阅读说明：本技术 基于复合位置控制器的永磁无刷直流电机位置伺服系统 (Permanent magnet brushless direct current motor position servo system based on composite position controller ) 是由 王会明 万谦 王雪闯 陈晓雷 唐贤伦 李锐 于 2020-12-03 设计创作，主要内容包括：本发明请求保护一种基于复合位置控制器的永磁无刷直流电机位置伺服系统,其包括：复合位置控制器模块、PI控制模块、驱动电路模块、电流采样模块、永磁无刷直流电机及位置检测与计算模块,其中复合位置控制器模块是基于指数趋近律的滑模反馈控制部分和基于扩张状态观测器的干扰估计与补偿部分组成的复合控制器,与传统线性控制方法相比,该方法在保证收敛速度的同时,既可以有效降低系统抖振,又可以提高系统抗干扰性能,满足了永磁无刷直流电机位置伺服系统在高性能领域的应用需求。(The invention discloses a permanent magnet brushless DC motor position servo system based on a composite position controller, which comprises: the system comprises a composite position controller module, a PI control module, a driving circuit module, a current sampling module, a permanent magnet brushless direct current motor and a position detection and calculation module, wherein the composite position controller module is a composite controller consisting of a sliding mode feedback control part based on an exponential approximation rule and an interference estimation and compensation part based on an extended state observer.)

1. A permanent magnet brushless DC motor position servo system based on a composite position controller is characterized by comprising: the system comprises a composite position controller module, a PI control module, a driving circuit module, a current sampling module, a permanent magnet brushless direct current motor and a position detection and calculation module, wherein the composite position controller module is connected with the PI control module, the PI control module is connected with the driving circuit module, the current sampling module is arranged at two ends of the PI control module and the driving circuit module in parallel, the driving circuit module is also connected with the permanent magnet brushless direct current motor, the permanent magnet brushless direct current motor is connected with one end of the position detection and calculation module, and the other end of the position detection and calculation module is connected with the composite position controller module;

the composite position controller module is formed by compounding sliding mode feedback control based on an exponential approximation law and feedforward control based on an extended state observer, and the position detection and calculation module is used for detecting a position sensor signal theta arranged on the permanent magnet brushless direct current motor; the current sampling module obtains an actual current i required by the PI control module; the input end of the compound position controller module is a position reference value theta_rAnd the difference value of the position sensor signal theta obtained by the position detection and calculation module is obtained by the composite position controller module to obtain the reference current i at the input end of the PI control module_r(ii) a The obtained reference current i_rThe difference value of the current I and the obtained actual current I is input into a PI control module, and then the input voltage u of the driving circuit module is obtained; the voltage u drives the permanent magnet brushless DC under the control of the driving circuitThe motor operates.

2. The position servo system of the permanent magnet brushless direct current motor based on the composite position controller according to claim 1, wherein the composite position controller is compounded by sliding mode feedback control based on exponential approximation law and feedforward control based on an extended state observer, and the composite position controller is designed by the following steps:

defining the position error e as:

e＝θ_r-θ

wherein theta is_rIs a reference position;

deriving e yields:

the slip form surface is designed as follows:

s represents the sign of the sliding mode surface, and c is a coefficient greater than 0;

derivation of s gives:

the composite position controller is designed as follows:

wherein a ═ k_tJ; c > 0, k > 0, q > 0, sgn (—) is a standard sign function;is a reference position theta_rThe second derivative of (a); i.e. i_rFor compound position controlThe output of the device; m represents the total disturbance of the system, and a is k_t/J，Is the torque coefficient, J is the moment of inertia, z₃Is an estimate of the lumped disturbance m;

let e_d(t)＝m-z₃For disturbance error estimation, assume e_d(t) is bounded and there is a constant k_ed>0, such that: | e_d(t)|≤k_ed，

Substituting a composite position controller expression intoThe following can be obtained:

taking the Lyapunov function as:then

It can be seen from this that when the gain satisfies k > k_edWhen the temperature of the water is higher than the set temperature,the position error of the system can be quickly converged to the sliding mode surfaceThen asymptotically approaches zero along the slip-form plane s-0.

3. The position servo system of a permanent magnet brushless direct current motor based on a compound position controller according to claim 2, wherein the expression of the extended state observer is as follows:

wherein p is₁＞0,p₂＞0,p₃0 is a parameter of the observer, z₁For the estimation of the position θ, z₂Is an estimate of the velocity w, z₃Is an estimate of the lumped perturbation m.Denotes z₃The derivative of (c).

4. A composite position controller based permanent magnet brushless dc motor position servo system according to claim 1, 2 or 3, wherein the mathematical model of the permanent magnet brushless dc motor is:

wherein theta, w, i and u are respectively a position signal, a rotating speed signal, a motor stator current and a motor stator voltage; j is moment of inertia; b is a viscous friction coefficient; l is a stator inductance; r is a stator resistor;is a torque coefficient; n is_pIs the number of magnetic pole pairs; psi_fFor rotor flux linkage；T_LIs the load torque; k_e＝n_pψ_fAlso a torque coefficient.

