Phase synchronization and control circuit

Abstract From the Canadian patent

Abstract of the disclosure, A circuit for generating control signals used in detecting a power failure in an uninterruptible power supply in which the A. C. signals of the power supply are examined to output a first signal representing the zero crossing of the A. C. signals. This first signal is used to reset an oscillator whose output clock signals are synchronized with the frequency of the A. C. signals by a phase lock loop circuit. The clock output of the phase lock loop circuit operates a counter whose output count is used to address a programmable read-only memory which outputs binary bits to a digital-to-analog converter which in turn outputs a full wave rectified sine wave operating …