1. Dr. Unnikrishnan P.C. Professor, EEE
EE305 Power Electronics
Dr. Unnikrishnan P.C.
Professor, EEE

2. Step-Up Chopper

3. Step-Up Chopper Chopper Switch kept ON for tON .
The inductor current increases and energy is stored in the inductor
As the chopper is turned OFF at t= tON, the free wheeling diode is forward biased. The energy stored in the inductor and source voltage cause a current through the diode and the load.
The energy stored in the inductor is thus transferred to the load
Voltage appearing across the load is (VS+vL) , hence the name step-up Chopper

4. Analysis Mode 1:Chopper switch is turned ON

5. Analysis Mode 1:Chopper switch is turned ON

6. Analysis Mode 2:Chopper switch is turned OFF

7. Analysis Mode 2:Chopper switch is turned OFF
Since 0<  <1, the output voltage, VO is always greater than the supply voltage, VO. When =0, VO = VS

8. Output Voltage Vs Duty Ratio