Single Phase Half Control Bridge with circuit details. It has two SCR’s T1(SCR1) and T2(SCR2) and two diodes D1 and D2. During the positive half-cycle of the ac supply, SCR T1 and diode D1 are forward biased. When the SCR T1 is turned-on at a firing angle alpha, supply voltage Vs appears across the load, i.e Vo Vs. The load current i0 flows through the path L-T1-load-D1-N.
During the negative half cycle of the ac supply, SCR-D2 and diode D2 are forward biased. When SCR T2 is turned on at a firing angle, the current would flows through the path N-T2-load-D2-L. This load current is continuous until the SCR T2 is turned off by reversal of supply voltage. Then T1 is triggered again and complete cycle repeats from pulse circuit.