Alternating current motor sensorless control method and system

Abstract

The invention relates to the technical field of AC motor control, and discloses an AC motor sensorless control method and system. The method comprises the following steps: acquiring output current, output voltage and high-frequency injection switching value information of an alternating current motor; establishing a position estimation model suitable for the full-speed range of the motor according to the active flux linkage model of the AC motor, and estimating the effective voltage vector according to the output current, the output voltage and the high-frequency injection switching value information of the AC motor; extracting an electrical angle estimation error of the motor rotor according to the estimation value of the effective voltage vector; estimating a motor electric angle and an electric angle speed according to the motor rotor electric angle estimation error; and controlling the motor according to the estimated values of the electric angle and the electric angular speed of the motor. According to the method, the position and the speed of the motor in the full-speed range are estimated by utilizing a position estimation model, the calculation amount is small, adjustable parameters are few, and independent NS magnetic pole identification is not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of AC motor control, and in particular to a position sensorless control method and system for an AC motor. Background Art

[0002] The problem of position sensorless control of AC motors has always been a research hotspot in industry and academia. Currently, the commonly used AC motor position sensorless control methods can be mainly divided into two categories: baseband model method and high-frequency model method. Since the back-EMF voltage amplitude of the AC motor is small under zero-speed conditions, it is limited by the problem of too low signal-to-noise ratio. At this time, it is impossible to effectively estimate the back-EMF voltage or flux of the motor, that is, the baseband model method will fail under zero-speed conditions, and it is only applicable to medium and high-speed conditions. In order to estimate the motor position and speed under zero-speed conditions, it is necessary to use a high-frequency model method, which injects high-frequency signals to demodulate the high-frequency response signal using a high-frequency model to achieve real-time observation of the motor position and speed. Therefore, the commonly used methods recently also include a hybrid model method that combines the baseband model method and the high-frequency model method. Usually, the hybrid model method includes two models, the baseband model method and the high-frequency model method, as well as a switching method between the two models. In addition, when the initial position of the motor is unknown, a separate NS magnetic pole identification stage is required to solve the problem of multiple convergence points of the high-frequency model method. This means that the hybrid model method will be more complicated, occupy more system resources, and be more cumbersome to debug, which reduces the practicality and reliability of the motor control system. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a position sensorless control method and system for an AC motor.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] In a first aspect, the present invention provides a position sensorless control method for an AC motor, comprising the following steps:

[0006] Obtain the output current, output voltage and high-frequency injection switch quantity information of the AC motor;

[0007] A position estimation model applicable to the full speed range of the motor is established based on the active flux model of the AC motor, and the effective voltage vector is estimated based on the output current, output voltage and high-frequency injected switching information of the AC motor.

[0008] Extracting the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector;

[0009] The electrical angle and electrical angular velocity of the motor are estimated according to the electrical angle estimation error of the motor rotor;

[0010] The motor is controlled based on the estimated values ​​of the motor electrical angle and electrical angular velocity.

[0011] Preferably, the active flux model of the AC motor is specifically:

[0012]

[0013] ψ a =2(L d -L q )i d

[0014] Among them, ψ α AF is the α-axis active flux component of the active flux vector, ψ β AF is the β-axis active flux component of the active flux vector, L d is the stator direct axis inductance, L d is the stator quadrature-axis inductance, i d is the direct axis current, ψ a is the stator excitation component of the active flux vector amplitude, ψ f is the rotor excitation component of the active flux vector amplitude, θ E It is the rotor electrical angle information.

[0015] Preferably, the position estimation model applicable to the full speed range of the motor is specifically:

[0016]

[0017]

[0018] in, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate, u α is the α-axis stator voltage component, u β is the β-axis stator voltage component, R s is the stator resistance value, i α is the α-axis stator current component, i β is the β-axis stator current component, L q is the stator quadrature-axis inductance, d is the differential operator, t is the time, S HFI Inject switch information into high frequency. is the α-axis effective voltage component of the fundamental frequency effective voltage vector estimate, is the β-axis effective voltage component of the fundamental frequency effective voltage vector estimate, ψ a is the stator excitation component, ψ f is the rotor excitation component, θ Eeis the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, k is the current control cycle, ω1 is the lower limit of the electrical angular velocity, and ω2 is the upper limit of the electrical angular velocity.

