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 using a plurality of measuring inductances, which are arranged, on the primary coil side, in distributed fashion, in the area of the primary coil, facing, during operation, a secondary coil of the electric vehicle, over the cross section of the field region of the primary coil. A plurality of consecutive measurements of different groups of measurement inductances is carried out. Each measurement on a group of measurement inductivities is carried out simultaneously for all the measurement inductances of the group. The measurement inductances of each group are separated from one another by a predetermined minimum distance, which is selected so that the crosstalk between the measurement signals of the individual measurement inductances of each group remains below a predetermined threshold.
1. 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,
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,
wherein the matrix has a grid dimension in a direction of the rows and in a direction of the columns,
the predetermined minimum distance is greater than the grid dimension in the direction of the rows and in the direction of the columns,
the predetermined minimum distance is such that measuring inductances that are adjacent to each other in a row or in a column of the matrix belong to different groups, 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.
2. The method according to claim 1 , wherein the measuring inductances of each group are arranged in distributed fashion in a regular pattern over the cross section of the field region of the primary coil.
3. The method according to claim 2 , wherein the measuring inductances of each group fill in the cross section of the field region of the primary coil sufficiently so that additional measuring inductances of the same group would be located outside of the cross section of the field region in case of continuation of the regular pattern.
4. The method according to claim 1 , wherein during a single measurement cycle in which all of the groups of measuring inductances are consecutively measured, the measurement signals acquired for one of the groups of measuring inductances are evaluated while the measurement signals of a next consecutive one of the groups of measuring inductances are detected.
5. The method according to claim 1 , wherein the measurement signal is evaluated by comparing at least one parameter of the measurement signal with a corresponding parameter of a reference signal determined without the presence of a conductive foreign body, and, using the comparison result, a determination is made regarding the presence of a conductive foreign body in the area of the measuring inductance.
6. The method according to claim 1 , wherein an alarm signal indicating the presence of a conductive foreign body is generated and input to at least one of a display unit and a control unit of the charging station when the presence of a conductive foreign body is detected.
7. The method according to claim 1 , wherein at the end of a measurement cycle, in which all the groups of measuring inductances were measured and the measurement results evaluated, from the results of the evaluation of all the individual measurement signals, data indicating the location and size of a conductive foreign body are determined.
8. The method according to claim 1 , wherein before the beginning of the measurement on a group, a group of measuring inductances is connected by an analog multiplexer in each case to one measurement device per measuring inductance.
9. The method according to claim 1 , wherein inductive energy transmission is blocked, interrupted, or reduced in power by a control unit of the charging station when the presence of a conductive foreign body is detected.
10. 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.
11. The method according to claim 10 , wherein during a single measurement cycle in which the groups of measuring inductances are consecutively measured, the measurement signals acquired for the first group of measuring inductances are evaluated while the measurement signals of the second group of measuring inductances are detected.
12. The method according to claim 10 , wherein the measurement signal is evaluated by comparing at least one parameter of the measurement signal with a corresponding parameter of a reference signal determined without the presence of a conductive foreign body, and, using the comparison result, a determination is made regarding the presence of a conductive foreign body in the area of the measuring inductance.
13. The method according to claim 10 , further comprising determining location and size data of a conductive foreign body using the measurement signals acquired for the first group of measuring inductances and the measurement signals of the second group of measuring inductances.
14. The method according to claim 10 , wherein inductive energy transmission is blocked, interrupted, or reduced in power by a control unit of the charging station when the presence of a conductive foreign body is detected.
15. The method according to claim 1 , wherein the predetermined minimum distance is at least three times the grid dimension in the direction of the rows and in the direction of the columns.
16. 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.
17. The method according to claim 16 , wherein the predetermined minimum distance is at least three times the grid dimension in the direction of the rows and in the direction of the columns.
18. The method according to claim 16 , wherein the predetermined minimum distance is at least two times the grid dimension in the direction of the rows and in the direction of the columns.