Patent ID: 7323827
Filing Date: 2008-01-29
Classification: H02M,H05B,Y02B

Abstract:
1. A continuous mode electronic ballast for operating a lamp comprising: a rectifying circuit which converts an alternating current (AC) voltage to a first direct current (DC) voltage; a filter which filters the first DC voltage and outputs the filtered first DC voltage, which includes an alternating current (AC) voltage component or ripple voltage, at filter output; a buck converter operationally coupled to the filter output, which buck converter receives the filtered first DC voltage and generates a second direct current (DC) bus voltage; a power control circuit operationally coupled to the buck converter, which power control circuit provides a control voltage signal to the buck converter so that the buck converter generates the second DC voltage of a predetermined value; and a ripple detection circuit operationally coupled to the filter output, which ripple detection circuit detects the ripple voltage in the filtered first DC voltage and modifies the control voltage signal so that the second DC voltage includes a predefined level of the ripple voltage; and wherein the level of the ripple voltage is less than 5% of the average amplitude of the second DC voltage.