POWER ELECTRONICS
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POWER ELECTRONICS Instructor: Eng. Jalal Al Roumy The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department م ي ح ر ل ا ن م ح ر ل ه ا ل ل م ا س بEELE 5450 — Summer 2012 Lecture 13
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بسم الله 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. - PowerPoint PPT Presentation
Transcript of POWER ELECTRONICS
POWER ELECTRONICS
Instructor: Eng. Jalal Al Roumy
The Islamic University of GazaFaculty of EngineeringElectrical Engineering Department
الرحمن الله بسمالرحيم
EELE 5450 — Summer 2012
Lecture 13
Chapter Five
AC Line Voltage ControlPhase-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 switchingAc 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 ControlThe 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
