The main objective of this project is to develop a concept of wireless power transfer for several applications such as wireless powered electric vehicle in stores, airports, departmental stores etc. It can also charge a rechargeable battery or a cell phone wirelessly suitably modified for the purpose.
AC 230V ,50 Hz mains is stepped down to low voltage ac by conventional 50 Hz iron cored transformer which is then rectified by a bridge rectifier to develop around 14 volt DC. This DC is again made to ac by a PWM inverter using half bridge concept comprising of 2 MOSFETs and 2 capacitors being switched at 40 KHz which is then fed to a resonating high frequency coil acting as primary of an air core transformer.
Another matching resonating coil formed as secondary drives a lamp load of 10 watts spaced at an air distance of 20 CMs. The overall efficiency of the power transfer in this case is more than 90% for perfectly coupled and matched series resonators. However, practically resonators with a Q of 1,000 should be able to send power over a distance 9 times the radius of the devices with an efficiency of 10%.
The secondary coil develops a voltage of 40 KHz at 12volt while it is kept spaced from the primary coil where air is used as the core. The output of the secondary can also be given to a high frequency bridge rectifier that can deliver DC which could then be regulated to maintain a constant voltage to a DC motor or current to feed to rechargeable battery or a cell phone. However, the overall efficiency of the power transfer shall be less than 50% for all such weakly coupled series resonators.
- Bridge-MOSFETs drive
- Two air filled inductor coils
- Voltage regulator
- MOSFET driver
- PWM inverter IC