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 capable of operating in a normal operation mode, a first operation mode, and a second operation mode, the primary unit having a primary to which electrical drive signals are applied to generate a field, and also comprising at least one secondary device, separable from the primary unit and having a secondary adapted to couple with said field when the secondary device is in proximity to the primary unit so that power can be transferred inductively from the primary unit to the secondary device without direct electrical conductive contacts therebetween, which method comprises:
- transferring power inductively, in the normal operation mode, from the primary unit to the at least one secondary device;
entering the first operation mode in response to a substantial parasitic load being detected in proximity to the primary unit, wherein, in the first operation mode, the primary unit probes to determine whether to enter the normal operation mode or the second operation mode;
entering a second operation mode in response to the at least one secondary device being at least one of removed from proximity to the primary unit and no longer desiring power from the primary unit, wherein, in the second operation mode, the primary unit probes to determine whether to enter the normal operation mode or the first operation mode.
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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.
125 Citations
15 Claims
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1. A method of controlling inductive power transfer in an inductive power transfer system comprising a primary unit capable of operating in a normal operation mode, a first operation mode, and a second operation mode, the primary unit having a primary to which electrical drive signals are applied to generate a field, and also comprising at least one secondary device, separable from the primary unit and having a secondary adapted to couple with said field when the secondary device is in proximity to the primary unit so that power can be transferred inductively from the primary unit to the secondary device without direct electrical conductive contacts therebetween, which method comprises:
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transferring power inductively, in the normal operation mode, from the primary unit to the at least one secondary device; entering the first operation mode in response to a substantial parasitic load being detected in proximity to the primary unit, wherein, in the first operation mode, the primary unit probes to determine whether to enter the normal operation mode or the second operation mode; entering a second operation mode in response to the at least one secondary device being at least one of removed from proximity to the primary unit and no longer desiring power from the primary unit, wherein, in the second operation mode, the primary unit probes to determine whether to enter the normal operation mode or the first operation mode. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A primary unit for transferring power inductively to at least one secondary device, the primary unit comprising:
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a primary element; electrical drive circuitry connected to the primary element, the electrical drive circuitry for driving the primary element to generate a field; and a controller unit for operating the primary unit in a normal operation mode, a standby mode, and a shutdown mode, the controller capable of controlling the electrical drive circuitry to transfer power inductively to the at least one secondary device and detecting presence of a substantial parasitic load in proximity to the primary unit, wherein, in the normal operation mode, the controller transfers power inductively to the at least one secondary device, wherein the controller operates the primary unit in a shutdown mode based on detecting presence of the substantial parasitic load in proximity to the primary unit, wherein the controller operates the primary unit in a standby mode based on determining that the at least one secondary device is at least one of (a) removed from proximity to the primary unit and (b) no longer desiring power from the primary unit. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification