초록 ▼

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

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 at the system frequency which is used as a reference to detect the occurrence of a power failure in the main source of A.C. power signals. A second control signal is generated indicating a power failure condition which is used in switching an inverter into the power supply for supplying A.C. signals to a load.

대표청구항 ▼

In an uninterruptible power supply which includes a main source of A. C. signals and an inverter for supplying A. C. signals from a D. C. source to a load upon failure of the main source to supply A. C. signals to the load, a circuit for generating control signals used to disable the main source fro

In an uninterruptible power supply which includes a main source of A. C. signals and an inverter for supplying A. C. signals from a D. C. source to a load upon failure of the main source to supply A. C. signals to the load, a circuit for generating control signals used to disable the main source from supplying A. C. signals to the load and for synchronizing the enabling of the main source to supply A. C. signals to the load comprising: means for sensing the voltage level of the A. C. signals to the main source; first means connected to said sensing means for comparing the voltage level of the A. C. signals to a zero voltage level for outputting a first control signal upon the occurrence of the coincidence; oscillator means connected to said comparing means for outputting a plurality of first clock signals in response to receiving said first control signal; a phase lock loop circuit connected to said oscillator means for outputting a plurality of second clock signals in response to receiving said first clock signals; counting means connected to said phase lock loop circuit for outputting a count in response to receiving each of said second clock signals; programmable memory means connected to said counting means for outputting a plurality of binary signals in response to receiving said count; and means connected to said memory means for converting said binary signals to a referenced A. C. signal for use in detecting the failure of the main source to supply A. C. signals to the load.