Uninterruptible power supplies

摘要

PCT No. PCT/GB96/00103 Sec. 371 Date Aug. 26, 1997 Sec. 102(e) Date Aug. 26, 1997 PCT Filed Jan. 18, 1996 PCT Pub. No. WO96/22627 PCT Pub. Date Jul. 25, 1996An uninterruptible power supply which is advantageous for use with a computer receives power alternatively from a utility main power source or a rechargeable battery. The uninterruptible power supply includes an input for receiving AC utility power, an AC to DC converter coupled to the input, receiving AC power from the input, having at least one regulated D.C. output, and generating DC power at an output of the converter, a transformer having a primary winding and a secondary winding, an inverter coupled between the AC to DC converter and the primary winding of the transformer and arranged to supply a chopped DC voltage to the primary winding to cause a corresponding chopped DC voltage having an amplitude Vs to be generated across a secondary winding of the transformer coupled to the output, an auxiliary power supply having an energy store having a supply terminal that is operable at a voltage Vb, and a diode isolation circuit coupled between a supply terminal of the energy store and the secondary winding. The diode isolation circuit is arranged to be in a non-conductive state when Vb is greater than Vb to isolate the energy store from the secondary winding and in a conductive state when Vb is greater than Vs to supply current through the diode isolation means to the secondary winding.