Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2000-04-06
2001-01-30
Berhane, Adolf Deneke (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
C363S127000
Reexamination Certificate
active
06181578
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to resonant reset forward converters and, more particularly, to a gate drive mechanism used in connection with the rectifying element used in resonant reset forward converters.
BACKGROUND OF THE INVENTION
The most commonly used method of resetting the transformer core of a forward converter is to allow the magnetizing inductance of the transformer to ring with a combination of lumped and parasitic capacitance during the off period of the power switch that controls current flow through the primary winding of the transformer. This method is inexpensive in application and allows for minimal size converter designs.
A drawback associated with self-driven synchronous rectifiers used in resonant reset forward converters is that it is difficult to maintain a suitable gate drive charge on the synchronous rectifier during the dead period of the converter. Conventional techniques for generating alternate gate drive signals to be provided to the synchronous rectifier often require the use of additional control circuitry. This additional control circuitry is often expensive and increases the overall size of the converter.
SUMMARY OF THE INVENTION
The aforementioned and related drawbacks associated with conventional resonant reset forward converters using self-driven synchronous rectification are substantially reduced or eliminated by the resonant reset forward converter of the present invention. The converter of the present invention includes both a forward and a free-wheeling rectifier on the secondary side of the converter and associated gate drive mechanisms which control the conduction of the forward and free-wheeling rectifiers, in order to minimize current shoot-through and reduce the effects of transformer dead time. The gate drive mechanism is operative to maintain the on state of the free-wheeling rectifier during the transformer reset and dead periods, and to rapidly turn off the free-wheeling rectifier at the beginning of a subsequent forward power cycle.
In an exemplary embodiment of the present invention the converter comprises a transformer having a primary winding and a secondary winding; a power switch in series communication with the primary winding and coupled to an input power source, the power switch capable of being alternately switched between an on period and an off period such that an ac voltage is generated across the secondary winding of the transformer in response thereto, the off period including a transformer reset period and a subsequent dead period; an output filter operative to provide a substantially constant dc voltage to an output load; a forward rectifier operative to provide a forward conduction path between the secondary winding of the transformer and the output filter during the on period of the power switch; a free-wheeling rectifier operative to provide a conduction path for the output filter inductor discharge during the reset and dead periods of the transformer; means for causing the free-wheeling rectifier to be conducting during the reset period; means for maintaining the conduction state of the freewheeling rectifier during the dead period of the transformer by maintaining a suitable charge on the gate of the free-wheeling rectifier; and means for causing the free-wheeling rectifier to be non-conducting at the beginning of a subsequent on period of the power switch.
An advantage of the present invention is that it provides the ability to reduce the adverse effects of dead time in a self-driven synchronous rectified resonant reset forward converter.
Another advantage of the present invention is that it provides a converter that is highly power efficient.
Yet another advantage of the present invention is that it provides a converter that has a small footprint.
A feature of the present invention is that it can be manufactured at low cost.
REFERENCES:
patent: 5392206 (1995-02-01), Peterson et al.
patent: 5521807 (1996-05-01), Chen et al.
patent: 5590032 (1996-12-01), Bowman et al.
patent: 5870299 (1999-02-01), Rozman
patent: 5956245 (1999-09-01), Rozman
patent: 6002597 (1999-12-01), Rozman
patent: 6011703 (2000-01-01), Boylan et al.
patent: 6038148 (2000-03-01), Farrington et al.
patent: 6084792 (2000-07-01), Chen et al.
patent: 6111769 (2000-08-01), Zhang et al.
Astec International Limited
Berhane Adolf Deneke
Brothers Coudert
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