Universal input/output power supply with inherent near unity power factor

Abstract

An electronic method and apparatus are described for an isolated, universal input, power supply in the form of a single-ended resonant converter that utilizes capacitive energy storage versus magnetic energy storage, for converting an ac or DC input voltage to a variable voltage and current DC output or a variable ac output voltage, current, frequency, or phase. The preferred topology is a direct ac to ac, single-ended resonant converter using a single switch ( 4 ) and integrated magnetic element ( 1 ) with inherent near-unity power factor. Advantages of this method include a significant reduction in global energy consumption, simpler circuitry, substantially lower cost, higher efficiency, and longer operational life.

I claim:  
     
         1 . An AC motor controller comprising: 
 a first input terminal and a second input terminal for receiving an AC input;    an input inductor, an input capacitor, and a transformer having a primary and a secondary winding, said input inductor, said input capacitor, and said primary winding connected in series between said first input terminal and second input terminal with said input capacitor between said input inductor and said primary winding;    a controllable switch having a control terminal for receiving a variable frequency control signal to open and close said switch at a predetermined frequency;    a rectifier connecting the junction of said input inductor and said input capacitor with said second input terminal, the controllable switch in series with the current path through said rectifier connected such that a rectified signal biased in accordance with the polarity of said switch is impressed across said switch;    an output circuit comprising an output inductor, an output capacitor, and said secondary winding connected in series, with output terminals across said output capacitor for connection to an AC motor;    whereby the speed of the AC motor is controlled by varying the frequency of the opening and closing of said controllable switch.