阅读说明：本技术 一种基于非奇异快速终端滑模观测器的spmsm无传感器矢量控制方法 (SPMSM sensorless vector control method based on nonsingular rapid terminal sliding-mode observer ) 是由 郑诗程 刘志鹏 赵卫 郎佳红 方四安 徐磊 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种基于非奇异快速终端滑模观测器的SPMSM无传感器矢量控制方法,属于电机控制技术领域。本发明的方法先建立永磁同步电机基于两相静止坐标系下的电压数学模型,并重构为定子电流状态方程；其次,以电流观测误差为状态变量设计积分型非奇异滑模面,推导出复合控制律获取扩展反电动势；最后,对反电动势进行重构,实现高频滤波,基于软件锁相环原理提取出电机转子位置和速度实现电机的无传感器控制。与传统滑模观测器相比,本发明在零低速和中高速阶段都能精确地估算电机转子位置和速度信息,具较强的鲁棒性,能够有效抑制控制系统中的抖振,解决了相位滞后问题,系统的稳态精度和动态性能较好。(The invention discloses SPMSM sensorless vector control based on a nonsingular rapid terminal sliding-mode observerThe method belongs to the technical field of motor control. Firstly, establishing a voltage mathematical model of the permanent magnet synchronous motor based on a two-phase static coordinate system, and reconstructing the voltage mathematical model into a stator current state equation; secondly, designing an integral nonsingular sliding mode surface by taking the current observation error as a state variable, and deducing a composite control law to obtain an extended back electromotive force; and finally, reconstructing the counter electromotive force to realize high-frequency filtering, and extracting the position of the motor rotor based on the software phase-locked loop principle And velocity The sensorless control of the motor is realized. Compared with the traditional sliding-mode observer, the method can accurately estimate the position and the speed information of the motor rotor at the zero low-speed stage and the medium-high speed stage, has stronger robustness, can effectively inhibit buffeting in a control system, solves the problem of phase lag, and has better steady-state precision and dynamic performance.)

1. A SPMSM sensorless vector control method based on a nonsingular fast terminal sliding-mode observer is characterized by comprising the following steps:

establishing a voltage state equation of the permanent magnet synchronous motor based on a two-phase static coordinate system alpha beta, reconstructing the voltage state equation into a stator current state equation, and constructing a current state observation equation;

step two, sampling three-phase current i_abcAnd three phase voltage u_abcAnd calculating a current error state equation;

step three, designing a sliding mode surface function S of the novel nonsingular rapid terminal sliding mode observer by taking the current observation error as a state variable_(t)And designing a sliding mode surface equivalent control function V based on a current error state equation and a sliding mode surface function_eqAnd a switching control function V_swThe stability of the Lyapunov function is proved by using a Lyapunov function stability criterion;

fourthly, reconstructing the extended back electromotive force by utilizing an extended Kalman filter, and extracting the estimated value of the back electromotive forceFinally, estimating the position of the motor rotor based on the phase-locked loop principleAnd velocity

2. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 1, which is characterized in that: in the first step, the voltage state equation of the three-phase permanent magnet synchronous motor under the two-phase static coordinate system is obtained through Clark coordinate transformation as shown in the formula (1),

wherein L is_d、L_qComponent of stator inductance in dq axis, R_sIs stator resistance, ω_eIn order to be the electrical angular velocity,is a differential operator, [ u ]_α u_β]^TFor stator voltage components in the α β axis, [ i ]_α i_β]^TFor stator current in the α β axis component, [ E ]_α E_β]^TTo spread the back electromotive force (EMF) in the α β axis component and satisfy:

in the formula, theta_eIs the electrical angle of the rotor position,for rotor flux linkage, [ i ]_d i_q]^TIs the stator current in the dq axis component;

and (3) transforming the equation (1) to reconstruct a stator current state equation:

in a surface-mounted three-phase permanent magnet synchronous motor, L_d＝L_q＝L_sIs a stator inductance;

to obtain an estimate of the extended back emf, a current state observer equation is constructed as:

in the formula (I), the compound is shown in the specification,is a current state observed value, [ u ]_α u_β]^TIs the control input of the observer, [ V ]_α V_β]^TThe control law function is a component of the sliding mode surface on an alpha and beta axis.

3. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 2, characterized in that: in the second step, three-phase current i output by the three-phase permanent magnet synchronous motor is collected_abcAnd three phase voltage u_abcObtaining the current i under a two-phase static coordinate system through Clark coordinate transformation_αβAnd voltage u_αβ(ii) a Will u_αβComparing the current state observations as input to a current state observerAnd current i_αβDefined as the current observation error, the stator current error state equation is derived from equations (3) and (4) as:

in the formula (I), the compound is shown in the specification,for current observation error, [ V ]_α V_β]^TThe control law function is a component of the sliding mode surface on an alpha and beta axis.

4. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 3, characterized in that: in the third step, the current observation error is taken as a state variable for designing a novel nonsingular rapid terminal sliding mode surface, a terminal attractor concept is introduced at the same time, and a novel nonsingular rapid terminal sliding mode surface function is designed by combining a terminal attractor function;

terminal attractor function ofAfter the function is deformed, the integral solution is carried out on two sides of the function to obtain:

in the formula: p is a radical of>q is a positive odd number, x₍₀₎Is the initial state of the system state variable x, t_(r)The time required for the state variable x in the terminal attractor to reach a balance point x from the initial state to be 0 is obtained;

designing a novel nonsingular rapid terminal sliding mode surface function as follows:

wherein the content of the first and second substances,is a function of the saturation of the light, is a hyperbolic tangent function, delta, gamma>0，And p is>q is positive odd number, and Delta is boundary layer thickness and is defined as

5. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 4, characterized in that: in the third step, when the system state enters the sliding mode, there are

The formula (8) is modified as follows:

from equation (9), when the error state is farther from the equilibrium point, the state convergence rate is represented by a linear termThe method has the main effects that a saturation function is added, so that the current error has a saturation characteristic, and a system can be quickly converged on a sliding mode surface in a preset control track; the rate of state convergence is governed by a non-linear term as the error state is closer to the equilibrium pointPlays a major role.

6. The nonsingular-based fast termination of claim 5The SPMSM sensorless vector control method of the end sliding mode observer is characterized by comprising the following steps: in the third step, the sliding mode control law V is an equivalent control function V_eqAnd a switching control function V_swThe equivalent control function is shown in formula (5) and formula (7):

wherein a, b ∈ R⁺；

Switching control function V_swThe method is compounded by a rapid power approach law and a terminal attractor function, namely:

V_sw＝-k|S|^μh(S)-ε|S|^υ (11)

in the formula, k>0，0<μ<1，0<ε<1；

The sliding mode control law function obtained from the equations (10) and (11) is:

7. the SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 6, which is characterized in that: in the third step, a Lyapunov function is selected to perform stability judgment on the system:

with V_αFor example, for V_αThe derivation is as follows:

in { | S_α|≤(min(|E_α|/k)^1/μ (|E_α|/ε)^1/υWithin the air flow channel of the air conditioner is arranged,is negative and can prove with the same principleAnd negative, i.e. the system is proved to be stable.

8. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 7, characterized in that: in the fourth step, the derivation is carried out on the formula (2):

in the formula, [ V ]_α V_β]^TFor the sliding mode surface control law function in the alpha beta axis component, omega_eIs the electrical angular velocity, theta_eIs the electrical angle of the rotor position,in order to provide a magnetic linkage of the rotor,is the rate of change of the motor speed;

equation (15) is simplified to:

from equations (15) and (16), the mathematical expression for the kalman filter can be derived as:

in the formula (I), the compound is shown in the specification,is the back electromotive force filtered by the Kalman filter in the alpha beta axis component, k_kIs the filter coefficient of the Kalman filter;

the reconstructed novel sliding-mode observer equation is as follows:

wherein m is a real number.

