Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2000-06-01
2001-03-06
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
C363S134000
Reexamination Certificate
active
06198640
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to DC to DC converters, and more particularly, to a three-switch add/subtract DC to DC converter.
BACKGROUND ART
Manufacturers of electronic equipment typically include electronic power converters as components of electronic products and systems.
For example, electronic power converters are widely used for battery charging systems, providing regulated DC voltages for computer circuits, and for providing sources of alternating voltage from a source of regulated DC power for motor control applications.
A switching converter can perform several basic functions, one basic function is to operate as a switching DC—DC converter. In a switching DC—DC converter, the DC input voltage is converted to a DC output voltage having a larger or smaller magnitude, with possibly opposite polarity and with the possibility of providing isolation of the input and output ground references.
High efficiency is essential in any power processing application. Low power conversion efficiency results in low component reliability because the components dissipate excessive power. High efficiency is also necessary in applications where limited input power is available.
Power conversion losses in a switching type DC to DC converter are a function of several parameters. Switching type DC to DC converters use switching elements in the process of power conversion. These switching elements dissipate power in the conversion process. Obviously, decreasing the number of required switching elements can reduce the switching losses.
The mass of a switching type DC to DC converter is also related to switching frequency. This is due to the direct relationship between the size of the magnetic components used within the converter and the switching frequency. Higher switching frequency results in a smaller size required for the magnetic components used in the converter. Higher switching frequency can result in a converter with lower mass because the magnetic components can be smaller. Unfortunately, higher switching frequencies result in higher switching losses in the switching elements within switching DC—DC converters. If the number of switches in a converter can be minimized, switching losses can be minimized, and the switching frequency can be increased to achieve a converter with both lower mass and high efficiency.
There is a need for switching DC—DC converter topologies that can minimize the number of switches required and also process power in such a way that high efficiency and low mass can be achieved simultaneously.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide an improved and reliable DC to DC converter. Another object of the invention is to improve DC to DC converter efficiency, while reducing the number of components required, and the mass of the converter.
In one aspect of the invention, a DC to DC converter includes a first inductor having a first primary circuit with a first terminal and a second terminal and a second primary circuit with a first terminal and a second terminal. The first inductor first primary first terminal is connected to a source of unregulated voltage. The first inductor second primary first terminal is connected to the first inductor first primary circuit first terminal. The DC to DC converter also includes a first transformer having a first primary circuit with a first terminal and a second terminal, and a second primary circuit with a first terminal and a second terminal, and a first secondary circuit with a first terminal and a second terminal. The first transformer first primary circuit first terminal is connected to the first inductor first primary circuit second terminal. The first transformer second primary circuit first terminal is connected to the first inductor second primary circuit second terminal.
The first transformer first primary circuit second terminal is connected to a second transformer first primary circuit first terminal. A first switching device is connected from the second transformer first primary circuit second terminal to ground. A second switching device is connected from the first transformer second primary circuit second terminal to ground.
The second transformer second secondary circuit first terminal is connected to the first inductor first terminal. A control switching device is connected from the second transformer second secondary circuit second terminal to ground.
The second transformer first secondary circuit first terminal is connected to the anode of a current rectifying device, the cathode of the current rectifying device is connected to the first inductor first terminal. The second transformer first secondary circuit second terminal is connected to ground.
The first transformer first secondary circuit terminal one is connected to a rectifying circuit. The first transformer first secondary circuit terminal two is connected to a rectifying circuit. The rectifying circuit is connected to a capacitor. The capacitor has two terminals, the first terminal supplies the regulated output voltage, the second terminal is tied to ground.
A control circuit is connected to the capacitor first terminal. The control circuit controls the frequency, time duration and switching sequence of the first switching device and the second switching device and the control switching device. The control switching device causes only that portion of the input power required to control the voltage at the capacitor terminal one to be added or subtracted from that portion of the input power processed by the first switching device and by the second switching device.
The present invention thus achieves an improved three-switch add/subtract DC to DC converter. The present invention is advantageous in that it converts a first DC voltage to a second DC voltage using less switches and primary rectifying diodes than the current art, which allows the present invention to operate at higher frequencies.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4943903 (1990-07-01), Cardwell, Jr.
patent: 5218522 (1993-06-01), Phelps et al.
patent: 6055162 (2000-04-01), Tarrillo et al.
Gudmestad T.
Hughes Electronics Corporation
Riley Shawn
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