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Design of Electrical System for Solar EV’s and Simulation of PV System under Partial Shading Condition.
Shivani M Bagul UG Student Electrical Engg. Dept.
AVCOE,Sangamner [email protected]
Pritam S Kadam
UG Student Electrical Engg. Dept.
AVCOE,Sangamner [email protected]
Adesh R Kadu
UG Student Electrical Engg. Dept.
AVCOE,Sangamner [email protected]
Prof. J. R. Rokde Assistant Professor Electrical Engg. Dept.
AVCOE,Sangamner [email protected] ABSTRACT
The main objective of this project is to construct a solar car for transportation with virtually no cost as it will run off on free renewable solar energy. Since cars are the major mode of transport shifting to this ecofriendly car would be beneficial on an enormous scale and the purpose of this project is to design the simulation of PV system to track the maximum power during shaded condition. Due to innumerable benefits of solar energy in environmental, economic and social aspects solar car and PV systems have becomes the world‟s fastest growing energy technology. The only limitation to solar power as an energy source is our understanding of developing efficient and cost effective technology which can be implemented. So in this project the cost effective solar car is designed and manufactured, also the limitations of PV System under partial shading has overcome and maximum efficiency can be obtained.
Keywords
Solar Vehicle,Simulation,MATLAB
1. INTRODUCTION
Nowadays, energy used for driving a car such as oil and natural gas decreases gradually, the result of such fuel is the pollution from the engine combustion which increases by the number of cars. In many countries solar cell energy has been used to substitute the use of the fuel. Solar cell energy does not create the pollution, so solar car is the future of the transportation system. The performance of a photovoltaic (PV) array is suffering from temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighbouring building sandtowers, trees, and utility and telephone poles. The situation is of particular interest just in case of huge PV installations like those utilized in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks.
Yet, it's vital to know and predict them so as to extract the utmost possible power. This project presents MATLAB-based modeling and simulation scheme suitable for studying the I–V and P–V characteristics of a PV array under a non-uniform insolation thanks to partial shading.
2. SYSTEM DEVELOPMENT 2.1 Solar Panel
Table .No 1 Ratings of Solar Panel
2.1.2 Charge Controller
Current of each solar panel = 5.6 Amps Voltage of each solar panel = 48 Volts Power of each solar panel = 325 Watt Power of the battery= 48 x 60 = 2880 Watt
Total time taken by solar panel to completely charge battery = 2880/650 = 4.43 Hrs.
At 11.2 Amperes:
RPM of motor = 830 Rpm Torque = 17.25 Nm Speed = 7.13 km/h
2.1.2 Charge Controller
Whenever the battery is going to be charged above 100% state of charge it is said to be over charged. Whenever the battery is discharged below 20% it is said to be over-discharged. To prolong battery life the charge controller must ensure the battery remains within the range of 100% to 20% of state of charge. A set of terminal voltage is found that corresponds to the 100% and 20% state of charge at a particular charging/discharging current based on this a corresponding set of controller set points can be determined. The charge controller would then protect the battery from over-charge if the battery voltage goes beyond its upper set point by disconnecting the solar panel charger from the battery. It would protect the battery from over-discharge if the battery voltage goes beyond its lower set point by disconnecting the load from the battery.
2.1.3 Selection of Charge Controller
2.2.3.1 Voltage Selection
A MPPT charge controller that is compatible with the system voltage is selected. The standard configurations are 12, 24, and 48 volts. The system voltage was 48V so accordingly 48V rating charge controller is selected. Some controllers are voltage specific, meaning that the voltage can't be changed or
substituted. Other more sophisticated controllers include a voltage auto-detect feature, which allows it to be used with different voltage settings. So voltage specific MPPT charge controller having 48 V rating is selected.
2.2.1.2 Current Capacity
A charge controller which will handle the utmost output current of the solar array (or solar array). The maximum possible current that a PV panel can generate is the “short circuit current,” indicated as Isc in the panel‟s label or specs sheet which was 12.06 A. It‟s recommended to incorporate a security factor for isolated events also . So solar panel with a Isc of 12.06 A could potentially produce an extra 25% on a sunny day this results in a possible maximum of 15.075 amp So a 20 Ampere charge controller was selected.
Fig. No 1 Charge Controller
2.1.4. Battery Calculetion
2.1.4.1. Discharge Time Calculation Total battery capacity(C) =60 Amp P=VI
1500=48 × I
Current drawn (c1) = 31.25 Amp/hrs.
t1=C/c1
t1=60/31.25=1.92 hrs.
Considering 20% efficiency loss, 1.92 × (20/100) =0.384 hrs
Total discharge time=1.92-0.57=1.35 hrs.
2.1.4.2 Charge Time Calculation Total battery capacity (C) = 60 Ampere Current provided (c2) = 15 Amperes/ hour t2=C/c2
t2=60/15= 4 hrs.
2.1.5. Motor Controller
The motor controller allows the motor to rotate at different speed; it takes the input from the battery and gives output for motor. The controller used in the solar car has an input and output rating of 30 to 72 volt and has a current rating of max 180 ampere. There are two outputs from the motor controller, one for the acceleration pedal and other for the motor. The internal circuitry for acceleration control further converts the input voltage into low current system. So Kelly KLS7212MC motor controller is selected with is compatible with the BLDC motor used .
.
