ELECTROMAGNETIC INTERFERENCE SUPPRESSION

• US 20100109444A1
• Filed: 09/17/2009
• Published: 05/06/2010
• Est. Priority Date: 09/18/2008
• Status: Active Grant

• Current Assignee: Philips IP Ventures B.V. (Koninklijke Philips N.V.)
• Original Assignee: Access Business Group International LLC (Alticor Incorporated)
• Inventors: Lemmens, Willy Henri
• Granted Patent: US 8,878,392 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H03H 7/0123 comprising distributed impedance elements together with lumped impedance elements

Abstract

An inductive power transmitter for transmitting electrical power to a device by electromagnetic induction, the transmitter being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the transmitter including a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency; and at least one impedance element connected along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.

Claims

1. An inductive power transmitter for transmitting electrical power to a device by electromagnetic induction, the transmitter being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the transmitter comprising:

a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency; and

at least one impedance element connected along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements has a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.

2. A transmitter as claimed in claim 1, wherein:

said fundamental frequency is a first fundamental frequency;

said current has a second fundamental frequency different from said first fundamental frequency; and

the impedance element or the combination of the impedance elements has a low enough impedance at the second fundamental frequency such that said power is predominantly conveyed to the field generator without loss in that impedance.

3. A transmitter as claimed in claim 1, wherein said current is an AC current.

4. A transmitter as claimed in claim 1, wherein said power source is a mains power source.

5. A transmitter as claimed in claim 1, wherein the element comprises an inductor.

6. A transmitter as claimed in claim 1, further comprising a mains cable, wherein the impedance element or at least one of combination of impedance elements is part of the mains cable.

7. A transmitter as claimed in claim 6, wherein the transmitter has a main body, the mains cable extending externally therefrom when in use, and wherein the impedance element or at least one of the combination of impedance elements is located within the main body.

8. A transmitter as claimed in claim 6, wherein the mains cable is detachable from a part of the transmitter.

9. A transmitter as claimed in claim 1, configured such that the impedance element or at least one of the combination of impedance elements is shielded from said electromagnetic field.

10. A transmitter as claimed in claim 1, comprising two of the impedance elements, and wherein:

said current is carried along first and second connections; and

said elements are located along different said connections from one another or along the same connection as one another.

11. A transmitter as claimed in claim 1, comprising two of the impedance elements, and wherein:

the impedance elements each comprise an inductor; and

the inductors are configured to have opposite orientations relative to one another such that coupling from the field generator by way of the electromagnetic field to one said inductor cancels out such coupling to the other said inductor.

12. A transmitter as claimed in claim 6, wherein the inductors are arranged such that there is substantially no mutual coupling between them.

13. A transmitter as claimed in claim 12, further comprising a filter located between the mains cable and the field generating means and configured to substantially block frequency components at the fundamental frequency of the electromagnetic field.

14. A transmitter as claimed in claim 1, wherein the field generator comprises a coil and driving means operable to drive a fluctuating current through the coil, and wherein both ends of the coil are decoupled from the driving means such that in use a voltage level at each end of the coil fluctuates with time.

15. An electrical conduit configured to convey power conductively by way of a current from a power source to a field generator of an inductive power transmitter, the field generator being operable to generate a fluctuating electromagnetic field having a fundamental frequency for transmitting electrical power to a device by electromagnetic induction, the conduit comprising:

at least one impedance element connected along an electrical path of the conduit configured to carry said current, the impedance element or a combination of the impedance elements has a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.

16. A conduit as claimed in claim 15, wherein:

said fundamental frequency is a first fundamental frequency;

said current has a second fundamental frequency different from said first fundamental frequency; and

the impedance element or the combination of the impedance elements has a low enough impedance at the second fundamental frequency such that said power is predominantly conveyed to the field generator without loss in that impedance.

17. A conduit as claimed in claim 15, wherein the conduit is a mains cable.

18. Equipment for use in the vicinity of an inductive power transmitter, the transmitter being for transmitting electrical power to a device by electromagnetic induction and comprising a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency, the equipment being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the equipment comprising:

at least one impedance element connected along an electrical path of the equipment configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the equipment.

19. A method of configuring an inductive power transmitter, the transmitter being for transmitting electrical power to a device by electromagnetic induction and being configured to receive power conductively via an electrical conduit by way of a current from an external power source, the transmitter comprising a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency, the method comprising:

connecting at least one impedance element along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.