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Regulators

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Regulators

Regulators are devices that are used to bring a controlled object to the desired state or to improve its unfavorable parameters. The controller generates the appropriate control signal and the controlled object behaves as expected.

Regulators - important elements of regulation systems

Although the control systems (circuits) consist of several elements, the only device influencing the value of the control signal is automatic regulator , whose task is to properly adjust the value of the control signal depending on the amount of time. The dynamics of the regulated circuit (of the system) and, consequently, its stability and control quality also depend on the value of the controller output signal.

What are the components of a typical control circuit?

It is worth knowing that regulation is a special case of control. There are two types of control in automation:

  1. in an open layout,
  2. in a closed loop with feedback (that is, regulation).

Open circuit control consists in the fact that the output signal of the controlled object is not monitored and can have different values. On the other hand, in closed loop control, the output signal of the object is monitored and thus the input signal of the controlled object is modified.

A typical control system consists of several elements:

  1. adder,
  2. regulator,
  3. of an actuator (e.g. actuator or valve),
  4. of the controlled object,
  5. of the measurement system (eg transducer or sensor).

How do regulators work?

The input of the control circuit is independently supplied with set signal, the parameters of which are the pattern for the signal controlling the given object in the system.

The reference signal arrives at a comparer (adder) where the signal is compared with the feedback signal generated by the feedback circuit from the output signal from the controlled object. The difference, i.e. The control deviation is the signal fed to the controller input. The controller compares the value of the error with the value of the control signal, adjusting it to the appropriate parameters and feeding the actuator to the input, which in turn sends the signal to the input of the controlled object (the so-called extortion). Here the signal value is measured and fed to the adder input, and the whole process starts all over again.

Criteria for the division of regulators

Regulators can be divided according to the type of energy causing the operation of the device into:

  1. direct action regulators - using mechanical energy (e.g. radiator thermostat),
  2. regulators for indirect action - using electric, pneumatic or hydraulic energy.

Another division can be made taking into account the purpose of devices and distinguishing universal and specialized regulators, as well as with regard to the form of the output signal. The following stands out in this group:

  1. controllers with an output signal of discontinuous operation (analog or digital), e.g. two-state, three-state - these are electrical controllers used, for example, in air conditioning systems,
  2. controllers with a continuous output signal (analog or digital), which allow for any signal value within the assumed range. They are usually made of electronic op-amps.

Regulation algorithms

Selection of automatic regulators with continuous operation depends to the greatest extent on the required time response in the control circuit and the control accuracy. The control signal at the controller output is generated based on the data of the error signal. This, in turn, can be processed by the controller using three elementary operations:

  1. reinforcements (P),
  2. integration (I),
  3. derivative (D).

The implementation of elementary operations has its consequences for the signal, e.g. its integration reduces the dynamics of the controlled cycle, and the differentiation - limiting the system only to transient states. Therefore, in practice, proportional (P), proportional - integral (PI), proportional - derivative (PD) and proportional - integral - derivative controllers are used, i.e. PID controllers .