CN106887987A - A kind of permagnetic synchronous motor System with Sliding Mode Controller with gain scheduling handoff gain - Google Patents

Abstract

The present invention relates to a kind of permagnetic synchronous motor System with Sliding Mode Controller with gain scheduling handoff gain；The control system is adjusted in real time using the method that gain scheduling and self adaptation are combined to the handoff gain of permanent-magnetic synchronous motor stator electric current sliding mode controller；The method according to the bounds of adaptive law on-line tuning handoff gain coefficient, while using on d-axis, quadrature axis current Integral Sliding Mode surface function as scheduling variable, allowing to carry out gain scheduling to handoff gain coefficient in bounds；Designed method weakens system chatter on the premise of the control system robustness is ensured, improves control performance.

Description

A sliding-mode control system for permanent magnet synchronous motor with gain-scheduled switching gain

technical field

The invention relates to a permanent magnet synchronous motor sliding mode control system with gain scheduling switching gain.

Background technique

Thanks to the successful development of new rare earth permanent magnet materials, the performance of permanent magnet synchronous motors has been qualitatively improved and has been widely used in many fields; permanent magnet synchronous motors are a multivariable, nonlinear, and strongly coupled system. It is extremely sensitive to the perturbation of internal parameters of the system and external disturbances, so the traditional linear control method cannot accurately describe the steady state and dynamic process of the system, nor can it adapt to the changes of system parameters, so it is difficult to ensure the stability of the motor within the global speed and torque range. running quality.

Sliding mode control is a special nonlinear control, which has the advantages of fast response, good robustness, and strong engineering practicability; however, the sliding mode control system will have chattering problems, and the source of chattering is mainly the switching gain , chattering can be eliminated if the switching gain is properly adjusted in the process of approaching the sliding mode surface.

Contents of the invention

The invention proposes a permanent magnet synchronous motor control method with gain scheduling switching gain to make up for the deficiency of the sliding mode control system.

The above object is achieved through the following technical solutions.

A permanent magnet synchronous motor sliding mode control system with gain scheduling switching gain is a speed and current double closed-loop control system based on the permanent magnet synchronous motor vector control, in which the current loop adopts a sliding mode controller. The overall system structure is shown in the figure 1; where the current sliding mode controller utilizes the principle of sliding mode control to effectively guarantee the response speed, robustness and engineering practicability of the system.

The current sliding mode controller takes the _d and q axis stator current errors ed and e q _as input state variables, and takes the d and q axis stator voltage u _d and u _q as the output of the controller; the design of the control law adopts the integral The sliding mode surface can achieve the purpose of weakening the steady-state error of the system and improving the control accuracy; and in order to obtain a higher approaching speed, the exponential approaching law is used, and chattering can also be weakened at the same time.

The switching gain coefficient of the control law should select an appropriate value, which is to ensure the dynamic response speed and effectively weaken chattering. If the coefficient is too small, the speed of the moving point approaching the sliding mode surface will be small, and if the coefficient is too large, it will cause a large system chattering; in order to solve this problem, the present invention proposes to give i _dr and electrical angular velocity according to the quadrature axis current pair switching gain factor The method of self-adaptive tuning of the boundary range; and the gain scheduling method is used to tune the switching gain of the sliding mode control within the range; in this way, a larger coefficient can be taken at a distance from the sliding mode surface to increase the tightening speed , select a smaller coefficient to reduce system chattering when the sliding mode surface is closer.

Description of drawings

Accompanying drawing 1 is a system structure diagram of the present invention.

Accompanying drawing 2 is the structural block diagram of the current sliding mode controller of the present invention.

detailed description

In order to describe the technical characteristics of this solution in detail, the present invention will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

The sliding mode control system of the permanent magnet synchronous motor with gain scheduling switching gain uses a sliding mode controller as the core; the input of the sliding mode controller is the stator current error, and the output is the stator voltage in the rotating coordinate system.

It is known that the stator voltage equation of the permanent magnet synchronous motor in the d-q synchronous rotating coordinate system is

(1)

In the formula: u _d , u _q are the d and q axis stator voltages respectively; i _d , i _q are the d and q axis stator currents respectively; L _d , L _q are the d and q axis stator inductances respectively; R _s is the stator phase resistance; is the rotor flux linkage; is the rotor electrical angular velocity.

For the current loop control system, the _d and q axis stator current errors ed and e q _are defined as state variables, and the d and q axis stator voltages u _d and u _q are defined as control inputs, then dq can be obtained from formula (1) The state space equation of the shaft current control system is

(2)

In the formula: ; ; ;

( i _dr , i _qr are d and q axis current setting respectively).

The sliding mode controller adopts the integral sliding mode surface design; the integral sliding mode surface design can eliminate the steady-state error of the system when the system encounters random external disturbances, improve the control accuracy, and achieve the performance index required by the design.

For the d-q axis current control system, the integral sliding mode surface is expressed as

(3)

In the formula: c ₁ and c ₂ are the integral coefficients of the d-axis and q-axis sliding mode surface respectively.

The sliding mode controller adopts an exponential reaching law, which can weaken system chattering and improve system control performance while obtaining fast approaching.

For the d-q axis current control system, the exponential reaching law is expressed as

(4)

In the formula: , are the switching gain coefficients of the d-axis and q-axis reaching laws, respectively; , are the reaching law index coefficients of the d and q axes, respectively.

