POWER ELECTRONICS Instructor: Eng.Moayed N. EL Mobaied The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department بسم الله الرحمن الرحيم EELE 5450 — Fall Lecture 14

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

Chapter Five Ө > φ

Chapter Five Ө < φ

Chapter Five Triggering by pulse train synchronization

Chapter Five Motor application

Chapter Five Zero Voltage Switching The control of rms ac voltage to the load could also be Achieved by changing the on and off periods of the ac Input wave to the load. There are basically two methods of control: On-off control Proportional control

Zero Voltage Switching

Synchronous tap changing If a small variation of ac output voltage is required, then the taps of a transformer would be changed by switching thyristors in the proper manner. End of Lecture **** Eng.moayed