / L d L represents the spur probability of the motor. d and L d To correct the inductance; i q and i d ψ is the current of the motor; f For the magnetic flux of the motor.

[0115] In the technical solution of this application embodiment, after injecting high-frequency voltage, the voltage signal of the motor is obtained based on the voltage balance equation of the motor, the corrected inductance, the current of the motor, and the magnetic flux of the motor. This can accurately reflect the real-time operating status of the motor. The accuracy of the voltage signal is improved by correcting the inductance based on real-time estimation, thereby enabling precise control, reducing electromagnetic losses, and improving the efficiency and reliability of motor operation.

[0116] In one example, the maximum torque-to-current ratio control or field weakening control of the motor is performed by modifying the inductance. The system based on the modified inductance improves the field weakening control. This system can estimate the motor parameters in real time and reduce the current vector angle of the motor under the same torque based on the modified inductance, thereby reducing the stator current, increasing the maximum speed that the motor can reach under the same load, and optimizing the performance of the motor field weakening control.

[0117] First, we will introduce how to improve field weakening control based on modified inductance.

[0118] Figure 3A block diagram of the modified inductance-enhanced field weakening control section of an embodiment of this application is shown.

[0119] like Figure 3 As shown, high-frequency square wave voltage signals are injected into the q-axis respectively. Inject a high-frequency square wave voltage signal into the d-axis The current angular velocity ω of the motor is read through the PI speed regulator. e And compare the target reference angular velocity ω* under the same torque with the current angular velocity ω e The angular velocity error is obtained by comparison (subtraction). This error is then input into the control system for speed control, and transmitted via the motor's voltage signal. (and (Expressions in different coordinate systems) and bus voltage U dc The voltage error ΔM between the two is calculated and determined. Based on the voltage error, a current loop closed-loop control is performed to obtain the input signal for controlling the motor, namely the lead current angle Δθ, which is then input to the control system. The control system estimates the inductance value (corrects the inductance) L. dq (Representing the inductance of the d-axis and the inductance of the q-axis) Perform field weakening control or maximum torque-current ratio control on the motor to increase the motor speed to the target angular velocity or decrease the stator current to the target current under the same torque.

[0120] Simultaneously, the d-axis reference current is read through the PI current regulator. and actual current i d and q-axis reference current and actual current i q The error between the reference current and the actual current is calculated, where the three-phase current i of the motor is... abc After smoothing by a filter (low-pass filter, LPF), the output i is passed through a stationary two-phase coordinate system (3s / 2s transformation). αβ The actual d-axis current i is output through a rotating coordinate system (2r / 2s transformation). d and the actual q-axis current i q .

[0121] Output motor voltage via a stationary two-phase coordinate system (2r / 2s transformation) Inverters (VSI, VoltageSource Inverters) use a modulation module to perform space vector pulse width modulation (SVPWM), dynamically adjusting the amplitude and frequency of the motor voltage according to the motor's operating status, and inputting the modulation result to the permanent magnet synchronous motor. This enables more efficient use of the DC bus voltage, improves motor efficiency, and reduces harmonic distortion.

[0122] Furthermore, the motor current i through the stationary two-phase coordinate system αβ (Representing the d-axis current and q-axis current in a stationary two-phase coordinate system) and high-frequency square wave injection voltage (Representing the high-frequency square wave injection voltage along the d-axis and the high-frequency square wave injection voltage along the q-axis) are used to estimate the inductance, resulting in the corrected inductance L. dq The input is used to control the system, forming a closed-loop control.

[0123] Figure 4 An overall block diagram of the modified inductance-enhanced field weakening control according to an embodiment of this application is shown.

[0124] like Figure 4 As shown, the operating status of the motor is estimated in real time. With the injection of a high-frequency square wave voltage signal, the motor is controlled by maximum torque-to-current ratio or field weakening based on the corrected inductance and the estimated motor voltage. Simultaneously, the SVPWM-modulated motor voltage is input to the permanent magnet synchronous motor, which can more effectively utilize the DC bus voltage, improve motor efficiency, and reduce harmonic distortion. The three-phase current i of the motor is... abc and the motor voltage passing through the stationary two-phase coordinate system (α-β) (Representing the voltage on the d-axis and q-axis in a stationary two-phase coordinate system) Input into the sliding mode observation module to obtain the estimated angular velocity of the motor. And estimating rotor position By forming a closed-loop control, the motor speed can be increased by field weakening control under the same torque, or the stator current can be reduced under maximum torque-current ratio control, thereby improving the motor's operating efficiency.

