SELF-POWERED SCR GATE DRIVE CIRCUIT WITH OPTICAL ISOLATION

摘要

The SCR gate driver circuit provides a continuous gate current whenever there is sufficient anode-to-cathode voltage difference across the SCR. This approach herein eliminates the need to monitor and reapply SCR gate current after each commutation due to load current distortions. A self-powered SCR gate drive circuit for driving an SCR device, connected between a voltage source (VA) and a load. A current regulating means (Q2, Q3, Q4) is coupled between the anode and the cathode of said SCR, having an input terminal and has a current output terminal connected to the gate of said SCR, for providing gate drive current (IG) to said SCR in response to a signal at said input terminal. A photo transistor (IC1b) is coupled between said input terminal of said regulator and said voltage source, having a switchable light source (IC1a) proximate thereto connected to an input control signal source (VC), for providing an energizing signal to said regulator in response to a signal from said control signal source. Said regulator and said photo transistor powered by said voltage source.