New-Tech Europe Magazine | Feb 2017

Sensors Special Edition

Figure 3. A complete contactless connectivity design integrates ICPT for power transfer and 2.45GHz wireless for data transmission, all within an M30-type form factor. [Image courtesy of TE Connectivity]

coupled power-transfer system is shown (Figure 2). It consists of a transmitter coil L1 and a receiver coil L2. Both coils form a system of magnetically coupled inductors. An alternating current in the transmitter coil generates a magnetic field, which induces a voltage in the receiver coil. The efficiency of the power transfer depends on the coupling (k) between the inductors and their quality, defined as their Q factor. The coupling is determined by the distance between the inductors (z) and the ratio of D2/D. The shape of the coils and the angle between them further determines the effective coupling. The performance of a wireless power link can be improved using resonant inductive coupling. Resonance of a circuit involving capacitors and inductors occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor, and then the discharging capacitor provides an electric current that builds the

Figure 4. Implemented in an M30-type connector, the near-field loop antenna design for a contactless connectivity-based data link is symmetrical to allow for rotation. [Image courtesy of TE Connectivity]

mathematically as:

through of how it works is useful in understanding its utility as a wireless power-transfer mechanism. Faraday's law of induction states that the induced electromotive force in any closed circuit is equal to the rate of change of the magnetic flux enclosed by the circuit, or

Where is the electromotive force (EMF) and ΦB is the magnetic flux. The basic principle of an inductively

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