ICPT SYSTEM, COMPONENTS AND DESIGN METHOD
A method for removing the effects of metallic objects in an inductively coupled power transfer system by providing a metallic casing around transmitting and/or receiving coils and compensating for their effect in the design of transmitting and/or receiving circuits. Whilst incurring some loss in performance this design reduces variability due to different metallic influences in an operating environment. Power transmitters and receivers and a system including the power transmitter and the power receiver are also disclosed.
1 . A method of designing a power transmitter for an inductively coupled power transfer system including the steps of:
a. determining the inductance of a transmitting coil having an associated metallic casing; and
b. designing a transmitter circuit for the transmitting coil based on the inductance determined in step a.
2 . A method as claimed in claim 1 wherein the power transmitter is designed to operate at a resonant frequency.
3 . A method as claimed in claim 1 wherein the power transmitter is designed to operate at a frequency other than a resonant frequency.
4 . A method as claimed in claim 3 wherein the transfer function of the power transmitter is selected to facilitate control of power transfer of the power transmitter.
5 . A method as claimed in claim 1 wherein the transmitting coil is generally cylindrical and the metallic casing includes a ring about the periphery of the transmitting coil.
6 . A method as claimed in claim 5 wherein the metallic casing includes a metallic end plate at one end of the transmitting coil.
7 . A method as claimed in claim 1 wherein the transmitting coil is a spiral wound coil.
8 . A method as claimed in claim 1 wherein the transmitting coil is a lumped coil.
9 . A method as claimed in claim 1 wherein the transmitter circuit includes a boost converter.
10 . A method of designing a power receiver for an inductively coupled power transfer system including a power transmitter and a power receiver, the method including the steps of:
a. determining the inductance of a receiving coil having an associated metallic casing that partially encloses the receiving coil; and
b. designing a receiver circuit based on the resonant frequency of the transmitter and the determined inductance in step a.
11 . A method as claimed in claim 10 wherein the power transmitter is designed in accordance with the method of claim 1 .
12 . A method as claimed in claim 10 wherein the power receiver is designed to operate at the resonant frequency of the power transmitter.
13 . A method as claimed in claim 10 wherein the power receiver is designed to operate over a frequency range about the resonant frequency of the power transmitter so as to control power transfer.
14 . A method as claimed in claim 10 wherein the receiving coil is generally cylindrical and the metallic casing includes a ring about the periphery of the receiving coil.
15 . A method as claimed in claim 14 wherein the metallic casing includes a metallic end plate at one end of the receiving coil.
16 . A method as claimed in claim 10 wherein the receiving coil is a spiral wound coil.
17 . A method as claimed in claim 10 wherein the receiving coil is a lumped coil.
18 . A method as claimed in claim 10 wherein the receiving circuit includes a buck converter.
19 . A power transmitter for an inductively coupled power transfer system comprising:
a. a transmitting coil having an associated metallic casing; and
b. a transmitter circuit for the transmitting coil wherein the transmitter circuit is designed for operation of the transmitting coil taking into account the effect of the associated metallic casing.
20 . A power transmitter as claimed in claim 19 wherein the transmitter circuit is designed to operate at a resonant frequency when driving the transmitting coil.
21 . A power transmitter as claimed in claim 19 wherein the transmitter circuit is designed to operate at other than a resonant frequency when driving the transmitting coil.
22 . A power transmitter as claimed in claim 21 wherein the transfer function of the power transmitter is selected to facilitate control of power transfer of the power transmitter.
23 . A power transmitter as claimed in claim 19 wherein the transmitting coil is generally cylindrical and the metallic casing includes a ring about the periphery of the transmitting coil.
24 . A power transmitter as claimed in claim 23 wherein the metallic casing includes a metallic end plate at one end of the transmitting coil.
25 . A power transmitter as claimed in claim 19 wherein the transmitting coil is a spirally wound coil.
26 . A power transmitter as claimed in claim 19 wherein the transmitting coil is a lumped coil.
27 . A power receiver for an inductively coupled power transfer system comprising:
a. a receiving coil having an associated metallic casing that partially encloses the receiving coil; and
b. a receiving circuit for the receiving coil wherein the receiving circuit is designed for operation of the receiving coil taking into account the effect of the associated metallic casing.
28 . A power receiver as claimed in claim 27 wherein the power transmitter is designed in accordance with the method of any one of claims 10 to 18 .
29 . A power receiver as claimed in claim 27 wherein the power receiver is designed to operate at the resonant frequency of the power transmitter.
30 . A power receiver as claimed in claim 27 wherein the operating frequency of the power receiver can be adjusted over a frequency range about the resonant frequency of the power transmitter so as to control power transfer.
31 . A power receiver as claimed in claim 27 wherein the receiving coil is generally cylindrical and the metallic casing includes a ring about the periphery of the receiving coil.
32 . A power receiver as claimed in claim 31 wherein the metallic casing includes a metallic end plate at one end of the receiving coil.
33 . A power receiver as claimed in claim 27 wherein the receiving coil is a spiral wound coil.
34 . A power receiver as claimed in claim 27 wherein the receiving coil is a lumped coil.
35 . A power receiver as claimed in claim 27 wherein the receiving circuit includes a buck converter.
36 . A system including a power transmitter as claimed in claim 19 and a power receiver.
37 .- 38 . (canceled)