阅读说明：本技术 一种基于改进指数趋近律的永磁同步电机模糊滑模控制方法 (Permanent magnet synchronous motor fuzzy sliding mode control method based on improved index approach law ) 是由 刘宗锋 杨其玺 高歌 谢凤芹 王树凤 姜宁 谢凯洋 韩铖 李俊龙 王宝云 杨凯利 于 2020-12-27 设计创作，主要内容包括：一种基于改进指数趋近律的永磁同步电机模糊滑模控制方法,提出了基于变指数系数趋近律的模糊滑模电机调速控制方法,在滑模控制中常规指数趋近律的基础上引入系统状态范数,使滑动运动阶段运动点趋近滑模面的速率以及滑动模态阶段抖振幅度与系统状态变量相关,使趋近速度与系统状态变化相关联,同时结合模糊控制抑制滑模控制产生的抖振,改进后的控制方法有效地提高了系统的响应速度和精确度,削弱了系统抖振,对不确定扰动具有较强的鲁棒性,大大改善了调速系统的性能,使电机具有更好的动、静态性能。(A permanent magnet synchronous motor fuzzy sliding mode control method based on an improved index approach law provides a fuzzy sliding mode motor speed regulation control method based on a variable index coefficient approach law, a system state norm is introduced on the basis of a conventional index approach law in sliding mode control, the speed of a motion point approaching a sliding mode surface in a sliding motion stage and the buffeting amplitude in a sliding mode stage are related to a system state variable, the approach speed is related to the system state change, meanwhile, the buffeting generated by sliding mode control is restrained by combining with the fuzzy control, the improved control method effectively improves the response speed and the accuracy of a system, weakens the buffeting of the system, has stronger robustness on uncertain disturbance, greatly improves the performance of a speed regulation system, and enables the motor to have better dynamic and static performances.)

1. A permanent magnet synchronous motor fuzzy sliding mode control method based on improved index approach law is characterized in that a permanent magnet synchronous motor control strategy adopts speed and current double closed-loop control, a current loop adopts a PI (proportional integral) controller, a rotating speed loop adopts fuzzy sliding mode control based on improved index approach law, and the method is characterized in that: the improved approximation law is that a state variable of a system is added on the basis of a traditional exponential approximation law, so that the speed of a motion point approaching a sliding mode surface in a sliding motion stage and the buffeting amplitude in a sliding mode stage are related to the state variable of the system; when the track of the system motion point is far away from the sliding mode surface, the norm value of the system state variable is relatively large, and the approaching speed is large, so that the motion point can be ensured to reach the sliding mode surface in the shortest time; when the track of the motion point is close to the sliding mode surface, the constant speed approaching term approaches to zero, the index approaching term plays a main role, then the motion point of the system passes through the two sides of the sliding mode surface back and forth and approaches to the original point, in the process, the value of the system state variable is gradually reduced, the buffeting amplitude of the motion point on the two sides of the sliding mode surface is reduced, and finally the motion point tends to be stable at the original point;

the method comprises the following specific steps:

step 1: the mathematical model of the permanent magnet synchronous motor under the d-q coordinate system is as follows:

in the formula: u. of_d、u_qD-q axis components of the stator voltage, respectively; i.e. i_d、i_qD-q axis components of the stator current, respectively; r_sIs a stator resistor; omega_eIs an electrical angle; l is_d、L_qD-q axis inductance components, respectively; psi_fIs a permanent magnet flux linkage; p is a radical of_nIs the number of pole pairs;

binding i_dThe control method with the value of 0 can be equivalently changed into a motor mathematical model as follows:

in the formula, L_sIs a stator inductance;

step 2: the state variables defining the system are:

in the formula, ω_rIs a rated rotating speed; omega is the actual rotating speed; e is the motor rotation speed error;

the following can be obtained:

and step 3: defining a sliding mode surface function s as:

s＝qx₁+x₂

wherein q is a constant and > 0;

the improved approach law is as follows:

in the formula (I), the compound is shown in the specification,is the system state norm; s is a system sliding mode surface function; epsilon is the approaching speed, k is the approaching coefficient, epsilon, k is more than 0;

and combining a mechanical motion equation and an electromagnetic torque equation of the permanent magnet synchronous motor to obtain a q-axis current reference value as follows:

in the formula, P_nFor the number of pole pairs, psi, of the motor rotor_fIs a permanent magnet flux linkage, and J is the rotational inertia of the motor;

and 4, step 4: in order to meet the requirements of motor parameter change and interference on the motor operation stability, fuzzy control and sliding mode control are combined to stably control signals. Motor speed error e and its rate of changeProportional to the sliding mode surface s, taking s and ds/dt as the input of the fuzzy controller, taking the approach law parameters k and epsilon as the output, setting the values of s, ds/dt and k and epsilon to be quantized to the fuzzy domain interval [ -33 ]]Inner, fuzzy set is { NBAnd NM, NS, ZO, PS, PM and PB, wherein NB is negative and large, NM is negative and medium, NS is negative and small, ZO is zero, PS is positive and small, PM is positive, PB is positive, a membership function is set as a triangular membership function, and finally the motor speed loop fuzzy sliding mode controller is established.

