WiTricity Corporation

The present disclosure provides systems and methods for foreign object detection within wireless power transfer systems. The disclosure comprises: generating a first probability distribution function (PDF) from a first dataset of FOD sensitivity values, the first dataset representing a foreign object detection threshold; generating a second PDF from a second dataset of foreign object detection values for an object; determining, by the processor, using the first PDF and the second PDF, a third PDF representing a probability of a missed detection of the object. The present disclosure aims to improve missed foreign object detection by providing more accurate foreign object detection and modification of parameters associated therewith, in wireless power transfer systems, to mitigate the associated efficiency and safety effects of missed detections.

A bidirectional wireless power transfer (WPT) system includes a WPT resonator, a power transfer connection for coupling to a battery, a bidirectional power converter coupled to the WPT resonator and to the power transfer connection, a communication interface for communicating with another bidirectional WPT system to which the WPT resonator is configured to be coupled, and a controller. The controller is configured to determine first, second, and third control parameters, control the bidirectional power converter based on the first and second control parameters, and communicate the third control parameter to the other bidirectional WPT system. The controller may operate in a power-controlled mode when delivering power to a vehicle battery, and in a voltage controlled mode when transferring power from the vehicle battery to a load or the Grid.

An apparatus for transferring power includes a first power converter coupled to a first power interface, an isolation transformer having a first transformer coil coupled to the first power converter and a second transformer coil magnetically coupled to and galvanically isolated from the first transformer coil, a second power converter coupled to the second coil of the isolation transformer and to a second power interface, a third transformer coil magnetically coupled to and galvanically isolated from the first transformer coil and magnetically coupled to the second transformer coil, and a third power interface for connecting the third transformer coil to a wireless power transmission (WPT) resonator.

Exemplary embodiments are directed to wireless charging and wireless power alignment of wireless power antennas associated with a vehicle. A wireless power charging apparatus includes an antenna including first and second orthogonal magnetic elements for detecting a horizontal component of a magnetic field generated from a second charging base antenna. A processor determines a directional vector between the antennas.

Wireless power receivers include a first inductive element featuring a planar coil occupying a first plane and having first and second terminals, a first capacitive element connected to the first terminal, a second capacitive element connected to the first capacitive element at a third terminal and to the second terminal, a rectifier connected to the second terminal and third terminal such that an oscillating magnetic field will induce a current in the first inductive element, resulting in a voltage across the input of the rectifier, a communications modulation circuit, and a layer of magnetic material centered over the planar coil in a second plane parallel to the first plane.

A multi-purpose detection circuit for object detection and vehicle position determination is described. For example, the circuit is configurable for detecting foreign metallic objects, living objects, and a vehicle or type of vehicle above an inductive wireless power transmitter. The circuit is also configurable for determining the vehicle's position relative to the inductive wireless power transmitter. An example apparatus includes a measurement circuit including a multiplexer, electrically connected to a plurality of inductive and capacitive sense circuits, for measuring one or more electrical characteristics in each of the inductive and capacitive sense circuits according to a predetermined time multiplexing scheme. The apparatus further includes a control and evaluation circuit for evaluating the measured electrical characteristics and determining at least one of a presence of a metallic object, a living object, a vehicle, or a type of vehicle, and a vehicle position based on changes in the measured electrical characteristics.

A multi-purpose detection circuit for object detection and vehicle position determination is described. For example, the circuit is configurable for detecting foreign metallic objects, living objects, and a vehicle or type of vehicle above an inductive wireless power transmitter. The circuit is also configurable for determining the vehicle's position relative to the inductive wireless power transmitter. An example apparatus includes a measurement circuit including a multiplexer, electrically connected to a plurality of inductive and capacitive sense circuits, for measuring one or more electrical characteristics in each of the inductive and capacitive sense circuits according to a predetermined time multiplexing scheme. The apparatus further includes a control and evaluation circuit for evaluating the measured electrical characteristics and determining at least one of a presence of a metallic object, a living object, a vehicle, or a type of vehicle, and a vehicle position based on changes in the measured electrical characteristics.

Systems and methods are described for active harmonics cancellation. A wireless charging apparatus includes a wireless-power transfer circuit comprising a wireless-power transfer coil configured to generate or couple to a magnetic field to transfer or receive power and a plurality of tuning capacitors electrically coupled to the wireless-power transfer coil. The apparatus also includes a power converter circuit electrically coupled to the wireless-power transfer circuit. Additionally, the apparatus includes a signal generation circuit different from the power converter circuit and electrically coupled to one or more nodes between capacitors of the plurality of tuning capacitors. The signal generation circuit is configured to generate and inject a signal into the wireless-power transfer circuit at the nodes between the capacitors. The signal generation circuit includes a rejection filter tuned to an operating frequency of the wireless-power transfer coil.

A method for pairing a vehicle to a wireless power transfer (WPT) station and determining their relative location using ultra-wideband (UWB) signaling is described. A Master UWB Tag transmits a Ping message and a Master UWB Anchor transmits a Pong message. The Master Tag and Master Anchor use single-sided two-way ranging (SS-TWR) or double-sided two-way ranging (DS-TWR) to determine the distance between them. The Master Tag and the Master Anchor exchange setup parameters to establish communication between the vehicle and the WPT station and determine their relative position. Each UWB tag and each UWB anchor in the WPT station determine a distance between each tag and each anchor. Based on the distances between tags and anchors and data describing the position of each anchor within the WPT station, a relative position of the vehicle and the WPT station is determined.

Disclosed herein are systems and methods for low power excitation of wireless power transmitters configured to transmit high power. The exemplary systems and methods include disabling a power factor correction circuit of the transmitter, and adjusting one or more variable impedance components of the impedance network to obtain a minimum attainable impedance. The variable impedance components can be configured to operate between the minimum attainable impedance and a maximum attainable impedance. The systems and methods can include adjusting a phase shift angle associated with one or more transistors of the inverter and driving the transmitter such that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.