Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2000-09-14
2001-09-04
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
Reexamination Certificate
active
06285567
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to power supplies and, more particularly, to methods and apparatus for utilizing the transformer leakage energy in a power supply.
BACKGROUND OF THE INVENTION
DC switching power supplies are vital components of electronic circuits. They are powered by a supply voltage and provide output voltages at various levels to power the electronic circuits. To produce these various output voltage levels, DC switching power supplies include DC-to-DC converters containing transformers. The primary and secondary windings of the transformer are not perfectly coupled to each other or to the magnetic material within the transformer. This imperfect coupling results in leakage energy in the magnetic characteristics of the transformer that builds up over time and is stored within the transformer. Subsequently, the stored leakage energy causes the transformer to operate as if inductors are connected in series with the windings, with the inductors storing the leakage energy. This is known as leakage inductance. Unless dissipated, the stored leakage energy will negatively impact the performance of the power supply. If the leakage energy is not dissipated, it may result in voltages and/or currents above the design specifications of the power supply components resulting in damage to the components or unsafe operating conditions.
To prevent the build up of the leakage energy, power supplies typically either dissipate the leakage energy in a resistor, or feed the leakage energy back to the DC input voltage source at the input to the transformer. The leakage energy is fed back by using a separate winding coupled to the primary winding of the transformer. The first approach is wasteful because the energy is dissipated. The second approach results in additional leakage energy from the separate winding that builds up if not dissipated. Also, power supplies typically contain circuitry that requires power from voltages higher than the DC input voltage source. In addition, power supplies typically have hold-up capacitors charged to a higher voltage than the DC input voltage source. These hold-up capacitors provide energy to the power supply circuitry during a momentary loss in the DC input voltage source. Obtaining these higher voltages requires additional circuitry such as additional transformer windings or additional DC-to-DC converter circuitry. Such additional circuitry is complicated, consumes space, adds weight, increases the cost of the power supply, and results in an inefficient use of power.
BRIEF SUMMARY OF THE INVENTION
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention, and is not intended to be a full description. A full appreciation of the various aspects of the invention can only be gained by taking the entire specification, claims, drawings, and abstract as a whole.
A method and apparatus for utilizing leakage energy from a transformer, including in one embodiment, a transformer having a primary winding and a secondary winding in communication with a switch and a capacitor, a rectifier and a functional load. In operation, any leakage energy from the transformer is communicated to the functional load, thereby preventing wasteful dissipation of the energy.
The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention or can be learned by practice of the present invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the spirit and scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow.
REFERENCES:
patent: 4788634 (1988-11-01), Schlecht et al.
patent: 5608613 (1997-03-01), Jansen
patent: 6069801 (2000-05-01), Hodge, Jr. et al.
Honeywell International , Inc.
Riley Shawn
LandOfFree
Methods and apparatus for utilizing the transformer leakage... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and apparatus for utilizing the transformer leakage..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and apparatus for utilizing the transformer leakage... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459060