0195136047.pdf

16.5 PRACTICAL APPLICATION: A CASE STUDY 815

• Basic notions of power semiconductor devices and analysis of power electronic circuits.


• Solid-state control of dc motors.


• Solid-state control of induction motors.


• Solid-state control of synchronous motors.


• Transfer functions and block diagrams of feedback control systems.


• Dynamic response of control systems.


• Steady-state error of linear systems.


• Error-rate control, output-rate control, and integral-error control.


• Elementary concepts of digital control systems and their applications.

16.5 PRACTICAL APPLICATION: A CASE STUDY

Digital Process Control

Figure 16.5.1 shows a block diagram for microcomputer-based control of a physical process, such
as a chemical plant. A slight variation of the system can be used for automotive instrumentation
in which sensors furnish various signals for speed, fuel reserve, battery voltage, oil pressure,
engine temperature, and so on. The data are presented to the driver in one or more displays on
the dashboard. In a physical process on the other hand, based on the display information, an
operator can assess and direct the operation of the control process through a keyboard or other
input devices to the microcomputer.
Various physical inputs, such as power and materials, are regulated by actuators, which
are in turn controlled by the microcomputer. Electric signals related to the controlled-process
parameters, such as pressure and temperature, are produced by various sensors, which in turn

Analog

sensors

A/D

converter

D/A

converter

Display

information

Operator

inputs

Microcomputer

Physical inputs

Acuators Contolled

Analog Digital process Product output

Digital

sensors

Figure 16.5.1Block diagram for miocrocomputer-based control of a physical process.