[0019] Preferably, extracting the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector comprises:

[0020] Projecting the estimated value of the effective voltage vector onto the estimated coordinate system to obtain the estimated value of the effective voltage vector in the estimated coordinate system;

[0021] The motor rotor electrical angle estimation error is extracted based on the effective voltage vector estimation value in the estimated coordinate system and the high-frequency injected switching quantity information.

[0022] Preferably, the estimated value of the effective voltage vector in the estimation coordinate system is specifically:

[0023]

[0024] in, is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimated value in the estimated coordinate system, θ Ee is the estimated value of the rotor electrical angle, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate.

[0025] Preferably, the motor rotor electrical angle estimation error is extracted according to the effective voltage vector estimation value in the estimation coordinate system and the high-frequency injected switch quantity information as follows:

[0026]

[0027] Where Δθ is the motor rotor electrical angle estimation error, S HFI Inject switch information into high frequency. is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimate in the estimated coordinate system.

[0028] Preferably, estimating the motor electrical angle and electrical angular velocity according to the motor rotor electrical angle estimation error is specifically as follows:

[0029]

[0030] Among them, θ Ee is the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, TLe is the estimated value of the equivalent load torque, b1, b2, b3 are the gain coefficients of the observer, Δθ is the estimated error of the motor rotor electrical angle, P is the number of motor pole pairs, J is the system inertia, T Elec is the electromagnetic torque, and t is the time.

[0031] In a second aspect, the present invention provides an AC motor position sensorless control system, comprising:

[0032] The position estimation module is used to obtain the output current, output voltage and high-frequency injection switch quantity information of the AC motor; establish a position estimation model suitable for the full speed range of the motor based on the active flux model of the AC motor, and estimate the effective voltage vector based on the output current, output voltage and high-frequency injection switch quantity information of the AC motor;

[0033] A motor rotor electrical angle estimation error extraction module, used to extract the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector;

[0034] A motor electrical angle and electrical angular velocity estimation module, used to estimate the motor electrical angle and electrical angular velocity according to the motor rotor electrical angle estimation error;

[0035] The motor control module is used to control the motor according to the estimated values ​​of the motor electrical angle and electrical angular velocity.

[0036] The present invention has the following beneficial effects:

[0037] The present invention uses the active flux model of the AC motor to construct a position estimation model suitable for the full speed range. The position estimation model contains both the fundamental frequency response information and the high-frequency response information of the motor. It only needs to perform seamless switching of the two types of response information according to the switch information of whether or not a high-frequency signal is injected. The method uses a position estimation model to estimate the position and speed of the motor in the full speed range. It has a small amount of calculation, fewer adjustable parameters, and does not require separate NS magnetic pole identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a method for controlling an AC motor without a position sensor;

[0039] Figure 2 The figure is a schematic diagram of the structure of an AC motor position sensorless control system. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0041] like Figure 1 As shown, an AC motor position sensorless control method provided by an embodiment of the present invention includes the following steps S1 to S5:

[0042] S1, obtaining the output current, output voltage and high-frequency injection switch quantity information of the AC motor;

[0043] S2. Establish a position estimation model applicable to the full speed range of the motor according to the active flux model of the AC motor, and estimate the effective voltage vector according to the output current, output voltage and high-frequency injected switching quantity information of the AC motor;

[0044] In an optional embodiment of the present invention, step S2 constructs the active flux model of the AC motor as follows:

[0045]

[0046] ψ a =2(L d -L q )i d

[0047] Among them, ψ α AF is the α-axis active flux component of the active flux vector, ψ β AF is the β-axis active flux component of the active flux vector, L d is the stator direct axis inductance, L d is the stator quadrature-axis inductance, i d is the direct axis current, ψ a is the stator excitation component of the active flux vector amplitude, ψ f is the rotor excitation component of the active flux vector amplitude, θ E It is the rotor electrical angle information.

