RU2568523C1 - Method for automatic control with reversible actuating mechanism - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to controlling continuous inertial processing objects with reversible electric drives and can be used in different industries and power engineering. The method comprises generating control action in the form of a bipolar series of pulses which move an electric drive in a forward and a reverse direction. The method includes, in each pulse-width modulation period, generating one control pulse having a width which is proportional to an increment calculated according to the control law of the control action. The value of the modulation period is set high whenever possible based on the inertia of the object, and the time constant of the integral component of the control law is set proportional to the selected modulation period.

EFFECT: high quality of control and reliability.

8 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of control of continuous inertial technological objects with reversible electric actuators, using pulse-width modulation, in particular using computing hardware (controllers), and can be used in various industries and energy.

State of the art

There is a known method of automatic control with pulse-width regulation, which consists in generating a high-speed signal of regulation error, generating a pulse-width signal from the control signal and the periodic timing signal, and the control signal is formed directly proportional to the ratio of the speed signal and the error signal (RU 2050575 C1 , 12.20.1995, G05B 13/02).

The known method as applied to inertial objects does not provide the required quality of regulation and reliability, since it does not provide for the possibility of using efficient control algorithms for such objects, for example, the PID law.

The closest in technical essence to the present invention is a method of automatic control with a pulse-width modulator and a positional actuator by converting the regulator to a control error in accordance with a given regulation law into a control action, further forming a series of pulses by the pulse-width modulator that move the actuator to the side “More” or “less”, affecting the object of regulation, as well as changes in the minimum length elnosti pulse based speed control module changes the error signal (RU 2325682 C1, 20.02.2007, G05V 11/28) (prototype).

The disadvantage of this method is the low quality of regulation of inertial objects due to the fact that the features of a specific regulation law are not taken into account, as well as the insufficient reliability of the regulation system in connection with the use of a modulation algorithm involving excessively frequent switching on of the actuator motor.

Disclosure of invention

The purpose of the invention is improving the quality of regulation of inertial objects and reliability.

This goal is achieved by the fact that, in contrast to the known technical solution, in the proposed method, in each modulation period, the increment of the discrete control action is calculated according to the regulation law according to the values of the control error at the boundaries of previous modulation periods and one control pulse is generated with a width proportional to the obtained increment, the magnitude of the modulation period is selected depending on the inertia of the object, and the time constant of the integral component of the law is regulated ings are set in proportion to the selected modulation period.

Description of drawings

The implementation and features of the proposed method are illustrated by drawings.

FIG. 1. Regulation scheme with ROME.

FIG. 2. The cycle diagram of the control ROME.

FIG. 3. Acceleration curves of the object and the approximating model.

FIG. 4. Transients at different modulation intervals.

a) T _M = 1 s; b) T _M = 4 s; c) T _M = 10 s.

FIG. 5. The effect of the choice of T _AND on transients at T _M = 30 s.

a) T _And = 15.3 s - optimal for continuous regulation;

b) Т _И = 46.5 s - calculated by the formula (4).

The implementation of the invention

The use of control systems using reverse actuators (ROM) has become widespread in industry. The control circuit with pulse width modulation (PWM) for the ROME, which implements the proposed method, is presented in FIG. one.

At the beginning of each modulation period, the increment of the control action U is calculated, for example, according to the discrete PID control algorithm, which we write in the following form:

where E = X ^ass -X - regulation error (in% of the variable scale);

i is the number of the modulation period;

T _M - PWM period, s;

K _P - coefficient of the proportional component of the regulation law;

T _I , T _D - time constants of the integral and differential components of the regulation law, p.

The obtained value of the increment ΔU _{i + 1} calculates the pulse width S _{i + 1} :

where T _ROME is the full stroke time of the actuator, sec.

The pulse is issued to the corresponding input of the ROME: “directly” or “back”, depending on the sign of the quantity ΔU _{i + 1} (see Fig. 2).

The main factors and parameters that determine the effectiveness of regulation in the systems under consideration are:

- dynamic characteristics of the control object;

- period of modulation;

- resolution, determined by the speed of the system (the time of issuing discrete effects on the electric drive and their response) and the time of full stroke of the ROME;

- settings of the regulation algorithm.

