Week 12- Scope & Limitation of Project

        The general scope of this project is to generate power that will be stored in super capacitor block, which then will be used to charge up low powered electronic device on the go.
           The specified scope of this project is to able to fully charge up the super capacitor block in a short time interval, that is around 30 minutes or less than an hour, which is less than the usual charging time consume by low powered electronic device and rechargeable battery, that is around an hour to two. To achieve this fast charging time, parallel and series circuitry connection need to be applied to the super capacitors in the super capacitor block made.
           Charging circuit plays an important role in giving a good charging time. Charging circuit that will be used to control the amount of current entering the super capacitor block need to be designed according to several specification taken into consideration, to ensure the best charging time achieved without damaging the super capacitors used.
            Another specified scope is to make this device portable by attaching a dynamo that will be the power supply, to it. This dynamo needs to be turned to generate power. As for that, a crank shaft will be attached to it. The dynamo used need to be ensured to able to supply enough power for charging the super capacitor block.

           Each and every product in present are not perfect and do have limitation, and so do this fast charging portable power supply. For this project, the limitation is that it may produce noise and the power produced might not be sufficient for high powered portable electronic device. When the crank shaft attached to the dynamo being turned, noise may produced from the friction between the mechanical part, such as the gear box and the shaft connected to the dynamo. For the insufficient power produced will be because the dynamo are being rotated or turned with low speed by hand. If the same dynamo being attached to a bicycle, it will be rotated with much higher speed and eventually generates higher power.

Week 11-Methodology_Project Parts

Input (Generator)

The input which is the generator or power supply in this project will be used to generate power. A dynamo of output power 6W 12V AC are used as the generator. The dynamo will generate power when it is being rotated by a crank shaft attached to it.

AC-DC converter

The power generate from the dynamo will enter the AC-DC converter that will convert AC power from dynamo into DC power. The AC-DC converter consists of bridge rectifier, capacitors, and voltage regulator IC as shown below:

 

Charging Circuit

The function of charging circuit is to control the amount of current used to charge the super capacitors in super capacitor block. Over amount of current entering super capacitors will damage it. To avoid any damage, the amount of current entering the super capacitors needs to be reduced when it is reaching its full capacity.

PIC Controller and Series / Parallel circuitry

The PIC controller is used to control and change the series or parallel connection between each and every super capacitor in the super capacitor block. In series connection the total capacitance will be reduced, so any capacitor will attain its full capacity much faster compare to when it is in parallel connection, and this also applies for super capacitor used in this project. The reason for the need of connecting super capacitors in parallel is to obtain higher output voltage from the super capacitor block. So, it can be said that the PIC controller will set the connection between super capacitors in series and parallel when charging and discharging respectively.

Super Capacitor Block

This super capacitor block is used in replacement of a rechargeable battery. The need of forming super capacitor block instead of using one super capacitor as the charge storage is due to its low capacity compared to that of a battery. Connecting capacitors in parallel will increase its capacity which makes it able to supply power for longer period as compare to using only one capacitor, and this also applies for super capacitor used in this project.

DC-DC Booster

The DC-DC booster is used to boost up the voltage produce from the super capacitor to a level that can be used to charge up electronic device. It is needed as the voltage produce from the super capacitor block may not be sufficient to give a good potential difference flow from the output to input of electronic device.