In general, to facilitate the design of a hybrid position controller for a permanent magnet brushless dc motor, it can be expressed in the form of:

wherein a ═ k_t/J，b＝1/L，

5. System according to one of claims 1 to 4, characterized in that its control comprises the following steps:

1) the position detection and calculation module obtains a motor rotor position theta;

2) detecting the bus current to obtain an actual current i required by the PI control module;

3) the input end of the compound position controller module is a position reference value theta_rThe difference value between the actual position theta obtained by the position detection and calculation module is processed by the composite position controller module to obtain the reference current i at the input end of the PI control module_r；

4) Reference current i obtained in step 3)_rObtaining the input voltage u of the driving circuit module after the difference value of the actual current i obtained in the step 2) passes through the PI control module;

5) and the voltage u drives the permanent magnet brushless direct current motor to operate under the control of the driving circuit.

Technical Field

The invention belongs to a control method of a permanent magnet brushless direct current motor, and particularly relates to a control method of a permanent magnet brushless direct current motor position servo system based on an extended state observer and sliding mode control.

Background

The permanent magnet brushless direct current motor is a novel direct current motor developed along with rapid development of power electronic technology, manufacturing industry and novel materials, and is widely applied to the industrial fields of aerospace, household appliances, instruments and meters, chemical engineering, medical appliances and the like because the permanent magnet brushless direct current motor has a series of advantages of simple structure, reliability in operation, convenience in maintenance, high efficiency, no excitation loss, good speed regulation performance and the like.

At present, a permanent magnet brushless direct current motor generally adopts a control mode of combining a PID control structure with a vector control structure, but because the motor is influenced by various interference factors such as external electromagnetic interference, load change, friction and the like in the operation process, the traditional linear control such as PID control cannot effectively deal with the interference factors, and further the system stability is influenced. Therefore, some non-linear control algorithms need to be designed to improve the system performance, such as robust control, predictive control, finite time control, sliding mode control, adaptive control, and intelligent control. Among the above-mentioned methods, sliding mode variable structure control has received much attention because of its advantages of strong robustness and easy implementation. However, the discontinuous control action of the sliding mode control law can cause a buffeting phenomenon, so that the application of the sliding mode control in a practical system is limited.

In order to weaken the phenomenon of buffeting, another effective method is provided, namely a composite controller consisting of a sliding mode control feedback part based on an exponential approaching law and an interference estimation and compensation part based on an extended state observer is designed, so that the composite controller has the advantages of simple structure, strong anti-interference performance, good tracking capability and the like, and the control performance of a position servo system can be obviously improved.

Disclosure of Invention

The present invention is directed to solving the above problems of the prior art. The permanent magnet brushless direct current motor position servo system and method based on the composite position controller can achieve good dynamic and steady-state performance and can effectively improve the tracking capability of the system. The technical scheme of the invention is as follows:

a permanent magnet brushless DC motor position servo system based on a composite position controller comprises: the system comprises a composite position controller module, a PI control module, a driving circuit module, a current sampling module, a permanent magnet brushless direct current motor and a position detection and calculation module, wherein the composite position controller module is connected with the PI control module, the PI control module is connected with the driving circuit module, the current sampling module is arranged at two ends of the PI control module and the driving circuit module in parallel, the driving circuit module is also connected with the permanent magnet brushless direct current motor, the permanent magnet brushless direct current motor is connected with one end of the position detection and calculation module, and the other end of the position detection and calculation module is connected with the composite position controller module;

the composite position controller module is formed by compounding sliding mode feedback control based on an exponential approximation law and feedforward control based on an extended state observer, and the position detection and calculation module is used for detecting a position sensor signal theta arranged on the permanent magnet brushless direct current motor; the current sampling module obtains an actual current i required by the PI control module; the input end of the compound position controller module is a position reference value theta_rAnd the difference value of the position sensor signal theta obtained by the position detection and calculation module is obtained by the composite position controller module to obtain the reference current i at the input end of the PI control module_r(ii) a The obtained reference current i_rThe difference value of the current I and the obtained actual current I is input into a PI control module, and then the input voltage u of the driving circuit module is obtained; and the voltage u drives the permanent magnet brushless direct current motor to operate under the control of the driving circuit.

