Abstract:
A negative resistance circuit such as a pulse-forming or relaxation oscillator circuit employing a unijunction transistor as the negative resistance element and adapted for firing an SCR or the like. The tendency of the negative resistance element to fail to recover to non-conducting condition after it has been triggered into conduction, due to a low valley current characteristic, is overcome by an improved recovery circuit that uses the interbase current to reduce the input current.
Abstract:
A single-phase full-wave regenerative SCR (silicon controlled rectifier) drive having a series and shunt, T-network, reactor configuration, minimum firing of both forward and regenerative SCR''s, and current feedback regulation. The reactor configuration along with the controlled minimum firing angle assures continuous current through the motor armature over substantially the entire load range except for the low 10 to 20 percent whereas normally continuous current occurred only in about the upper half of the load range. This allows the current regulator to be designated for continuous current rather than discontinuous current, having higher gain, and affording better control. By continuous current, heating also is reduced.