2. The improved exponential approximation law-based fuzzy sliding-mode control method for the permanent magnet synchronous motor according to claim 1, characterized in that: the improvement index approach law is as follows:on the basis of a traditional exponential approximation law, a system state norm | X | is introduced, so that the speed of a motion point in a sliding motion stage approaching a sliding mode surface and the buffeting amplitude in a sliding mode stage are related to a system state variable.

3. The improved exponential approximation law-based fuzzy sliding-mode control method for the permanent magnet synchronous motor according to claim 1, characterized in that: the speed loop fuzzy sliding mode control is implemented by taking a motor rotating speed error e as an input and obtaining a reference current component i of a q axis through a sliding mode control algorithm_qrefAnd taking sliding mode surface functions s and ds/dt as input of fuzzy control, and adjusting parameters k and epsilon in the improved approximation law in real time through fuzzy logic.

Technical Field

The invention relates to a motor control strategy, in particular to a fuzzy sliding mode control strategy of a permanent magnet synchronous motor.

Background

Patent numbers: CN201510410455.5, inventive name: a permanent magnet synchronous motor sliding mode control strategy based on an approach law discloses a hydro-magnetic synchronous motor sliding mode control strategy based on the approach law, and the permanent magnet synchronous motor control strategy adopts speedCurrent double closed-loop control is carried out, a PI controller is adopted for a current loop, and sliding mode control based on an approach law is adopted for a rotating speed loop; the speed regulator adopts a variable speed approach law containing speed error and sliding mode surface information, takes the deviation of the given rotor angular speed and the feedback rotor angular speed as input quantity, and outputs a q-axis current given value i through sliding mode control quantity_q. The invention solves the problems of slow approaching speed and large steady-state buffeting of the traditional approach law, can quickly track the given rotating speed in a dynamic state, reduces speed overshoot and current fluctuation, reduces the harmonic content of the system caused by high-frequency buffeting in a steady state, greatly improves the performance of the system, and realizes high-precision vector control of the permanent magnet synchronous motor speed regulating system.

Patent numbers: CN201610961782.4, inventive name: a variable index coefficient approximation rule sliding mode variable structure control method of a permanent magnet synchronous motor discloses a variable index coefficient approximation rule sliding mode variable structure control method of a permanent magnet synchronous motor. Aiming at the requirements of a high-performance permanent magnet synchronous motor control system, on the basis of a conventional exponential approach law, an exponential variable function term is introduced, a first-order norm of a system state variable is taken as an index of an exponential function, and the approach speed of the exponential variable term and the approach speed of a speed change term are adaptively adjusted according to the distance between the system and a sliding mode surface, so that the dynamic response speed of the system is increased. And taking the first-order norm of the system state variable as the exponent of the function, and relating the system state variable, wherein an s function is introduced to replace a sign function for further suppressing system buffeting. Therefore, the sliding mode variable structure control method of the permanent magnet synchronous motor with the variable index coefficient approximation law is provided. Compared with the integral sliding mode variable structure control method, the method effectively improves the dynamic characteristic and the steady-state characteristic of the system and increases the robustness of the system.

Patent numbers: CN201910259384.1, inventive name: a permanent magnet synchronous motor fuzzy sliding mode control system and method for improving an index approach law are disclosed, wherein the method comprises the following steps of (1) calculating speed deviation, (2) calculating a sliding mode switching function s (t), (3) s normalization processing, (4) s fuzzification processing, (5) checking a fuzzy rule table, (6) k defuzzification, and (7) calculating the output of FSMC. The method adopts integral sliding mode variable structure control based on an exponential approximation law, the improved exponential approximation law is a square variable introducing errors into constant velocity terms, and the approximation speed of the control system state motion point is related with the errors, so that buffeting of the control system state motion point is in a damping trend. The method has the characteristics of low output buffeting, strong robustness, quick response, good stability and the like.

With the development of a plurality of high and new technologies and high and new technology industries, the permanent magnet synchronous motor is widely applied to the industrial field due to the characteristics of high power density, high efficiency, large speed regulation range, small size, light weight and the like. In order to further improve the control performance of the driving motor of the electric automobile, in recent years, some advanced control algorithms are gradually applied to the control of the permanent magnet synchronous motor, the sliding mode variable structure control becomes an important control method for improving the performance of the permanent magnet synchronous motor by the characteristics of high response speed, strong robustness and the like, but due to the influence of the self characteristics of the sliding mode control, the buffeting phenomenon cannot be completely eliminated, and the buffeting phenomenon can only be weakened to a proper range to a certain extent. The method for restraining buffeting through the sliding mode approach law is widely accepted by scholars at home and abroad, the method is improved on the basis of the conventional index approach law, and the novel sliding mode index approach law is provided, so that the purposes of shortening the system convergence time and restraining high-frequency buffeting at a central point in the conventional index approach law are achieved.

Disclosure of Invention

The invention aims to design a fuzzy sliding mode control method of a permanent magnet synchronous motor based on an improved index approach law. In order to overcome the defects of poor dynamic performance, low robustness and the like of a variable-structure sliding mode control permanent magnet synchronous motor speed regulating system based on a conventional approach law, inhibit buffeting in a sliding mode control strategy and further improve the control performance of the control system, the variable-index-coefficient approach law-based sliding mode motor speed regulating control method is provided. The system state norm is introduced on the basis of a conventional exponential approach law in sliding mode control, so that the speed of a motion point approaching a sliding mode surface in a sliding motion stage and the buffeting amplitude in a sliding mode stage are related to a system state variable, and the approach speed is related to the system state change, so that the system response speed and the approach speed are effectively increased, and the buffeting of the system is reduced. The improved control method effectively improves the response speed and the accuracy of the system, weakens the buffeting of the system, has stronger robustness to uncertain disturbance, greatly improves the performance of a speed regulating system and enables the motor to have better dynamic and static performances.

In order to achieve the above object, the present invention adopts the following technical solutions

A permanent magnet synchronous motor fuzzy sliding mode control method based on improved index approach law, the permanent magnet synchronous motor control strategy adopts speed, current double closed-loop control, the current loop adopts PI controller, the rotating speed loop adopts fuzzy sliding mode control based on improved index approach law, wherein, the permanent magnet synchronous motor speed loop fuzzy sliding mode controller uses fuzzy control algorithm to adjust approach law parameter on line and smooth control signal, the improved approach law is that the state variable of the system is added on the basis of traditional index approach law, so that the speed of the sliding mode surface approach of the moving point in the sliding motion stage and the buffeting amplitude in the sliding mode stage are related to the state variable of the system; when the track of the system motion point is far away from the sliding mode surface, the norm value of the system state variable is relatively large, and the approaching speed is large, so that the motion point can be ensured to reach the sliding mode surface in the shortest time; when the track of the motion point is close to the sliding mode surface, the constant speed approaching term approaches to zero, the index approaching term plays a main role, then the motion point of the system passes through the two sides of the sliding mode surface back and forth and approaches to the original point, in the process, the value of the system state variable is gradually reduced, the buffeting amplitude of the motion point on the two sides of the sliding mode surface is reduced, and finally the motion point tends to be stable at the original point;

the method comprises the following specific steps:

step 1: the mathematical model of the permanent magnet synchronous motor under the d-q coordinate system is as follows:

in the formula: u. of_d、u_qD-q axis components of the stator voltage, respectively; i.e. i_d、i_qRespectively stator currentA d-q axis component; r_sIs a stator resistor; omega_eIs an electrical angle; l is_d、L_qD-q axis inductance components, respectively; psi_fIs a permanent magnet flux linkage; p is a radical of_nIs the number of pole pairs;

binding i_dThe control method with the value of 0 can be equivalently changed into a motor mathematical model as follows:

in the formula, L_sIs a stator inductance;

step 2: the state variables defining the system are:

in the formula, ω_rIs a rated rotating speed; omega is the actual rotating speed; e is the motor rotation speed error;

the following can be obtained:

and step 3: defining a sliding mode surface function s as:

s＝qx₁+x₂

wherein q is a constant and > 0;

the improved approach law is as follows:

in the formula (I), the compound is shown in the specification,is the system state norm; s is a system sliding mode surface function; epsilon is the approaching speed, k is the approaching coefficient, epsilon, k is more than 0;

and combining a mechanical motion equation and an electromagnetic torque equation of the permanent magnet synchronous motor to obtain a q-axis current reference value as follows:

