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 2Vm sin a and load current is transferred from
T2 to T1,, T1 conducts from α to ( Π + α).