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Unmanned petrol bunk system using RFID
Introduction:
Nowadays the number of vehicles has increased and proportionally the need for fuels also rapidly growing. Since the need for fuel increases there arises a necessity of installing the petrol bunks frequently between areas. The Indian government had taken huge number of measures to solve this problem by increasing the number of petrol bunks. Even though there are more petrol bunks we require more efficiency, less time consuming and no man power when compared to the other countries. To overcome these problems we are designing an unmanned petrol bunk using RFID. This system can be implemented in every petrol bunk and the need of the man power in bunks can be reduced.
Existing System:
Today almost all petrol pumps have a controlling unit to perform the tasks like managing the electrical pump, drive the display, measure the flow & accordingly turn OFF the electrical pump. But still a person is required to collect the money and there are possibilities of human errors.
Proposed System:
This project aims at designing a system to eliminate this human interaction so that there is no need of workers to fill the petrol. In this system all drivers have a RFID card called as ‘PETRO CARD’. This ‘Petro Card’ can be recharged at ‘RECHARGE POINTS’. At the Petrol Pump the driver swaps the card, the petrol pump is equipped with a RFID reader. The RFID reader reads the amount in the card & it is displayed on the LCD. The driver then enters the quantity of petrol that has to be filled. The corresponding amount is calculated & deducted from the PETRO CARD. The electrical pump is then turned ON according to the entered amount. LCD is used to display the number of units consumed by the user and display the related messages.
Power Supply for 8051 Microcontroller
The ac voltage, typically 220V rms, is connected to a transformer, which steps that ac voltage down to the level of the desired dc output. A diode rectifier then provides a full-wave rectified voltage that is initially filtered by a simple capacitor filter to produce a dc voltage. This resulting dc voltage usually has some ripple or ac voltage variation.
A regulator circuit removes the ripples and also remains the same dc value even if the input dc voltage varies, or the load connected to the output dc voltage changes. This voltage regulation is usually obtained using one of the popular voltage regulator IC units.
Working principle
Transformer
The potential transformer will step down the power supply voltage (0-230V) to (0-6V) level. Then the secondary of the potential transformer will be connected to the precision rectifier, which is constructed with the help of op–amp. The advantages of using precision rectifier are it will give peak voltage output as DC, rest of the circuits will give only RMS output.
Bridge rectifier
When four diodes are connected as shown in figure, the circuit is called as bridge rectifier. The input to the circuit is applied to the diagonally opposite corners of the network, and the output is taken from the remaining two corners.
Let us assume that the transformer is working properly and there is a positive potential, at point A and a negative potential at point B. the positive potential at point A will forward bias D3 and reverse bias D4.
The negative potential at point B will forward bias D1 and reverse D2. At this time D3 and D1 are forward biased and will allow current flow to pass through them; D4 and D2 are reverse biased and will block current flow.
The path for current flow is from point B through D1, up through RL, through D3, through the secondary of the transformer back to point B. this path is indicated by the solid arrows. Waveforms (1) and (2) can be observed across D1 and D3.
One-half cycle later the polarity across the secondary of the transformer reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current flow will now be from point A through D4, up through RL, through D2, through the secondary of T1, and back to point A. This path is indicated by the broken arrows. Waveforms (3) and (4) can be observed across D2 and D4. The current flow through RL is always in the same direction. In flowing through RL this current develops a voltage corresponding to that shown waveform (5). Since current flows through the load (RL) during both half cycles of the applied voltage, this bridge rectifier is a full-wave rectifier.
