A method for back-EMF reconstruction and position and speed extraction of permanent magnet synchronous motor

Abstract

The present invention relates to the technical field of motor control technology, and specifically provides a method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor, comprising the following steps: establishing a mathematical dynamics model of the permanent magnet synchronous motor in a static coordinate system, and designing an improved super-helical observer based on the model to enhance the reconstruction accuracy and convergence speed of the back electromotive force; standardizing the reconstructed back electromotive force, and extracting the position and speed of the permanent magnet synchronous motor rotor through an integral compensation phase-locked loop. The present invention significantly improves the system convergence speed and position estimation accuracy by improving the existing super-helical observer and phase-locked loop.

Description

Technical Field

[0001] The invention relates to the technical field of motor control, and specifically provides a method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have been widely used in ship propulsion, railway traction systems, wind power generation and other fields due to their high reliability, high power density and low vibration. In the vector control framework, permanent magnet synchronous motors usually require an encoder to obtain the rotor position. However, in extreme environments with rapid changes in temperature and humidity, the encoder may fail. Therefore, in order to improve the operating reliability and stability of permanent magnet synchronous motors, position sensorless control is a control method with great development potential. For permanent magnet synchronous motors running at medium and high speeds, the position and speed extraction scheme based on back electromotive force has attracted widespread attention from academia and industry due to its simple design and easy application. An observer is usually used to estimate the back electromotive force, and a phase-locked loop is used to extract the position and speed. However, the traditional sliding mode observer has jitter and cannot converge within a limited time. The traditional phase-locked loop cannot handle the position estimation error during speed ramp acceleration and deceleration, which seriously affects the position estimation accuracy of position sensorless control.

[0003] Therefore, there is an urgent need to design a new back-EMF observer and phase-locked loop strategy to achieve accurate reconstruction of the back-EMF and extraction of position and speed through the designed position sensorless control strategy, thereby improving the position estimation accuracy. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for reconstructing the back-electromotive force and extracting the position and speed of a permanent magnet synchronous motor. The back-electromotive force of the permanent magnet synchronous motor is accurately reconstructed through a super-helical observer, and an integral compensation link is added to the traditional phase-locked loop, thereby reducing the position estimation error during ramp acceleration and deceleration, thereby improving the position estimation accuracy and realizing high-performance permanent magnet synchronous motor control.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] The method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor provided by the present invention comprises:

[0007] S1: Establish the mathematical dynamics model of permanent magnet synchronous motor;

[0008] S2: Design a super-helical observer including linear and nonlinear correction terms based on the mathematical dynamics model, and reconstruct the back electromotive force of the permanent magnet synchronous motor through the super-helical observer;

[0009] S3: The reconstructed back electromotive force is normalized in amplitude, and the rotor position of the permanent magnet synchronous motor is estimated from the back electromotive force through an integral compensation phase-locked loop.

[0010] Preferably, in S1, In the stationary coordinate system, the mathematical dynamics model of the permanent magnet synchronous motor is:

[0011] ;

[0012] in, for Stator voltage under the shaft, for Stator voltage under the shaft, for The stator current under the shaft, for The stator current under the shaft, is the stator inductance, is the stator resistance, for The back EMF under the shaft, for The back EMF under the shaft, Indicates time.

[0013] Preferably, in S2, the superhelix observer is:

[0014] ;

[0015] in, for Estimated stator current under the shaft, for Estimated stator current under the shaft, for The difference between the estimated stator current under the shaft and the stator current, for The difference between the estimated stator current under the shaft and the stator current, and are gain parameters, , , and All of them are nonlinear function operations. and is the linear correction term, , , and is the nonlinear correction term.

[0016] Preferably, the nonlinear function operation is:

[0017] ;

[0018] in, That is or , , sign represents the sign function.

[0019] Preferably, the reconstructed back electromotive force is:

[0020] ;

[0021] in, and They are and The estimated value of is the reconstructed back EMF.

[0022] Preferably, the calculation formula for performing amplitude normalization processing on the reconstructed back electromotive force is:

[0023] ;

[0024] in, and After standardization and .

[0025] Preferably, the integral compensation phase-locked loop is: adding an integral compensation link in the phase-locked loop.

[0026] Preferably, the rotor position estimation error of the phase-locked loop is compensated based on the integral for:

[0027] ;

[0028] in, The estimated rotor position of the integral compensation phase-locked loop, is the rotor position.

[0029] Preferably, the estimated rotor position is obtained by integrating the compensation phase-locked loop for:

[0030] ;

[0031] in, is the estimated rotor position obtained by the phase-locked loop, is the integral compensation term, is the gain of the integral compensation phase-locked loop, S is the complex frequency of the Laplace transform.

[0032] Preferably, the estimated rotor position obtained by the phase-locked loop for:

[0033] ;

[0034] in, is the proportional gain, is the integral gain, is the rotor position estimation error of the phase-locked loop.

