How to make a full wave rectifier using SCR ?
For full-wave rectification two SCRs are connected across the centre taped secondary, as shown in figure-a. The gates of both SCRs are supplied from two gate control supply circuits. One SCR conducts during the positive half cycle and the other during the negative half cycle and thus unidirectional current flows in the load circuit. The main advantage of this circuit over ordinary full-wave rectifier circuit is that the output voltage can be controlled by adjusting the gate current.
Now if the supply voltage v = VMAX sin θ and the firing angle is a, then average voltage output will be given by the expression
Vav = VMAX / ∏ (1 + Cos α)
That is, average voltage output of full-wave rectifier circuit is double of that of half-wave rectifier circuit, which is obvious.
Iav = VMAX / ∏RL (1 + Cos α)