Working Principle of DC Chopper

Introduction of DC Chopper

The main function of the DC chopper is to convert fixed DC voltage into variable DC voltage. It is similar to DC transformer.

Principle of DC Chopper

The function of the DC chopper is to convert fixed DC into variable DC. A DC chopper is connected between supply source and load. 

The variable output voltage is obtained by switching on and off SCR at regular interval. The on and off time of the SCR is in the micro second. When the SCR is switched ON during T_ON time, the output voltage across load is V_dc.  The output voltage across load becomes zero when the SCR is switched OFF during T_OFF time. 

Principal of DC Chopper: Duty Cycle

The average output voltage across load depends upon switching time  ( Turn on time + Turn off time ) of the SCR.

V_O = ( T_ON / T_ON + T_OFF ) V_dc

= (T_ON / T) V_dc

                    = K V_dc

                 Where V_O = Output voltage

V_dc = Input voltage

T_ON = Chopper on time

          T_OFF = Chopper off time

T = Chopper time period

K = Duty cycle

If K > 1, Step up chopper

K < 1, Step down chopper

The DC chopper works as DC transformer and variation of output voltage is obtained by duty cycle.

Principal of DC Chopper: Circuit Diagram and Waveforms

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