ELECTRIC AND HYBRID ENERGY VEHICLES Fossil fuels are the primary source of energ
ID: 2265817 • Letter: E
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ELECTRIC AND HYBRID ENERGY VEHICLES Fossil fuels are the primary source of energy to power our modern day vehicles and to generate the electricity to power our homes and manufacturing industry. Fossil fuels have resulted in environmental problems and are blamed for global warming. To reduce our dependence on fossil fuels for transportation we have emphasized the increased production of Electric and Hybrid Energy Vehicles. While these vehicles will not completely eliminate our dependence on fossil fuels they are expected to greatly reduce the amount of fossil fuels we use for vehicular transportation The energy conversions class will divide into groups to study the Global economic, societal impact, environmental and health issues associated with the introduction and future use of electric and hybrid energy vehicles. It will a chairman and determine duties of each group member to develop a final paper. Each paper is expected to include at the minimum, the following. be left up to each group to select a) Detailed description of how electric and hybrid vehicles make use of electric motors and/or gasoline assisted motors to power the vehicle (special attention should given to Toyota Prius). b) What types of electric motors are used( synchronous, induction, DC) c) Environmental effect of electric and hybrid vehicles d) Global economic and societal impact of energy efficient vehicles The paper is due at final exam time. The paper should include a title sheet, table of contents, a sign off sheet with all member signatures, detailed research description with supporting pictures and graphs. There should also be a bibliography listing all reference sources. Diagrams, pictures and sketches with captions should be included as needed to describe the motor system with appropriate detailed description. All material used fronm another source should be referenced.Explanation / Answer
Power electronics is definitely one of the areas that provide more significant technological advances in our society. We can mention for example the transportation systems, electric power distribution, distributed generation systems, among others. It is common to current pedagogical projects of Engineering programs in the areas of electricity / electronics, a set of disciplines treating with this issue. In case of power electronics, also the close connection with contents instrumentation and control these issues make the image even further complex. On repetitive learning, students are limited to memorize, without knowing what it is for knowledge. In meaningful learning, students, adds what you already know (prior knowledge) with new knowledge, not only ensuring the continuity of learning, but permitting go chalking up higher levels of knowledge. This is the cognitive evolutionary pedagogical action that aims to maximize the natural lines of the cognitive and affective development. Thinking about how we construct knowledge naturally, or we design a system, we realize that it always occurs, to the global for the particular. The children realize the 'whole' to with the passage of time understand the workings of equipment or even a toy. The engineer 'imagine' a complex system and then divide it and only then design it part by part. In this sense a clear view of the whole, allows the academic interest on a particular subject is enhanced. Making their learning, something more pleasurable once your interest is concentrated on the design . Concrete projects involve many concepts. These are characterized mostly for being multidisciplinary. In this sense, the work curses completion may have a strong bias design. In these cases, the main objective is the development of a product. Now we are going to deal with the design and development of an individual electric vehicle.
ELECTRIC VEHICLES
With the increasing the demand for more efficient transport systems both from the point of view of energy and environmentally, many researchers and designers are concentrating efforts on developing electricalvehicles . These vehicles are light, small and typically allow transporting one or two people. These are vehicles that use one or more electric motors for propulsion, being fed by continuous voltage source. Therefore, depending on the electrical power source there are many different types of UEVs. UEVs not yet have become popular in a similar manner to conventional vehicles powered by internal combustion motors. This is justified principally by low autonomy and supply difficulties (recharge). However, concomitantly, there are other challenges that must be overcome in such vehicles as: high efficiency, robustness, small size, comfort, safety and low cost. It should be emphasized that overcoming these depends on the advancement in various technologies such as energy storage, battery management, control and power electronics, regenerative braking, electric motors, independent wheel drivers, among others. The design and development of electric cars can motivate students of engineering, electrical and mechanical, to focus their formation in power electronics . At the realization of the degree Course Conclusion Work allows showing the multidisciplinary nature of power electronics while actively learn, since it uses the method of hands-on experiences. There are several universities in Brazil doing research to develop UEVs. The UNIJUI has also sought to contribute to this segment, developing its first ElectricalVehicle.
