In this circuit six diodes, Q3 transformer whose primary delta winding and secondary is star winding is used. The rectifier consist on D4, D5 and D6 are conducts during +ve half cycle of 3 phase - i/p supply, the diodes D1,D2 and D3 are conducts during the –ve half cycle. The upper three diodes D1,D2,D3 are produce –ve o/p while the diodes D4,D5 and D6 produce +ve o/p.
As clear from the figure that the +ve terminal of load is connected to the cathode of D4,D5 & D6 while the anode of these diodes are connected with i/p supply. The –ve terminal of load is connected with the anode of D1, D2 & D3, while the cathodes are connected with i/p supply. It may be seen that each secondary terminal is connected to the anode of one diode and cathode of the other diode. Thus diode D1 & D4 are connected to faze “A” of the secondary. However the diodes D1& D4 are connected to the same phase but do not conduct at the same time because the phase have +ve and –ve peaks at the same time.
The figure also shows the o/p wave from of 3 phase. Full wave form of voltage at anode D1,D2 & D3 while the curve 4,5, 6 shows the wave form of diodes D4,D5& D6 respectively.