[0125] The system with improved field weakening control through the above-described modified inductance can estimate the motor's operating status in real time, and then perform maximum torque-to-current ratio control or field weakening control on the motor based on the modified inductance and motor voltage. Two examples are described below.

[0126] Figure 5 The diagram illustrates MTPA control under modified inductance and fixed inductance parameters according to embodiments of this application.

[0127] For example, such as Figure 5 As shown, the horizontal axis represents the d-axis current i. d The vertical axis represents the q-axis current i. q When the voltage signal indicates that the motor is in Maximum Torque Per Ampere (MTPA) control mode, the target current angle is determined based on the corrected inductance. Based on the target current angle, MTPA control is applied to the motor to reduce the motor current at the same torque. The target current angle (θ) is... if () smaller than the reference fixed current angle (θ)io ).

[0128] Specifically, please refer to Figure 5 Based on the above-mentioned modified inductance improved field weakening control system, when the error between the motor voltage signal and the voltage limit value is less than 0, the maximum torque current ratio control is adopted for the motor based on the modified inductance. The voltage limit value of the motor can be calculated first based on formula (12) to obtain formula (13):

[0129] (u lim / ω e ) 2 =(L q i q ) 2 +(L d i d +ψ f ) 2 (13)

[0130] Among them, based on the above formulas (1) and (12), the motor voltage u in formula (12) is... s Replace with u lim (i.e. u s =u lim ), u lim This is the voltage limit value. Motor voltage signal u s , Error between voltage limit value U dc The maximum torque-current ratio control is performed when the bus voltage is ΔM < 0, i.e., when the motor voltage is within the voltage limit value.

[0131] The inductance of the motor when it is unloaded or at its rated current is a fixed inductance, and the current vector angle is θ. io (Referencing a fixed current angle), the motor is controlled based on the corrected inductance identification parameters (corrected inductance). Under the action of the current loop, when the motor is at the same torque (constant torque curve), the load current vector angle decreases to θ. if (Target current angle), the difference in current vector angle Δθ when the motor's operating point changes from point A to point B. i For Δθ i =θ io -θ if Motor current i d i q The absolute values ​​of all values ​​have decreased, which improves the dynamic response and control delay caused by control through fixed inductance, improves control accuracy and dynamic response speed, and effectively reduces motor current under the same torque.

[0132] In the technical solution of this application embodiment, when the motor voltage signal indicates that the motor is in the maximum torque-to-current ratio control state, the target current angle is determined according to the correction inductance, so that the target current angle is less than the reference fixed current angle under the current same torque of the motor. That is, the current vector angle is reduced according to the correction inductance parameter, and then the maximum torque-to-current ratio control of the motor is performed based on the target current angle, so that the current of the motor is reduced under the same torque, thereby more accurately suppressing the back electromotive force, reducing electromagnetic losses, and improving the stability, efficiency and power output capability of the motor operation. In addition, it improves the dynamic response and control delay caused by control through fixed inductance, and improves the control accuracy and dynamic response speed.

[0133] The following details how to adjust the target current angle θ based on the corrected inductance. if Perform the calculation.

[0134] For example, the target current angle θ is determined based on the modified inductance. if For example, firstly, based on the modified inductance, the motor current, and the motor flux linkage, an electromagnetic torque equation representing the relationship between the motor torque and the current angle is obtained; then, the electromagnetic torque equation is differentiated by the current angle to obtain the target current angle.

[0135] Specifically, the electromagnetic torque equation of the permanent magnet synchronous motor is as shown in formula (14):

[0136]

[0137] Among them, T e For electromagnetic torque; n p For the extreme logarithm, Ψ f For permanent magnet flux linkage; i s For stator current, i q =i s sinθ, i d =i s cosθ.

