Control System to Turn On And off Battery Backup

Control System to Turn On And off Battery Backup

       A control system optimizes the use of a battery backup
unit. The system only uses batteries when the power supply can no
longer keep the output voltage up.  This increases the batteries
life/reliability and saves battery power until it is really needed.
It also will not turn batteries on into a fault condition, and it
controls both on and off transitions smoothly.

      The control system senses the AC line voltage and the DC output
so the batteries do not turn on during AC line dips that the power
supply could handle without battery backup.

      This control system is used to turn on and off a battery backup
unit for a  volt power supply.  The control system controls the on
and off transitions, eliminates unneeded battery usage, and protect
the batteries from turning on during a fault condition.  A block
diagram of the control system is shown in Fig. 1.

      Under normal running conditions, both "AC bad" and "battery UV"
lines are low.  In this state, the batteries are off.

      If the AC line dips below its normal operating range, the "AC
bad" line goes high.  If the AC dip is long enough or deep enough
that the power supply is unable to keep the volt output above the
battery UV range, the "battery UV" line goes high.  The output of
"B3" goes high, causing the batteries to turn on and, after a delay,
the "delayed battery on" line goes high.  The delay is used to give
the batteries...