Further, the composite position controller is formed by combining sliding mode feedback control based on exponential approaching law and feedforward control based on an extended state observer, and the design steps of the composite position controller are as follows:

defining the position error e as:

e＝θ_r-θ

wherein theta is_rIs a reference position;

deriving e yields:

the slip form surface is designed as follows:

s represents the sign of the sliding mode surface, and c is a coefficient greater than 0;

derivation of s gives:

the composite position controller is designed as follows:

wherein a ═ k_tJ; c > 0, k > 0, q > 0, sgn (—) is a standard sign function;is a reference position theta_rThe second derivative of (a); i.e. i_rIs the output of the compound position controller; m represents the total disturbance of the system, and a is k_t/J，Is the torque coefficient, J is the moment of inertia, z₃Is an estimate of the lumped disturbance m;

let e_d(t)＝m-z₃For disturbance error estimation, assume e_d(t) is bounded and there is a constant k_ed>0, such that: | e_d(t)|≤k_ed，

Substituting a composite position controller expression intoThe following can be obtained:

taking the Lyapunov function as:then

It can be seen from this that when the gain satisfies k > k_edWhen the temperature of the water is higher than the set temperature,the position error of the system can be quickly converged to the sliding mode surfaceThen asymptotically approaches zero along the slip-form plane s-0.

Further, the expression of the extended state observer is as follows:

wherein p is₁＞0,p₂＞0,p₃0 is a parameter of the observer, z₁For the estimation of the position θ, z₂Is an estimate of the velocity w, z₃Is an estimate of the lumped perturbation m.Denotes z₃A derivative of (a);

further, the mathematical model of the permanent magnet brushless dc motor is:

wherein theta, w, i and u are respectively a position signal, a rotating speed signal, a motor stator current and a motor stator voltage; j is moment of inertia; b is a viscous friction coefficient; l is a stator inductance; r is a stator resistor;is a torque coefficient; n is_pIs the number of magnetic pole pairs; psi_fIs a rotor flux linkage; t is_LIs the load torque; k_e＝n_pψ_fAlso a torque coefficient.

In general, to facilitate the design of a hybrid position controller for a permanent magnet brushless dc motor, it can be expressed in the form of:

wherein a ═ k_t/J，b＝1/L，

Further, the control of the system comprises the steps of:

1) the position detection and calculation module obtains a motor rotor position theta;

2) detecting the bus current to obtain an actual current i required by the PI control module;

3) the input end of the compound position controller module is a position reference value theta_rThe difference value between the actual position theta obtained by the position detection and calculation module is processed by the composite position controller module to obtain the reference current i at the input end of the PI control module_r；

4) Reference current i obtained in step 3)_rObtaining the input voltage u of the driving circuit module after the difference value of the actual current i obtained in the step 2) passes through the PI control module;

5) and the voltage u drives the permanent magnet brushless direct current motor to operate under the control of the driving circuit.

The invention has the following advantages and beneficial effects:

1. an extended state observer is added into the composite position controller, so that disturbance can be well estimated to perform feedforward compensation, and the buffeting phenomenon is reduced.

2. Based on exponential approximation lawThe sliding mode control is adopted, and the exponential term-qs can ensure that the system state can approach to a sliding mode at a higher speed when s is larger, so that the exponential approach law is particularly suitable for solving the response problem with large step. In the index approach, the approach speed is gradually reduced from a larger value to zero, so that the approach time is shortened, and the speed of the motion point reaching the switching surface is small. Adding an isokinetic approach termMaking the approach velocity k instead of zero as s approaches zero ensures a finite time to arrive. In the exponential approximation law, in order to attenuate buffeting while ensuring a fast approach, k should be decreased while increasing q.

3. Compared with the traditional method, the sliding mode control method based on the exponential approximation law is adopted, and proper approximation law parameters are selected, so that steady-state errors can be eliminated, overshoot of the system is reduced, the time of a transition process is shortened, the dynamic quality of the system is improved, and the problem of high-frequency jitter in sliding mode control can be effectively solved.

Drawings

FIG. 1 is a schematic diagram of a control system according to a preferred embodiment of the present invention;

FIG. 2 is a detailed functional block diagram of the control system of the present invention;

FIG. 3 is a functional block diagram of the compound position controller of the present invention;

FIG. 4 is a system position curve in the PI control mode;

FIG. 5 is a plot of system position in the recommended control mode;

FIG. 6 is a system current curve in the PI control mode;

FIG. 7 is a system current curve for a recommended control mode;

FIG. 8 is a system voltage curve for two control modes;

FIG. 9 is an output curve of an observer in a preferred control mode of the present invention;

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail and clearly with reference to the accompanying drawings. The described embodiments are only some of the embodiments of the present invention.

The technical scheme for solving the technical problems is as follows:

the mathematical model of the permanent magnet brushless direct current motor is as follows:

wherein theta, w, i and u are respectively a position signal, a rotating speed signal, a motor stator current and a motor stator voltage; j is moment of inertia; b is a viscous friction coefficient; l is a stator inductance; r is a stator resistor;is a torque coefficient; n is_pIs the number of magnetic pole pairs; psi_fIs a rotor flux linkage; t is_LIs the load torque; k_e＝n_pψ_fAlso a torque coefficient.