9. The SPMSM sensorless vector control method based on the nonsingular fast terminal sliding-mode observer according to claim 8, characterized in that: in the fourth step, the counter electromotive force after double filtering is used as the input of the phase-locked loop, and the motor counter electromotive force difference equation output by the phase-locked loop is as follows:

when estimating the rotor positionWith measured rotor position theta_eThe difference being small, i.e.At this time, it can be considered that

Simplified formula (19) to

The electrical angle and the electrical angular velocity of the rotor position can be accurately estimated by adjusting the parameters of the PI regulator based on the phase-locked loop principle.

Technical Field

The invention relates to the technical field of motor control, in particular to an SPMSM sensorless vector control method based on a nonsingular rapid terminal sliding-mode observer.

Background

The permanent magnet synchronous motor has high energy density, low noise during operation, lower torque fluctuation than other motors and easy maintenance, so the permanent magnet synchronous motor is widely applied to military and commercial unmanned aerial vehicles, electric automobiles with very hot fire at present and national defense military, and the permanent magnet synchronous motor control speed regulation system becomes a hot point of domestic and foreign research. In practical application of the system, a sensor is generally adopted to directly acquire the position and rotation speed information of the rotor. However, the installation of such mechanical sensors increases the cost of the whole system, and has certain requirements on the surrounding working environment, so that the application range of the system is limited, and meanwhile, the system has some problems which are difficult to overcome. Scholars at home and abroad have conducted a great deal of research on the position and the rotating speed of a motor rotor obtained by replacing a traditional mechanical sensor with a sensorless control algorithm.

The sensor-less technology of the permanent magnet synchronous motor is mainly divided into two categories, namely a model observer method for medium and high speed and a salient pole tracking method for zero and low speed. The sensorless control method suitable for medium and high speed is to extract position and speed information by using the back electromotive force of the motor, and the main methods include a sliding mode observer method, a model self-adaption method, a disturbance observer method and the like. The sliding mode observer is designed based on the deviation between the actual value of the stator current and the observed value obtained by the motor mathematical model and combined with the sliding mode variable structure theory. But due to the specific discontinuity of the sliding mode control, the buffeting cannot be completely eliminated, and only a new method for restraining can be found. The traditional sliding mode observer also has phase lag, generates high-frequency signals and noise, and can further amplify errors when estimating the position of the rotor based on a positive and negative tangent function. Many scholars have made intensive studies on the buffeting problem, the phase delay, the rotor position estimation and other problems of the sliding mode algorithm.

Journal "Motor and control applications journal" 03 in 2020, pages 28-33, a new sliding mode observer design for sensorless permanent magnet synchronous motors based on an improved filter is proposed, an S-shaped function is used as a switching function to reduce buffeting, and a cascade filter formed by combining a low-pass filter and a complex filter is used for high-frequency filtering of back electromotive force, so that measurement noise and measurement errors are reduced. However, in this system, a low-pass filter is used to filter high-frequency chattering and noise in the counter electromotive force, and a certain phase lag is caused, so that a large error is recognized in the initial rotor position at the time of starting the motor. In addition, the overshoot of the system is large, the dynamic response process is poor, and the defects existing in the dynamic response process are not further researched.

