METHOD AND SYSTEM FOR CELL EQUALIZATION WITH SWITCHED CHARGING SOURCES
First Claim
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1. A charging system for charging a rechargeable battery, comprising:
- N battery cells coupled in series forming a series string, wherein said series string comprises;
a first battery cell coupled to a load end, a Nth battery cell coupled to a ground end, and a cell junction between each pair of adjacent battery cells;
a first set of charging sources coupled to said series string, wherein each charging source in said first set comprises an input terminal and an output terminal, wherein an output terminal of a first charging source in said first set is coupled to said load end, and an output terminal of any other charging source is coupled to a respective cell junction occurring thereafter; and
a second set of charging sources coupled to said series string, wherein each charging source in said second set comprise an input terminal and an output terminal, wherein an input terminal of each charging source in said second set is coupled to a respective cell junction, and an output terminal of each charging source in said second set is coupled to said ground end.
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Abstract
A system and method for charging a rechargeable, or secondary, battery including a series string of cells, includes a topology of charging sources that selectively provides charging current to cells that need to be charged, but avoids overcharging cells that are already charged above a predetermined voltage threshold. Based on individual cell voltage measurements, the charging current is controlled in a manner to direct charging current to the battery cell(s) needing charge until these cells are fully charged, and by-passes battery cells that are fully charged or become fully charged.
31 Citations
18 Claims
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1. A charging system for charging a rechargeable battery, comprising:
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N battery cells coupled in series forming a series string, wherein said series string comprises;
a first battery cell coupled to a load end, a Nth battery cell coupled to a ground end, and a cell junction between each pair of adjacent battery cells;
a first set of charging sources coupled to said series string, wherein each charging source in said first set comprises an input terminal and an output terminal, wherein an output terminal of a first charging source in said first set is coupled to said load end, and an output terminal of any other charging source is coupled to a respective cell junction occurring thereafter; and
a second set of charging sources coupled to said series string, wherein each charging source in said second set comprise an input terminal and an output terminal, wherein an input terminal of each charging source in said second set is coupled to a respective cell junction, and an output terminal of each charging source in said second set is coupled to said ground end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for equalizing voltage of a secondary battery being charged, the method comprising the steps of:
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coupling N battery cells in series to form a series string, wherein said coupling N battery cells step comprises the steps of;
coupling a first battery cell to a load end, coupling a Nth battery cell to a ground end, and forming a respective cell junction between each adjacent pair of battery cells in said series string;
coupling a first set of charging sources to said series string, wherein said coupling a first set of charging sources step comprises the steps of;
coupling a first charging source of said first set to said first cell at said load end, and coupling each remaining charging source in said first set to each cell junction formed on said series string; and
coupling a second set of charging sources to said series string, wherein said coupling a second set of charging sources step comprises the step of;
coupling each charging source of said second set to each cell junction formed on said series string. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for equalizing voltage of a secondary battery being charged, the method comprising the steps of:
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providing charging current to at least one battery cell in a series string containing a terminal voltage below a pre-determined threshold amount, wherein said charging current is provided to charge said at least one battery cell; and
preventing charging current from being provided to any battery cell in said series string containing a terminal voltage above said pre-determined threshold amount utilizing a charging source, wherein said preventing step comprises the step of;
causing a first electrical path to possess an impedance lower than a second electrical path, wherein said second electrical path includes at least one battery cell containing a terminal voltage above said pre-determined threshold amount. - View Dependent Claims (18)
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Specification