III. DESIGN AND DEVELOPMENT OF AN INDIVIDUAL ELECTRIC VEHICLE URBAN
When we think about electric cars, we imagine a vehicle powered by an electric motor, fed by the energy supplied by batteries. But there are several different technologies that are applied to electric vehicles. According to [6], there are six basic types of electric vehicles.
Larminie and Lowry classify these vehicles based on the type of energy storage: • Electric vehicles with batteries; • Hybrid electric vehicles that combines batteries with internal combustion motor; • Electric vehicles with fuel cells; • Vehicles powered by electric power lines; • Electric vehicles using solar power; • Vehicles that store energy by alternative means, such as flywheels.
The electricvehicle developed in this work possesses several components and subsystems. Between them we can highlight the drive system, the motors used, the battery system, the DC motor drivers and the command circuit and control. A. Traction Systems Used In Electric Vehicles The traction system for an electric vehicle includes several components and can have a different arrangement, depending on the type of application intended. In many applications it is desired a simple and inexpensive. On the others a system performance is the most important factor. In relation to the propulsion means, this can be implemented by: AC motors, DC motors or special motors. As for the location of these motors, they can be connected by example, a transmission system composed of mechanical gearboxes and a differential or be directly connected to the vehicle wheel, depending on the type of vehicle and the land upon which will getting around, creating different topologies related to traction systems. Analyzing the characteristics and possible topologies for the traction system of the vehicle developed, was chosen one that connects directly to the motors in the wheels. Searching then between suppliers, met for use in the prototype some models of electric motors built into the wheel. This system makes it even easier their implementation since it does not require of the use of speed reduction gears or other coupling systems. Topology chosen for use in the prototype. This is due to its mechanical simplicity, reduced weight and volume, as well as the possibility of independent control of each wheel. Besides the advantages mentioned above, this topology used in a three-wheeled vehicle, enables the use of motors not only for the traction of the vehicle, but also to the steering control provided through the variation of motor speed. This simplification of the mechanical parts of the vehicle proposed, is essential so that it could be completely assembled. They also helped reduced the overall weight of the vehicle, removed bearings, axles and components. This has allowed the steering control more comfortable and flexible, since it is performed electronically. B. Motors Based on the analysis of the characteristics desired, the motors more suitable for use in electric vehicles are induction motors and brushless DC motors. They are the motors that present the most advantages in all parameters analyzed. To simplify the control system, among the available options, the motor most appropriate to the proposed project was the type brushless DC. Brushless DC motors have similar operation to a synchronous motor, the rotor field turns at a same frequency as the field generated by the stator, the slip does not occur as in the asynchronous motors. The armature winding may be one, two or three phases, the which uses three phases the most widely used type. Fig. 2. Brushless motor used in prototype (48V 1000W). brushless motor used, which was directly mounted on wheels, a feature that facilitated the assembly of the prototype, reducing the need for additional components and suiting a topology chosen for the drive system. In the motor used in the prototype (Brushless DC), the armature winding has 51 poles and is located in the stator. This is coupled to the shaft being supplied with a voltage of 48V through an electronic switching circuit, such that by reading sensors installed inside the motor. The input voltage applied to the windings trapezoidal sequentially, as shown in Figure 3, allowing its continuous motion. Based on the information of Figure 3 one can build a framework for a better understanding of the sequence of pulses of the sensors and the respective energization sequence of the stator windings. The reversal of the direction of motor rotation can be accomplished by reversing the voltages applied to the coils or by inverting the 744 signal generated by the sensors, where a logic level 0 becomes 1 and vice versa. Signals used to control a DC motor Brushless . Sequence of energizing the windings of a brushless DC motor The current consumed by the motor when a voltage of 48V is applied through its respective driver is 1.8A when operating without load. The motor behavior when subjected to load is 85.4% by developing a torque of 11.4N.m at a speed of 400rpm. Already in noload condition the motor operates with a very low efficiency, which is below 25%. The maximum power developed by the motor is 1002.55W, where it develops a torque of 29.19N.m at a speed of 328rpm, with a yield of 77%. C. Batteries The choice of battery pack considered only the energy needed to power the propulsion system of the vehicle, excluding the installation of additional devices such as displays, lamps and signaling devices. So, after checking the options for