Abstract: A wireless power transfer system includes a power transmitter (101) arranged to provide a power transfer to a power receiver (105) via a wireless inductive power signal. A parasitic power loss detector (207) is arranged to detect a parasitic power loss for the power transfer, and a user indicator (209) is arranged to initialize a user alert in response to the detection of the parasitic power loss. The system comprises an input (211) for receiving user inputs; and a controller (213) which is arranged to initiate an adaptation of a parasitic power loss detection operation performed by the parasitic power loss detector (207) to detect parasitic power losses if a user input meeting a criterion is not received. Each of the individual features may be implemented in the power transmitter (101), the power receiver (105), or may e.g. be distributed between these. The approach may allow improved foreign object detection in a wireless power transfer system.

Abstract: A power transmitter (501) for a wireless power transfer system includes a parallel resonance circuit (601) comprising at a transmitter coil (503) for generating the power transfer signal. A power source (605) has a current sink terminal and a power source terminal providing current to the parallel resonance circuit (601) with a limited rate of change of the current drawn. A first switch element (607) is coupled between a first end of the parallel resonance circuit (601) and the current sink terminal. A second switch element (609) is coupled between the other end and the current sink terminal. A driver (611) generates a cyclic drive signal such that each cycle comprises a two time intervals in which one switch element (607, 609) is closed and the other (607, 609) is open; and a third time interval in which both the first switch element (607) and the second switch element (609) are closed, the third time interval being between the other two intervals.

Abstract: Power loss is calculated in an inductive power transfer system comprising a power transmitter for transmitting power inductively to a power receiver via transmitter coil and receiver coil. The power transmitter obtains time information for time alignment to enable the power transmitter to align the time of calculating the power loss with the power receiver. Power loss is calculated during power transfer according to the obtained time information and received power parameter communicated from the power receiver.

Abstract: A wireless power transmitter (101)) comprises a resonance circuit (201) comprises a transmitter inductor (103) for generating a power transfer signal for wirelessly transferring power to the power receiver (105). A driver (203) generates a drive signal for the resonance circuit (201) and a resonance modification circuit (505) aligns the resonance frequency of the resonance circuit (201) with the drive frequency of the drive signal by slowing a state change for resonance circuit (201) for a fractional time interval of cycles of the drive signal. A load estimator (509) generates a load estimate reflecting an equivalent load resistor for the transmitter inductor (103) reflecting the loading of the power transfer signal. A drive frequency adapter (511) then adapts the drive frequency in response to the load estimate. The invention may in particular improve load modulation communication quality.

Abstract: A wireless power transfer system includes a power receiver (105) comprising a coil (107) for extracting power from an electromagnetic signal generated by a power transmitter (101). A load controller (305, 309) disconnects a load (303) during a foreign object detection interval and a power controller (307, 311) transmits power control messages reflecting a difference between an induced signal level and a reference level. A message transmitter (307, 313) transmits a predetermined loading indication for the reference level to the power transmitter (101) indicating a predetermined amount of power being extracted from the electromagnetic signal by the power receiver (105) when the load is disconnected and the induced signal is at the reference level.

Abstract: The invention relates to a system for transmitting power inductively from a transmitter (11) to a receiver (10), the receiver (10) comprising a signal generator for generating a signal, triggered by an event reflecting that the receiver intends to receive power from the transmitter, wherein said signal intends to activate said transmitter from standby mode to activated mode; and comprising a signal transmitting coil (103) for transmitting said signal to said transmitter; said transmitter (11) comprising a signal receiving coil (112); a detector (114) for detecting said signal received by the receiving coil; and a unit (115) for activating the transmitter from standby mode to activated mode upon the detection of said signal.

Abstract: A wireless power transfer system comprises a power transmitter generating a wireless power signal providing power to a plurality of power receivers (105, 109). The power transmitter (101) comprises a receiver (203) receiving data messages from the power receivers (105, 109) on a load modulation channel divided into time slots. A time slot processor (205) allocates time slots as dedicated time slots for individual power receivers or as common time slots for load modulation by any power receiver (105, 109). An identity controller (207) links a temporary identity to each of the power receivers (105) and a message processor (209) determines the source power receiver for messages in response to temporary identity information in the messages.

