17 March 2017

Speed Control of DC Series Motor By Chopper

  • The speed control of DC series motor by using chopper is shown in the figure A. 
  •  This speed control is achieved through constant frequency control or variable frequency control.
  • When chopper CH is switched on, the DC motor gets input supply voltage Vdc
  • The DC motor does not get any voltage when chopper CH is switched off. 
  • The load current completes its path through freewheeling diode or we can say that stored energy of inductor dissipates in the freewheeling diode during chopper turn off time.
  • The average output voltage across load is
                         VO = [ TON / ( TON + TOFF ) ] Vdc
                              = ( TON / T )Vdc     
                        VO = KVdc
  • The voltage across load can be adjusted to any value by switching chopper with suitable time interval.

speed control of dc series motor by chopper

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