Controlling Inductive Power Transfer Systems
First Claim
1. A method of controlling inductive power transfer in an inductive power transfer system comprising a primary unit operable to generate an electromagnetic field and at least one secondary device, separable from the primary unit, and adapted to couple with said field when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, which method comprises:
- detecting if there is a substantial difference between, on the one hand, a power drawn from the primary unit and, on the other hand, a power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices; and
following such detection, restricting or stopping the inductive power supply from the primary unit.
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Accused Products
Abstract
An inductive power transfer system comprises a primary unit 10, having a primary coil 12 and an electrical drive unit 14 which applies electrical drive signals to the primary coil so as to generate an electromagnetic field. The system also comprises at least one secondary device 30, separable from the primary unit and having a secondary coil 32 which couples with the field when the secondary device is in proximity to the primary unit. A control unit 16 causes a circuit including said primary coil to operate, during a measurement period, in an undriven resonating condition. In this condition the application of the drive signals to the primary coil by the electrical drive unit is suspended so that energy stored in the circuit decays over the course of the period. A decay measurement unit 18 takes one or more measures of such energy decay during the measurement period. In dependence upon said one or more energy decay measures, the control unit controls the electrical drive unit so as to restrict or stop inductive power transfer from the primary unit.
312 Citations
35 Claims
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1. A method of controlling inductive power transfer in an inductive power transfer system comprising a primary unit operable to generate an electromagnetic field and at least one secondary device, separable from the primary unit, and adapted to couple with said field when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, which method comprises:
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detecting if there is a substantial difference between, on the one hand, a power drawn from the primary unit and, on the other hand, a power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices; and
following such detection, restricting or stopping the inductive power supply from the 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)
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32. An inductive power transfer system comprising:
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a primary unit operable to generate an electromagnetic field;
at least one secondary device, separable from the primary unit, and adapted to couple with said field when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween;
a detector which detects if there is a substantial difference between, on the one hand, a power drawn from the primary unit and, on the other hand, a power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices; and
a controller operable, following such detection, to restrict or stop the inductive power supply from the primary unit.
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33. A primary unit, for use in an inductive power transfer system that also has at least one secondary device separable from the primary unit, the primary unit comprising:
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a field generator that generates an electromagnetic field which couples with said at least one secondary device when it is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween;
a detector which detects if there is a substantial difference between, on the one hand, a power drawn from the primary unit and, on the other hand, a power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices; and
a controller operable, following such detection, to restrict or stop the inductive power supply from the primary unit.
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34. A secondary device, for use in an inductive power transfer system that comprises a primary unit which generates an electromagnetic field, the secondary device comprising:
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a secondary coil adapted to couple with said field generated by said primary unit when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween;
a load connection unit means, connected to said secondary coil and adapted to be connected when the secondary device is in use to a load requiring power from the primary unit, for supplying such inductively-received power to the load; and
a detector which detects a synchronisation signal transmitted by the primary unit; and
a controller, responsive to the detection of the synchronisation signal, to set the secondary device into a no-load state in which supply by the load connection means of any of the inductively-received power to said load is substantially prevented.
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35. A secondary device, for use in an inductive power transfer system that comprises a primary unit which generates an electromagnetic field, the secondary device comprising:
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a secondary coil adapted to couple with said field generated by said primary unit when the secondary device is in proximity to the primary unit so that power can be received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween;
a load connection unit, connected to said secondary coil and adapted to be connected when the secondary device is in use to a load requiring power from the primary unit, for supplying such inductively-received power to the load; and
a RFID communication unit operable to supply to the primary unit, using an RFID communication method, information relating to a power requirement of the secondary device.
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Specification