[0138] Differentiate both sides of the above formula by θ to obtain the current vector angle θ. i As in formula (15):

[0139]

[0140] The above equation is then transformed into a quadratic equation in one variable with cosθ as the unknown, as shown in formula (16):

[0141] 2(L d -L q )i s cos 2 θ+Ψ f cosθ-(L d -L q)i s =0 (16)

[0142] and let the two roots of the equation be cosθ1 and cosθ2 respectively, with cosθ1<0<cosθ2, then according to Vieta's formulas, the relationship between the two roots is as shown in Equation (17):

[0143]

[0144] Based on the above formula, let the d-axis inductance under load be L df , and the q-axis inductance be L qf , the d-axis inductance at no-load be L do , and the q-axis inductance be L qo , then L df =L d0 -ΔL d ,L qf =L q0 -ΔL q . ΔL d is the difference between the d-axis inductance before and after loading, ΔL q is the difference between the q-axis inductance before and after loading. According to the actual variation of inductance in operation (i.e., the characteristics of salient-pole motors), 0<ΔL d <ΔL q , and L d -L q <0. Then the relationship between the d-axis and q-axis inductance differences before and after loading is as shown in Equation (18):

[0145] L do -L qo <L df -L qf <0 (18)

[0146] According to Equation (18), when the motor transitions from no-load to load, L d -L q increases from L do -L qo to L df -L qf , then according to Equation (17), the sum cosθ1+cosθ2 increases at this time. Assuming that cosθ2 decreases, according to cosθ1·cosθ2=-1 / 2, cosθ1 also decreases, then cosθ1+cosθ2 decreases, which contradicts the actual variation trend. Assuming that cosθ2 increases, according to cosθ1·cosθ2=-1 / 2, cosθ1 also increases, and their sum increases, which is consistent with the actual variation trend. Therefore, when the motor transitions from no-load to load, both cosθ1 and cosθ2 increase.

[0147] Since the value range of the current vector angle θ i is: π / 2<θi <π, i.e., -1 <cosθ i If <0, then only one root of formula (16), cosθ1, is determined as the final cosθ. i (Another root cosθ2 was discarded because it did not conform to the actual electrode operating rules), the final cosθ i Represented as formula (19):

[0148]

[0149] That is, when the motor changes from no-load to load, cosθ i If θ increases, then i Decrease. The current vector angle θ under no-load conditions. io Current vector angle θ with load if The relationship between them is shown in formula (20):

[0150] θ if <θ io (20)

[0151] That is, the current vector angle θ under load if The target current angle.

[0152] Figure 5 The fixed inductor shown (corresponding to the reference fixed current angle (θ)) io The inductance can be either the inductance under no-load conditions or the inductance under other specific conditions (such as rated current). Compared to related technologies that control the motor by using a fixed inductance under no-load or load conditions, this application uses a corrected inductance obtained through real-time inductance identification for control, thereby improving motor performance.

[0153] In the technical solution of this application embodiment, by correcting the inductance, the motor current and the motor flux linkage, an electromagnetic torque equation representing the relationship between the motor torque and the current angle is obtained, so as to determine the current angle controlled by correcting the inductance. Then, the electromagnetic torque equation is differentiated by the current angle to obtain the target current angle, so as to control the motor with the maximum torque-current ratio based on the target current angle, reduce the motor current under the same torque, improve the dynamic response speed, effectively suppress back electromotive force and reduce electromagnetic loss.

[0154] Figure 6 A schematic diagram of the field weakening control principle of an embodiment of this application is shown.

[0155] For example, such as Figure 6 As shown, the horizontal axis represents the d-axis current i. d The vertical axis represents the q-axis current i. qT represents the constant torque curve, the dashed circle represents the voltage limit circle at different angular velocities, and the solid circle represents the current circle at constant torque. When the voltage signal indicates that the motor has entered the field weakening control state, field weakening control is performed on the motor based on the lead current angle. For example, first, the voltage error ΔM between the voltage signal and the voltage limit signal is determined; then, when the voltage error is greater than a preset threshold (e.g., 0), closed-loop control is performed based on the voltage error to obtain the lead current angle Δθ; finally, field weakening control is performed on the motor based on the lead current angle. Combined with... Figure 4 The voltage error ΔM is input into the closed-loop controller for closed-loop control to obtain the leading current angle Δθ. The closed-loop controller includes PID (Proportional, Integral, Derivative) controller, P proportional controller, I integral controller, D derivative controller, etc. In this application, I controller is preferred.

