Method and device for determining a charge state of a battery with the aid of a fluxgate sensor

摘要

A method for determining the charge state of a battery in a motor vehicle includes steps of applying a measuring voltage to a coil, cyclically reversing the polarity of the measuring voltage if the absolute value of the secondary current flowing through the coil exceeds a predetermined threshold value, scanning the secondary current, reconstructing the curve of the secondary current based on the scanned secondary current values, and determining the charge state based on the curve of the secondary current values.

主权项

1. A method for determining a charge state of a battery in a motor vehicle, comprising:
applying a measuring voltage to a coil, which is a secondary coil, wherein the coil surrounds a conductive element which is connected to the battery; cyclically reversing the polarity of the measuring voltage when the absolute value of a secondary current flowing through the secondary coil exceeds a predetermined threshold value; scanning values of the secondary current; reconstructing a curve of the secondary current based on the scanned secondary current values so as to provide a secondary current curve; and determining the charge state of the battery based at least on the curve of the secondary current values; wherein points in time for the scannings are determined based on a cycle duration of a preceding measuring cycle as predetermined relative points in time, wherein the scannings of the secondary current, which occur in select time periods, are used to improve a determination of secondary current at points in time, and wherein the secondary current, which results in a sought compensation of magnetic fields in the coil, is found in the center of areas of a curve of the secondary current in which the coil behaves with a high inductance characteristic, and wherein the scannings of the secondary current, which occur in certain time periods are used to improve the determination of the secondary current at points in times during the time periods due to a linearity of the curve in these time periods.