Inductive power transfer
First Claim
1. A detection method for use in a primary unit of an inductive power transfer system, the primary unit being operable to transmit power wirelessly by electromagnetic induction to at least one secondary unit of the system located in proximity to the primary unit and/or to a foreign object located in said proximity, said at least one secondary including a regulator with an operating threshold, the method comprising:
- driving the primary unit to transmit power sufficient to operate the regulator at or above the operating threshold and so that in a driven state a magnitude of an electrical drive signal supplied to one or more primary coils of the primary unit changes from a first value to a second value, wherein power transmitted at the first value is sufficient to operate the regulator at or above the operating threshold and power transmitted at the second value is sufficient to operate the regulator at or above the operating threshold;
assessing the effect of such driving on an electrical characteristic of the primary unit based on a difference between a first measurement of the electrical characteristic at the first value and a second measurement of the electrical characteristic at the second value; and
detecting in dependence upon the assessed effect the presence of a said secondary unit including said regulator and/or a foreign object located in proximity to said primary unit.
1 Assignment
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Accused Products
Abstract
A detection method for use in a primary unit of an inductive power transfer system, the primary unit being operable to transmit power wirelessly by electromagnetic induction to at least one secondary unit of the system located in proximity to the primary unit and/or to a foreign object located in said proximity, the method comprising: driving the primary unit so that in a driven state the magnitude of an electrical drive signal supplied to one or more primary coils of the primary unit changes from a first value to a second value; assessing the effect of such driving on an electrical characteristic of the primary unit; and detecting in dependence upon the assessed effect the presence of a said secondary unit and/or a foreign object located in proximity to said primary unit.
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Citations
42 Claims
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1. A detection method for use in a primary unit of an inductive power transfer system, the primary unit being operable to transmit power wirelessly by electromagnetic induction to at least one secondary unit of the system located in proximity to the primary unit and/or to a foreign object located in said proximity, said at least one secondary including a regulator with an operating threshold, the method comprising:
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driving the primary unit to transmit power sufficient to operate the regulator at or above the operating threshold and so that in a driven state a magnitude of an electrical drive signal supplied to one or more primary coils of the primary unit changes from a first value to a second value, wherein power transmitted at the first value is sufficient to operate the regulator at or above the operating threshold and power transmitted at the second value is sufficient to operate the regulator at or above the operating threshold; assessing the effect of such driving on an electrical characteristic of the primary unit based on a difference between a first measurement of the electrical characteristic at the first value and a second measurement of the electrical characteristic at the second value; and detecting in dependence upon the assessed effect the presence of a said secondary unit including said regulator and/or a foreign object located in proximity to said primary unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A primary unit for use in an inductive power transfer system, the primary unit being operable to transmit power wirelessly by electromagnetic induction to at least one secondary unit of the system located in proximity to the primary unit and/or to a foreign object located in said proximity, said at least one secondary unit including a regulator with an operating threshold, the primary unit comprising:
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driving means operable to transmit power sufficient to operate the regulator at or above the operating threshold, the driving means operable to drive the primary unit so that in a driven state the magnitude of an electrical drive signal supplied to one or more primary coils of the primary unit changes from a first value to a second value, wherein power transmitted at the first value is sufficient to operate the regulator at or above the operating threshold and power transmitted at the second value is sufficient to operate the regulator at or above the operating threshold; means for assessing the effect of such driving on an electrical characteristic of the primary unit based on a difference between a first measurement of the electrical characteristic at the first value and a second measurement of the electrical characteristic at the second value; and means for detecting in dependence upon the assessed effect the presence of a said secondary unit including said regulator and/or a foreign object located in proximity to said primary unit. - View Dependent Claims (37)
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38. An inductive power transfer system, comprising a primary unit and at least one secondary unit, said at least one secondary unit including a secondary coil, the primary unit being operable to transmit power wirelessly by electromagnetic induction to at least one said secondary unit located in proximity to the primary unit and/or to a foreign object located in said proximity, the system comprising:
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means for regulating such that a power drawn from said secondary coil at or above an operating threshold is a known function of an input level; driving means operable to transmit power sufficient to operate the means for regulating at or above the operating threshold, said driving means operable to drive the primary unit so that in a driven state a magnitude of an electrical drive signal supplied to one or more primary coils of the primary unit changes from a first value to a second value, wherein power transmitted at the first value is sufficient to operate the regulator at or above the operating threshold and power transmitted at the second value is sufficient to operate the regulator at or above the operating threshold; means for assessing the effect of such driving on an electrical characteristic of the primary unit based on a difference between a first measurement of the electrical characteristic at the first value and a second measurement of the electrical characteristic at the second value; means for detecting in dependence upon the assessed effect the presence of a said secondary unit and/or a foreign object located in proximity to said primary unit. - View Dependent Claims (39, 40, 41, 42)
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Specification