Abstract: A method is presented of allocating communication time slots contained in repeating frames for communication between an inductive wireless power transmitter and at least two inductive wireless power receivers, wherein the power transmitter and the power receivers are arranged to communicate by means of modulation and demodulation of an inductive power signal. The transmitter sends synchronization messages marking the start of the communication time slots and the frames, and messages indicating if a time slot is unallocated. A receiver may send, during an unallocated time slot, send a message to the transmitter requesting allocation of the unallocated communication time slot. The transmitter subsequently sends messages to indicate if the communication was successfully received, and if the allocation request is granted.

Abstract: A wireless inductive power transfer system comprises a power transmitter for transmitting power inductively to a power receiver via transmitter coil 11 to receiver coil 21. In the system, a communication method comprises a step 37 of transmitting, by the power receiver, first data and second data to the power transmitter, the first data indicating a modulation requirement, and the second data indicating an inquiry message; a step 32 for receiving, by the power transmitter, the first data and the second data from the power receiver; a step 34 for transmitting, by the power transmitter, a response message for responding to said inquiry message, by modulating a power signal according to said modulation requirement so as to carry the response message; and a step 35 for receiving the response message by the power receiver by demodulating the modulated power signal carrying the response message received via the receiver coil from the power transmitter.

Abstract: A method of detecting a receiver (214) by a transmitter and a transmitter for detecting a receiver are provided. The transmitter is intended to transmit power inductively to the receiver (214). The transmitter comprising a first transmission coil as a first electrode (204) and a second electrode (206). The first electrode (204) and the second electrode (206) form a capacitor (202). The method comprises the steps of applying a voltage (216) to any one of the electrodes (204, 206) and detecting a capacitance change of the capacitor (202).

Abstract: A power transmitter (2) for transferring power to a power receiver comprises a first inductor (307) for providing power and a second inductor (407) for receiving data signals from a power receiver. The first (307) and second (407) inductors are separate inductors in a power transfer circuit (701) and a data signal receiving circuit (702). The data signal receiving circuit (702) comprises a data extracting circuit (1007) for extracting the data signals received by the second inductor (407). The power transmitter comprises a control circuit (401) for controlling the power in dependence on the data signals. The power transmitter transfers power during power transfer periods and receives data during communication periods, communication periods corresponding to periods wherein power is low.

Abstract: A wireless inductive power transfer system comprises a power transmitter for transmitting power inductively to a power receiver via transmitter coil 11 to receiver coil 21. In the system, a communication method comprises a step 37 of transmitting, by the power receiver, first data and second data to the power transmitter, the first data indicating a modulation requirement, and the second data indicating an inquiry message; a step 32 for receiving, by the power transmitter, the first data and the second data from the power receiver, a step 34 for transmitting, by the power transmitter, a response message for responding to said inquiry message, by modulating a power signal according to said modulation requirement so as to carry the response message; and a step 35 for receiving the response message by the power receiver by demodulating the modulated power signal carrying the response message received via the receiver coil from the power transmitter.

Abstract: A method of detecting a receiver (214) by a transmitter and a transmitter for detecting a receiver are provided. The transmitter is intended to transmit power inductively to the receiver (214). The transmitter comprising a first transmission coil as a first electrode (204) and a second electrode (206). The first electrode (204) and the second electrode (206) form a capacitor (202). The method comprises the steps of applying a voltage (216) to any one of the electrodes (204, 206) and detecting a capacitance change of the capacitor (202).

Abstract: A power transmitter (101) is arranged to transfer power to a power receiver (105) via a wireless inductive power transfer signal transmitted from a transmit coil (103) to a power receiver (105). A first communication unit (305) communicates a message to the power receiver (105) on a first communication link A second communication unit (307) receives data from the power receiver (105) on a separate second communication link having a longer range. The power receiver (105) comprises a third communication unit (405) which receives the first message. A response generator (407) generates a response message to the message and a fourth communication unit (409) transmits the response message to the power transmitter (103) over the second communication link.

