Patent ID: 8228046

Claim:
An uninterruptable power supply, comprising: an input circuit including a first transistor and a first inductor, the input circuit being configured to receive an AC voltage at an input and provide a DC voltage at an output; a controller having a digital signal processor and a field programmable gate array, the controller being coupled to the input circuit to detect inductor current and to provide a detected inductor current value to the digital signal processor, the controller being configured to apply a pulse width modulation control signal to the first transistor to adjust a switching frequency of the first transistor to generate the DC voltage at the output; and wherein the first transistor forms part of a first boost converter circuit; wherein the second transistor forms part of a second boost converter circuit; wherein the input circuit includes a three phase rectifier; wherein the controller is further configured to apply the pulse width modulation control signal to the first transistor to switch a mode of operation of the first boost converter circuit between variable frequency just-discontinuous and fixed frequency continuous modes of operation during a first portion of a line cycle; and the controller is further configured to apply a second pulse width modulation control signal to the second transistor to switch a mode of operation of the second boost converter circuit between variable frequency just-discontinuous and fixed frequency continuous modes of operation during a second portion of the line cycle.