[0048] According to the active flux model of the AC motor and the stator voltage equation of the AC motor, the stator voltage equation of the AC motor can be written as follows:

[0049]

[0050] From the above formula, we can see that the two components of the stator voltage vector are the α-axis stator voltage uα and β-axis stator voltage u β The two components of the stator current vector are the α-axis stator current i α and the β-axis stator current i β . R s is the stator resistance value, and d represents the differential operator.

[0051] The differential of the active flux vector is defined as the effective voltage vector. The two components of the effective voltage vector are the α-axis effective voltage V α ae and β-axis effective voltage V β ae , expressed as:

[0052]

[0053] According to the above formula combined with the stator voltage equation of the AC motor, we can get:

[0054]

[0055] It can be seen from the above formula that the effective voltage vector is composed of two parts, namely the high-frequency effective voltage vector and the base-frequency effective voltage vector, which are expressed as:

[0056]

[0057] From the above formula, we can know that the two components of the high-frequency effective voltage vector are the α-axis effective voltage V αH ae and β-axis effective voltage V βH ae The two components of the fundamental frequency effective voltage vector are the α-axis effective voltage V αB ae and β-axis effective voltage V βB ae ω E is the motor electrical angular velocity.

[0058] It can be seen from the above formula that under zero low speed conditions, the base frequency effective voltage vector amplitude is proportional to the motor electrical angular velocity. Taking the motor electrical angular velocity as zero as an example, the base frequency effective voltage vector amplitude is also zero. The high frequency effective voltage vector amplitude has nothing to do with the motor electrical angular velocity. Taking high frequency square wave voltage injection as an example, when a high frequency voltage signal is injected into the direct axis voltage of the motor, due to the existence of the direct axis current differential term, the high frequency effective voltage vector amplitude can still maintain a certain amplitude when the motor electrical angular velocity is zero, so that the system can still achieve effective estimation of the motor position.

[0059] At the same time, in order to avoid the high-frequency effective voltage vector and the base-frequency effective voltage vector being correctly distinguished under low-speed working conditions, the base-frequency effective voltage vector can be estimated online based on the estimated value of the motor electrical angle and the estimated value of the electrical angular velocity.

[0060] Therefore, a position estimation model suitable for the full speed range of the motor can be constructed as follows:

[0061]

[0062] in, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate, u α is the α-axis stator voltage component, u β is the β-axis stator voltage component, R s is the stator resistance value, i α is the α-axis stator current component, i β is the β-axis stator current component, L q is the stator quadrature-axis inductance, d is the differential operator, t is the time, S HFI Inject switch information into high frequency. is the α-axis effective voltage component of the fundamental frequency effective voltage vector estimate, is the β-axis effective voltage component of the fundamental frequency effective voltage vector estimate, ψ a is the stator excitation component, ψ f is the rotor excitation component, θ Ee is the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, k is the current control cycle, ω1 is the lower limit of the electrical angular velocity, ω2 is the upper limit of the electrical angular velocity, that is, when the estimated rotor electrical angular velocity is greater than ω2, high-frequency injection is stopped, and when the estimated rotor electrical angular velocity is less than ω1, high-frequency injection is started. When the estimated rotor electrical angular velocity is between the upper and lower limits of the electrical angular velocity, the switch quantity information S HFI The value of the previous beat is maintained. HFI (k) is the high-frequency injection switch information S of the current control cycle HFI The value of S HFI (k-1) is the high-frequency injection switch information S of the previous control cycle HFI The numerical value of .

[0063] According to the constructed position estimation model applicable to the full speed range of the motor, we choose to directly calculate the effective voltage vector to obtain the α-axis effective voltage and β-axis effective voltage You can also choose to construct a disturbance observer to realize the effective voltage of the α axis and β-axis effective voltage Estimates.

[0064] S3, extracting the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector;

[0065] In an optional embodiment of the present invention, step S3 of extracting the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector comprises:

[0066] Projecting the estimated value of the effective voltage vector onto the estimated coordinate system to obtain the estimated value of the effective voltage vector in the estimated coordinate system;

[0067] The motor rotor electrical angle estimation error is extracted based on the effective voltage vector estimation value in the estimated coordinate system and the high-frequency injected switching quantity information.

[0068] In order to extract the electrical angle information of the motor rotor, this embodiment projects the estimated effective voltage vector to the estimated coordinate system, and the estimated effective voltage vector can be expressed as:

[0069]

[0070] in, is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimated value in the estimated coordinate system, θ Ee is the estimated value of the rotor electrical angle, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate.

[0071] The rotor electrical angle estimation error Δθ is defined as:

[0072] Δθ=θ E -θ Ee

[0073] According to the high-frequency effective voltage vector and the base-frequency effective voltage vector in the estimated coordinate system, as well as the estimated value of the effective voltage vector and the rotor electrical angle estimation error in the estimated coordinate system, when the rotor electrical angle estimation error Δθ is small, Δθ is approximately equal to its corresponding sinusoidal component sin(Δθ), so the q-axis effective voltage d-axis effective voltage And combined with high frequency injection switch information S HFI To extract the rotor electrical angle estimation error information. Therefore, the rotor electrical angle estimation error information can be expressed as:

[0074]

[0075] Where Δθ is the motor rotor electrical angle estimation error, S HFIInject switch information into high frequency. is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimate in the estimated coordinate system.

[0076] S4, estimating the electrical angle and electrical angular velocity of the motor according to the motor rotor electrical angle estimation error;

[0077] In an optional embodiment of the present invention, this embodiment can optionally directly calculate the electrical angular velocity of the motor based on the rotor electrical angle estimation error Δθ, or use the position error Δθ as the input of a phase-locked loop to estimate the electrical angle and electrical angular velocity of the motor, or use an observer to observe the electrical angle and electrical angular velocity of the motor, etc.

[0078] In this embodiment, the position error Δθ is used as the input of the Romberg observer, and the Romberg observer is then used to observe the motor electrical angle, electrical angular velocity and equivalent load torque.

[0079] The motor electrical angle and electrical angular velocity are estimated based on the motor rotor electrical angle estimation error as follows:

[0080]

[0081] Among them, θ Ee is the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, T Le is the estimated value of the equivalent load torque, b1, b2, b3 are the gain coefficients of the observer, Δθ is the estimated error of the motor rotor electrical angle, P is the number of motor pole pairs, J is the system inertia, T Elec is the electromagnetic torque, and t is the time.

[0082] S5. Control the motor according to the estimated values ​​of the motor electrical angle and electrical angular velocity.

[0083] like Figure 2 As shown, an embodiment of the present invention further provides an AC motor position sensorless control system, comprising:

[0084] The position estimation module is used to obtain the output current, output voltage and high-frequency injection switch quantity information of the AC motor; establish a position estimation model suitable for the full speed range of the motor based on the active flux model of the AC motor, and estimate the effective voltage vector based on the output current, output voltage and high-frequency injection switch quantity information of the AC motor;

[0085] A motor rotor electrical angle estimation error extraction module, used to extract the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector;

[0086] A motor electrical angle and electrical angular velocity estimation module, used to estimate the motor electrical angle and electrical angular velocity according to the motor rotor electrical angle estimation error;

[0087] The motor control module is used to control the motor according to the estimated values ​​of the motor electrical angle and electrical angular velocity.

[0088] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0089] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0090] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0091] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0092] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A position sensorless control method for an AC motor, characterized in that: The following steps are involved: Obtain the output current, output voltage and high-frequency injection switch quantity information of the AC motor; A position estimation model applicable to the full speed range of the motor is established based on the active flux model of the AC motor, and the effective voltage vector is estimated based on the output current, output voltage and high-frequency injected switching information of the AC motor. Extracting the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector; The electrical angle and electrical angular velocity of the motor are estimated according to the electrical angle estimation error of the motor rotor; The motor is controlled based on the estimated values ​​of the motor electrical angle and electrical angular velocity.