Fig. No 2 Motor Controller
2.1.6 BLDC Motor
The electrical motor actuated with DC power supply named as DC motors such as PMDC, BLDC Hub motor, and Brushed DC motors. This type of motors is controlled by a motor controller which commands as well as monitors the operation of motor using position sensors installed inside the motor and detects the rotating position of permanent.
Fig.No 3 BLDC Motor Table No.2 Specification
TYPE BLDC Motor POWER 1500 watt VOLTAGE 48 volts CURRENT 32 Amp TORQUE 40 Nm
RPM 3000
Calculations
Vehicle weight = 300kg Rolling resistance = 0.01 Wheel radius = 0.228 m Rpm = 3000
Torque = 40 Nm Speed = 45 km/h
• • Tractive force (Tf) = μmg
= 0.01×300×9.81
= 29.43N
• • Starting torque = (Tf) × Wheel radius
= 29.43×0.228
= 6.71 N-m
• • Force provided by motor = Torque/Wheel radius
= 40/0.228
= 175.43 N Since, F=ma Then, a = f/m
• • Force= (Force of motor – Tf)/Weight a = (175.43-29.43/300)
a = 0.4866 m/s2
• • Circumference=2 𝜋 r
=2×3.14×0.228
= 1.43 m
• • Velocity= Circumference × rpm/60
= 1.43×600/60
= 14.3 m/s
=51.5 km/h
2.1.7. Electrical Circuit Diagram
The electrical wiring system of the Solar car is simply a electrical conversion or wiring anatomy in lieu of a conventional engine driven car. In a electrical system it interconnects the motor, motor controller, acceleration paddle, batteries, charger, panel, charge controller and along with its key safety high power and low power instrumentation and safety measurement components. Below figure shows the system at a glance.
The electrical system divided into two basic parts.
• High-Voltage, High-Current Power System
• Low-Voltage, Low-Current Instrumentation System.
Fig No 4 Circuit Diagram
The bold and thick lines in figure denote the high-current connections. In this part motor controller, motor, battery and gear box are the main components to be put together in solar car. Other than these some safety instruments and voltage- current reading circuitry is additionally connected. A DC or main contactor works a bit like relay. Its heavy duty contacts (typically rated at 30 to 60 ampere) allow us to control heavy currents with a low-voltage. A single-pole, normally open main contractor is placed in the high-current circuit between the battery and motor controller. When it is energized typically by turning the ignition switch on- high current power is made available to the motor controller which then follows to the motor. It is also put for an emergency shutdown option, for example when the battery reaches its minimum depth of discharge the motor has to be disconnected; in this case the contactor is disconnected to make sure no more current is drawn from the battery by motor provided that the electrical system is active by any means. A DC circuit breaker is like a
switch and resetting fuse. The purpose of this heavy-duty circuit break of 62 A is to instantly interrupt main battery power in the event of a drive system malfunction and to routinely interrupt battery power when servicing and recharging. For convenience, this breaker is generally located near the battery pack. The purpose of the safety fuse is to interrupt current flow in the event of an inadvertent short- circuit across the battery pack. The low voltage system includes a key switch, throttle control, monitoring wiring and to 48 to 12 volt converter. The low voltage power source will simply be provided from the car‟s battery pack by using 48 to 12 converter. This will help us to avoid an additional charge controller installation for using an auxiliary battery. Using a converter will thus require only one charge controller for the entire system.
3. MATLAB SIMULATION
This section describes the procedure used for simulating the I– V and P–V characteristics of a partially shaded PV array. It is important to understand how the shading pattern and the PV array structure are defined in MATLAB using the proposed scheme.
Fig.No 5 Simulation Diagram
Above figure shows a PV array with bypass and blocking diodes connected in the array. It is important to note that the characteristics of an array with bypass and blocking diodes differ from that of an array without these diodes. The developed simulation tool has a provision to simulate the array characteristics, for any value of temperature, insolation, and for any array configuration, with and without the bypass and blocking diodes.
3.1 Simulation of PV Module With Partial Shading.
A partially shaded module can be represented by, three groups of PV cells in series. All groups receive different levels of irradiance. PV array when, one of the PV modules under shading, condition equal to 50%. The output parameter for the solar panel with and without bypass diodes under different
shading condition are summarized in below table
Fig. No 6 Partial irradiance (one cell with partial shading effect) and with bypass diode.
Fig No 7 Partial irradiance (one cell with partial shading effect) and without bypass diode
Similarly ,the other results can be obtained for different values irradiance and temperature and analysis can be done based upon results obtained from simulation.
Table No 3 MPP under different Partial shading condition with and without bypass diode
Cell 1 Irrad.
Cell 2 Irrad.
Cell 3 Irrad.
MPP W
V at MPP
I at MPP 1000 500
with B.D.*
1000 218.39 55.7 3.92
1000 500 without B.D.
1000 217.5 55.4 3.93
1000 0 with B.D.
1000 195.9 25.47 7.69 1000 0
without B.D.
1000 0.38 16.65 0.023
500 0 with B.D.
500 95.23 24.80 3.84
500 0
without B.D
500 0.30 15.45 0.020
CONCLUSION
We have designed an eco vehicle which runs without emission of any gases or by-products that is on solar energy.
The vehicle can use both direct supply from solar photo voltaic as well as battery as energy source for operation. The vehicle is very economical as well as environmental friendly.
As traditional sources of fuel used for vehicles are finite and exhausting faster day by day, this vehicle has possibility to replace traditional vehicles and become the future means of transport. The proposed reconfiguration method for designing solar vehicle helps to obtain maximum output under partial shading condition.
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