220 VOLTS TO 12 VOLTS POWER SUPPLY AND STORAGE

This project is to create a 220 A.C to 12V DC power supply that can also store the power for a long time. The circuit used is an efficient one and has brought many improvements into current D.C power supplies such as voltage regulation and removal of ripples in output. The 220 A.C voltage is first converted into 12 V A.C by a step down transformer, then a full wave rectifier bridge (based on wheat stone bridge) is used to convert the A.C into D.C. Then this output is filtered twice by two mechanisms.

>In order to remove the ripples in the waveform of the bridge circuit.

> Create a regulated and efficient power supply.

A NPN transistor with a base connected to the Zener diode is also used as a switching the circuit. Then 12 V is received as output voltage. The circuit s and wave forms are created using PSpice. Due to the voltage regulation and removal of ripples in the output this power supply can also be used as a “battery eliminator” which provides constant and efficient output to the load without the need for a battery.

The need of D.C Power supply is always there in the field of electrical engineering. The main advantages these D.C power supplies bring are portability and cost effectiveness as compared to A.C power supplies but sometimes the cheapness of these D.C power supplies results in the lack in efficiency of the output. That is the output of most of the D.C power supplies present in the market has ripples in it and is not pure D.C. Moreover the output voltage is not exact due to losses in the circuit. To remove these draw backs in D.C power supplies we have made an efficient circuit that not only removes the ripples in the output voltage to make a pure D.C signal but also regulates the voltage to a constant and desired value. This is achieved by using a filter circuit and transistor which is used as a switch. We have used a bridge rectifier instead of two diode rectifier (which also produces full wave rectification) because the bridge rectifier does not require a high “peak inverse voltage” as it utilizes most of the windings of the transformer. We have also used a simple transformer instead of center tap because it is cheaper and produces compact and cheaper power transmission. The use of a RL circuit as a filter has improved the efficiency of the circuit by removing the ripples in the D.C that is rectified by the bridge. The use of transistor as a switch has brought the other improvement in the circuit I.e. it has regulated the voltage to a constant value that has saved our load from voltage fluctuation damages. Rechargeable Nickel Metal Hydride batteries are used, which are being used extensively in consumer electronics these days. These also have lower charging time and are very long-lasting. Due to the efficient combination of the values of the circuit elements a variety of loads can be attached to the output circuit i.e., any circuit element having voltage 12 V and resistance greater than 10 Ωs.

APPLICATIONS

>The circuit can be used as a “battery eliminator” as it provides constant regulated voltage and ripple free output. It can be used to give output directly to a load instead of a battery first. This reduces the cost of battery.

>It can be used as Battery charger. This can be detached from the circuit and then used to supply power to a variety of electronic devices.

>It can be used as a D.C voltage regulator which is capable of providing ripple free voltage.

>To recharge an electric vehicle (EV) battery pack.

>To recharge a fuel vehicle’s starter battery, where a modular charger is used.