Three Phase Fully Contolled Bridge Rectifier

The circuit consist of 6 thyristors, T1, T2, T3, T4, T5, T6, a three phase supply and a RL load.
 The thyristors T1, T3, T5 form the positive group.
 The thyristors T4, T6, T2 form the negative group.
 Thyristors T1, T3, T4, T6 produces the full wave recitified output of Vab across the load.
 Thyristors T3, T5, T6, T2 produces the full wave recitified output of Vbc across the load.
 Thyristors T1, T5, T4, T2 produces the full wave recitified output of Vca across the load.
 All these 3 outputs are given simultaneously to the same RL load. The effect is that all the 3
individual output mentioned above gets superimposed on each other to get the final output.
 The waveform of the output for different firing angles are shown below.
 The average output voltage can be varied by varying the firing angle.
 For firing angle < 90, the circuit works as rectifier.
 For firing angle > 90, the circuit works as Line commutated inverter.