Transcript lecture23

‫بسم هللا 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 23
STEP-UP CHOPPERS
The chopper can be used to step up voltage as well as to
step it down; it behaves in fact like a d.c. transformer.
STEP-UP CHOPPERS
When the transistor is switched on, current ramps up in the inductor
and energy is stored. When the transistor is switched off, the
inductor voltage reverses and acts together with the battery voltage
to forward bias the diode, transferring energy to the capacitor.
STEP-UP CHOPPERS
When the transistor is switched on again, load current is maintained
by the capacitor, energy is stored in the inductor and the cycle can
start again. The value of the load voltage is increased by increasing
the duty cycle or the on-time of the transistor.
Error1:
D=tn/T
Error2:
Vo=vb(1+DT/T
T(1-D).
STEP-UP CHOPPERS
When the steady variation of battery current has been
reached, the variation will be between Io and I1
STEP-UP CHOPPERS
STEP-UP CHOPPERS
STEP-UP CHOPPERS
End of Lecture