Semi-regulated power supply using forward converter leakage energy
AssigneeInterpoint Corporation
InventorsLee I. Silberkleit, David R. Perchlik
Life of this patent
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Abstract
A forward converter circuit transfers a reset current to a capacitor each switching cycle that is independent of the value of input voltage. The reset current stored in a capacitor is transferred to an inductor and, in turn, transferred to a filter capacitor each cycle, thereby providing a semi-regulated voltage to a constant resistive load.
Claims14
In a forward converter for converting DC power at a first voltage applied between first and second input terminals to DC power at a second voltage applied to a first pair of output terminals, said forward converter having a transformer with a primary winding connected in series with a selectively closing first switch between said input terminals, said first switch closing during a portion of each of a plurality of operating cycles, a circuit for generating semi-regulated DC voltage at a second pair of output terminals, comprising:
- a capacitor having first and second leads;
- a second switch connected in series with said capacitor between the junction of said primary winding and said first switch and a voltage that varies according to the magnitude of said first voltage, said second switch being closed during at least a portion of the time when said first switch is open and when the voltage on a lead of said capacitor has a predetermined magnitude with respect to said first voltage causing a charge to be transferred to said capacitor each operating cycle having a magnitude that is independent of the magnitude of said first voltage;
- and
- a first energy transferring circuit coupled to said capacitor, said energy transferring circuit receiving a portion of the energy stored in said capacitor during each operating cycle and transferring said energy to said second pair of output terminals.
A forward converter for converting DC power at a first voltage applied between first and second input terminals to DC power at a second voltage applied to a first pair of output terminals and to a semi-regulated DC voltage at a second pair of output terminals, said forward converter comprising:
- a transformer having a primary winding and a secondary winding, said primary winding having first and second leads, said first lead being connected to said first input terminal;
- a selectively closing first switch connected between the second lead of said primary winding and said second input terminal, said first switch closing during a portion of each of a plurality of operating cycles;
- a rectifier circuit connected to the secondary winding of said transformer, said rectifier circuit rectifying a voltage generated across said secondary winding responsive to opening and closing of said first switch and coupling said rectified voltage to said first pair of output terminals;
- a capacitor;
- a diode connected in series with said capacitor between the first and second leads of said primary winding so that a charge is transferred to said capacitor each operating cycle having a magnitude that is independent of the magnitude of said first voltage;
- and
- a first energy transferring circuit connected to the second lead of said capacitor, said energy transferring circuit receiving a portion of the energy stored in said capacitor during each operating cycle and transferring said energy to said second pair of output terminals.
A method of generating a semi-regulated DC voltage from reset energy in a forward converter having a transformer with a primary winding connected in series with a selectively closing first switch between a pair of input terminals to which input power is applied so that a reset current is produced by said transformer when said switch opens, said method comprising:
- connecting a capacitor in series with a second switch;
- connecting the series combination of said capacitor and said second switch between the junction of said first switch and the primary winding of said transformer and a voltage that varies with the voltage of said input voltage;
- closing said second switch during at least a portion of the time that said first switch is open so that said reset current charges said capacitor until the voltage across said capacitor reaches a peak value;
- opening said second switch after the voltage across said capacitor has reached said peak value;
- and
- transferring at least a portion of the reset current stored in said capacitor to output terminals, thereby generating said semi-regulated DC voltage.
Dependencies are inferred from the claim text.