Switch mode power supply with reduced input current distortion

A switch mode power supply, comprising:

• a source of an AC, mains supply voltage and an AC, mains supply current;
• a filter capacitor;
• a first rectifier coupled to said mains source and to said capacitor for rectifying said mains supply voltage to develop current pulses in said capacitor at a frequency that is related to said frequency of said mains supply voltage for producing a second supply voltage at a terminal of said capacitor, said capacitor current pulses producing a distortion in said mains supply current that tends to decrease a power factor associated with said mains source;
• means coupled to said capacitor for lengthening a pulse-width of a given current pulse and for decreasing a peak amplitude of said given current pulse so as to reduce the distortion and increase the power factor;
• first switching means responsive to a first switching signal for generating in an inductance that is coupled to said mains source, a first plurality of current pulses at a substantially higher frequency than said frequency of said mains supply voltage, said first plurality of current pulses being coupled via a rectifier to produce a first portion of a rectified output supply current, said first plurality of current pulses having magnitudes that vary during a period of said mains supply voltage in accordance therewith in a manner to increase said power factor;
• and
• second switching means responsive to a second switching signal for generating, in an inductance that is coupled to said terminal where said second supply voltage is developed, a second plurality of current pulses at a substantially higher frequency than said frequency of said mains supply voltage, said second plurality of current pulses being coupled via a rectifier to produce a second portion of said rectified output supply current, in a manner to reduce a ripple component at an output of said power supply.

A switch mode power supply, comprising:

• a source of an AC, mains supply voltage;
• a filter capacitor;
• a first rectifier coupled to said mains source and to said capacitor for rectifying said mains supply voltage to develop current pulses in said capacitor for producing a rectified, first supply voltage in said capacitor;
• means coupled to said capacitor for lengthening a pulse-width and decreasing a peak amplitude of a given current pulse in said capacitor;
• first switching means coupled to said first supply voltage and responsive to a first switching signal for developing in an inductance that is coupled to said capacitor a first plurality of current pulses at a frequency that is substantially higher than that of said mains supply voltage, said first plurality of current pulses being coupled via a rectifier to produce a first portion of a rectified output supply current;
• a second rectifier coupled to said mains source for rectifying said mains supply voltage to develop a rectified, second supply voltage;
• and
• second switching means responsive to a second switching signal and coupled to an inductance having applied thereto said second supply voltage for developing a second plurality of current pulses at a frequency that is substantially higher than that of said mains supply voltage via a current path that bypasses said capacitor, said second plurality of current pulses being coupled via a second rectifier to produce a second portion of said rectified output supply current.