초록 ▼

An inductive power transfer system (1) comprises a primary unit (10) operable to generate an electromagnetic field and at least one secondary device (30), 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

An inductive power transfer system (1) comprises a primary unit (10) operable to generate an electromagnetic field and at least one secondary device (30), 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.

대표청구항 ▼

The invention claimed is: 1. A method of controlling inductive power transfer in an inductive power transfer system, the system comprising a primary unit operable to generate an electromagnetic field and at least one secondary device, separate from the primary unit, and adapted to couple with said f

The invention claimed is: 1. A method of controlling inductive power transfer in an inductive power transfer system, the system comprising a primary unit operable to generate an electromagnetic field and at least one secondary device, separate 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 is received inductively by the secondary device from the primary unit without direct electrical conductive contacts therebetween, the method comprising:receiving, in the primary unit, information relating to a power required by the secondary device or devices therefrom;determining, in the primary unit, in dependence upon the received information the power required by the secondary device or, if there is more than one secondary device, a combined power required by the secondary devices;measuring a power, and determining that there is a foreign object in addition to the secondary device or devices present in said proximity to the primary unit by detecting a substantial difference between the measured power and the required power; andfollowing such determination of the presence of the foreign object, restricting or stopping the inductive power supply from the primary unit.