The idea is to convert the DC supply into a high frequency AC supply with the help of an oscillator, which we need in order to transfer wirelessly [7]. For the oscillator we used a simple Colpitts oscillator. The oscillator is a simple one to implement and being a current oscillator it is helpful for the system [1]. The AC power is then transferred wirelessly through inductive coupling. In inductive coupling power is transferred between coils of wire by a magnetic field. Fig. 2 shows the block diagram for the wireless power transfer through inductive coupling. The transmitter and receiver coils together form a transformer. An alternating current (AC) through the transmitter coil (L1) creates an oscillating magnetic field (B) by Ampere's law. The magnetic field passes through the receiving coil (L2), where it induces an alternating EMF (voltage) by Faraday's law of induction, which creates an AC current in the receiver. One important parameter for coupling is frequency, as the efficiency shows a proportional relationship with frequency for such systems [9].

Fig 2 Block diagram of WPT (Collected from [9]) Both of the coils act like a transformer using which the power is transferred. The power …show more content…
For this system, a 24AWG Magnetic Enameled Wire have been used. The diameters and number of turns of both the transmitting coil and receiving coil are chosen in such a way that they both resonate at the same frequency. The diameter and number of turns were arbitrarily chosen to be 15cm and 20 turns respectively. The coils were then separately connected to the transmitting end or Colpitts oscillator. The number of turns of both the coils were varied to get the expected outcome. When both the coils resonated at the same frequency, then the receiving part was accordingly. The chosen frequency was 66 KHz approximately. To find the inductance of the coils, the following formula were