To sum up, from the state equation (2), sliding mode surface expression (3) and reaching law expression (4), considering d ₁ and d ₂ as disturbance items, the dq axis current sliding mode controller is obtained The control law of

(5)

According to the control law formula (5), the structural block diagram of the current sliding mode controller is shown in Figure 2.

According to the Lyapunov stability theory, the existence and accessibility conditions of sliding modes are expressed as

(6)

For the dq axis current sliding mode control system, , the above formula can be rewritten as

(7)

Substituting state equation (2), sliding mode surface expression (3) and control law expression (5) into the above formula, the robustness condition of the current sliding mode control system can be obtained as

(8)

In the formula: ; ; ; .

It can be seen that in the control law (5), the switching gain coefficient , The system robustness condition needs to be satisfied with the change of parameter perturbation and external disturbance; however, increasing the switching gain coefficient will aggravate the system chattering, and reducing the switching gain coefficient will delay the system dynamic response; therefore, it is necessary to balance the above two In this case, select an appropriate switching gain factor.

In order to solve the problem of system chattering, the present invention uses the method of gain scheduling to adjust the switching gain coefficient; the gain scheduling rule is as follows: if the switching gain coefficient If is smaller, the velocity of the moving point approaching the sliding surface is smaller, and the chattering of the system caused by it is smaller; and if If is larger, the velocity when the moving point reaches the sliding mode surface is larger, and the chattering of the system is also larger; therefore, the switching gain coefficient The gain scheduling rule of is: select a larger gain at a distance from the sliding surface , to ensure a fast approach; and a smaller one is selected closer to the sliding surface , to reduce system chattering.

The switching gain coefficient of the control law is adjusted according to the gain scheduling method; this method does not need to determine the typical operating point, and it is not necessary to find the optimal parameters one by one through simulation or experimental research at each typical operating point, but only needs to use the appropriate The design method determines the boundary range of the control parameters, and uses a suitable interpolation method to schedule the gain of the control parameters within the allowable boundary range.

The present invention uses the absolute value of the q-axis sliding mode surface function As a scheduling variable, consider the switching gain coefficient Should be within the allowable border , then switch the gain factor about the q-axis The gain scheduling rule of is designed as

(9)

In the formula: s _{q max} is the q-axis scheduling variable the maximum value of .

In the same way, about the d-axis switching gain coefficient The gain scheduling rule of is designed as

(10)

In the formula: s _{d max} is the scheduling variable the maximum value of ; , Respectively d-axis switching gain coefficient upper and lower boundaries of .

The present invention proposes to give i _dr and electrical angular velocity according to the quadrature axis current pair switching gain factor A method for adaptive tuning of the boundary range.

If considering that the motor is in the electric running mode, the given d-axis current , q-axis current given ; Generally, the electromagnetic parameters of the motor satisfy ;ignore distractors , Relatively small items in , ;So, , ; Therefore, according to formula (8), it can be seen that the d-axis switching gain coefficient the boundaries of the irrelevant; while the q-axis switches the gain factor The boundaries of the restrictions, that is, if If the value is too small, the robustness of the sliding mode control system cannot be guaranteed; if If the value is too large, it is not conducive to reducing system chattering.

In view of the above factors, the switching gain coefficient will be the border The adaptive adjustment law of is designed as

(11)

In the formula: k _s is the adjustment coefficient of the switching gain boundary, and k _s is a constant greater than 1.

On the premise of satisfying the sliding mode existence and accessibility conditional formula (8), consider a certain degree of parameter perturbation, external disturbance and speed measurement error, etc., and comprehensively measure dynamic indicators such as system chattering, overshoot, and adjustment time , the adjustment coefficient k _s generally takes 1.3-2.2; therefore, the q-axis switching gain coefficient The boundary range of can be expressed as

(12)

The principle of the permanent magnet synchronous motor control system described in the present invention is clear and easy to understand; a kind of permanent magnet synchronous motor sliding mode control system with gain scheduling switching gain proposed by the present invention has the characteristics of easy implementation; the self-adaptive method overcomes the The conventional gain scheduling method needs to determine the typical operating point and optimize the control parameters through a large number of simulation research work; the sliding mode surface function is used as the scheduling variable, and the coefficients are adjusted in real time according to the gain scheduling rules, so that the system has a global operating range. Good control characteristics.

What is not described in the present invention is all the content known to experimenters in the art; through the above description, users in the art know the better part of this invention; it should be declared that without departing from the present invention In the case of the core, any form of relatively easy deformation and modification is within the protection scope of the present invention.

Claims (3)

1. A permanent magnet synchronous motor sliding mode control system with gain scheduling switching gain, characterized in that: based on vector control and current, rotating speed double closed-loop, using rotating speed PI adjustment, maximum torque-to-current ratio and current sliding mode control principle. 2. The current sliding mode controller according to claim 1 is characterized in that: the _d , q axis stator current errors ed, e q _are used as state variables input by the controller, and the d, q axis stator voltages u _d , u _q As the output of the controller, the design scheme of integral sliding mode surface is adopted to eliminate the steady-state error of the system, and the scheme of exponential reaching law is used to increase the approaching speed and weaken chattering. 3. according to the switching gain of claim 1 or 2 described current sliding mode controllers, it is characterized in that: adopt self-adaptive method online to adjust the boundary range of switching gain coefficient, be scheduling variable with sliding mode surface function, according to gain scheduling rule to Switch gain coefficients for real-time tuning.