MATLAB Simulation of Solar Electric Vehicle

2018 Joint International Conference on Energy, Ecology and Environment (ICEEE 2018) and International Conference on Electric and Intelligent Vehicles (ICEIV 2018) ISBN: 978-1-60595-590-2 MATLAB Simulation of Solar Electric Vehicle Mehdi Korki 1, Krishna K Bhati 1, Sithara P S B 1, Shamin Pandit 1, Aswathi S Nair 1, Darshan M Talati 1 1 Swinburne University of Technology, Hawthorn, Melbourne 3122, Australia Abstract This paper presents the simulation of Electrical components of a solar car that is been built for the Bridgestone World Solar Car Challenge 2019 along a 3000km from Darwin to Adelaide, Australia. The Electrical components demonstrates how the energy from the sun captured by solar panel is converted into mechanical energy which is used to run the motor. The simulation is all represented by MATLAB simulation tool. Keywords: SolarCar, Simulink, Solar Irradiation, Temperature, MPPT Nomenclature Abbreviation PV Photo-Voltaic MPPT Maximum Power Point Tracking DC Direct Current BLDC Brushless Direct Current IGBT Insulated Gate Bipolar Transistor AC Alternate Current Demux Demultiplexer PI Proportional Integral IOT Internet of Things IEEE Institute of Electrical and Electronics Engineers 1. Introduction One major concern in the sector of power generation is day-by-day increase of power demand. However, quantity and availability of conventional energy sources are insufficient to meet this increasing power demand. Moreover, looking at future availability of non-renewable energy resources, it seems very important that the use of renewable energy sources must began along non-renewable energy sources to fulfil the rising demand of energy. Solar energy is one of these renewable energy resources, obtained from sun radiation. With a steady growth and cost reduction in the field of solar PV power generation, and the further inflation of energy crisis, solar PV power technology obtains more applications." Since a decade, the fuel costs and the pollution due to conventional vehicles have been risen in a drastic manner such that, use of electric vehicles in the society has become a necessity. Solar vehicles and hybrid vehicles which are currently available in market could be a future to overcome the problems in current scenario. 1.1 Literature Review In the previously developed solar cars most of the solar car team has gone with the mono crystalline silicon solar cells because it has more efficiency and life span as compared to polycrystalline silicon solar cells. MPPT technique is used in the solar car because the power coming from the solar panel is varying so to increase it and make the output power stable. Solar cars which was developed till date used a brushless DC motor because it has some advantages like smaller size, improved efficiency, better torque and speed control but we are planning to use 3 phase induction motor because bldc motor has low power output such as 3-4 kW while 3 phase induction/synchronous motor output is greater than that. In addition to that 3-phase induction/synchronous motor has low initial and maintenance cost. As we are using 3 phase induction motor there will be harmonics so to remove the harmonics there are some techniques for example fundamental switching frequency, mixed switching frequency and high switching frequency. So most likely fundamental switching frequency will be used in our case, it has space vector control in which the angel of inverter switches is matched with the requirement of harmonics which needs to be eliminated. Paper ID: ICEEE2018-xxx 2. Design Approach Figure 1 Block Diagram of Solar Car The above figure shows the block diagram of our approach to Solar Car and the detailed explanation of each module is as explained below; 2.1 Solar Panel Solar panel is the foremost important component of the design. It consists of series and parallel connections of small sized solar cells, that converts the collision energy of photons in the sunlight i.e. as the photons possess certain amount of energy the electrons in the solar cell captures that energy and as per conservation of energy and conservation of momentum the electrons in the solar cell gets energized and tries to escape the area, and is thus captured by the arrangement of silver wires( for low resistance) which allows these electrons to pass through it thus producing the electrical current. Each solar cell can generate certain small amount of electrical current and voltage, complex connection of these cells ensures practical usable output from each array of it. Solar panel works on the principal of energy conservation. Sometimes the ejected electron falls back in the same region of its escape rather than moving through the metallic silver, thus situation reduces the overall efficiency of the solar panel. This implies, larger the energy of the photonic collision, larger the loss in energy. This module was implemented in Simulink using an Iphoton which is dependent on the inputs such as solar irradiation, temperature and feedback voltage and current being its output. The mathematical modelling of PV panel at specified temperature, which is directly proportional to product of reverse saturation current and ideal factor for silicon poly crystalline. Voltage gradient with respect to current at operating open circuit voltage is inversely proportional to number of cells used in PV panel which are connected in series. Above relationships resulted in mathematical equations which were coded in the Iphoton function of the PV block. Figure 2 PV Module using Simulink 2 Copyright © by ICEEE Paper ID: ICEEE2018-xxx 2.2 MPPT – Maximum Power Point Tracking Solar irradiation and temperature is always varying and unstable, which results in lower efficiency of solar panels to capture the sunlight and convert it to usable electrical energy efficiently is a complex task. Thus, the load or the output connected to the solar panels will have to be matched to the input of the solar cells to improve the efficiency of the power generated using solar