It is a difficult task to carry everywhere the charger of mobile phones or any electronic gadgets while traveling, and the tangled cords make the situation even worst. Frequent use of the adapters or chargers causes wear and tear of both the cord and the port of the device, which is now one of the major problem in today’s electronic gadgets. Though the concept of wireless electricity is not new but a proper wireless charger is still under development by companies like Wi-Tricity.
Companies like Samsung, Nokia, etc. have also developed wireless charging but these need proper alignment and close contact of the device with the charging pad making it as a major drawback. We are proposing a better wireless mobile battery charger using the method of “Resonant inductive coupling” which doesn’t need any proper alignment or close contact. The goal of this project is to charge a low power device using wireless power transmission.
“Resonant inductive coupling” or “electrodynamic induction” is the near field wireless transmission of electrical energy between two magnetically coupled coils that are part of resonant circuits tuned to resonate at the same frequency. This project has mainly two sections, wireless power transmitter and a wireless power receiver sections. The transmitter of wireless charger circuit consists of a DC power supply, oscillator and a transmitter coil. A constant DC voltage is provided by a DC power source, and this DC signal is the input to the oscillator circuit. This oscillator converts this DC voltage to a high frequency AC power, and is supplied to the transmitting coil. Due to this high frequency AC current, the transmitter coil energizes, and generates an alternating magnetic field in the coil which is then received by a receiver coil and get converted into 5V DC output by a set of filter circuit and voltage regulator making it suitable for mobile charging.
By all the above procedures we are able to charge batteries of some low power devices like mobile phone, power banks and also able to lit some LED bulbs at the same time. This wireless transmission works in a range of about 4-5 cms. away from the transmitter coil. This circuit can be placed under your desk board and simply just by keeping your mobile on the desk starts charging it. This circuit is stable and safe for all standards of mobile phones due to the usage of voltage regulator. Since USB delivers 5V which is same as our receiver output, so most mobile phones are compatible with this voltage level as well as our project. The lithium batteries work on 3.7V and because of that the mobile phones have their own power converters. This fact makes universal compatibility of our project a lot easier. This technology will replace cables and standardize on one interface for charging low power electronic devices (just equipping them with a receiver coil).
By: Swagat Mohanty