in the formula, P_nFor the number of pole pairs, psi, of the motor rotor_fIs a permanent magnet flux linkage, and J is the rotational inertia of the motor;

and 4, step 4: in order to meet the requirements of motor parameter change and interference on the motor operation stability, fuzzy control and sliding mode control are combined to stably control signals. Motor speed error e and its rate of changeProportional to the sliding mode surface s, taking s and ds/dt as the input of the fuzzy controller, taking the approach law parameters k and epsilon as the output, setting the values of s, ds/dt and k and epsilon to be quantized to the fuzzy domain interval [ -33 ]]And in the fuzzy set, the fuzzy set is { NB, NM, NS, ZO, PS, PM, PB }, wherein NB is negative and large, NM is negative and medium, NS is negative and small, ZO is zero, PS is positive and small, PM is positive and PB is positive, the membership function is set as a triangular membership function, and finally the motor speed ring fuzzy sliding mode controller is established.

In some embodiments, the improvement index approach law is:on the basis of a traditional exponential approximation law, a system state norm | X | is introduced, so that the speed of a motion point in a sliding motion stage approaching a sliding mode surface and the buffeting amplitude in a sliding mode stage are related to a system state variable.

In some embodiments, the speed loop fuzzy sliding mode control takes a motor rotation speed error e as an input, and a reference current component i of a q axis is obtained through a sliding mode control algorithm_qrefAnd taking sliding mode surface functions s and ds/dt as input of fuzzy control, and adjusting parameters k and epsilon in the improved approximation law in real time through fuzzy logic.

Advantageous effects

The invention relates to a permanent magnet synchronous motor fuzzy sliding mode control method based on an improved index approach law, which aims to improve the torque output performance and the speed regulation performance of a permanent magnet synchronous motor and reduce the buffeting of the traditional index approach law in sliding mode control, provides the improved index approach law, establishes a motor rotating speed loop fuzzy sliding mode control system by combining fuzzy control, and compared with the traditional index approach law, the improved index approach law has the advantages that the speed is higher when a system moving point approaches a sliding mode surface, the reaching time is shorter, and the problem that the traditional index approach law generates larger steady buffeting at an origin can be improved; the improved index approaching law can ensure that the system moving point is stabilized at the original point when the system is in a steady state, greatly reduces buffeting in the steady state and ensures that the system has better steady-state performance. The permanent magnet synchronous motor under the control of the speed regulating system adopting the improved index approach law has the advantages of higher response speed, stronger disturbance resistance, good speed regulating performance and more stable torque output characteristic; compared with the traditional exponential approaching law method, the time for the motor to reach the steady state is greatly shortened, overshoot does not exist, the torque fluctuation is smaller, the system can be quickly and accurately adjusted to the steady state when the load suddenly changes, the dynamic responsiveness is better, and the robustness is improved to some extent.

Drawings

FIG. 1 is a control system block diagram of a permanent magnet synchronous motor fuzzy sliding mode control method based on an improved index approach law according to the present invention;

FIG. 2 is a speed ring fuzzy sliding mode control principle diagram of the permanent magnet synchronous motor fuzzy sliding mode control method based on the improved index approach law according to the present invention;

FIG. 3 is a phase trajectory graph of an improved approximation law of a permanent magnet synchronous motor fuzzy sliding mode control method based on the improved index approximation law of the present invention;

FIG. 4 is a control signal output curve diagram of the improved approximation law of the fuzzy sliding mode control method of the permanent magnet synchronous motor based on the improved index approximation law according to the present invention;

FIG. 5 is an improved approximation law step response curve of the fuzzy sliding mode control method of the permanent magnet synchronous motor based on the improved index approximation law of the present invention;

FIG. 6 is an improved approximation law approach process curve of the permanent magnet synchronous motor fuzzy sliding mode control method based on the improved index approximation law of the present invention;

fig. 7 is a comparison graph of a motor rotation speed change curve when the permanent magnet synchronous motor fuzzy sliding mode control method based on the improved index approach law receives disturbance under the control of the traditional approach law and the improved approach law.

Detailed Description

The invention is further illustrated by the following figures and specific examples:

the invention relates to a permanent magnet synchronous motor fuzzy sliding mode control method based on an improved index approach law, which is shown in attached figures 1, 2, 3, 4, 5, 6 and 7_d，i_qThe position sensor provides real-time rotating speed and position signals for the system, and the system adopts i_dVector control of 0 with measured d-axis current i_dThe difference is made to obtain the input of the d-axis PI current regulator, and the q-axis given current is obtained from the output of the sliding mode speed regulator, i.e. i_qrefWhich is compared with the measured q-axis current i_qObtaining the input of a q-axis PI current regulator by making a difference, and respectively outputting a given value u of the stator voltage under a rotating coordinate system through two current regulators_dAnd u_qObtaining stator voltage u under a two-phase static coordinate system through Park inverse transformation_αAnd u_βAnd the switching signal is used as the input of voltage space vector modulation to generate a switching signal acting on a power device in a power conversion circuit, and finally the permanent magnet synchronous motor is driven to operate.

