We must acknowledge the strength, energy and patience that almighty GOD bestowed upon us to start & accomplish this work with the support of all concerned, a few of them weam trying to name hereunder.
We would like to express our deep sense of gratitude to our Supervisor, Prof. Abirami Rajagopal, Assistant Professor,Electrical Engineering Department for his valuable guidance and motivation throughout our study.
We would like to express our sincere respect and profound gratitude to Prof. (Dr.) S.C.VORA, Professor & Head of Electrical Engineering Department for supporting and providing the facilities for ourminor project work.
We would also like to thank all our friends who have helped us directly or indirectly for the completion of ourminor project.
No words are adequate to express our indebtedness to our parents and for their blessings and good wishes. To them we bow in the deepest reverence.
The use of solar power system for generation of electricity nowadays it is widely used.
The solar light is most favored source of energy, because it is environment friendly and pollution free. The sun vitality is independent and boundless while other sources like petroleum, natural gas and coal are demonstrating their end. To raise the proficiency of sun based vitality framework, solar panel based multi mobile charger and street lamp system can be executed. Nowadays, mobiles are the key things for each individual and for that purpose a charging station of mobiles are needed in the open areas.
Accordingly, an idea, solar based mobile charger framework is executed in the proposed system which will be utilized as open spot in areas like railway stations, transport stands, Hospitals, parks, hilly areas, rural areas and so on. At night, in such areas lighting system will be required. Consequently, a thought for this a street lamp based on solar energy on the same charging station is executed in the following framework.
Mobile phone is lifesavers as they help in emergencies. Mobile phones are a comfortable way of communication overa long distance. Now a day’s mobile phone had become one of the basic necessities of life. The first and foremost role that mobile phones play in our lives is that they provide easy and fast communication. Mobile phones are not only meant to stayin connected with friends and relatives. The tremendous Development of technology had increased the usage of mobile phones in emergency services, internet access and social media, business purposes, and also it ensures safety .as per the analysis there are more mobile phones than people living on earth. By this we can understand how the mobile phone had become an essential part of human life. Mobile phone charging had become the major drawback which everyone is facing these days.
To charge a mobile phone battery we required a DC source or supply which we are obtain from AC power source generally. Hence, it is very difficult to get charging in mobile phone without AC supply or backup batteries. While travelling someone hardly find an AC power source to charge their mobile phone battery. As the technology and software has been updating daily the operating system in mobile phones required lot of power. To increase its energy storage capacity and long duration power, mobile phone companies are increasing its battery size .but when the application in your mobile phone has increased the battery in it will drain quickly.
A back up battery has been carried to reduce the problem. But this won’t give permanent solutions if mobile battery wants to come for long time period without charging from AC supply or backup battery. we are proposing a new model in which the primary source of charging a mobile phone will be from Photovoltaic (PV) and the AC power source will become the secondary option. In case of emergency. It has a major advantage of two way power source. By installing solar cellson the mobile phone these cells will continuously supply power to the battery. Hence, battery can be work for long time period without discharging even mobile is running for long time.
Cost Effective: Compared to the other mobile chargers, the solar chargers are cost effective as it absorbs power from the sun. It does not require electric power.
Versatile: It is also known to be versatile as it can be used for all types of mobile phones.
Uninterrupted Power Supply: One of the greatest advantages of solar mobile phone charger is that it can be used to charge mobiles even during power outages.
Emergency Purposes: Another benefit is that it hardly requires any electrical outlet. It can therefore be used during emergencies and outdoor purposes.
The main advantage of using a solar battery charger is that it can be used to store energy, which can be used later when sun is not available on a wet or cloudy day.
You can select a suitable charger as per your needs.
You can carry it along with when you are going out with friends on a picnic or a party.
Thus, you can remain connected with your friends and family members when you are out of home and do not have a power source to charge your devices by using this unique charger.
The number of solar panels available on the charger determines the amount of power it can store. The specifications of the charger also depend upon the device that you want to charge.
Quite expensive: One of the most important drawbacks is its price compared to the ordinary mobile phone chargers, it is quite expensive as it utilizes solar energy captivators.
Charging time large: Another significant drawback is the time frame required by the chargers to charge mobile phones. It can take six to eight hours to charge mobile phones compared to the other.
Taking a cell phone with you on a trip may be necessary as an emergency measure. As solar chargers only work during the day and take time to charge up, a cell phone may no longer seem like a practical emergency communication means.
Although pollution related to solar energy systems is far less compared to other sources of energy, solar energy can be associated with pollution. Transportation and installation of solar systems have been associated with the emission of greenhouse gases. There are also some toxic materials and hazardous products used during the manufacturing process of solar photovoltaics, which can indirectly affect the environment. Nevertheless, solar energy pollutes far less than other alternative energy sources.
