Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2000-04-20
2001-10-16
Riley, Shawn (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C323S225000
Reexamination Certificate
active
06304068
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a voltage converter, and in particular to a bi-directional switched capacitor voltage converter.
BACKGROUND OF THE INVENTION
In current technology, most VSLI chips operate at low voltages and as a consequence ultimately require DC—DC converters that are compact, lightweight, of high power density, high conversion efficiency and that ideally can be realized in IC technology. To meet these objectives many switched-capacitor (SC)-based converters have been developed that use semiconductor switches and capacitors to convert or invert DC voltages. As they do not require magnetic devices they are small in size and amenable to monolithic integration. With the increase in popularity of SC-based converters, a range of designs have been produced.
However, existing SC-based converters are normally limited to unidirectional power conversion for a specific designed circuit structure. What would be highly desirable would be a bi-directional converter that could perform both high to low and low to high voltage conversion with a single circuit design.
SUMMARY OF THE INVENTION
According to the present invention there is provided a bidirectional switched-capacitor power converter, wherein said power converter comprises a single circuit configuration having two modes of operation, a first mode providing for energy conversion from a high-voltage side to a low-voltage side, and a second mode providing for energy conversion from a low-voltage side to a high-voltage side.
In a preferred embodiment the circuit configuration comprises a capacitor that in both the first and second modes is charged in a first topology and is discharged in a second topology. When the circuit is operated in a first step-up mode the capacitor is charged from the low-voltage side and is discharged to the high-voltage side. When the circuit is operated in a second step-down mode the capacitor is charged from the high-voltage side and discharged to the low-voltage side.
Preferably the converter comprises a plurality of semiconductor switches and each topology corresponds to a different switch configuration, and the topology switching means comprising means for changing the configuration of said switches.
Preferably means are also provided for controlling the conversion factor of the converter both in the step-up and the step-down modes. The conversion factor is in fact dependent on the charge of the capacitor when the converter changes from the first to second topologies. Preferably therefore the means for controlling the conversion factor comprises means for controlling the charge of the capacitor. One way of achieving this is to charge the capacitor by means of a charging current and providing means for controlling the magnitude of the charging current. This may be achieved, for example, by applying an appropriate control voltage to the gate-source of a MOSFET switch.
In its most basic embodiment the invention provides a converter as described above in which power is converted (either in a step-up or a step-down mode) in only half of an operating cycle as a capacitor is charged and discharged. To provide smooth input current and output voltage waveforms therefore, the present invention provides a bidirectional switched-capacitor power converter comprising first and second converters arranged in parallel, each converter having step-up and step-down modes of operation, wherein said first and second converters each include a capacitor and each mode of operation comprises a capacitor charging-discharging cycle, and wherein said first and second converters are operated out of phase whereby when the first converter is in a capacitor charging phase the second converter is in a capacitor discharging phase, and vice versa.
REFERENCES:
patent: 4347474 (1982-08-01), Brooks et al.
patent: 4736151 (1988-04-01), Dishner
patent: 4999568 (1991-03-01), Gulczynski
patent: 5629607 (1997-05-01), Callahan et al.
patent: 5880581 (1999-03-01), Yang
Chung Shu-Hung Henry
Hui Shu-Yuen Ron
City University of Hong Kong
Merchant & Gould P.C.
Riley Shawn
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