Single pulse half wave thyristor controller - is for control of DC motor reversals and has extended phase angle control for braking purposes

摘要

The dc motor (M) is connected to an ac supply (U) via a half wave thyristor rectifier. Two thyristors in anti-parallel connection (n1,n2) are provided in order to permit control in both directions of motor rotation. The thyristors are under the control of a phase shifter (St). In order to permit finer braking the phase angle control is extended to 270 deg. by employing the thyristors not normally conducting for the direction of rotation in question. - By using both thyristors in this manner discontinuities in motor current are largely avoided and smooth braking even at quite low current values made possible. Control is improved in the extended range if a saw tooth waveform generator (SG) is provided to set the firing instant.