Use lot of space:- The more electricity you want to produce, the more solar panels you will need, as you want to collect as much sunlight as possible. Solar panels require a lot of space and some roofs are not big enough to fit the number of solar panels that you would like to have. An alternative is to install some of the panels in your yard but they need to have access to sunlight. If you don’t have the space for all the panels that you wanted, you can opt for installing fewer to still satisfy some of your energy needs.
Public solar chargers permanently installed in public places, such as parks, squares and streets, which passersby can use for free.
Small portable models designed to charge a range of different mobile phones, iPods or other portable audio equipment.
For low-power portable electronics, like calculators or small fans, a photovoltaic array may be a reasonable energy source rather than a battery.
In other situations, such as solar battery chargers, watches, and flashlights the photovoltaic array is used to generate electricity that is stored in batteries for later use.
By using over voltage protection circuit we can protect our battery from over charging. Charge discharge control circuit contain two-way Switch. It gets active when voltage exceeds above threshold voltage level.
As their name suggests, lithium-ion batteries are all about the movement of lithium ions: the ions move one way when the battery charges (when it’s absorbing power); they move the opposite way when the battery discharges (when it’s supplying power):
During charging, lithium ions (yellow circles) flow from the positive electrode (red) to the negative electrode (blue) through the electrolyte (gray). Electrons also flow from the positive electrode to the negative electrode, but take the longer path around the outer circuit. The electrons and ions combine at the negative electrode and deposit lithium there.
When no more ions will flow, the battery is fully charged and ready to use.
During discharging, the ions flow back through the electrolyte from the negative electrode to the positive electrode. Electrons flow from the negative electrode to the positive electrode through the outer circuit, powering your laptop. When the ions and electrons combine at the positive electrode, lithium is deposited there.
When all the ions have moved back, the battery is fully discharged and needs charging up again.
The mobile battery required a constant voltage for charging and the life time of a battery will be reduced if not providing constant voltage. Moreover, the battery life also will be reduced by either fully charging or discharging the battery. Further, the solar irradiation is depends on weather conditions, hence PV output voltage will fluctuate according to solar irradiation. Therefore, the direct charging of mobile battery from PV cells causes damage of mobile battery.
In order to improve the life time of battery as well as safe operation, DC to DC converter is used for maintaining constant voltage irrespective of weather conditions. The voltage of PV system is depends on solar irradiation, hence,the voltage may be lower than or higher than the voltage required to be charge the battery. Battery unable to charge from the voltage which is lower than required voltage and higher voltage will damage the battery quickly. Therefore,buck boost DC to DC converter is required to maintain the constant voltage from any value of input of buck boost converter which is coming from PV system. The model diagram of buck boost converter is shown in Fig.4.1.
Fig. No – 4.1
PV system will produce the Voltage and this will be used as an input to buck boost converter. And the output voltage of buck boost converter is comparing with reference voltage(Vref) then given to proportional plus integral (PI) controller.
The PI generates the required duty cycle to maintain the voltage at Vref and switch S1 will be operated accordingly pulses generated by pulse width modulation (PWM) controller with the help of duty cycle which is generated by PI controller.
A new approach to charge the mobile phone is by connecting a 0 to 9V PV system through buck boost converter with regulated output voltage at required voltage for chargingthe battery. The schematic diagram of proposed system is
shown in Fig.5.1. To prevent the damages of battery, SOC based controller can be incorporated to regulate the DC to DCconverter. The switch will be switched off automatically to charge the batter when SOC of the battery will reaches the allowable higher limit.
Fig. No.- 5.1
The proposed method is tested in matlab simulink for change in irradiance. The dc output voltage (i.e., input voltage of buckboost converter) of PV system decreases with decreasing in irradiance. The circuit is tested at irradiance reduces as shown in Fig.5.2.
The corresponding output voltage of PV system as shown in Fig. 5.3 This
decreased voltage is now input voltage of buck boost converter and the mobile is required voltage more than 4.2V to get charge the battery. Hence, in order to charge the battery we need to boost the voltage to required level. The buck boost converter will do the same by boosting the voltage.
The same buck boostconverter will act as boost converter when irradiance reduces.
The corresponding output voltage of buck boost converter as shown in Fig. 5.3. It seems, the response of buck boost converter as satisfactory to boost the voltage to required level for charging the mobile battery.
Fig. No.- 5.2
Fig. No.- 5.3
In this project, the work carried out is designing and implementation of a MPPT charge controller circuit for solar power mobile charger. The main purpose was to deliver power from an array of solar panels to a Li-ion battery in order to charge it. The PV systems voltage will vary according to solar irradiance. Hence, to prevent the damages of mobile battery from fluctuations of voltage from PV due to changes in irradiance so, DC to DC buck boost convert is connected to regulate the voltage. The extensive Matlab simulation is done and result is presented.