[0035] Compared with the prior art, the invention can achieve the following beneficial effects:

[0036] The present invention can more effectively respond to the dynamic changes of the system by introducing nonlinear correction terms in the superhelical observer, and can process the nonlinear characteristics and uncertainty of the system, enhance the convergence speed of the observer, and improve the reconstruction accuracy of the back electromotive force. The introduction of nonlinear terms can enable the observer to maintain high estimation accuracy and robustness when facing complex dynamics and external disturbances. Compared with the traditional superhelical observer, the improved superhelical observer of the present invention can significantly improve the system convergence speed and position estimation accuracy.

[0037] The present invention adds an integral compensation link on the basis of the traditional phase-locked loop, which can reduce the position estimation error caused by speed ramp acceleration and deceleration. The present invention can significantly improve the motor control performance through the improved super spiral observer and integral compensation phase-locked loop, and can provide more accurate and stable position and speed estimation under various operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0039] Figure 1 is a flow chart of a method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor provided in an embodiment of the present invention;

[0040] Figure 2 is a control block diagram of a permanent magnet synchronous motor provided according to an embodiment of the present invention;

[0041] Figure 3 is a control block diagram of reconstructing back electromotive force by an improved super-helical observer according to an embodiment of the present invention;

[0042] Figure 4 4 is a control block diagram of extracting position speed through an integral compensation phase-locked loop according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0045] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0046] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0048] See also Figure 1 In one embodiment of the present invention, a method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor is provided, which is mainly used in Figure 2 The speed controller in the permanent magnet synchronous motor control system is mainly used to receive the desired speed , and according to the desired rotor speed Estimated rotor speed with feedback The error between the two generates the control current and , used to adjust the d-axis and q-axis currents of the permanent magnet synchronous motor. The current controller receives the control current and and the three-phase current detected by the motor rotor , , The actual current obtained by Clark transformation and For comparison, the current controller outputs a control voltage and , and then after Park transformation, the control voltage output by the current controller is converted into a PWM signal suitable for the inverter through space vector pulse width modulation, namely PWM11, PWM2, PWM3, PWM4, PWM5 and PWM6 in the figure, which are used to control the three-phase current of the permanent magnet synchronous motor, thereby realizing the control of the motor speed. In this control process, the embodiment of the present invention mainly improves the reconstruction accuracy of the back electromotive force and the system convergence speed by improving the super-helical observer, and introduces an integral compensation link in the phase-locked loop control to reduce the rotor position estimation error during ramp acceleration and deceleration, and obtain a high-precision rotor estimated position , and then get the estimated rotor speed , in order to achieve high-precision closed-loop control of the permanent magnet synchronous motor and improve the performance of the motor control system. Specifically, the specific process of the method given in the embodiment of the present invention is as follows:

[0049] S1: The permanent magnet synchronous motor in the embodiment of the present invention is a surface mounted permanent magnet synchronous motor. In the stationary coordinate system, the mathematical dynamics model of the surface-mounted permanent magnet synchronous motor can be constructed as follows:

[0050] ;

[0051] in, for Stator voltage under the shaft, for Stator voltage under the shaft, for The stator current under the shaft, for The stator current under the shaft, is the stator inductance, is the stator resistance, for The back EMF under the shaft, for The back EMF under the shaft, Indicates time.

[0052] Back EMF under the shaft and Back EMF under the shaft It can be modeled as:

[0053] ;

[0054] in, is the electrical angular velocity of the rotor, is the permanent magnet flux linkage of the permanent magnet synchronous motor, is the rotor position angle.

[0055] S2: Please refer to Figure 3 According to the mathematical dynamics model of the permanent magnet synchronous motor constructed in S1, the embodiment of the present invention introduces a nonlinear correction term on the basis of the traditional observer, improves the super-helical observer, and processes the nonlinear characteristics caused by the system current estimation error through the nonlinear term. The linear term in the super-helical observer represents the motor stator resistance. The voltage drop caused by the linear correction term and the nonlinear correction term can work together to improve the estimation accuracy and convergence speed of the super spiral observer for the back electromotive force. Specifically, the improved super spiral observer is:

[0056] ;

[0057] in, for Estimated stator current under the shaft, for Estimated stator current under the shaft, for The difference between the estimated stator current under the shaft and the stator current, for The difference between the estimated stator current under the shaft and the stator current, and are gain parameters, , , and All of them are nonlinear function operations. and is the linear correction term, , , and is the nonlinear correction term.

[0058] The difference and use Represented as: The nonlinear function in the superhelical observer can be constructed as:

[0059] ;

[0060] in, It is an operation rule, and sign represents the symbol function.

