Patent ID: 6198257
Filing Date: 2001-03-06
Classification: H02M,Y10S

Abstract:
A transformerless uninterruptible power supply for providing motor starting currents in excess of rated operating currents comprising:AC power input terminals for receiving an AC power input signal;DC power input terminals for receiving a DC power input signal;AC power output terminals for producing an AC power output signal;a power conversion circuit for generating backup AC power output signal from a DC power input signal comprising:a control element;a transformerless DC-to-DC boost regulator, coupled to the control element, including a plurality of switched transformerless boost stages coupled in series for receiving a DC input signal and producing a boosted DC power signal wherein at least one of the stages comprises a series coupled inductor and a diode for substantially providing applied DC power, from the DC power input terminals, as the boosted DC power signal, when the inductor saturates due to an AC motor starting current being drawn from the AC power output terminals, anda transformerless DC-to-AC converter coupled to the transformerless DC-to-DC boost regulator and the control element, for receiving the boosted DC power signal and generating a backup AC power output signal;a sense circuit coupled to the AC power input terminals for sensing the integrity of the AC power input signal; anda switch circuit coupled to the AC power input terminals, the power conversion circuit for receiving the backup AC power output signal, and the sense circuit, wherein the switch circuit couples the AC power input signal to the AC power output terminals when the integrity of the of AC power input signal is above a predetermined threshold, and couples the backup AC power output signal to the AC power output terminals when the integrity of the AC power input signal is below a predetermined threshold.