1. 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
Instructor: Eng.Moayed N. EL Mobaied
Lecture 4

2. 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).

3. 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.

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

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

6. 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

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

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

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

10. 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

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