Patent ID: 8803489
Filing Date: 2014-08-12
Classification: H02M,Y02B,Y02P

Abstract:
1. A method of operating a power factor correction circuit, said method comprising steps of applying a cyclically varying voltage to an input of said power factor correction circuit, performing switching to control conduction of pulses of current at said cyclically varying input voltage to a filter/inductor at a frequency, which is sufficiently high to supply a predetermined current at a desired output voltage to a load, said switching defining a predetermined on-time and a predetermined off-time in accordance with said predetermined current and said desired output voltage and defining a switching cycle such that current through said filter/inductor is continuous in a continuous conduction mode, reducing said predetermined current supplied to supply a reduced current to said load, determining if said reduced current is less than one half of a current ripple produced by said switching on-time and off-time, and if said reduced current is less than one-half of said current ripple, reducing said frequency of said pulses by extending said off-time during at least a portion of a cycle of said cyclically varying voltage in accordance with said reducing of said predetermined current such that current through said filter/inductor is discontinuous in a discontinuous conduction mode.