[0156] Specifically, please refer to Figure 6 Under the same torque, when the motor speed increases from ω1 to ω2, the effective value of the combined output voltage of the motor (combined d-axis and q-axis voltages) is greater than... That is, ΔM>0. At this point, the system switches from MTPA control to field weakening control. By introducing a lead angle Δθ as the control input, the current deflection angle (lead angle) is precisely calculated and adjusted through a voltage feedback mechanism (closed-loop control). The reference current of the control loop (i.e., the current circle) is used. Under the influence of the leading angle Δθ, it increases in the opposite direction. The motor's operating point is reduced, thereby controlling the weak magnetic current to shift from point B to point C, and the motor's angular velocity increases from ω1 to ω2, i.e., ω1 < ω2, completing the speed increase process under constant torque. Among them, the advance angle Δθ is different from the current angle estimated in formulas (5) and (7)-(11) above in the previous moment and the current moment.

[0157] In the technical solution of this application embodiment, by determining the voltage error between the voltage signal and the voltage limit signal, and when the voltage error is greater than a preset threshold, closed-loop control is performed to obtain the lead current angle. Then, field weakening control is performed on the motor based on the lead current angle, so that the motor can achieve speed increase under constant torque under the stable and reliable control of the lead angle. Optimizing the field weakening control ensures that the motor can smoothly transition within a wide speed ratio range and ensures safe and reliable operation under complex working conditions.

[0158] Figure 7 A schematic diagram of the modified inductance-enhanced field weakening control according to an embodiment of this application is shown.

[0159] For example, such as Figure 7 As shown, field weakening control introduces a lead angle Δθ, with the horizontal axis representing the d-axis current i. d The vertical axis represents the q-axis current i. qT represents the constant torque curve, the dashed line represents the voltage limit circle at different angular velocities, and the solid line represents the current circle at constant torque. The error between the voltage signal and the voltage limit value... When ΔM < 0, Δθ = 0, and the motor is under MTPA control; when ΔM > 0, Δθ > 0, and the motor enters the field weakening control state.

[0160] Without the corrected inductor, the motor operates at point A with a speed (angular velocity) of ω5. When the corrected inductor is used, due to the difference in current vector angle Δθ... i The function of this control is as follows: When the motor operates at point B, its speed is ω4. Under the same torque, the current vector angle of the motor decreases under the current circular control loop, resulting in a decrease in stator current. This means that under the same load, a smaller stator current and a lower required speed are needed. At this point, if ΔM < 0 and Δθ = 0, the motor does not enter field weakening control and is under MTPA control, at which point the motor stabilizes at point B. When ΔM > 0, the control system outputs a lead angle Δθ, and the motor enters the field weakening state, increasing its speed to ω6. Since ω4 < ω5 < ω6, the motor stabilizes at point C. Therefore, during the process of switching from point A to point B and then to point C, under the same torque, the maximum achievable speed of the motor increases from ω5 to ω6. Figure 7 ω4 and Figure 6 In this context, ω1 can be equal to or correspond to ω6. Figure 6 ω2 in the equation can be equal or correspond to each other.

[0161] Next, combined Figure 4 , Figure 8 and Figure 9 This describes how the motor's current angle and speed are estimated based on a sliding mode observation module. Figure 4 The sliding mode observation module shown includes Figure 8 and Figure 9 The structure.

[0162] For example, by inputting the motor's current signal and voltage signal into the sliding mode observation module for estimation, the motor's current angle and speed can be obtained.

[0163] Specifically, the sliding mode observation module includes an observer based on nonlinear control theory. The sliding mode observation module may include structures such as a sliding mode observer (SMO) and a phase-locked loop (PLL). By inputting the current signal and voltage signal of the motor under the current torque into the sliding mode observation module, the current angle and speed of the motor can be estimated. This allows the corresponding feedback signal to the field weakening control system based on the corrected inductance. For example, based on the current operating state of the motor, the motor can be controlled by MTPA through the corrected inductance to reduce the current angle of the motor under the same torque, or the motor can be controlled by field weakening to increase the speed of the motor under the same torque.

[0164] In the technical solution of this application embodiment, by inputting the voltage signal of the motor current signal into the sliding mode observation module for estimation, the current angle and speed of the motor are obtained. The motor state can be estimated quickly and accurately under real-time operating conditions, thereby performing corresponding control and realizing sensorless control of the motor at high speed.

[0165] Next, the part of the sliding mode observation module that estimates the back electromotive force will be introduced in detail.

[0166] Figure 8 A partial block diagram of the sliding mode observation module implementation according to an embodiment of this application is shown.