[0061] Furthermore, the super-helical observer can be used to reconstruct the back electromotive force of the permanent magnet synchronous motor as:

[0062] ;

[0063] in, and They are and The estimated value of is the reconstructed back EMF.

[0064] S3: Please refer to Figure 4 , the back EMF reconstructed in S2 and Amplitude normalization is performed to eliminate the change in the back EMF amplitude at different speeds, so that the amplitude of the back EMF remains consistent under different operating conditions. The formula for normalizing the amplitude of the back EMF to a standard level is:

[0065] ;

[0066] in, and After standardization and .

[0067] In order to improve the position estimation accuracy of the permanent magnet synchronous motor rotor, for the standardized back electromotive force, the embodiment of the present invention designs an integral compensation phase-locked loop with an integral compensation link based on the traditional phase-locked loop. The integral compensation phase-locked loop accurately estimates the position and speed information of the motor rotor from the standardized back electromotive force to reduce the rotor position estimation error during acceleration and deceleration.

[0068] For a traditional phase-locked loop, when the position error is small enough, there is a rotor position estimation error for:

[0069] ;

[0070] in, is the estimated rotor position obtained by a conventional phase-locked loop, is the rotor position, the actual position angle of the rotor.

[0071] From the above formula, the estimated rotor position obtained by the phase-locked loop can be further It is expressed as:

[0072] ;

[0073] in, is the proportional gain, is the integral gain.

[0074] Based on the traditional phase-locked loop, an integral compensation link is designed. Accordingly, the rotor position estimation error based on the integral compensation phase-locked loop It can be expressed as:

[0075] ;

[0076] in, Estimated rotor position for the integral-compensated phase-locked loop.

[0077] Furthermore, the estimated rotor position obtained by the integral compensation phase-locked loop It can be expressed as:

[0078] ;

[0079] in, is the integral compensation term, is the gain of the integral compensation phase-locked loop, S is the complex frequency of the Laplace transform.

[0080] The embodiment of the present invention compensates for the accumulated position error by adding an integral compensation term, and can adjust the position estimation more quickly when facing dynamic changes of the system (such as acceleration and deceleration), reduce the estimation error of the rotor position, and improve the position estimation accuracy.

[0081] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the protection scope of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included in the protection scope of this specification.

[0082] The systems, devices, modules or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0083] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0084] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0085] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor, characterized in that: include: S1: Establish the mathematical dynamics model of permanent magnet synchronous motor. In the stationary coordinate system, the mathematical dynamics model of the permanent magnet synchronous motor is: ； in, for Stator voltage under the shaft, for Stator voltage under the shaft, for The stator current under the shaft, for The stator current under the shaft, is the stator inductance, is the stator resistance, for The back EMF under the shaft, for The back EMF under the shaft, Indicates time; S2: Design a supercoil observer including linear and nonlinear correction terms according to the mathematical dynamics model, wherein the supercoil observer is: ； in, for Estimated stator current under the shaft, for Estimated stator current under the shaft, for The difference between the estimated stator current under the shaft and the stator current, for The difference between the estimated stator current under the shaft and the stator current, and are gain parameters, , , and All of them are nonlinear function operations. and is the linear correction term, , , and is a nonlinear correction term; the nonlinear function operation is: ； in, That is or , , sign represents the sign function; The back electromotive force of the permanent magnet synchronous motor is reconstructed by the super-helical observer, and the reconstructed back electromotive force is: ； in, and They are and The estimated value of , i.e., the reconstructed back EMF; S3: The reconstructed back electromotive force is normalized in amplitude, and the rotor position of the permanent magnet synchronous motor is estimated from the back electromotive force through an integral compensation phase-locked loop.

2. The method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor according to claim 1, characterized in that: The formula for normalizing the amplitude of the reconstructed back electromotive force is: ； in, and After standardization and .

3. The method for reconstructing back electromotive force and extracting position and speed of a permanent magnet synchronous motor as described in claim 1 or 2, wherein the integral compensation phase-locked loop is: adding an integral compensation link in the phase-locked loop.

4. The method for reconstructing the back electromotive force and extracting the position and speed of a permanent magnet synchronous motor according to claim 3, wherein the rotor position estimation error of the integral compensation phase-locked loop is compensated. for: ； in, is the estimated rotor position of the integral compensation phase locked loop, is the rotor position; the estimated rotor position obtained by the integral compensation phase-locked loop for: ； in, is the estimated rotor position obtained by the phase-locked loop, is the integral compensation term, is the gain of the integral compensation phase-locked loop, S is the complex frequency of the Laplace transform.

5. The method for reconstructing the back electromotive force and extracting the position and speed of a permanent magnet synchronous motor as claimed in claim 4, wherein the estimated rotor position is obtained by a phase-locked loop. for: ； in, is the proportional gain, is the integral gain, is the rotor position estimation error of the phase-locked loop.

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