Controlling inductive power transfer systems
First Claim
1. A portable device separable from a primary unit, said portable device comprising:
- a secondary adapted to couple with a field generated by a primary unit such that power is received inductively from the primary unit without direct electrical conductive contacts;
a load capable of receiving power from said secondary;
a load connection unit operably coupled to said secondary and said load of said portable device, said load connection unit capable of selectively connecting said load and said secondary, wherein said load connection unit, in a connected state, enables said secondary to provide power to said load, wherein said load connection unit, in a disconnected state, isolates said load from said secondary; and
a communication unit operable to receive communication from the primary unit, wherein, based on communication from the primary unit, said load connection unit isolates said load from said secondary.
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Accused Products
Abstract
An inductive power transfer system comprises a primary unit, having a primary coil and an electrical drive unit 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, separable from the primary unit and having a secondary coil which couples with the field when the secondary device is in proximity to the primary unit. A control unit 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 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.
53 Citations
22 Claims
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1. A portable device separable from a primary unit, said portable device comprising:
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a secondary adapted to couple with a field generated by a primary unit such that power is received inductively from the primary unit without direct electrical conductive contacts; a load capable of receiving power from said secondary; a load connection unit operably coupled to said secondary and said load of said portable device, said load connection unit capable of selectively connecting said load and said secondary, wherein said load connection unit, in a connected state, enables said secondary to provide power to said load, wherein said load connection unit, in a disconnected state, isolates said load from said secondary; and a communication unit operable to receive communication from the primary unit, wherein, based on communication from the primary unit, said load connection unit isolates said load from said secondary. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of controlling inductive power transfer in an inductive power transfer system comprising a primary unit having a primary and electrical drive circuitry connected to the primary for applying electrical drive signals thereto so as to generate an electromagnetic field, the system including at least one portable device separable from the primary unit and having a secondary adapted to couple with the primary to receive power inductively without direct electrical conductive contacts, said method comprising:
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transferring power inductively from the primary unit to the at least one portable device; providing inductively received power from the secondary to a load of the at least one portable device, wherein the at least one portable device is capable of selectively connecting the secondary to the load; receiving communication from the primary unit; based on communication from the primary unit, isolating the load from the secondary; and operating the primary unit to determine presence of a parasitic load in proximity to the primary unit. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An inductive power transfer system including a primary unit having a primary and electrical drive circuitry connected to the primary for applying electrical drive signals thereto so as to generate an electromagnetic field, the system also including at least one portable device separable from the primary unit and having a secondary adapted to couple with the primary to receive power inductively without direct electrical conductive contacts, the inductive power transfer system comprising:
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a control unit operable to control the electrical drive circuitry to control application of the electrical drive signals to the primary; and a measurement unit operable to take a first measurement in a first measurement period and a second measurement in a second measurement period, wherein a first load of the portable device is imposed on the primary unit in the first measurement period, and wherein a second load of the portable device is imposed on the primary unit in the second measurement period; wherein the control unit is operable, in dependence upon the first measurement and the second measurement, to detect presence of a parasitic load in proximity to the primary. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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Specification