Wireless inductive power transfer

A power receiver for receiving power from a power transmitter using a wireless inductive power signal, the power receiver comprising:

• an inductor for receiving the power signal;
• a transmitter for transmitting data messages to the power transmitter;
• a receiver for receiving a message from the power transmitter;
• wherein the data messages being communicated by load modulation of the power signal in repeating load modulation intervals, the repeating load modulation intervals being separated by intervening time intervals, and
• wherein the receiver is arranged to demodulate a single bit of the message across a plurality of the intervening time intervals in accordance with a predetermined modulation pattern, the modulation pattern defining modulation deviations to match to the power signal in each of the plurality of intervening time interval.

A power transfer system, comprising:

• a power transmitter for transferring power to a power receiver using a wireless inductive power signal, the power transmitter comprising:
• an inductor for providing the power signal;
• a power signal generator for driving the inductor to provide the power signal;
• a receiver for receiving data messages from the power receiver;
• a transmitter for transmitting data to the power receiver by modulating the power signal with a message, wherein the data messages are communicated by load modulation of the power signal in repeating load modulation intervals, the repeating load modulation intervals being separated by intervening time intervals, and wherein the transmitter is arranged to modulate a single bit of the message across a plurality of the intervening time intervals in accordance with a predetermined modulation pattern, the modulation pattern defining modulation deviations to apply to the power signal in each of the plurality of intervening time intervals;
• and
• the power receive for receiving power from the power transmitter using a wireless inductive power signal, the power receiver comprising:
• an inductor for receiving the power signal;
• a transmitter for transmitting data messages to the power transmitter;
• a receiver for receiving a message from the power transmitter;
• wherein the data messages being communicated by load modulation of the power signal in repeating load modulation intervals, the repeating load modulation intervals being separated by intervening time intervals, and wherein the receiver is arranged to demodulate a single bit of the message across a plurality of the intervening time intervals in accordance with a predetermined modulation pattern, the modulation pattern defining modulation deviations to match to the power signal in each of the plurality of intervening time interval.

A method of operation for a power transmitter arranged to transfer power to a power receiver using a wireless inductive power signal, the power transmitter comprising an inductor for providing the power signal, and a power signal generator for driving the inductor to provide the power signal, the method comprising:

• receiving data messages from the power receiver;
• transmitting data to the power receiver by modulating the power signal with a message;
• wherein the data messages are communicated by load modulation of the power signal in repeating load modulation intervals, the repeating load modulation intervals being separated by intervening time intervals,
• wherein the transmitting data comprises modulating a single bit of the message across a plurality of the intervening time intervals, and
• wherein transmitting comprises modulating the single bit in accordance with a predetermined modulation pattern, the modulation pattern defining modulation deviations to apply to the power signal in each of the plurality of intervening time intervals.

A method of operation for a power receiver arranged to receive power from a power transmitter using a wireless inductive power signal, the power receiver comprising an inductor for receiving the power signal, and the method comprising:

• transmitting data messages to the power transmitter;
• and
• receiving a message from the power transmitter by demodulating the power signal;
• wherein the data messages are communicated by load modulation of the power signal in repeating load modulation intervals, the repeating load modulation intervals being separated by intervening time intervals, and
• wherein receiving comprises demodulating a single bit of the message across a plurality of the intervening time intervals and comprises demodulating the single bit in accordance with a predetermined modulation pattern, the modulation pattern defining modulation deviations to match to the power signal in each of the plurality of intervening time interval.