Electricity: battery or capacitor charging or discharging – Battery or cell charging – Pulsed
Reexamination Certificate
2000-10-18
2001-08-28
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
Pulsed
C320S139000
Reexamination Certificate
active
06281662
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a DC/DC converter, and more particularly, to a DC/DC converter that allows battery charging from a high voltage battery to a low voltage battery.
BACKGROUND
Battery chargers for charging a low voltage battery from a high voltage battery typically use the entire high voltage battery to reduce down and charge the low voltage battery. Commonly, a high voltage battery is formed of a plurality of lower voltage cells in series. The state of charge of the low voltage battery cells may unequally be discharged when charging the low voltage battery. This may result in a reduced life for the 42 volt battery due to the uneven charging.
It would therefore be desirable to provide a system that increases the life of the high voltage battery by allowing even discharging of portions of the high voltage battery when charging the low voltage battery or providing power to a load.
SUMMARY OF THE INVENTION
It would therefore be desirable to provide a charging and DC/DC converter system that allows the state of charge of the portions of the high voltage battery to be monitored and use evenly discharged so that a relatively even state of charge is maintained at the high voltage battery.
In one aspect of the invention a circuit for battery charging and a DC/DC converter includes a high voltage source having a first battery portion having a first positive terminal and a first negative terminal coupled in series with a second battery portion having a second positive terminal and a second negative terminal so that the second negative terminal is coupled to the first positive terminal. A first switch has an input terminal coupled to the first negative terminal, a control terminal coupled to the controller, and an output terminal coupled to a load. A second switch has a second input terminal coupled to a second negative terminal, a second control terminal is coupled to the controller, and a second output terminal coupled to the load.
One advantage of the invention is that the state of charge of each of the battery portions of the high voltage battery may be monitored and evenly distributed. Another advantage of the invention is that redundancy due to the switches may be obtained. That is, where one or more of the switches fails in the open position, the DC/DC converter can still function and provide a limited amount of energy transfer from the high voltage battery to the load by selecting the remaining good switches. If one of the switches fails in the closed position, the control circuit may select the switch corresponding to the opposite pole of the battery to provide a limited amount of energy transfer from one of the battery portions to the load.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 5504415 (1996-04-01), Podrazhansky et al.
patent: 6031355 (2000-02-01), Rich
patent: 6157165 (2000-12-01), Kinoshita et al.
patent: 6194875 (2001-02-01), Takimoto et al.
Ford Global Technologies Inc.
Luk Lawrence
Stec Jennifer
Wong Peter S.
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