US Patent 10097035 Uninterruptible power supply unit

An uninterruptible power supply unit includes: an input/output terminal connected in parallel with a power supply line which supplies power from an external power supply to a load device; a battery unit whose rated voltage is a voltage equal to a voltage of the external power supply; a DC/DC converter for converting the voltage of the external power supply into an output voltage corresponding to a difference between the rated voltage of the battery unit and the charging voltage of the battery unit; a charging circuit for charging the battery unit with a voltage equal to the voltage of the external power supply added with the output voltage of the DC/DC converter; and a discharging circuit that discharges power to the load device from the battery unit through the input/output terminal in the event that the external power supply is interrupted.