Balancing method
A method for controlling the cell balancing of a battery of electrical accumulators of an electrical system includes balancing, for each subgroup, the cell having the largest amount of electrical charge to be balanced with selected cells.
1. A method for controlling balancing of the cells of a battery of electrical accumulators of an electrical system comprising a main management unit and a plurality of stand-alone slave devices,
said cells of said battery being separated into a plurality of sub-groups, each associated with one stand-alone slave device, and said cells of each sub-group being arranged beside one another,
each cell of each sub-group being each connected to a circuit in the stand-alone slave device comprising an associated controlled switch and an associated resistor,
said resistors of each stand-alone slave device being connected in a row;
for each sub-group, each stand-alone slave device is configured to receive control commands from said main management unit and to control said controlled switches depending on the received control commands so as to balance the charges of said cells of said sub-group;
said method comprising, for each stand-alone slave device of each sub-group of cells:
receiving, for each cell associated with said stand-alone slave device, the amount of electric charge to be balanced;
determining, among the set of cells-associated with said stand-alone slave device, the cell-having the greatest amount of electric charge to be balanced;
selecting, as candidate cells for balancing, the other cells of said sub-group that are associated with a resistor not adjacent to the resistor associated with said cell having the greatest amount of electric charge to be balanced;
excluding, from said selection of candidate cells, cells for which the charge to be balanced is less than a predetermined threshold value;
commanding said stand-alone slave device to control the connected switches so as to balance the cell having the greatest amount of electric charge to be balanced with the cells of said selection of candidate cells; and
shutting down the main management unit during balancing.
2. The method as claimed in claim 1 , wherein, for each sub-group, the resistors associated with said cells are identified by the stand-alone slave device by a numerical identifier, the resistors being arranged in each sub-group so that two adjacent resistors have a numerical identifier of different parity, wherein the selecting step is preceded by an identifying step in which the parity value of the resistor associated with said cell having the greatest amount of electric charge to be balanced is identified,
the selecting step comprising selecting, as candidate cells for balancing, cells associated with resistors having a parity identical to the parity determined for the resistor of the cell having the greatest amount of electric charge to be balanced.
3. The method as claimed in claim 1 , wherein said predetermined threshold value is determined depending on a maximum duration of stand-alone operation of the stand-alone slave devices multiplied by a maximum balancing current between two cells.
4. The method as claimed in claim 1 , wherein said predetermined threshold value is set in a step prior to implementation of said method.
5. A main management unit of an electrical system comprising a battery of electric accumulators and a plurality of stand-alone slave devices,
said cells of said battery being separated into a plurality of sub-groups, each associated with one stand-alone slave device, and said cells of each sub-group being arranged beside one another,
each cell of each sub-group being each connected to a circuit in the stand-alone slave device comprising an associated controlled switch and an associated resistor,
said resistors of each stand-alone slave device being connected in a row;
for each sub-group, each stand-alone slave device is configured to receive control commands from said main management unit and to control said controlled switches depending on the received control commands so as to balance the charges of said cells of said sub-group;
said main management unit comprising:
means for receiving, for each cell associated with said stand-alone slave device, the amount of electric charge to be balanced;
means for determining, among the set of cells associated with each stand-alone slave device, the cell having the greatest amount of electric charge to be balanced, for each stand-alone slave device;
means for selecting, as candidate cells for balancing, the other cells of said sub-group that are associated with a resistor not adjacent to the resistor associated with said cell having the greatest amount of electric charge to be balanced;
means for excluding, from said selection of candidate cells, cells for which the charge to be balanced is less than a predetermined threshold value, for each stand-alone slave device;
means for commanding each stand-alone slave device to control the connected switches so as to balance the cell having the greatest amount of electric charge to be balanced with the cells of said selection of candidate cells; and
means for achieving auto-shutdown during balancing.
6. An electrical system comprising a battery of electrical accumulators, a plurality of stand-alone slave devices, and the main management unit as claimed in claim 5 .
7. A motor vehicle comprising the electrical system as claimed in claim 6 .