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 28

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

End of Lecture