System and method for precharging and discharging a high power ultracapacitor pack
First Claim
1. A method for discharging an energy storage in a hybrid electric vehicle, the energy storage including a plurality of ultracapacitor energy storage cells, the hybrid electric vehicle including an internal combustion engine, a generator, a DC power bus, and at least one braking resistor, the method comprising:
- shutting off fuel to the internal combustion engine;
electrically coupling the energy storage to the generator;
spinning the internal combustion engine via the generator;
discharging the energy storage to a first voltage at least in part via the spinning the internal combustion engine;
electrically coupling the energy storage to the braking resistor; and
,discharging the energy storage from the first voltage to a second voltage through the braking resistor.
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Accused Products
Abstract
This invention is a system and a method that uses the braking resistor, commonly used and available in electrically or hybrid-electrically propelled vehicles, to limit the precharge current during the startup of a high power ultracapacitor pack energy storage device and/or safely and rapidly discharge an ultracapacitor pack for maintenance work or storage to lengthen the life of the individual ultracapacitor cells and, correspondingly, the whole pack. The use of the braking resistor for precharging an ultracapacitor energy storage pack is an effective and less expensive method compared to other methods such as a separate DC-to-DC converter. This method includes the control logic sequence to activate and deactivate switching devices that perform the connections for the charging and discharging current paths.
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Citations
16 Claims
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1. A method for discharging an energy storage in a hybrid electric vehicle, the energy storage including a plurality of ultracapacitor energy storage cells, the hybrid electric vehicle including an internal combustion engine, a generator, a DC power bus, and at least one braking resistor, the method comprising:
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shutting off fuel to the internal combustion engine; electrically coupling the energy storage to the generator; spinning the internal combustion engine via the generator; discharging the energy storage to a first voltage at least in part via the spinning the internal combustion engine; electrically coupling the energy storage to the braking resistor; and
,discharging the energy storage from the first voltage to a second voltage through the braking resistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for discharging an energy storage in a hybrid electric vehicle, the energy storage including a plurality of ultracapacitor energy storage cells, the hybrid electric vehicle including an internal combustion engine, a generator, the system comprising:
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a DC power bus; at least one braking resistor; and
,a controller configured to shut off fuel to the internal combustion engine, electrically couple the energy storage to the generator, spin the internal combustion engine via the generator, discharge the energy storage to a first voltage at least in part via the internal combustion engine, electrically couple the energy storage to the braking resistor, and, discharge the energy storage from the first voltage to a second voltage through the braking resistor. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification