Patent attributes
An inductive power transfer system comprises a power transmitter (101) and a power receiver (105). The power transmission system supports two-way communications. The power receiver (105) first initiates a mandatory configuration phase by transmitting a signal strength package and the power transmitter and receiver then operates (505, 507) the mandatory configuration phase wherein a first set of power transfer operating parameters are selected for the power transmitter (101) and the power receiver (105). The power receiver (105) subsequently transmits (509) a request to enter a negotiation phase and the power transmitter (101) acknowledges (511) the request by transmitting an acknowledgement. It then enters the negotiation phase. The power receiver (105) enters the negotiation phase in response to receiving the acknowledgment message. The power receiver (105) and power transmitter (101) then determines (513, 515) a second set of operating parameters by performing the negotiation phase. The approach is particularly suitable for a Qi power transfer system.