Instructor: Eng.Moayed N. EL Mobaied بسم الله الرحمن الرحيم The Islamic University of Gaza Faculty of Engineering Electrical Engineering Department POWER ELECTRONICS EELE 5450 — Fall 2009-2010 Instructor: Eng.Moayed N. EL Mobaied Lecture 4

Series and Parallel operation Chapter Two Series and Parallel operation In many applications, the power handling capability of a single power diode is not sufficient. (HVDC applications).

Series and Parallel operation Chapter Two Series and Parallel operation Series and parallel combination of diodes are essentially for handling the high voltage and high current necessary in such applications. Steady-state and transient voltages must be equally shared when diodes are connected in series. When diodes are connected in parallel, each diode must share the total load current equally, both under transient and under steady state conditions.

Series operation of diodes Series-Connected Diodes Chapter Two Series operation of diodes Series-Connected Diodes

Chapter Two Series operation of diodes Series-Connected Diodes with Voltage Sharing

Series operation of diodes Is=Is1+IR1=Is2+IR2,IR1=VD1/R1,IR2=VD2/R2 Chapter Two Series operation of diodes Is=Is1+IR1=Is2+IR2,IR1=VD1/R1,IR2=VD2/R2

Series operation of diodes Chapter Two Series operation of diodes More than two diodes

Chapter Two Series operation of diodes Series-Connected Diodes with Dynamic Voltage Sharing

Chapter Two Example: Find the diode voltages if R1 = R2 =R = 100 k Find the voltage sharing resistancesR1 and R2 for equal diode voltages

Chapter Two Example: Find the diode voltages if R1 = R2 =R = 100 k Vd1=2750V Vd2=2250V Find the voltage sharing resistancesR1 and R2 for equal diode voltages Let R1=100k R2= 125K

Parallel-Connected Diodes Chapter Two Parallel-Connected Diodes End of Lecture **** Eng.moayed