Inductive power transfer system and method
AssigneeAuckland Uniservices Limited
InventorsGrant Anthony Covic, John Talbot Boys
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Abstract
Foreign object detection apparatus for an IPT system, includes a control means adapted to detect the presence of a foreign object on or adjacent to an IPT primary pad of the system.
Claims31
A foreign object detection apparatus comprising a control adapted to detect the presence of a foreign object on or adjacent to a primary magnetic structure of an Inductive Power Transfer (IPT) system, the control configured to place a secondary magnetic structure of the IPT system under a no-load condition and detect the no-load current of the secondary magnetic structure to detect the presence of the foreign object, wherein at least one of:
- the apparatus is adapted to measure the phase and magnitude of the no-load current in the secondary magnetic structure to determine the lateral offset of the primary and secondary magnetic structures;
- the control is configured to detect a foreign object on or adjacent the primary magnetic structure from a reduction in the no-load current in the secondary magnetic structure;
- or
- the apparatus is configured to detect VAR currents in the primary magnetic structure, estimate a component of the detected VAR currents that is attributable to misalignment of the primary magnetic structure and the secondary magnetic structure, and determine that the foreign object is on or adjacent the primary pad when the detected VAR currents deviate from an expected range of VAR currents.
A foreign object detection apparatus comprising a control adapted to detect the presence of a foreign object on or adjacent to a primary magnetic structure of an Inductive Power Transfer (IPT) system, the control configured to place a secondary magnetic structure of the IPT system under a no-load condition and detect the no-load current of the secondary magnetic structure to detect the presence of the foreign object, wherein the control detects the foreign object when the secondary is in the no-load condition by at least:
- determining an expected rate of power transfer;
- determining the actual rate of power transfer;
- and
- comparing the expected rate of power transfer with the actual rate of power transfer.
A method of operating an Inductive Power Transfer (IPT) system comprising a primary magnetic structure and a secondary magnetic structure to detect the presence of a foreign object adjacent to the primary magnetic structure, the method comprising placing the secondary magnetic structure under a no-load condition and detecting the no-load current of the secondary magnetic structure to detect the presence of the foreign object, wherein the method further comprises at least one of:
- determining that a foreign object is on or adjacent the primary magnetic structure from a reduction in the no-load current in the secondary magnetic structure;
- or
- measuring the phase and magnitude of no-load current in the secondary magnetic structure, and estimating the relative position of the secondary magnetic structure and the primary magnetic structure from the measured no-load current.
A method comprising periodically shorting the coil of a resonant secondary pad, while the secondary pad is receiving power from a primary pad, to detect the presence of a foreign object on or adjacent the primary pad, wherein the method comprises detecting at least one of a reduction in short circuit current in the coil secondary pad, or an increase in current supplied to a coil of the primary pad when the secondary coil is shorted.
Dependencies are inferred from the claim text.