The method is based on the results of a study based on digital modeling and optimization by the integral criterion using, as an approximating model, a control object of the first order aperiodic link with delay, having the following transfer function:

where K _OB - gain;

T _EKV - time constant;

τ _EQ is the time of “pure” delay.

Such an approximation allows us to describe a wide range of inertial objects when the delay τ _EEC and the time constant T _EEC are not actual, but equivalent. In FIG. Figure 3 shows the transient process on the stepwise input effect for a complex inertial object (line 1) and its approximating model (line 2).

In the systems under consideration, the most important task is the choice of the modulation period T _M. Reducing T _M to a certain level increases the quality of regulation (static and dynamic accuracy), but reduces the reliability of the system due to an increase in the frequency of turning on the engine ROME. A further decrease in T _M , when resolution begins to affect, causes an increase in static error. The selection of a small value of T _{M is} also hindered by measurement errors and interference.

существенное ухудшение качества регулирования наступает, когда значение Т_М приближается к Т_ЭКВ. Выбор оптимального Т_М предлагается осуществлять в зависимости от инерционности объекта: чем медленнее процесс (большие Т_ЭКВ и отношение $$\frac{{\tau }_{ЭКВ}}{{Т}_{ЭКВ}}$$

), тем Т_М может иметь большее значение.The influence of the modulation period T _M on the quality of regulation is illustrated by examples of transients on the step change of the task for T _EQV = 20 s, τ _EQV = 10 s, T _ROME = 30 s (Fig. 4). The control settings here are set to equal values that are optimal by the integral criterion for continuous control with an analog actuator. When the ratio of the delay to the time constant of the object $$\frac{{\tau }_{E\mathrm{TO}\mathrm{AT}}}{T_{E\mathrm{TO}\mathrm{AT}}}=0.5$$

a significant deterioration in the quality of regulation occurs when the value of T _M approaches T _EQ . The choice of the optimal T _{M is} proposed to be carried out depending on the inertia of the object: the slower the process (large T _EQ and ratio $$\frac{{\tau }_{E\mathrm{TO}\mathrm{AT}}}{T_{E\mathrm{TO}\mathrm{AT}}}$$

), so T _M may be of greater importance.

постоянная времени интегральной составляющей может быть определена так:It was found that when implementing the proposed algorithm (1), the action of the integral component (in contrast to other components) largely depends on the selected period T _M. It is recommended to choose the coefficient T _AND proportional to T _M : for example, for an object (3) with the ratio $$\frac{{\tau }_{E\mathrm{TO}\mathrm{AT}}}{T_{E\mathrm{TO}\mathrm{AT}}}=0.5$$

the time constant of the integral component can be defined as follows:

- оптимальная настройка для непрерывного регулирования.Where $$T_{\mathrm{AND}}^{\mathrm{ABOUT}}$$

- optimal setting for continuous regulation.

This is especially effective for large periods of modulation. In FIG. 5 shows transients for T _M = 30 s:

a) at a setting optimal for the continuous controller (T _AND = 15.3 s);

b) with the adjustment specified by formula (4) (Т _И = 46.5 s).

The proposed method provides effective regulation using RIM with a sufficiently large period of modulation. Choosing an acceptable quality of regulation, you can achieve a significant increase in reliability.

The control calculations for inertial objects of a higher order with delay showed that the results obtained for the 1st order are also confirmed for more complex objects.

To implement the method, for example, the BAZIS-21.2PP control controller or another from the BAZIS® series manufactured by Ecoresource CJSC can be used. Implementation of the proposed method in commercially available BASIS® series controllers is scheduled for 2014-2015.

Claims (1)

A method of automatic control with a reversing actuator by determining a control error, generating, on the basis of pulse width modulation, a control action in the form of a bipolar series of pulses moving the actuator in the forward or reverse direction, characterized in that in order to improve the quality of regulation and reliability in each period modulations are calculated in accordance with the regulation law the increment of the discrete control action by the values of the regulation error Hovhan at the boundaries of previous modulation periods and generating a control pulse having a width proportional to an increment, the magnitude of the modulation period is selected depending on the inertia of the object, and the time constant of the integral component of the control law is set in proportion to the selected modulation period.

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