Journal "journal of western's university of transportation" Vol.50, No. 01, pp.87-91, 99, propose a novel nonsingular terminal sliding mode observer (NFTSMO) based on tracking differentiator, design a fast terminal sliding mode surface of integral type nonsingular, adopt the tracking differentiator to realize the accurate tracking to the back electromotive force, realize the filtering function at the same time, can track the set value accurately when the motor control system operates in steady state, can estimate the rotor position accurately. But the method has the following disadvantages: when the load torque applied to the motor is stepped, the system cannot well follow the set value, the anti-interference performance is poor, and the estimation error after disturbance is applied is further increased. In addition, when the tracking differentiator is designed, a mathematical model is complex and also contains a sign function, and the performance of the designed sliding mode control algorithm system is poor.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention provides an SPMSM sensorless vector control method based on a nonsingular fast terminal sliding-mode observer, which aims at solving the problems that a sliding-mode observer is used for estimating the position and speed information of a motor rotor in a permanent magnet synchronous motor control speed regulation system, high-frequency buffeting, noise, phase delay and the like can occur, and can realize sensorless vector control of a surface-mounted permanent magnet synchronous motor. In practical application, the position and the speed of the motor rotor are effectively tracked, the running cost of the motor is reduced, and the steady-state precision and the dynamic performance of the system are improved.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention discloses a SPMSM sensorless vector control method based on a nonsingular fast terminal sliding-mode observer, which comprises the following steps:

establishing a voltage state equation of the permanent magnet synchronous motor based on a two-phase static coordinate system alpha beta, reconstructing the voltage state equation into a stator current state equation, and constructing a current state observation equation;

step two, sampling three-phase current i_abcAnd three phase voltage u_abcAnd calculating a current error state equation;

step three, designing a sliding mode surface function S of the novel nonsingular rapid terminal sliding mode observer by taking the current observation error as a state variable_(t)And designing a sliding mode surface equivalent control function V based on a current error state equation and a sliding mode surface function_eqAnd a switching control function V_swThe stability of the Lyapunov function is proved by using a Lyapunov function stability criterion;

step four, utilizing the extended KalmanThe filter reconstructs the expanded back electromotive force and extracts the estimated value of the back electromotive forceFinally, estimating the position of the motor rotor based on the phase-locked loop principleAnd velocity

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

the invention discloses a non-singular rapid terminal sliding-mode observer-based SPMSM sensorless vector control method, which effectively inhibits the problems of high-frequency buffeting, large torque pulsation and the like in the traditional sliding observer, selects an extended Kalman filter to reconstruct back electromotive force, smoothes the waveform of the back electromotive force, realizes high-frequency filtering, and simultaneously solves the problem of phase lag of the traditional observer. The novel sliding mode of the system has small dependence on motor parameters and strong anti-interference capability, and the position and the speed of the motor rotor can be accurately estimated at the zero low-speed stage and the medium-high speed stage. Compared with the traditional singular sliding-mode observer, the singularity problem of the system is solved.

Drawings

FIG. 1 is a diagram of a sensor-less vector control of a surface-mounted permanent magnet synchronous motor (SPMSM) based on NFTSMO according to the present invention;

FIG. 2 is a schematic diagram of a novel Nonsingular Fast Terminal Sliding Mode Observer (NFTSMO) according to the present invention;

FIG. 3 is a schematic diagram of a conventional Sliding Mode Observer (SMO);

FIG. 4 is a block diagram of an Extended Kalman Filter (EKF) architecture;

FIG. 5 is a PLL schematic;

FIG. 6(a) is a comparison waveform of predicted and actual rotational speeds using the control method of the present invention;

FIG. 6(b) is a comparison waveform diagram of the predicted rotation speed and the actual rotation speed of the conventional Sliding Mode Observer (SMO);

FIG. 7(a) is a comparison waveform of the error between the predicted rotational speed and the actual rotational speed using the control method of the present invention;

FIG. 7(b) is a comparison waveform diagram of errors between the predicted rotating speed and the actual rotating speed of the conventional Sliding Mode Observer (SMO);

FIG. 8(a) is a comparison waveform diagram of three-phase current from no load to sudden load change by using the control method of the present invention;

FIG. 8(b) is a comparison waveform diagram of three-phase current when the conventional Sliding Mode Observer (SMO) changes suddenly from no load to load;

FIG. 9(a) is a waveform of alpha-axis back EMF after a single filtering in accordance with the present invention;

FIG. 9(b) is a waveform of the alpha axis back EMF after being filtered by the extended Kalman filter according to the present invention;

FIG. 10(a) is a comparison waveform of predicted rotor position and actual rotor position using the control method of the present invention;

fig. 10(b) is a comparison waveform of the predicted rotor position and the actual rotor position of a conventional Sliding Mode Observer (SMO).

Detailed Description

For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.

Example 1

Fig. 1 is a block diagram of sensorless vector control of a surface-mounted permanent magnet synchronous motor (SPMSM) based on NFTSMO according to this embodiment. As shown in fig. 1, ASR is a speed regulator, ACR is a current regulator, and a PI regulator double closed-loop vector control scheme of a speed outer loop and a current inner loop is adopted. Obtaining alpha and beta axis given voltage u after PI regulation and Park inverse transformation_α，u_βAnd as an input value of voltage space vector modulation SVPWM, controlling the on-off of an inverter thyristor by adjusting the duty ratio of a PWM waveform, thereby realizing the double closed-loop speed regulation of the permanent magnet synchronous motor.

Sampling three-phase current i_abcAnd three phase voltage u_abcSit through ParkAfter the mark transformation, the coordinate value is a two-phase stationary coordinate value i_αβThe deviation after the difference with the stator current observation value is used as a state variable for designing a nonsingular rapid terminal sliding mode surface function, a sliding mode control law is designed by combining a terminal attractor function, secondary filtering is carried out after the extended back electromotive force is reconstructed through an extended Kalman filter, and finally the speed of the motor is predicted through a software phase-locked loop (PLL) principleAnd rotor positionThe method comprises the following specific steps:

step one, establishing a voltage state equation of a Permanent Magnet Synchronous Motor (PMSM) based on a two-phase static coordinate system alpha beta, reconstructing the voltage state equation into a stator current state equation, and constructing a current state observation equation:

in order to simplify the analysis, a three-phase PMSM is assumed to be an ideal motor, a three-phase voltage equation of the three-phase PMSM under a natural coordinate system ABC can be known, and a voltage state equation under a two-phase static coordinate system can be obtained through Clark coordinate transformation:

wherein L is_d、L_qComponent of stator inductance in dq axis, R_sIs stator resistance, ω_eIn order to be the electrical angular velocity,is a differential operator, [ u ]_α u_β]^TFor stator voltage components in the α β axis, [ i ]_α i_β]^TFor stator current in the α β axis component, [ E ]_α E_β]^TTo spread the back electromotive force (EMF) in the α β axis component and satisfy:

in the formula, theta_eIs the electrical angle of the rotor position,in order to provide a magnetic linkage of the rotor,]i_d i_q]^Tis the component of the stator current in the dq axis.

And (3) transforming the equation (1) to reconstruct a stator current state equation:

the embodiment is a study on a surface-mounted three-phase permanent magnet synchronous motor (SPMSM), that is, there are: l is_d＝L_q＝L_s，L_sFor stator inductance, all equations hereinafter are used with L_sAnd (4) showing.

To obtain an estimate of the extended back emf, a current state observer equation is constructed as:

in the formula (I), the compound is shown in the specification,is a current state observed value, [ u ]_α u_β]^TIs the control input of the observer, [ V ]_α V_β]^TThe control law function is a component of the sliding mode surface on an alpha and beta axis.

