Single stage high power-factor converter

An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

• an input for connection to a source of single phase AC and an output for connection to a load;
• a first circuit for converting single phase AC into DC, the first circuit including a first transformer with primary and secondary windings, a first rectifier coupled to said input and to a primary winding of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;
• a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with primary and secondary windings, a third rectifier coupling a primary winding of the second transformer to said input, a capacitor intermediate said third rectifier and the primary winding of the second transformer for smoothing the current and a fourth rectifier coupled to a secondary winding of the second transformer for providing a rectified current;
• a combining circuit coupled to the second rectifier and to the fourth rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the fourth rectifier current;
• a first switch in series with the primary winding of the first transformer for providing a current at the secondary winding of the first transformer which has a predetermined wave shape and a second switch means in series with the primary winding of the second transformer for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape;
• and
• control means coupled to said output and to said first switch and said second switch to provide second and fourth rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

• an input for connection to a source of single phase AC and an output for connection to a load;
• a first circuit for converting single phase AC into DC, the first circuit including a first transformer with at least two primary windings and a secondary winding, a first rectifier coupled to said input and to one of the primary windings of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;
• a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with primary winding coupled to said input and a secondary winding, a capacitor intermediate said input and the primary winding of the second transformer for smoothing the current and a third rectifier coupled to a secondary winding of the second transformer for providing a rectified current;
• the other of the primary windings of the first transformer being coupled to the primary winding of the second transformer;
• a combining circuit coupled to the second rectifier and to the third rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the third rectifier current;
• switching means electrically in series with said one of the primary windings of the first transformer and electrically in series with the primary winding of the second transformer for providing a current at the secondary winding of the first transformer which has a predetermined wave shape and for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape;
• and
• control means coupled to said output, to said first transformer and to said switching means to provide second and third rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

• an input for connection to a source of single phase AC and an output for connection to a load;
• a first circuit for converting single phase AC into DC, the first circuit including a first transformer with primary and secondary windings, a first rectifier coupled to said input and to a primary winding of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;
• a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with a primary winding coupled to said input and a secondary winding, a capacitor intermediate said input and the primary winding of the second transformer for smoothing the current and a third rectifier coupled to a secondary winding of the second transformer for providing a rectified circuit;
• the primary winding of the first transformer being coupled to the primary winding of the second transformer;
• a combining circuit coupled to the second rectifier and to the third rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the third rectifier current;
• a first switch electrically in series with the primary winding of the first transformer and a second switch electrically in series with the primary winding of the second transformer for respectively providing a current at the secondary winding of the first transformer which has a predetermined wave shape and for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape;
• and
• control means coupled to at least said output and to each of said first switch and said second switch to provide second and third rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.