High performance single-chip gating circuit for a phase-controlled bridge

The increasing availability of single-chip low cost microcontrollers has made it possible to reconsider conventional hardware designs for a variety of gating circuits. This paper, in particular, presents the design of a gating circuit for a six-pulse phase-controlled bridge utilizing a single-chip programmable microcontroller. The dynamic performance of the proposed gating circuit is similar to an analog circuit implementation. The resolution of the firing angle is better than 0.1 degrees at 60 Hz. Moreover, the system is designed to operate over a frequency range of 3 Hz to 120 Hz, and to automatically adapt to changes in line frequency. The experimental verification of the performance criteria are also presented. Finally, an example of a special application for a dual-bridge AC to DC converter is presented