POWER ELECTRONICS Instructor: Eng. Jalal Al Roumy The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department بسم الله الرحمن الرحيم EELE 5450 — Summer 2012 Lecture 9

Chapter Four Phase-Controlled Rectifiers (AC-DC) The thyristor switches allow forward current to be turned on at arbitrary times. But do not permit turn-off or commutation with out special turn-off circuitry. In normal AC-DC conversion the thyristor could be operated : 1- Natural commutation mode. ”when Vak < 0” (Easy to design) ( used in DC Motor drivers) 2- Forced commutation mode.

Chapter Four Basic controlled Rectifier circuits Assume that Peak supply voltage never exceeds the forward and reverse blocking rating.

Chapter Four Basic controlled Rectifier circuits 1- One voltage drop 2- Symmetrically PWM(SPWM) alpha=beta

Chapter Four Average Dc voltage value across resistance load

Chapter Four RMS voltage across resistance load

Chapter Four Average Dc voltage & RMS across resistance load

Chapter Four Half-Wave controlled rectifier with inductive load

Chapter Four Single Phase full-wave circuit (resistive load)

Chapter Four Single Phase full-wave circuit (resistive load) End of Lecture