Method for detecting an electrically conductive foreign body

A method for detecting an electrically conductive foreign body on a primary coil of an inductive charging station for an electric vehicle having a secondary coil, the method comprising:

• arranging a plurality of measuring inductances over a cross section of a field region of the primary coil on the primary coil side facing the secondary coil during a charging operation, the measuring inductances forming a matrix, and the plurality of measuring inductances including at least a first group of measuring inductances and a second group of measuring inductances;
• taking measurements of the first group of the measuring inductances such that each measurement on the first group of measuring inductances is carried out simultaneously for all of the measuring inductances of the first group, and the measuring inductances of the first group are separated from one another by at least a predetermined minimum distance;
• and
• taking measurements of the second group of the measuring inductances such that each measurement on the second group of measuring inductances is carried out simultaneously for all of the measuring inductances of the second group, and the measuring inductances of the second group are separated from one another by at least the predetermined minimum distance,
• wherein the predetermined minimum distance is selected so that crosstalk between measurement signals of individual measuring inductances of each group during the simultaneous measurements on that group remains below a predetermined threshold that prevents mutual interference between the individual measuring inductances of that group during the simultaneous measurements on that group,
• taking measurements of the first group occurs before taking measurements of the second group,
• each of the groups includes at least two of the measuring inductances, and
• no measuring inductance of the first group is adjacent to another of the measuring inductances of the first group in a row or in a column of the matrix, and no measuring inductance of the second group is adjacent to another of the measuring inductances of the second group in a row or in a column of the matrix.

A method for detecting an electrically conductive foreign body on a primary coil of an inductive charging station for an electric vehicle, the method comprising:

• arranging a plurality of measuring inductances on the primary coil side facing during a charging operation a secondary coil of the electric vehicle over the cross section of a field region of the primary coil, the measuring inductances forming a matrix with a grid dimension in a direction of the rows and in a direction of the columns,
• taking a plurality of consecutive measurements of different groups of the measuring inductances such that each measurement on one of the groups of measuring inductances is carried out simultaneously for all of the measuring inductances of the group, and the measuring inductances of each of the groups are separated from one another by at least a predetermined minimum distance which is selected so that crosstalk between measurement signals of individual measuring inductances of each group during the simultaneous measurements on that group remains below a predetermined threshold,
• wherein each of the measuring inductances belongs to one of the groups, and each of the groups includes at least two of the measuring inductances,
• the predetermined minimum distance is greater than the grid dimension in the direction of the rows and in the direction of the columns, and
• the crosstalk between measurement signals of individual measuring inductances is mutual interference caused by the magnetic fields originating from those individual measuring inductances during their simultaneous measurement.