Electrical transmission or interconnection systems – Plural supply circuits or sources – One source floats across or compensates for other source
Reexamination Certificate
2000-09-01
2002-04-09
Riley, Shawn (Department: 2838)
Electrical transmission or interconnection systems
Plural supply circuits or sources
One source floats across or compensates for other source
C307S066000, C307S023000, C429S010000, C429S006000
Reexamination Certificate
active
06369461
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electrical power transmission and distribution equipment, and more particularly to a high efficiency power conditioner for providing electrical power to a load.
BACKGROUND OF THE INVENTION
A fuel cell typically produces a low voltage at high current. The low voltage produced by the fuel cell varies with the operating conditions and load. When a positive load step occurs, the fuel cell is typically unable to quickly respond to the load change. It is therefore necessary to use an energy storage element such as a battery to provide the balance of power while the fuel cell “catches up” in its ability to provide all of the required power to the load.
Many applications for a fuel cell require an alternating current (ac) output that provides power efficiently over a large range of load. The high-efficiency requirements of these applications typically preclude the use of multiple stages of power conversion. Since a high-efficiency system must minimize the number of power conversion stages, it is difficult to produce a system that can control the sharing of power between the fuel cell and battery while maintaining high system efficiency over a large load range.
A goal of the present invention is to solve this problem by providing a high efficiency power conditioner while avoiding the need for multiple stages of power conversion along the main power path.
SUMMARY OF THE INVENTION
The present invention provides a power conditioner that converts varying dc power from a dc source (such as, e.g., a fuel cell) to ac power in such a way as to provide a very high efficiency during normal operation as well as allowing control of power from the de source. Such control can be very useful for small generation devices, and particularly fuel cells that require very high operating efficiencies at partial loads but would also profit from the ability to control power flow from the fuel cell.
One exemplary implementation of the invention provides a power conditioner for conditioning electrical power provided by a generation device to a load. The generation device could be a fuel cell, for example, or a combination of a fuel cell (or other medium) in parallel with energy storage media, such as an electrolytic capacitor and/or flywheel system. This embodiment of the power conditioner includes a dc-to-ac inverter; a dc bus coupled to the dc-to-ac inverter; a low voltage power supply operatively coupled to the dc bus; a buck converter coupled between the low voltage power supply and the dc bus; and a boost converter coupled between the low voltage power supply and the dc bus. The low voltage power supply may include a battery or other device for supplying power.
Other aspects of the present invention are disclosed below.
REFERENCES:
patent: 5150032 (1992-09-01), Ho
patent: 5373195 (1994-12-01), De Doncker et al.
patent: 6198177 (2001-03-01), Mao et al.
patent: 6225708 (2001-05-01), Furukawa et al.
Bapat Vinod
Jungreis Aaron M.
ABB Inc.
Riley Shawn
Woodcock & Washburn LLP
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