Single Phase Full Wave Mid Point Type  Rectifier

A single  phase full wave  mid point  type controlled  rectifier consists  two  thyristors  one centre tapped  transformer  and a RL load  as shown in figure.

 Here O is the  point of secondary winding  of transformer  and turns ration from  primary  to each secondary is unity. Let  the output  current is continuous. For  positive  half  cycle of the input voltage terminal a will be positive  with respect ot O and terminal O will be positive with respect to terminal b.

In this  condition thyristor  T₁ is  forward biased. For  negative half  cycle  of  input  voltage  thyristor T₂ will be  conducing when  gate  pulse is applied to its gate terminal. Let  us suppose T₂ is already conducting. After  positive  and T₁  remains in forward  biased .when  gate pulse is applied to T1 at = a it will get turned on and T₂  get tumed off with  reverse voltage  2_Vm sin a and  load  current  is transferred  from

T₂ to T₁,, T₁ conducts from α to ( Π + α).