In general, to facilitate the design of a hybrid position controller for a permanent magnet brushless dc motor, it can be expressed in the form of:

wherein a ═ k_t/J，b＝1/L，A control method of a permanent magnet brushless direct current motor position servo system based on an extended state observer and sliding mode control comprises a composite position controller module, a PI control module, a driving circuit module, a current sampling module, a permanent magnet brushless direct current motor and a position detection and calculation module. The composite position controller module is connected with the PI control module, the PI control module is connected with the driving circuit module, the current sampling module is arranged at two ends of the PI control module and the driving circuit module in parallel, the driving circuit module is also connected with the permanent magnet brushless direct current motor, the permanent magnet brushless direct current motor is connected with one end of the position detection and calculation module, and the other end of the position detection and calculation module is connected with the composite position controller module;

the composite position controller module is formed by compounding sliding mode feedback control based on an exponential approximation law and feedforward control based on an extended state observer, and the position detection and calculation module is used for detecting a position sensor signal theta arranged on the permanent magnet brushless direct current motor; the current sampling module obtains an actual current i required by the PI control module; the input end of the compound position controller module is a position reference value theta_rAnd the difference value of the position sensor signal theta and the obtained position sensor signal theta is processed by the composite position controller module to obtain the reference current i at the input end of the PI control module_r(ii) a The obtained reference current i_rThe difference value of the current I and the obtained actual current I is input into a PI control module, and then the input voltage u of the driving circuit module is obtained; and the voltage u drives the permanent magnet brushless direct current motor to operate under the control of the driving circuit.

Fig. 1 is a schematic diagram of the control system of the present invention, and fig. 2 is a detailed schematic block diagram of the control system of the present invention, from which, as will be readily appreciated,

the present embodiment includes the following steps:

1) the position detection and calculation module obtains a motor rotor position theta;

2) detecting the bus current to obtain an actual current i required by the PI control module;

3) the input end of the compound position controller module is a position reference value theta_rThe difference value between the actual position theta obtained by the position detection and calculation module is processed by the composite position controller module to obtain the reference current i at the input end of the PI control module_r；

4) Reference current i obtained in step 3)_rObtaining the input voltage u of the driving circuit module after the difference value of the actual current i obtained in the step 2) passes through the PI control module;

5) and the voltage u drives the permanent magnet brushless direct current motor to operate under the control of the driving circuit.

As can be seen from the attached figure 3, the composite position controller is compounded by the sliding mode feedback control based on the exponential approximation law and the feedforward control based on the extended state observer; the expression for the position compound position controller is:

wherein a ═ k_tJ; c > 0, k > 0, q > 0, sgn (—) is a standard sign function;is a reference position theta_rThe second derivative of (a); i.e. i_rIs the output of the compound position controller; z is a radical of₃Is an estimate of the lumped perturbation m.

In the present invention, the expression of the extended state observer is:

wherein p is₁＞0,p₂＞0,p₃0 is a parameter of the observer, z₁For the estimation of the position θ, z₂Is an estimate of the velocity w, z₃Is an estimate of the lumped perturbation m.

As shown in fig. 4 and 5, comparing the method for controlling a position servo system of a permanent magnet brushless dc motor based on an extended state observer and sliding mode control with a conventional control method (PI control), it can be seen that the method for controlling a position servo system of a permanent magnet brushless dc motor according to the present invention can track an input signal more accurately after the position servo system of the permanent magnet brushless dc motor is started, and the adjustment time is short; when a constant load is applied when t is 5s, the system quickly returns to a steady-state value in the case of load disturbance, and the regulation time is extremely short.

As shown in fig. 6, it is a curve of the actual current and the reference current of the system under the PI control mode.

Fig. 7 shows a curve of the actual current and the reference current of the system in the preferred embodiment of the present invention.

As shown in fig. 8, the system voltage curves are shown in two control modes.

Fig. 9 shows the output curve of the observer in the control mode recommended by the present invention. Curves shown in FIG. 9(a) are θ and its estimated z, respectively₁The observer can accurately observe the change of the position loop of the permanent magnet brushless direct current motor position servo system in real time, and the system is subjected to the observation when t is 5sTo the case of external load disturbances. The observed value z is shown as a curve in FIG. 9(b)₃，z₃The subsystem (position loop) is subject to interference.

The systems, devices, modules or units illustrated in the above embodiments may be implemented by a computer chip or an entity, or by a product with certain functions. One typical implementation device is a computer. In particular, the computer may be, for example, a personal computer, a laptop computer, a cellular telephone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure. After reading the description of the invention, the skilled person can make various changes or modifications to the invention, and these equivalent changes and modifications also fall into the scope of the invention defined by the claims.