Boost mode power conversion

A method of obtaining a regulated d.c. voltage output from a source of d.c. voltage, comprising:

• (a) coupling the source of d.c. voltage to the primary of a transformer, said transformer further having a secondary and a leakage inductance;
• (b) coupling a chopper circuit to the source of d.c. voltage and the primary of the transformer;
• (c) operating the chopper circuit to provide a chopped voltage to the primary of the transformer;
• (d) rectifying the output from the secondary of the transformer to a d.c. voltage;
• (e) selectively shorting the output from the secondary of the transformer for predetermined time periods so as to store electrical energy within the leakage inductance of the transformer, the predetermined time periods defining an on-time duty cycle;
• and
• (f) regulating the on-time duty cycle so as to obtain a regulated d.c. output.

An apparatus for providing regulated a.c voltage at a load from a source of d.c. voltage, comprising:

• (a) a transformer further comprising a primary winding, a load secondary winding coupled to the load, a control secondary winding, a mutual inductance providing magnetic coupling between the load secondary winding and the control secondary winding, and a leakage inductance between the primary winding and the control secondary winding, the primary winding of the transformer coupled to the source of d.c. voltage;
• (b) a chopper circuit coupled to the primary for chopping the voltage supplied to the primary winding;
• (c) a rectifier circuit coupled to the control secondary winding for converting the voltage therefrom to a d.c. voltage;
• (d) a power circuit having an on-time duty cycle associated therewith, said power circuit being operatively coupled to the rectifier circuit for selectively shorting the voltage from the control secondary winding so as to store electrical energy within the leakage inductance of the transformer;
• and
• (e) a control circuit operatively coupled to the power circuit for regulating an on-time duty cycle of the power circuit to maintain a substantially constant a.c. voltage output from the power circuit.

A method of obtaining a regulated a.c. voltage output from a source of d.c. voltage, comprising:

• (a) coupling the source of d.c. voltage to the primary of a transformer, said transformer further having a load secondary winding, a control secondary winding, a mutual inductance providing magnetic coupling between the load secondary winding and the control secondary winding, and a leakage inductance between the primary winding and the control secondary winding;
• (b) coupling a chopper circuit to the source of d.c. voltage and the primary of the transformer;
• (c) operating the chopper circuit to provide a chopped voltage to the primary of the transformer;
• (d) rectifying the output from the control secondary of the transformer to a d.c. voltage;
• (e) selectively shorting the output of the control secondary of the transformer for predetermined time periods so as to store electrical energy within the leakage inductance of the transformer, the predetermined time periods defining an on-time duty cycle;
• and
• (f) regulating the on-time duty cycle so as to obtain a regulated a.c. output.