[0167] For example, such as Figure 8 As shown, a sliding mode observation module in a stationary two-phase coordinate system is used. This module, for example, may include a sliding mode observer to estimate the back electromotive force of a permanent magnet synchronous motor. The motor's d-axis voltage u... d Motor q-axis voltage u q Estimating angular velocity Input sliding mode observer, output d-axis predicted current q-axis predicted current The predicted d-axis current of the motor is calculated using the sign function sign(s). With actual current i d Error between, q-axis predicted current With actual current i q The error between them, and then the error result and the d-axis voltage V output by the sign function sign(s) are calculated. d q-axis voltage V q After filtering with a low-pass filter, the back electromotive force is estimated. The rotor position is estimated by transforming the coordinates to a synchronous rotating coordinate system using Park transformation, normalizing the back electromotive force in the resulting synchronous rotating coordinate system, and finally outputting the result via a phase-locked loop (PLL). The phase-locked loop also outputs an estimated angular velocity. Estimating angular velocity The d-axis voltage V output by the sliding mode function d q-axis voltage V q And estimating back electromotive force It also inputs the sliding mode observer in reverse to perform closed-loop calculations.

[0168] Figure 9 A partial block diagram of a phase-locked loop implementation according to an embodiment of this application is shown.

[0169] like Figure 9 As shown, estimating the back electromotive force Transform to a synchronously rotating coordinate system using the Park transformation (rotation transformation), and output... The back electromotive force in the synchronous rotating coordinate system is obtained Normalize the output and output the estimated back electromotive force in the normalized rotating coordinate system. And after each through the integral gain k i , proportional gain k q To eliminate errors, integral gain and integral processing are used. Combined with the proportional gain, the output estimates the angular velocity. Then, through a second integration process Output estimated rotor position

[0170] Figure 10 A block diagram of a permanent magnet motor control system according to an embodiment of this application is shown.

[0171] This application provides a permanent magnet motor control system 1000, with reference to... Figure 10 The permanent magnet motor control system 1000 includes a memory 1010 and a processor 1020. The memory 1010 stores a computer program, and the processor 1020 executes the computer program to implement the steps of the method in any of the above embodiments.

[0172] Figure 11 A block diagram of a motor control device according to an embodiment of this application is shown.

[0173] This application provides a motor control device 1100, the device 1100 including:

[0174] The estimation module 1110 is used to estimate the inductance of the motor in real time to obtain the corrected inductance.

[0175] The module 1120 is used to obtain the voltage signal of the motor based on the corrected inductance.

[0176] The control module 1130 is used to perform field weakening control on the motor based on the lead current angle when the voltage signal indicates that the motor has entered the field weakening control state, so that the current angle of the motor changes from the first current angle to the second current angle under the same torque, wherein the difference between the second current angle and the first current angle is the lead current angle, and the speed of the motor under the second current angle is greater than the speed under the first current angle.

[0177] For example, the control module 1130 is further configured to: determine the voltage error between the voltage signal and the voltage limit signal; perform closed-loop control based on the voltage error when the voltage error is greater than a preset threshold to obtain the lead current angle; and perform field weakening control on the motor based on the lead current angle.

[0178] For example, the motor control device 1100 further includes a maximum torque-to-current ratio control module, configured to: determine a target current angle based on a correction inductance when the voltage signal indicates that the motor is in a maximum torque-to-current ratio control state; and perform maximum torque-to-current ratio control on the motor based on the target current angle so that the motor current is reduced under the same torque, wherein the target current angle is less than a reference fixed current angle.

[0179] For example, determining the target current angle based on the modified inductance includes: obtaining an electromagnetic torque equation representing the relationship between the motor torque and the current angle based on the modified inductance, the motor current, and the motor flux linkage; and differentiating the electromagnetic torque equation by the current angle to obtain the target current angle.

[0180] For example, the estimation module 1110 is further configured to: inject a high-frequency square wave voltage signal into the motor and acquire the motor's response current signal; and estimate the corrected inductance based on the high-frequency square wave voltage signal and the response current signal.

[0181] For example, the corrected inductance is estimated based on a high-frequency square wave voltage signal and a response current signal, including: estimating the corrected inductance based on the signal amplitude and signal period of the high-frequency square wave voltage signal, and the current angle and current difference between different times of the response current signal.

[0182] For example, injecting a high-frequency square wave voltage signal into a motor includes: simultaneously injecting a first high-frequency square wave voltage signal into the d-axis of the motor and injecting a second high-frequency square wave voltage signal into the q-axis of the motor, wherein the signal period of the first high-frequency square wave voltage signal is greater than the signal period of the second high-frequency square wave voltage signal.

