Controlling inductive power transfer system
First Claim
1. A method of controlling inductive power transfer in an inductive power transfer system, the system including a primary unit, having a tank circuit and switching circuit, operable to generate an electromagnetic field and at least one secondary device, separate from the primary unit, and adapted to couple with the field when the secondary device is in proximity to the primary unit so that power is received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, the method comprising:
- determining there is an unacceptable amount of parasitic metal present in proximity to the primary unit;
entering a shutdown mode in response to a determination that the unacceptable amount of parasitic metal is present in proximity to the primary unit; and
remaining in the shutdown mode until the primary unit is reset.
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Accused Products
Abstract
An inductive power transfer system comprises 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 the 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. The system 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. Following such detection, the system restricts or stops the inductive power supply from the primary unit. Such a system can detect the presence of unwanted parasitic loads in the vicinity of the primary unit reliably.
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Citations
18 Claims
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1. A method of controlling inductive power transfer in an inductive power transfer system, the system including a primary unit, having a tank circuit and switching circuit, operable to generate an electromagnetic field and at least one secondary device, separate from the primary unit, and adapted to couple with the field when the secondary device is in proximity to the primary unit so that power is received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, the method comprising:
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determining there is an unacceptable amount of parasitic metal present in proximity to the primary unit; entering a shutdown mode in response to a determination that the unacceptable amount of parasitic metal is present in proximity to the primary unit; and remaining in the shutdown mode until the primary unit is reset. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of controlling inductive power transfer in an inductive power transfer system including a primary unit, having a tank circuit and switching circuit, operable to generate an electromagnetic field and at least one secondary device, separate from the primary unit, and adapted to couple with the field when the secondary device is in proximity to the primary unit so that power is received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, the method comprising:
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measuring power drawn by the at least one secondary device; restricting or stopping power supply based on the measured power drawn by the at least one secondary device; and maintaining restriction or stoppage of power until the inductive power transfer system is reset. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A primary unit, having a tank circuit and switching circuit, operable to generate an electromagnetic field for transferring power to at least one secondary device, separate from the primary unit, and adapted to couple with the field when the secondary device is in proximity to the primary unit so that power is received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, the primary unit comprising:
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a manual reset; one or more sensors for measuring one or more characteristics of power in the primary unit; a controller configured to; determine whether there is an unacceptable amount of parasitic metal present in proximity to the primary unit based on output of said one or more sensors; enter a shutdown mode in response to a determination that the unacceptable amount of parasitic metal is present in proximity to the primary unit; and remain in the shutdown mode until the primary unit is manually reset. - View Dependent Claims (16, 17, 18)
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Specification