Step two, sampling three-phase current i_abcAnd three phase voltage u_abcObtaining the current i under a two-phase static coordinate system alpha beta through Clark coordinate transformation_αβAnd voltage u_αβAnd calculating a current error state equation according to the stator current state equation and the current state observation equation:

with reference to fig. 2, it can be known from the design idea of the conventional sliding mode surface that the current error is used as the state variable of the sliding mode surface function, and the novel nonsingular sliding mode surface function is slid on the basis of the conventional sliding mode observerDie face design. The embodiment adopts a given rotating speedThe outer ring of the ring is provided with a plurality of grooves,in the double-closed-loop speed regulating system with double inner loops of current, the deviation of the given current and the feedback current is subjected to PI regulation to obtain direct-axis voltageAnd quadrature axis voltageObtaining a voltage value u under a two-phase static coordinate system through Park inverse transformation_α，u_βThe input voltage is input to a voltage space vector modulation SVPWM, and the on-off of an inverter thyristor is controlled by adjusting the duty ratio of the PWM waveform, so that the double closed-loop speed regulation of the permanent magnet synchronous motor is realized.

Therefore, it is necessary to obtain a current error value by sampling the three-phase current i output from the three-phase permanent magnet synchronous motor_abcAnd three phase voltage u_abcObtaining the current i under a two-phase static coordinate system through Clark coordinate transformation_αβAnd voltage u_αβ，u_αβAs input to a current state observer, a current state observed valueWith a two-phase current i_αβAnd the compared current observation error is used as the input for designing a novel nonsingular rapid terminal sliding mode surface. And (3) obtaining a stator current error state equation after the difference is made between the formula (2) and the formula (3):

in the formula (I), the compound is shown in the specification,for current observation error, [ V ]_α V_β]^TThe control law function is a component of the sliding mode surface on an alpha and beta axis.

Step three, designing a sliding mode surface function S of the novel nonsingular rapid terminal sliding mode observer by taking the current observation error as a state variable_(t)Designing a sliding mode surface equivalent control function V based on a current error state equation and a sliding mode surface function_eqAnd a switching control function V_swAnd the stability of the compound is proved by utilizing a Lyapunov (Lyapunov) stability criterion:

and taking the current observation error as a state variable for designing a novel nonsingular rapid terminal sliding mode surface, introducing a terminal attractor concept, and designing a novel nonsingular rapid terminal sliding mode surface function by combining a terminal attractor function.

Terminal attractor function ofAfter the function is deformed, the integral solution is carried out on two sides of the function to obtain:

in the formula: p is a radical of>q is a positive odd number, x₍₀₎Is the initial state of the system state variable x, t_(r)The time required for the state variable x in the terminal attractor to reach the equilibrium point x from the initial state to 0 is taken. The terminal attractor model indicates that the system state can converge to the equilibrium point within a limited time, and the terminal attractor has the characteristic of accelerating convergence near the equilibrium point. In the embodiment, an integral link is added in the design of a novel sliding mode surface, the torque pulsation can be smoothed, the buffeting effect is weakened, and the second derivative of the state variable can not occur in the design of a sliding mode control law.

Designing a novel nonsingular rapid terminal sliding mode surface function as follows:

wherein the content of the first and second substances,is a function of the saturation of the light,is a hyperbolic tangent function, delta, gamma>0，And p is>q is positive odd number, and Delta is boundary layer thickness and is defined as

When the system state enters the sliding mode, there areNamely:

the formula (8) is modified as follows:

from equation (9), when the error state is farther from the equilibrium point, the state convergence rate is represented by a linear termThe method has the main effects that a saturation function is added, so that the current error has a saturation characteristic, and a system can be quickly converged on a sliding mode surface in a preset control track; the rate of state convergence is governed by a non-linear term as the error state is closer to the equilibrium pointPlays a major role. Therefore, in the sliding stage, the nonsingular fast terminal sliding mode surface (7) can realize global fast convergence, andthe method does not contain a state with negative index, thereby avoiding the singular phenomenon.

