DC to DC Boost converter (PSPICE)

Supppose you have 5 volts battery . Ever wondered how to convert it to 12 volts?. With maximum efficiency?Hmmm, Yes, it is possible with Boost converter.
The basic diagram of boost converter is here

 Ok it basically has
Power supply
Inductor
Diode
Switch

  case 1) If switch is closed

When the switch is closed. you can see only inductor is in path betwenn voltage source. So VL=vin,where

VL=Ldi/dt.So current il flows through the circuit as shown above.

Basic idea : As we know Inductor resists the change in the current. If current is changed instantaneously it will try to increase its own voltage to bring back the original current.Thats the reason we use flyback diode in any transistor circuit, having relay in collector part. Or say this circuit with open switch.

If switch is opened suddenly, we are literally pushing current  to zero, which inductor will resist. So,  it will generate more voltage to maintain that current. We use this same idea in boost converter.

2) IF switch is Open

When the switch is open, current flowing now will be less than what it was in the first scenario( case 1)(Because of increased load), but inductor will resist this change in the current.So only way it can do so, is to increase the voltage in the circuit. So, voltage polarity changes as shown above.  Vi+Vl will appear across the load.

Need of a Diode : The load usually is capacitor, when switch is off, Capacitor  is charged to  Vi+VL .  If switch was closed and there were no diode, the capacitor would discharge it via that path.So this Diode isolates Left and Right path when the switch is closed.

Here is the Pspice simulation of Boost converter

The output is not constant because it is in discontinuous mode which is out of scope as far as this discussion is concerned. For now, we saw that Inductor is primarily responsible for stepping up the voltage in the circuit. Visit edaboard.com for more details on this subject. I will try to write a post on this topic at some other time.