I have used a TRIAC and an MOC3021 opto-coupler connected to a PIC16F887A to simulate a a full wave rectifier. I am now to design the same using an SCR h-Bridge. My question is, in order to trigger the SCRs, do i need 4 separate triggers for each SCR? or could i use two trigger pulses, one for each pair of the SCRs? I would appreciate any advice. am fairly new to the field. Thanks. The following is the layout of the circuit. Specs:220VAC, 60 Hz. Load 1Kohms. These were provided by my senior supervisor.
Answer for How to Trigger the SCRs.
You have to trigger U6 and U5 simultaneously. This causes current flow in the direction of u6-load-u5-neutral (return path) during Positive half cycle of input.
During Negative half cycle of AC input SCR U6 and U5 turned-off. Due to Natural Commutation.
And then you have to trigger U3 and U7 simultaneously. This time current take path U7-load-u3.
You can control the output Voltage by adjusting the Firing angle of SCRs
And also UJT Relaxation Oscillator with Pulse Transformer is good choice for firing this SCRs
it looks to me that U6 and U7 could share a common drive (via a pair of resistors to split the current.
U3 and U5 will be harder to drive and will probably need individual drive - could you replace them with ordinary diodes instead?