Download Fuzzy Logic Speed Controllers Using FPGA Technique For Three

‫بسم هللا الرحمن الرحيم‬
The Islamic University of Gaza
Faculty of Engineering
Electrical Engineering Department
POWER ELECTRONICS
EELE 5450 — Summer 2012
Instructor: Eng. Jalal Al Roumy
Lecture 13
Chapter Five
AC Line Voltage Control
Phase-Control technique give the simplest ac regulating system
and are the best known.
There are other methods by which thyristor control of ac lines
is possible:
Zero voltage switching
Ac chopper control
synchronous tap changing
Ac line voltage controllers are employed to vary the rms value
of the alternating voltage applied to a load by using thyristors
as a switch.
Chapter Five
AC Line Voltage Control
The applications of ac line voltage controllers include the
following:
 Lighting controls
 Induction heating
 Industrial heating
 Transformer tap changing
 Speed control of induction motor
Chapter Five
AC Phase Control With resistive Load
This circuit provides a fixed half-cycle of power and a power
control range of half-power minimum and full-power
maximum, but with a strong dc component.
Chapter Five
AC Phase Control With resistive Load
This circuit is back-to-back SCRs which allows symmetrical
control of ac voltage during both halves of the ac wave and
eliminates and dc component.
Chapter Five
AC Phase Control With resistive Load
The most simple, efficient and reliable method of controlling ac
power is by using the Triac. Triac is bidirectional device, and a
single control circuit is sufficient to control power flow in the
load during both halves of the ac input wave.
Chapter Five
Analysis of Full-wave controller : resistive Load
Chapter Five
Full-wave controller With Inductive Load
In actual practice most loads have some amount of inductance.
Motors, solenoids, transformers, and even some resistive heaters
have inductive components as apart of their impedance.
The effect of this reactance is that the rms-to-average-current
ratio is lowered. Higher average current can be passed through
the SCR.
With an inductive load , current flow is maintained through the
SCR even after the input voltage has reversed polarity and goes
negative. The duration of this interval is determined bu the
load power factor.
Chapter Five
Full-wave controller With Inductive Load
Chapter Five
Full-wave controller With Inductive Load
End of Lecture