Electromagnetic interference mitigation
First Claim
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1. A primary unit for wirelessly transmitting at least one of power and data by electromagnetic induction to a secondary unit separable from the primary unit, the primary unit comprising:
- a coil operable to transmit the at least one of power and data by electromagnetic induction to the secondary unit;
drive circuitry operable to drive a fluctuating current through the coil, wherein both ends of the coil are capacitively decoupled from the drive circuitry such that in use a voltage level at each end of the coil fluctuates with time; and
wherein the coil includes first and second coil portions, the first coil portion and the second coil portion coupled to a reference such that the first coil portion has a voltage that is substantially equal to and the opposite of the voltage of the second coil portion with respect to the reference, whereby a net charge induced by capacitive coupling of the coil with a proximate object would be substantially zero.
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Abstract
A primary unit for transmitting power and/or data wirelessly by electromagnetic induction to a secondary unit separable from the primary unit, the primary unit comprising: a coil (L1, L2); and driving means (30) operable to drive a fluctuating current through the coil, wherein both ends of the coil are decoupled from the driving means so that in use a voltage level at each end of the coil fluctuates with time.
11 Citations
19 Claims
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1. A primary unit for wirelessly transmitting at least one of power and data by electromagnetic induction to a secondary unit separable from the primary unit, the primary unit comprising:
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a coil operable to transmit the at least one of power and data by electromagnetic induction to the secondary unit; drive circuitry operable to drive a fluctuating current through the coil, wherein both ends of the coil are capacitively decoupled from the drive circuitry such that in use a voltage level at each end of the coil fluctuates with time; and wherein the coil includes first and second coil portions, the first coil portion and the second coil portion coupled to a reference such that the first coil portion has a voltage that is substantially equal to and the opposite of the voltage of the second coil portion with respect to the reference, whereby a net charge induced by capacitive coupling of the coil with a proximate object would be substantially zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A primary unit for wirelessly transmitting at least one of power and data by electromagnetic induction to a secondary unit separable from the primary unit, the primary unit comprising:
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a coil operable to transmit the at least one of power and data by electromagnetic induction to the secondary unit; and drive circuitry operable to drive a fluctuating current through the coil, wherein; the coil comprises first and second coil portions, the first coil portion and the second coil portion coupled to a reference; the first coil portion is a driven portion, configured to be driven by said drive circuitry; the second coil portion is a passive portion, configured to be undriven by said drive circuitry; and the primary unit is configured such that in use the first coil portion drives the second coil portion by way of magnetic coupling between the first and second coil portions, the first coil portion and the second coil portion are physically arranged so that the magnetic fields of the first coil portion and the second coil portion are substantially coextensive and cooperatively induce power in the secondary unit. - View Dependent Claims (18, 19)
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Specification