Abstract: A wireless power transfer system includes a power transmitter (101) providing power to a power receiver (105) via an inductive power signal. The power transmitter (101) and receiver (105) can operate in different modes including a test mode and a power transfer mode. Operating parameters of the power receiver (105) are constrained in the test mode relative (and specifically the loading). A foreign object detector (209) generates a foreign object detection estimate from a comparison of a measured load to an expected load of the inductive power signal when the power receiver is operating in the test mode. A controller (211) enters the power transmitter (101) and receiver (103) into the power transfer mode when the foreign object detection estimate is indicative of no detection of a foreign object. In the power transfer mode, a parasitic power loss detector (207) generates a parasitic power loss detection for the power transfer if a parasitic power loss estimate is outside a range.

Abstract: An intermediate device for supporting a power transfer to an electromagnetic load (505) from a power transmitter (201) comprises a resonance circuit (507) including an inductor (801) and a capacitor (803) where the inductor (801) is arranged to couple to the power transmitter (201) through a first surface area (509) and to the electromagnetic load (505) through a second surface area (511). The resonance circuit (507) is arranged to 5 concentrate energy of the power transfer electromagnetic signal from the first surface area (509) towards the second surface area (511). The device further comprises a communicator (807) for exchanging messages with the power transmitter (201). The communicator (807) transmits a request message to the power transmitter (201) comprising a request for the power transmitter (201) to generate a measurement electromagnetic signal.

Abstract: A power transmitter (101) of a wireless power transfer system comprises a resonance including a transmitter coil (103) for generating a power transfer signal for wirelessly transferring power to a power receiver (105). Further, a driver (1303) generates a drive signal for the resonance circuit (201) and a message receiver (1305) is arranged to receive messages from the power receiver (105). A power loop controller (1307) implements a power control loop by adapting the power of the drive signal in response to power control messages received from the power receiver (105). However, the regulation is subject to a constraint of at least one of a current or voltage of the resonance circuit and a power of the drive signal being below a maximum limit. Further, the power transmitter (101) comprises an adapter (1309) which adapts the maximum limit in response to a load indication indicative of a loading of the power transfer signal by the power receiver (105).

Abstract: A power transmitter (101) provides power transfer to a power receiver (105) using a wireless inductive power transfer signal. The power transmitter (101) comprises an inductor (103) generating the power transfer signal when a voltage drive signal is applied. A measurement unit (311) performs measurements of a current or voltage of the inductor (103). The measurements are performed with a time offset relative to a reference signal synchronized to the voltage drive signal. An adaptor (313) can vary the time offset to determine an optimum measurement timing offset resulting in a maximum demodulation depth which reflects a difference measure for measurements for different modulation loads of the power transfer signal. A demodulator (309) then demodulates load modulation of the inductive carrier signal from measurements with the time offset set to the optimum measurement timing offset. In some scenarios, both the timing and duration of measurements may be varied. The approach improves communication reliability.

Abstract: A wireless power transmitter (101)) comprises a resonance circuit (201) comprises a transmitter inductor (103) for generating a power transfer signal for wirelessly transferring power to the power receiver (105). A driver (203) generates a drive signal for the resonance circuit (201) and a resonance modification circuit (505) aligns the resonance frequency of the resonance circuit (201) with the drive frequency of the drive signal by slowing a state change for resonance circuit (201) for a fractional time interval of cycles of the drive signal. A load estimator (509) generates a load estimate reflecting an equivalent load resistor for the transmitter inductor (103) reflecting the loading of the power transfer signal. A drive frequency adapter (511) then adapts the drive frequency in response to the load estimate. The invention may in particular improve load modulation communication quality.

Abstract: A power transmitter transfers power to a power receiver using a wireless power signal. The power transmitter comprises an inductor driven by a power signal generator to provide the power signal. A calibration controller determines whether a power loss calibration has been performed for the power transmitter and power receiver pairing. The calibration adapts an expected relationship between a received power indication provided by the power receiver and a transmitted power indication for the power transmitter. A power limiter restricts the power provided to the inductor to not exceed a threshold unless a power loss calibration has been performed for the pairing. The expected relationship may be used to detect unaccounted for power losses, e.g. due to foreign objects being present. The calibrated expected relationship may provide improved accuracy allowing accurate detection at higher power levels. At lower power levels such accuracy is not needed, and no calibration needs to be performed.