Switch mode power supply with reduced input current distortion

A switch mode power supply, comprising:

• a source of an AC, mains supply voltage;
• a flyback transformer;
• a rectifier coupled to said mains source for rectifying said mains supply voltage to develop in a first winding of said transformer a first rectified supply voltage such that said rectified supply voltage is developed without low-pass filtering with respect to a frequency and low order harmonics of said mains supply voltage;
• first switching means responsive to a switching signal at a frequency that is substantially higher than a frequency of said mains supply voltage for generating a first plurality of current pulses in said first winding;
• means generating a second supply voltage;
• and
• second switching means coupled to said transformer and synchronized to said first switching means for coupling said second rectified supply voltage to said transformer and for decoupling said first rectified supply voltage from said transformer to generate in said transformer from said second rectified supply voltage a second plurality of current pulses, such that a given current pulse of said first plurality of current pulses and a given current pulse of said second plurality of current pulses occur, during a given period of said switching signal, said first and second pluralities of current pulses being transformer-coupled via said transformer to a load circuit to develop in said load circuit an output supply voltage and an output supply current.

A switch mode power supply, comprising:

• a source of an AC mains supply voltage and an AC mains supply current;
• first switching means 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 current pulses being coupled via a rectifier to an output of said power supply 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 with said mains supply voltage and in a manner to increase a power factor associated with said mains source;
• a filter capacitor;
• a rectifier coupled to said mains source and to said capacitor for rectifying said mains supply voltage to develop a second plurality of current pulses in said capacitor at a low frequency that is related to said frequency of said mains supply voltage and that is of substantially lower frequency than that of said first plurality of current pulses for producing a rectified second supply voltage at a terminal of said capacitor;
• and
• second switching means for generating, in an inductance that is coupled to said capacitor terminal, a third plurality of current pulses at a substantially higher frequency than said frequency of said mains supply voltage, said third plurality of current pulses being coupled via a rectifier to said output of said power supply to produce a second portion of said rectified output supply current, in a manner to reduce a ripple component at said output of said power supply.

A switch mode power supply, comprising:

• a source of an AC mains supply voltage and an AC mains supply current;
• a rectifier coupled to said mains source for developing a second supply voltage at a terminal;
• first switching means 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 current pulses being coupled via a rectifier to an output of said power supply 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 with said mains supply voltage and in a manner to increase a power factor associated with said mains source;
• and
• second switching means for generating, in an inductance that is coupled to said second supply voltage terminal, a second plurality of current pulses at a substantially higher frequency than said frequency of said mains supply voltage, such that a given current pulse of said second plurality of current pulses occurs close in time to a corresponding current pulse of said first plurality of current pulses, said second plurality of current pulses being coupled via a rectifier to an output of said power supply to produce a second portion of said rectified output supply current in a manner to reduce a ripple component at said output of said power supply.

A switch mode power supply, comprising:

• a source of an AC mains supply voltage;
• a rectifier coupled to said mains source for developing a second supply voltage at a terminal;
• first switching means 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 current pulses being coupled via a rectifier to an output of said power supply 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 with said mains supply voltage and in a manner to increase a power factor associated with said mains source;
• and
• second switching means for generating, in an inductance that is coupled to said second supply voltage terminal, 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 an output of said power supply to produce a second portion of said rectified output supply current such that a ratio between a magnitude of a given current pulse of said first plurality of current pulses and a current pulse of said second plurality of current pulses that is adjacent to said given current pulse varies, during said period of said mains supply voltage, in a manner to reduce a ripple component at said output of said power supply.