The formula (2) shows that the extended back electromotive force is needed to obtain the value of the back electromotive force before extracting the position and speed information of the motor rotor, so that the sliding mode control law V of the novel sliding mode observer needs to be solved. Sliding mode control law is composed of equivalent control function V_eqAnd a switching control function V_swAnd (4) forming. The equivalent control function is that the system is in an ideal sliding modal region on the assumption that the system modeling is accurate without influence of other factors and external disturbanceOn the premise of (1), the obtained average control quantity is solved. From equations (5) and (7), the equivalent control function is:

wherein a, b ∈ R⁺。

Switching control function V_swThe system state is forced to be switched near the sliding mode surface, and the robustness control on uncertainty and disturbance is realized. Switching control function V_swThe method is compounded by a rapid power approach law and a terminal attractor function, namely:

V_sw＝-k|S|^μh(S)-ε|S|^υ (11)

in the formula, k>0，0<μ<1，0<ε<1。

The sliding mode control law function obtained from the equations (10) and (11) is:

in analyzing the sliding mode variable structure control, certain control characteristics need to be satisfied, and in the analysis, it is known that the system state variable can be converged within a certain time. In order to ensure the stability of the system, a Lyapunov (Lyapunov) function is selected to judge the stability of the system:

with V_αFor example, for V_αThe derivation is as follows:

in { | S_α|≤(min(|E_α|/k)^1/μ(|E_α|/ε)^1/υWithin the air flow channel of the air conditioner is arranged,is negative, and the same principle can proveAnd negative, i.e., the system can be proven to be stable.

Fourthly, reconstructing the extended back electromotive force (EMF) by utilizing an Extended Kalman Filter (EKF) to extract the estimated value of the back electromotive forceFinally, the position of the rotor of the motor is estimated based on the phase-locked loop Principle (PLL)And velocity

When a sliding mode control system is designed, a switching control function with low buffeting is used for replacing an absolute value function, but when a sliding mode switching motion is carried out on a sliding mode surface, a plurality of high-frequency signals and higher harmonics can be generated, and ripples in the estimated expanded back electromotive force are larger on the basis. Therefore, an integral link is added to carry out primary filtering on the back electromotive force waveform when the nonsingular sliding mode surface is designed, and a smoother back electromotive force waveform is obtained.

However, in practical applications, a large amount of system noise and measurement noise are often accompanied in a high-frequency signal, a ripple component of a back electromotive force cannot be filtered out by an integration link, and meanwhile, a phase delay is caused by using a low-pass filter in a conventional sliding mode observer. Therefore, in order to suppress the interference of noise and remove the high-frequency ripple component, and simultaneously eliminate the delay phase, the electrical angle identification precision of the rotor position is higher. With reference to fig. 4, a kalman filter is introduced to perform secondary filtering on the back electromotive force obtained after filtering by the integrator, and actually, the kalman filter is equivalent to perform primary reconstruction on the back electromotive force, and the back electromotive force after the double filtering is used as the input of the sliding mode observer, so that the control system can be adaptively adjusted, buffeting can be suppressed to the maximum extent, and estimation errors can be reduced.

The derivation of equation (2) yields:

in the formula, [ V ]_α V_β]^TFor the sliding mode surface control law function in the alpha beta axis component, omega_eIs the electrical angular velocity, theta_eIs the electrical angle of the rotor position,in order to provide a magnetic linkage of the rotor,is the rate of change of the motor speed. The sampling frequency of the system is far greater than the change rate of the rotating speed of the motor, so that the system can be approximately subjected to zero processing.

Equation (15) is simplified to:

from equations (15) and (16), the mathematical expression for the kalman filter can be derived as:

in the formula (I), the compound is shown in the specification,is the back electromotive force filtered by the Kalman filter in the alpha beta axis component, k_kIs the filter coefficient of the Kalman filter.

The reconstructed novel sliding-mode observer equation is as follows:

wherein m is a real number.