Binding i_dIn the control method of 0, the available motor model is equivalently changed as follows:

in the formula, L_sIs the stator inductance.

The state variables defining the system are:

in the formula, ω_rIs a rated rotating speed; omega is the actual rotating speed; and e is the motor rotating speed error.

The following can be obtained:

defining a sliding mode surface function s as:

s＝qx₁+x₂

wherein q is a constant and > 0;

derivation of the above equation yields:

in order to improve the performance of the sliding mode control motion stage, an improved approach law is selected to ensure the dynamic quality of the permanent magnet synchronous motor speed regulating system. The improvement index approach law adopted by the invention is as follows:

on the basis of a traditional exponential approach law, a system state norm (X) is introduced, so that the speed of a motion point in a sliding motion stage approaching a sliding mode surface and the buffeting amplitude in a sliding mode stage are related to a system state variable, the approach law is improved to introduce the system state variable, when the track of the motion point of the system is far away from the sliding mode surface, the value of the system state norm (X) is relatively large, the approach speed is large at the moment, and the motion point can be guaranteed to reach the sliding mode surface in the shortest time; when the track of the motion point is close to the sliding mode surface, -k | | X | | | s approaches to zero, -epsilon | | X | | | sgn(s) plays a main role, then the system motion point passes through back and forth on the two sides of the sliding mode surface and approaches to the original point through the sliding mode, in the process, the value of | | | X | | | | is gradually reduced, the buffeting of the motion point on the two sides of the sliding mode surface is reduced, and finally the motion point tends to be stable at the original point, so that the buffeting phenomenon of the traditional index approach law at the original point is well inhibited.

The phase trajectories of the traditional exponential approximation law and the improved approximation law are shown in fig. 3, and the results show that the improved approximation law can reach the sliding mode surface in a short time and can also weaken high-frequency vibration at an original point.

In order to meet the requirements of motor parameter change and interference on the motor operation stability, fuzzy control and sliding mode control are combined to stably control signals. Motor speed error e and its rate of changeProportional to slip form surface s, as s andthe input of the fuzzy controller is the approximate law parameters k and epsilon as the output, and the variation range of the actual value variation of the control process is [ -N, N]The domain value of the ambiguity is [ -S, S]Thus the quantization factor of the input quantity is K_e＝K_ecS/N, the quantization factor of the output is K_uk＝K_uεN/S. Setting s,And the values of k and epsilon are quantized to the ambiguity domain interval [ -33 [ ]]And the fuzzy set is { NB, NM, NS, ZO, PS, PM, PB }, wherein NB is negative and large, NM is negative and medium, NS is negative and small, ZO is zero, PS is positive and small, PM is positive and PB is positive, and the membership function is set as a triangular membership function. The fuzzy control rules for setting the parameters k and epsilon are shown in the table.

TABLE 1 fuzzy rule Table

Tab 1 Fuzzy control rule table

And (3) establishing a fuzzy controller by utilizing a fuzzy control module of MATLAB and combining the fuzzy rule of the table 1. The defuzzification method adopts a gravity center method:

in the formula, u (z)_i) As an output variable z_iCorresponding membership function.

3-7, the improved index approach law of the invention can be obtained that the speed of the system motion point approaches the sliding mode surface is larger, the arrival time is short, and the improved index approach law can make the system motion point stable at the origin point when the system is in a steady state, thereby greatly reducing buffeting in the steady state and making the system have better steady state performance; the permanent magnet synchronous motor under the control of the speed regulating system adopting the improved index approach law has the advantages of higher response speed, stronger disturbance resistance, good speed regulating performance and more stable torque output characteristic; compared with the traditional exponential approaching law method, the time for the motor to reach the steady state is greatly shortened, overshoot does not exist, the torque fluctuation is smaller, the system can be quickly and accurately adjusted to the steady state when the load suddenly changes, the dynamic responsiveness is better, and the robustness is improved to some extent.

The foregoing description is of the embodiments of the invention and the technical principles applied thereto, and the functional effects produced by the changes made in the conception of the invention are not beyond the spirit of the description and the drawings, and are within the scope of the invention.