Electric power conversion systems – Current conversion – Including an a.c.-d.c.-a.c. converter
Reexamination Certificate
2000-05-10
2001-10-02
Berhane, Adolf Deneke (Department: 2838)
Electric power conversion systems
Current conversion
Including an a.c.-d.c.-a.c. converter
C363S024000, C363S142000, C307S064000
Reexamination Certificate
active
06297972
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to power conversion and, more specifically, to a dual input power supply, a method of operating the power supply and a telecommunications power plant incorporating the power supply or the method.
BACKGROUND OF THE INVENTION
The reliability of telecommunication systems that users have come to expect and depend on is based, in part, on the systems' reliance on redundant equipment and power supplies. Telecommunication switching systems, for example, route tens of thousands of calls per second. The failure of such systems, due to, for instance, the loss of incoming AC power, may result in a loss of millions of telephone calls and a corresponding loss of revenue.
Power plants, such as battery plants, attempt to alleviate the power loss problem by providing the telecommunication system with a backup power supply for use in the event that the incoming AC power is interrupted. Since the backup power supply is often called upon to provide power to the load for durations longer than just a few seconds, the implementation of a battery backup system has a significant impact on both the performance and the cost of the power plant.
A concern with respect to battery plants is managing the transition from a normal or primary mode of operation to a backup mode of operation requiring the use of a backup power system. A control circuit used to manage such a transition is required to detect when there is an absence of primary power to a primary power system and switch to the backup power system. Typically, the primary power system and the backup power system are voltage sources having a low output impedance. Since the outputs of the low output impedance voltage sources cannot generally be directly coupled together without causing serious circulating current problems (resulting in probable component damage), the transition must be orchestrated carefully. This requirement typically increases the complexity and therefore the cost of such control circuits.
Another perhaps more strategic concern is the ability of the power system to continue to operate when a component or collection of components experience a fault. Present fault-tolerant structures often depend on a multiplicity of completely redundant circuits or systems wherein one or more of such circuits or systems may be completely removed from the system if they become faulted. This approach, of course, increases the overall cost proportionally and may raise the overall reliability only marginally depending on a particular configuration.
Accordingly, what is needed in the art is a dual input power supply and a method of operating the power supply that overcomes the deficiencies of the prior art.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides a dual input power supply, a method of operating the power supply and a telecommunications power plant incorporating the power convertor or the method. In one embodiment, the power supply includes: (1) a single stage power converter, coupled to an input of the power supply, configured to receive primary power subject to interruption and provide therefrom DC power to a DC bus; (2) an output power stage, coupled to the DC bus, configured to condition the DC power for delivery to an output of the power supply; and (3) a backup power stage, couplable to a backup power source and having an output coupled to the DC bus, configured to provide backup power during the interruption, the single stage power converter configured to restrict a reverse flow of the backup power therethrough during the interruption.
The present invention introduces, in one aspect, a power supply architecture that is capable of isolating the single stage power converter from the rest of the power supply in the event that primary power to the single stage power converter is interrupted. The single stage power converter is also isolated from the rest of the power supply in the event of a fault in the single stage power converter. The power supply allows substantially the full capacity of the backup power source to be delivered to the output of the power supply without having a substantial portion of the backup power being diverted to the single stage power converter. The conversion from primary power to backup power is provided seamlessly, without having to connect the backup power stage or disconnect the single stage power converter to the output power stage of the power supply.
In one embodiment of the present invention, the primary power is AC power. In this embodiment, the power supply further includes an input filter coupled to the input of the power supply. The power supply further includes a rectifier coupled to the input filter. The input filter filters the AC power to develop filtered AC power and prevents noise generated by the power supply from being injected into the AC line. The rectifier rectifies the filtered AC power to provide rectified power for delivery to the single stage power converter. In a related embodiment, the single stage power converter is configured to provide power factor correction, isolation and voltage regulation of the primary power.
In one embodiment of the present invention, the output power stage includes a DC-AC converter. In an alternative embodiment, the output power stage includes a DC-DC converter. In a related embodiment, the output power stage further includes an output filter coupled to the output of the power supply. The output filter smooths and filters the output voltage. A wide variety of output filter topologies may be employed as required.
In one embodiment of the present invention, the backup power stage includes a bi-directional DC-DC converter. The DC-DC converter may transfer power from the DC bus to the backup power source to charge the backup power source. Alternatively, the DC-DC converter may transfer power from the backup power source to the DC bus to allow the output power stage to provide power to a load coupled thereto.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
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