The sliding mode control is accompanied with the generation of high-frequency signals under the sliding mode, the back electromotive force obtained in the traditional sliding mode observer has phase delay and high-frequency noise, the rotor position and speed are obtained in the traditional sliding mode observer based on an arctangent function, the high-frequency signals are directly introduced into the back electromotive force, the back electromotive force is divided, and then the arctangent value is obtained to estimate the rotor position, so that the electric angle error is further amplified. To overcome this drawback, rotor position and speed information is modulated from the back emf based on the phase locked loop principle, as shown in fig. 5. The double filtered back emf is used as an input to a phase locked loop,

when estimating the rotor positionWith measured rotor position theta_eThe difference is small, i.e.:at this time, it can be considered thatSimplifying formula (19) to obtain:

the electrical angle and the electrical angular velocity of the rotor position can be accurately estimated by adjusting the parameters of the PI regulator based on the phase-locked loop Principle (PLL).

The design process of the method of the embodiment is subjected to simulation verification through a Matlab/Simulink simulation platform. The SPMSM sensorless vector control system based on the traditional Sliding Mode Observer (SMO) and the novel Nonsingular Fast Terminal Sliding Mode Observer (NFTSMO) is compared through simulation. The parameters of the permanent magnet synchronous motor are as follows: given rotational speedStator resistance R_s0.258 omega, quadrature-direct axis inductance L_d＝L_q0.827mH, rotor flux linkagePole pair number P is 4, damping coefficient B is 0N · m · s, moment of inertia J is 0.0065kg · m². Motor no-load (T)_m0N · m) is started, the system is given a rotational speed ofWhen the motor control system operates at 0.1s, the load torque is suddenly changed from the no-load operation state to T_m10N m, the given rotation speed of the system is still equal toThe time for the simulation run was 0.2 s.

As can be seen from the analysis of FIG. 6, the system is started and operated under the no-load condition at a given rotation speedDuring the process, the two control algorithms can reach a given value quickly, and the overshoot of the novel sliding mode observer control system is about 4.8% less and the overshoot of the traditional observer control system is about 5.6% as can be seen from a local amplification oscillogram at the initial stage when the response process reaches the given value. Applying T to the system at time 0.1s_mThe rotating speed of the motor is basically unchanged when the novel sliding mode observer control system suddenly applies load disturbance, the jumping range of the rotating speed amplitude is +/-3 rad/min and is quickly stabilized near a given value, and the response process is quick; the traditional sliding mode observer control system has large amplitude of step change of the rotating speed of the motor when load disturbance is suddenly applied (+ -30 rad/min), and the rotating speed is reduced after the load disturbance is applied.

Analyzing fig. 7(a), when the motor operates in no-load operation or in steady state operation with load, the rotation speed error of the novel sliding mode control is very small, and when the load disturbance is suddenly applied, the rotation speed error of the motor is almost the same as that of the steady state operation, and it can be seen from fig. 7(b) that the rotation speed error has a large deviation in a zero low speed stage when the motor is started under the traditional sliding mode observer, and the rotation speed error is also very large when the motor operates in steady state. Therefore, the sensorless control system based on the novel nonsingular fast terminal sliding mode observer can effectively restrain buffeting of the sliding mode control system.

As can be seen from fig. 8, under the control of the low buffeting switching function, the three-phase current fluctuation under the novel sliding mode observer is very small, and the three-phase stator current can quickly reach a stable state after the load disturbance is applied for 0.1S; as can be seen from fig. 9, the back electromotive force is subjected to primary filtering by the integral sliding mode observer and high-order filtering after reconstruction of the back electromotive force, so that a smooth back electromotive force estimation value is obtained.

As can be seen from fig. 10, when the rotor position is estimated based on the Nonsingular Fast Terminal Sliding Mode Observer (NFTSMO), the accuracy of identifying the initial rotor position is higher at the zero-low speed stage of the motor start, and the rotor position is accurately tracked at the medium-high speed steady state operation stage, with the tracking accuracy of 0.01052%; the traditional Sliding Mode Observer (SMO) has a large estimation error on the position of a motor rotor in a zero low-speed stage of motor starting, and can generate a phase lag phenomenon, and the tracking precision of the traditional sliding mode observer is 0.02514% in a medium-high speed steady-state operation stage.

The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.