Designed and created a charger to harvest the energy of renewable sources like solar and vibration energy and use it to charge a mobile device. Energy from vibrations is harvested using the principles of electromagnetic induction and piezoelectricity. The project involved building a Buck-Boost converter to regulate the energy accumulated using solar and vibrational energy.
A schematic diagram of our entire project can be seen below.
The prototype we made consists of 2 sub-systems, namely solar and vibrational, both of which are then subsequently connected to the protection circuit followed by the battery.
The solar part is a PCB which houses the boost converter setup. The SMD components like Schottky diode, inductor, capacitor, and the switching IC E5OD are soldered appropriately on the board. The Schottky diode has a lesser voltage drop than normal diodes and has a faster response due to which it is much better for switching applications. The output of this IC is used later. The IC regulates the voltage output to 5V, which is suitable for our application since the maximum voltage given by the solar cell is also of the order of 5V.
To harness the voltage generated by the relative motion of the coil due to EMI, we used a transformer coil with 5000 turns and connected it to two cylindrical extensions as to ensure smooth motion of the magnet across the coil. The alternating EMF generated through the motion of magnet across the coil, fed to a bridge rectifier which is soldered on another PCB.
The output currents of the solar and vibrational part are added together and then fed to the battery. The output of the battery is connected to a protective circuit, which has a Zener diode to ensure that the circuit does not have a surge in the output voltage. The final output then is fed to the USB connector that charges the phone.
The entire report of our project can be found over here.