2. The method for controlling an AC motor without a position sensor according to claim 1, characterized in that: The active flux model of the AC motor is specifically: ψ a =2(L d -L q )i d Among them, ψ α AF is the α-axis active flux component of the active flux vector, ψ β AF is the β-axis active flux component of the active flux vector, L d is the stator direct axis inductance, L d is the stator quadrature-axis inductance, i d is the direct axis current, ψ a is the stator excitation component of the active flux vector amplitude, ψ f is the rotor excitation component of the active flux vector amplitude, θ E It is the rotor electrical angle information.

3. The method for controlling an AC motor without a position sensor according to claim 1, characterized in that: The position estimation model applicable to the full speed range of the motor is as follows: in, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate, u α is the α-axis stator voltage component, u β is the β-axis stator voltage component, R s is the stator resistance value, i α is the α-axis stator current component, i β is the β-axis stator current component, L q is the stator quadrature-axis inductance, d is the differential operator, t is the time, S HFI Inject switch information into high frequency. is the α-axis effective voltage component of the fundamental frequency effective voltage vector estimate, is the β-axis effective voltage component of the fundamental frequency effective voltage vector estimate, ψ a is the stator excitation component, ψ f is the rotor excitation component, θ Ee is the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, k is the current control cycle, ω1 is the lower limit of the electrical angular velocity, and ω2 is the upper limit of the electrical angular velocity.

4. The method for controlling an AC motor without a position sensor according to claim 1, characterized in that: Extracting the motor rotor electrical angle estimation error based on the estimated value of the effective voltage vector includes: Projecting the estimated value of the effective voltage vector onto the estimated coordinate system to obtain the estimated value of the effective voltage vector in the estimated coordinate system; The motor rotor electrical angle estimation error is extracted based on the effective voltage vector estimation value in the estimated coordinate system and the high-frequency injected switching quantity information.

5. The method for controlling an AC motor without a position sensor according to claim 4, characterized in that: The estimated value of the effective voltage vector in the estimated coordinate system is: in, is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimated value in the estimated coordinate system, θ Ee is the estimated value of the rotor electrical angle, is the α-axis effective voltage component of the effective voltage vector estimate, is the β-axis effective voltage component of the effective voltage vector estimate.

6. The method for controlling an AC motor without a position sensor according to claim 4, characterized in that: The motor rotor electrical angle estimation error is extracted based on the effective voltage vector estimation value in the estimation coordinate system and the high-frequency injected switch quantity information: Where Δθ is the motor rotor electrical angle estimation error, S HFI Inject switch information into high frequency. is the d-axis effective voltage component of the estimated value of the effective voltage vector in the estimated coordinate system, is the q-axis effective voltage component of the effective voltage vector estimate in the estimated coordinate system.

7. The method for controlling an AC motor without a position sensor according to claim 1, characterized in that: The motor electrical angle and electrical angular velocity are estimated based on the motor rotor electrical angle estimation error as follows: Among them, θ Ee is the estimated value of the rotor electrical angle, ω Ee is the estimated value of the rotor electrical angular velocity, T Le is the estimated value of the equivalent load torque, b1, b2, b3 are the gain coefficients of the observer, Δθ is the estimated error of the motor rotor electrical angle, P is the number of motor pole pairs, J is the system inertia, T Elec is the electromagnetic torque, and t is the time.

8. An AC motor position sensorless control system, characterized in that: include: Position estimation module, used to obtain the output current, output voltage and high-frequency injection switch quantity information of the AC motor; A position estimation model applicable to the full speed range of the motor is established based on the active flux model of the AC motor, and the effective voltage vector is estimated based on the output current, output voltage and high-frequency injected switching information of the AC motor. A motor rotor electrical angle estimation error extraction module, used to extract the motor rotor electrical angle estimation error according to the estimated value of the effective voltage vector; A motor electrical angle and electrical angular velocity estimation module, used to estimate the motor electrical angle and electrical angular velocity according to the motor rotor electrical angle estimation error; The motor control module is used to control the motor according to the estimated values ​​of the motor electrical angle and electrical angular velocity.

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