Device and method for wireless power transfer and improved foreign object detecion

Abstract

A wireless power transmitter (101) or power receiver (105) comprises a power transfer coil (103, 107) for receiving or generating a power transfer signal and a controller (201, 301) for controlling the device to perform power transfer during a power transfer phase. The power transfer phase comprises power transfer intervals where power is transferred and foreign object detection time intervals during which a power level of the power transfer signal is reduced. A magnetic shielding element (503, 505) is positioned between the power transfer coil (103, 107) and a power transfer coil of a complementary device. The magnetic shielding element (503, 505) comprises a magnetic shield material having a saturation point such that it operates in a saturated and non- saturated mode during respectively power transfer intervals and foreign object detection time intervals. The saturation point is above a magnetic field strength generated by the power transfer signal during the power transfer time intervals and below that generated during the foreign object detection time intervals.

Description

technical field [0001] The present invention relates to wireless power transfer systems, and in particular, but not exclusively, to apparatus and methods for supporting high power wireless power transfer, such as for supporting kitchen appliances. Background technique [0002] Most electrical products today require dedicated electrical contacts to be powered from an external source. However, this is often impractical and requires the user to physically insert the connector or otherwise establish physical electrical contact. Typically, power requirements also vary widely, and most devices today are provided with their own dedicated power supplies, resulting in a typical user having a large number of different power supplies, each dedicated to a particular device. While using an internal battery can avoid the need for a wired connection to a power source during use, this only provides a partial solution since the battery needs to be recharged (or replaced). Using batteries a...

AI Technical Summary

Problems solved by technology

In particular, they may cause the presence of foreign objects not to be detected, or to be falsely detected when they are not present

[0021] Accurate foreign object detection is particularly difficult in scenarios where the power level of the power transfer signal is high and / or when the power level of the power transfer signal varies

Foreign object detection is therefore particularly difficult during the power transfer phase

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