Improved Pulse Delay Circuit for Phase-Controlled Rectifiers and Ac Voltage Controllers

The paper presents a new method of synchronization of the pulse delay control circuits for, triggering thyristors in line commutated converters, where an exact 180° phase difference is ensured between the firing ing pulses sent to the thyristors in the same mains phase. In 3-phase systems, it provides small deviation from the desired ± 120° difference with respect to the other two phases. The delay angle is, proportional to the control voltage; and can be varied throughout the appropriate interval for phase controlled rectifiers and AC voltage controllers. The circuit consists of integrated linear and logic elements and is suitable both for manually-controlled and closed-loop systems.