Buck Converter ( Step Down Converter )

 

Definition of step down converter?

In buck converter advantage output voltage is lass then the input voltage , Thus it’s called step down converter.

 

The transistor acts as a Switch . The pulse is to be given thought external circuit because if the pulse generator  has same source as convertor, there is probability of short circuit which may damage entire circuit.

When switch closed KVL gives, Vs = VL + V0 , VL= Vs – V0  [Diode R.B.]

When Switch open VL+V0 =0, VL= -V0   [Diode F.B.]

Inductor will keep following switch current when the switch open because pulse provide the path of the current along inductor to be de-energized capacitor is large so that  V0 is constant.

 

 

 

 

Working process of buck converter / step down converter

Step-Down Converter Working process is two mode : 

 1. Switch Open

2. Switch Closed.

 

Mode 01: Switch Open                

  (t=0=ton / DT)

                                                               

Diode is R.B                 Open Inductor energized

 

 

Mode 02: Switch Closed            [t=Ton=T]

In this mode inductor will supply voltage to load.

 

 

 

 

For steady state Operation, net change inductor current over one period is zero.