AC to DC converter having an enhanced power factor

An AC to DC converter having an enhanced power factor comprising

• A) a first and a second converter input terminal for connection to a source of AC electrical energy at a first frequency;
• B) a positive and a negative converter DC output terminal for connection to a load;
• C) a full wave rectifier coupled to said first and said second converter input terminals for converting AC electrical energy to DC, said rectifier having positive and negative output terminals, said negative rectifier output terminal being connected to said negative converter output terminal;
• D) an inductor connected between said positive rectifier output terminal and a first node;
• E) a solid state switch having a control electrode, and two principal electrodes one of which is connected to said negative converter output terminal and the other of which is connected to said first node;
• F) a diode having its anode connected to said first node and its cathode to said positive converter output terminal;
• G) an energy storage capacitor connected between said positive and negative converter output terminals;
• said converter under load, when said transistor is quiescent, drawing energy primarily from said AC source during the middle portion, about the peak of each half cycle of the instantaneous AC voltage waveform of said source of AC electrical energy,
• H) voltage sensing means coupled between said input terminals for sensing when the magnitude of the voltage of the instantaneous AC voltage waveform of said source of AC electrical energy is less than a threshold value above zero on the rising and falling portion of each half cycle, and
• I) means responsive to said voltage sensing means coupled to said gate electrode for operating said solid state switch at a high frequency rate in relation to said first frequency during the beginning and ending of each half cycle of the instantaneous AC waveform that are below said threshold;
• said inductor, solid state switch, diode and capacitor forming a boost converter, operating at said high frequency rate at the beginning and ending of each half cycle to increase the instantaneous energy drawn from said AC source in order to increase the withdrawal of energy throughout each cycle and enhance the power factor.