[0183] For example, the obtaining module 1120 is further configured to: obtain the voltage signal of the motor based on the voltage balance equation, the corrected inductance, the motor current and the motor flux linkage.

[0184] For example, the motor control device 1100 further includes a second estimation module, used to: input the motor current signal and the motor voltage signal into the sliding mode observer for estimation, to obtain the motor current angle and the motor speed.

[0185] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method in any of the above embodiments.

[0186] This application provides a computer program product, including a computer program, which, when executed by a processor, implements the method of any of the above embodiments.

[0187] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequential list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this application, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0188] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0189] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A motor control method, characterized in that, The method includes: The inductance of the motor is estimated in real time to obtain the corrected inductance; Based on the corrected inductance, the voltage signal of the motor is obtained; When the voltage signal indicates that the motor has entered a field weakening control state, field weakening control is performed on the motor based on the leading current angle, so that the current angle of the motor changes from a first current angle to a second current angle under the same torque. The difference between the second current angle and the first current angle is the leading current angle, and the motor speed at the second current angle is greater than the speed at the first current angle.

2. The method according to claim 1, characterized in that, When the voltage signal indicates that the motor has entered a field-weakening control state, the method of performing field-weakening control on the motor based on the lead current angle includes: Determine the voltage error between the voltage signal and the voltage limit signal; When the voltage error is greater than a preset threshold, closed-loop control is performed based on the voltage error to obtain the leading current angle; The motor is subjected to field weakening control based on the lead current angle.

3. The method according to claim 1 or 2, characterized in that, The method further includes: When the voltage signal indicates that the motor is in a maximum torque-to-current ratio control state, the target current angle is determined based on the corrected inductance; The motor is controlled by maximum torque-to-current ratio based on the target current angle so that the current of the motor is reduced under the same torque, wherein the target current angle is smaller than the reference fixed current angle.

4. The method according to claim 3, characterized in that, The determination of the target current angle based on the corrected inductance includes: Based on the corrected inductance, the current of the motor, and the magnetic flux linkage of the motor, an electromagnetic torque equation representing the relationship between the motor torque and the current angle is obtained. The target current angle is obtained by differentiating the electromagnetic torque equation by the current angle.

5. The method according to any one of claims 1-4, characterized in that, The step of estimating the inductance of the motor in real time to obtain the corrected inductance includes: A high-frequency square wave voltage signal is injected into the motor, and the response current signal of the motor is acquired; The corrected inductance is estimated based on the high-frequency square wave voltage signal and the response current signal.

6. The method according to claim 5, characterized in that, The estimation of the corrected inductance based on the high-frequency square wave voltage signal and the response current signal includes: The corrected inductance is estimated based on the signal amplitude and period of the high-frequency square wave voltage signal, the current angle of the response current signal, and the current difference between different times.

7. The method according to any one of claims 5-6, characterized in that, The injection of a high-frequency square wave voltage signal into the motor includes: Simultaneously, a first high-frequency square wave voltage signal is injected into the d-axis of the motor, and a second high-frequency square wave voltage signal is injected into the q-axis of the motor, wherein the signal period of the first high-frequency square wave voltage signal is greater than the signal period of the second high-frequency square wave voltage signal.

8. The method according to any one of claims 1-7, characterized in that, The process of obtaining the motor voltage signal based on the corrected inductance includes: Based on the voltage balance equation, the voltage signal of the motor is obtained using the corrected inductance, the current of the motor, and the magnetic flux linkage of the motor.

9. The method according to any one of claims 1-8, characterized in that, The method further includes: The motor's current signal and voltage signal are input into the sliding mode observation module for estimation to obtain the motor's current angle and speed.

10. A permanent magnet motor control system, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps of the method according to any one of claims 1-9.

11. A motor control device, characterized in that, The device includes: An estimation module is used to estimate the inductance of the motor in real time to obtain a corrected inductance; The module is used to obtain the voltage signal of the motor based on the corrected inductance; The control module is configured to perform field weakening control on the motor based on the leading current angle when the voltage signal indicates that the motor has entered the field weakening control state, so that the current angle of the motor changes from a first current angle to a second current angle under the same torque. The difference between the second current angle and the first current angle is the leading current angle, and the motor speed at the second current angle is greater than the speed at the first current angle.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-9.

13. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method according to any one of claims 1-9.

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