Method for detecting the voltage in battery cells

摘要

The invention relates to an evaluation circuit for detecting the voltage in battery cells of a battery system which are preferably connected in series. The evaluation circuit includes serially connected resistors, the number of which is equal to the number of battery cells for which the voltage is to be detected. One of the resistors is associated with each of the battery cells. The evaluation circuit further includes a power source for generating a current that is continuous in some sections and is applied to the serially connected resistors, a number of comparators equal to the number of resistors to compare a voltage released at a resistor associated with a battery cell to the voltage in the battery cell with which the resistor is associated, and output a respective output signal when the voltage released at a resistor associated with a battery cell is equal to, exceeds, or drops below the voltage in the battery cell, and an evaluation circuit for deriving the voltage in each battery cell on the basis of a point in time when the respective output signal is output and on the basis of the variation of the current that is continuous in some sections.

主权项

1. A method for detecting the voltage in battery cells of a battery system, which are connected in series, having the steps of:
applying a current, which has a continuous plot in some sections, to a series circuit of resistors, the series circuit of resistors including a respective resistor for each one of the battery cells whose voltage is being detected, each of the battery cells being associated with one of the resistors; coupling a first battery terminal located at a first end of each of the battery cells whose voltage is being detected to a first terminal of the associated resistor and coupling a second terminal of the associated resistor to a first input of a comparator associated with the battery cell; coupling a second battery terminal located at a second end of the each of the battery cells whose voltage is being detected to a second input of the comparator associated with the battery cell; comparing a first voltage received at the first input of each comparator to a second voltage received at the second input of the comparator, the first voltage corresponding to a voltage at the first battery terminal of the associated battery cell which is dropped across the associated resistor, the second voltage corresponding to a voltage at the second battery terminal of the associated battery cell; and deriving a voltage of a respective battery cell from the comparison based on a time at which the voltage drop at the resistor associated with it corresponds to, exceeds, or falls below the voltage of the respective battery cell and based on the plot of the current that has a continuous plot in some sections.