The function of
charging circuit is to control the amount of current used to charge the super
capacitors in super capacitor bank. 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
with the slow, medium and fast charging option provided on the charging
circuit.
- For charging circuit, the simulation is as shown in figure above. At the input, input voltage of 12V DC will be step down to 5V using voltage regulator circuits with LM7805 voltage regulator IC as shown in figure below. Output 5V produced will pass through a relay whose function is to connect or disconnect the supply to the charging speed controller which comprises three resistors each in series with a switch and the entire three resistors in parallel to load. The values of all three resistors are much lower (100Ω, 220Ω, and 330Ω) compared to the load. When all three resistors is turned on by closing the switch, slow charging takes place as resistance of resistor in parallel will drop to a value lower than each of the resistor, thus allow more current flow through it rather than flowing into load with higher resistance which satisfies the equation V=IR. Fast charging occurs when all the three resistors are disconnected and medium charging takes place when only one or two resistors are switched on
Figure of LM7805 voltage regulator IC.
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