light by the solar panels. The process of obtaining maximum power at all the varying conditions of solar cells is called as maximum power point tracking. the Perturb and Observation method to obtain maximum power from solar panels to run the load. The Perturb and Observe works on the principle of controlling the voltage levels till the power does not increase more than the required level, which is basically a trial and error method of applying voltage and checking for the increase in the output power and the process continues. This process can be represented using the above operational flow chart. Figure 4 MPPT algorithm using Simulink The above figure depicts the implementation of MPPT module using Simulink. Figure 3 MPPT Algorithm 2.3 Buck Boost Converter Figure 5 Buck-Boost Converter using Simulink 3 Copyright © by ICEEE Paper ID: ICEEE2018-xxx The output obtained from the solar cells are slightly unregulated, which needs to be regulated to operate a load at the output and this stage of Buck-Boost converter are used to regulate the output of solar cells, where a control block in the converter produces a gate signal to drive the IGBT to perform the function of a switch and allows the current to flow through and an inductor at the output of this section would store the energy and then discharges the same to the load. A snubber circuit is used in the module in order to protect the circuit from sudden high currents flowing due to varying conditions and also a capacitor at the output will eliminate all the ripples at the output end. 2.4 Three Phase Inverter The three- phase inverter used here drives the DC output of above buck boost converter as input and converts to AC correspondingly to drive the motor connected as load to the system. The energy from solar cells are converted to a signal to drive a motor. Figure 6 Inverter Module The control block produces 3 phase pulse signals with a frequency of 50Hz to convert DC to AC. This block provides gate signals for the IGBT’s implemented in the 6-pulse inverter block. The gate signals are activated and IGBT conducts and allows the current to flow through. The switching behavior of IGBT alternatively turns ON/OFF in different cycles. Final 3 phase output is measured by a 3 phase V-I measurement block to determine the voltage and current of the signal which can be observed in the scope connected at the output. 2.5 Self-Control Synchronous Motor Drive Figure 7 Motor Block In the Simulink, AC5 block of Sandscape Power Systems Library is used which is a self- 4 controlled synchronous motor drive and has an active rectifier at its input. Internal design of this synchronous motor includes a speed control Copyright © by ICEEE Paper ID: ICEEE2018-xxx loop that utilizes a PI regulator and henceforth produces references of flux and current that are further utilized by the vector controller block. Later the controller calculates the motor line currents which are directly corresponding to the reference of torque, this feeds the motor with the help of three phase current regulator. Vector controller also calculates flux difference and helps in generating the field excitation voltage. The AC block consists of inputs as Speed reference and load torque which is the characteristic of the load connected. The output of the motor block is read with the help of a demux which splits Ia (stator current), Rotor Speed, Electromagnetic Torque, DC bus voltage, Flux and shows the corresponding outputs at the scope. In the motor simulation, a discrete system with 1e-6 sampling time is used. 2.6 Overall System of Implementation Figure 8 Overall Implementation The above figure shows the o verall implementation of the MATLAB simulation of solar electric vehicle. We can see the motor driven by solar panels in the above figure. 2.7 Results Figure 9 MPPT Output Figure 10 Inverter Output. The above snapshots indicate the outputs obtained after simulation using the MATLAB Simulink software. MPPT is used to obtain 5 maximum power at all varying conditions can be seen from the output in Fig 10 and we have converted the output to 3 phase using an Copyright © by ICEEE Paper ID: ICEEE2018-xxx inverter which can be observed from the inverter output screen shot in Fig 11. 2.8 Conclusion & Future Scope Solar car is an initiative by Swinburne University of Technology to take part in the Bridgestone Solar Car Challenge. The main concept behind building up this car is to utilize the abundantly available solar energy and convert it to the mechanical energy to drive a car from Darwin to Adelaide covering over 3021 Km’s in about 6 days. Design involves Solar cells whose output is depending on the solar irradiance at real time and provides the energy to the car. We began with designing the entire system from a solar cell to motor. Our aim was to implement the model using MATLAB Simulink and obtain relevant output that in future works would help us in the practical implementation. In Future a solar tracker can be implemented to capture the more sunlight. IOT (Internet of Things) can be used and sensors can be installed to show the temperature, battery level and current-voltage drop. However, project cost can be a trade-off. Development and use of more efficient inverters can be a future scope of this project. Reference [1] Farooq, M., et al. (2014). Economically designed solar car for developing countries (Pakistan). Global Humanitarian Technology Conference (GHTC), 2014 IEEE, IEEE. [2] Hongmei, T., et al. (2012). "A detailed performance model for photovoltaic systems." Sol. Energy J. [3] Lopa, S. A., et al. (2015). "Design and Simulation of DC-DC Converters." International Journal of Electronic and Electrical Engineering ISSN: 2395-0056. [4] Menasce, D., et al. (2013). High Power Electrical Systems Design for a Solar Car: Designing and building the solar car IlangaI. I. AFRICON, 2013, IEEE. [5] Shao, X., et al. (2016). Solar irradiance forecasting by machine learning for solar car races. Big Data (Big Data), 2016 IEEE International Conference on, IEEE. 6 Copyright © by ICEEE