Bayerische Motoren Werke Aktiengesellschaft

Tobias Hollweg

Benno Schweiger

Johannes Kurtz

A device balances an energy storage module having multiple energy storage cells connected in series. The device includes: an interface for communication with a monitoring electronics system of the energy storage module; a charge determining device for determining a relative electrical charge quantity based on respective cell voltages and a respective resting voltage characteristic curve for each energy storage cell; a balancing requirement calculation unit for determining a respective relative balancing requirement by forming a difference between the relative electrical charge quantity of a respective energy storage cell and the relative electrical charge quantity of the energy storage cell for which the lowest relative electrical charge quantity was determined, for every energy storage cell with the exception of the energy storage cell for which the lowest relative electrical charge quantity was determined, and for determining an absolute balancing requirement for each energy storage cell; a discharging circuit which is configured to be connected to the energy storage module in such a way that a respective energy storage cell can be separately discharged by the discharging circuit; and a control device that can control the discharging circuit in such a way that the respective determined absolute balancing requirement can be removed from the respective energy storage cells.

Device and method for balancing an energy storage module

A method for operating an energy storage system, which includes at least one energy store with a plurality of cells and is designed to supply an electric drive system of a vehicle is provided. The method includes identifying a reference cell from among the cells, and carrying out a first symmetrization procedure for the cells at a first point in time, at which the reference cell has a first reference charge state. The method also includes carrying out a second symmetrization procedure for the cells, if the following conditions a) and b) are met at a second point in time following the first point in time: a) the voltage difference between the voltage of the cell with the lowest voltage and the voltage of the cell with the highest voltage is greater than or equal to a specified voltage difference; and b) the reference state of charge of the reference cell at the second point in time lies within a specified state of charge range, the state of charge range being determined in such a way that it includes the first reference state of charge.

Method for operating an energy storage system and energy storage system

A method tests a balancing circuit for a battery having a plurality of battery cells. The method detects first voltage states of the battery cells by way of a control unit; activates the balancing circuit with the aim of achieving a voltage equalization of at least two of the battery cells; detects second voltage states of the battery cells by way of the control unit; and determines a functional capability of the balancing circuit based on the first voltage states and the second voltage states of the battery cells by way of the control unit.

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Shenyang, China

Tobias Hollweg