CONTROL OF POWER TRANSFER
An apparatus comprising: a first transmitter configured to transmit in a first channel defined by a first frequency band; a second transmitter configured to transmit in a second channel defined by a second frequency band; and a controller configured to control power transfer via the first channel in dependence upon an impedance of the first channel and an impedance of the second channel.
1 . An apparatus for contactless charging a receiver device, comprising:
at least one transmitter for transferring energy through a non-radiative electromagnetic field to the receiver device in at least two channels,
a controller configured to control power transfer by said at least one transmitter via a first channel out of said at least two channels, defined by a first frequency band, in dependence upon:
a measurement, during transmission in the first channel, dependent upon an impedance of the first channel and
a measurement, during transmission in a second channel out of said at least two channels, defined by a second frequency band, dependent upon an impedance of the second channel.
2 . An apparatus as claimed in claim 1 , wherein said at least one transmitter comprises:
a first transmitter configured to transmit in a first channel defined by a first frequency band; and
a second transmitter configured to transmit in a second channel defined by a second frequency band.
3 . An apparatus as claimed in claim 1 , wherein the controller is configured to enable power transfer via the first channel when it is determined that there is a significant difference between the impedance of the first channel and the impedance of the second channel and wherein the controller is configured to disable power transfer via the first channel when it is determined that there is not a significant difference between the impedance of the first channel and the impedance of the second channel.
4 . An apparatus as claimed in claim 1 , wherein the controller is configured to control power transfer via the first channel in dependence upon the impedance of the first channel and the impedance of the second channel as a precursor to the initial transfer of power via the first channel.
5 . An apparatus as claimed in claim 1 , wherein the controller is configured to control power transfer via the first channel in dependence upon the impedance of the first channel and the impedance of the second channel intermittently during power transfer via the first channel.
6 . An apparatus as claimed in claim 1 , wherein the first channel and the second channel are distinct and separate channels wherein the first frequency band and the second frequency band do not overlap.
7 . An apparatus as claimed in claim 1 , wherein the first frequency band is less than 1 kHz and the second frequency band is greater than 100 kHz.
8 . An apparatus as claimed in claim 1 , wherein the controller is configured to control transmission of a first signal in the first channel to determine the measurement dependent upon the impedance of the first channel and wherein the controller is configured to control transmission of a second signal in the second channel to determine the measurement dependent upon the impedance of the second channel.
9 . An apparatus as claimed in claim 8 , wherein the controller is configured to control the first transmitter to send the first signal and then to determine whether the measurement dependent on the impedance of the first channel lies within a first range, and wherein if the measurement dependent upon the impedance of the first channel lies within the first range then the controller is configured to control the second transmitter to transmit the second signal and determine if the measurement dependent upon the impedance of the second channel is within a second range, and wherein if the measurement dependent upon the impedance of the second channel is within the second range then the controller is configured to enable power transfer via the first channel.
10 . An apparatus as claimed in claim 9 , wherein the controller is configured, if the measurement dependent upon the impedance of the first channel is outside the first range, to provide an indication to a user to reposition a receiver device to which power is to be transferred.
11 . An apparatus as claimed in claim 9 , wherein the controller is configured, if the measurement dependent on impedance of the second channel is outside the second range, to provide an indication to the user to remove a foreign object.
12 . An apparatus as claimed in claim 1 , configured as a contactless charger.
13 . A method of contactless charging of a receiver device, comprising:
controlling transmission of energy through a non-radiative electromagnetic field to the receiver device in a first channel defined by a first frequency band to determine a measurement dependent upon impedance of the first channel;
controlling transmission of energy through a non-radiative electromagnetic field to the receiver device in a second channel defined by a second frequency band to determine a measurement dependent upon impedance of the second channel; and
controlling power transfer in the first channel in dependence upon the measurement dependent upon impedance of the first channel and the measurement dependent upon impedance of the second channel.
14 . A method as claimed in claim 13 , further comprising enabling power transfer via the first channel when there is a significant difference between the measurement dependent upon impedance of the first channel and the measurement dependent upon impedance of the second channel.
15 . A method as claimed in claim 13 , further comprising disabling power transfer via the first channel when there is not a significant difference between the measurement dependent upon impedance of the first channel and the measurement dependent upon impedance of the second channel.
16 . A method as claimed in claim 13 , wherein controlling power transfer via the first channel in dependence upon the measurement dependent upon impedance of the first channel and the measurement dependent upon impedance of the second channel is as a precursor to any power transfer via the first channel and wherein controlling power transfer in the first channel in dependence upon the measurement dependent upon the impedance of the first channel and the measurement dependent upon impedance of the second channel occurs intermittently during power transfer via the first channel.
17 . (canceled)
18 . (canceled)
19 . (canceled)
20 . A method as claimed in claim 13 , comprising controlling transmission of a first signal of short duration in the first channel to determine the measurement dependent upon impedance of the first channel and transmitting a second signal of short duration in the second channel to determine the measurement dependent on impedance of the second channel.
21 . A method as claimed in claim 20 , comprising transmission of the first signal in the first channel, then, if the measurement dependent upon the impedance of the first channel is within a first range, transmitting the second signal in the second channel, then, if the measurement dependent on the impedance of the second channel is within a second range, enabling power transfer via the first channel.
22 . A method as claimed in claim 21 , wherein if the measurement dependent upon the impedance of the first channel is outside the first range, providing an indication to a user to reposition a receiver device to which power is to be transferred and wherein when the measurement dependent upon the impedance of the second channel is outside the second range, providing an indication to the user to remove a foreign object.
23 . (canceled)
24 . (canceled)
25 . (canceled)
26 . (canceled)
27 . An apparatus comprising:
a first transmitter configured to transmit in a first channel defined by a first frequency band;
a second transmitter configured to transmit in a second channel defined by a second frequency band; and
a controller configured to control power transfer via the first channel in dependence upon an impedance of the first channel and an impedance of the second channel.