storage commercially available, the options that presented themselves economically and technically viable for use in the prototype were the lead acid batteries and lithium iron phosphate (LiFePO4), batteries respectively. The option of lead acid battery was the most economically viable, having a relatively minor cost, for example, that the lithium or nickel cadmium batteries, but the major problem in using these batteries is that its energy density is extremely low, significantly increasing the overall weight of the vehicle, obviously increasing the power consumption of the vehicle. Already batteries lithium iron phosphate are those showing the higher energy density and compared the others, also feature a longer service life, these being the best option for use in the prototype. Considering that the voltage required to drive the the motors chosen is of 48V was decided by using LiFePO4 type batteries with a capacity of 12Ah. TABLE I Battery Specifications Specifications 1 Model Number PP-48V12Ah,Electric vehicle batteries 2 Type LiFePO4 3 Nominal Capacity 12Ah 4 Voltage 48V 5 Size 398×75.5×110mm 6 Weight 5,5kg 7 Cycle Life Up to 1800 cycles D. Brushless DC motor drive The circuit used to drive the brushless DC motor . 5. Individual drive controls for the high and low drivers permit high drive, low drive, and floating drive at each motor terminal. One precaution that must be taken with this type of driver circuit is that both high side and low side drivers must never be activated at the same time. Fig. 5. Three phase bridge used E. Command and Control System Developed The microcontroller used to control vehicle was PIC16F877A manufactured by Microchip ®, PIC16C7XX/F87X family of microcontrollers. In the prototype, this microcontroller has function of receiving the signals from the transducers of the vehicle and send a signal to the motors control modules in accordance with the selected operation. Additionally, the microcontroller sends the information of speed, battery voltage, acceleration and other data from the vehicle to a 14x2 line LCD display aimed at interaction with the user. To read the signs of the steering wheel, throttle and the voltage levels of the batteries we used the existing analog inputs, these signals being sent to the A/D converter and converted to an internal 10-bit value. The speedometer of the vehicle has been implemented through the Hall sensors, existing in the motor, because each full turn of the wheel are emitted in pulses voltage (5V). Th 745 Fig. 6. Control circuit implemented with PIC16F877A The diagram of control circuitry designed and assembled in the laboratory . 6. The prototype card installed in the vehicle . Control board installed in the vehicle To develop the algorithm implemented in the microcontroller was used C + +, using the MPLAB ® software. The basic structure of the program is shown in the flowchart of Figure 8.. Fig. 8. Control circuit implemented with PIC16F877A After initiated basic routines and checked the battery voltage, the program enters an infinite loop, checking entries, defining outputs and sending the vehicle information display Fig. 9. The prototype developed The assembled prototype presented in figure 9. It can be seen that the whole structure of aluminum is significantly reducing its weight. The internal panel, the steering wheel and steering controls and display panel . The internal panel of prototype developed The first scan was performed signs on the control board, which analyzed the generated PWM signals, measured in CCP1 and CCP2 pin microcontroller. The first test was an acceleration of 50% with the steering wheel and the center position after the steering wheel moved to one side.
CONCLUSION prototype used the academic knowledge of the subjects power electronics, microcontrollers, analog and digital control in addition to electromechanical energy conversion. This paper documents that a student has a clear vision of the whole, the project is more motivating, that help for it to overcome its challenges. The results obtained in this trial experience and educational surprised everyone, first as the interest shown by the students, as normally the desktop choice is related to something that arouses curiosity. Thus, usually the work (or project) achieves much higher degree of difficulty than that which would be proposed by the teacher in other activities of student learning assessment. Besides these projects arouse the initiative, creativity and search for information, for the chosen subject is seen as a target to be accomplished. A second important aspect relates to the diversity of issues that end up being addressed in the development work. It is at this stage that the student uses all your creativity so that the problem can be resolved satisfactorily. And, finally, because the interaction between content (interdisciplinarity) is very expressive. This connection established between the numerous components of the course curriculum provides the resumption of many previously explored content and thus promotes the interchange of knowledge. Furthermore, it can be stated that establishes a connection between the theoretical foundations and the practical application of it, openly and therefore quite wide. This work is obviously not imagining this, at this time, no revolution in the teaching-learning process, but give the young man what he expects from an engineering course without, of course, give the teachings that are needed. This transformation requires simply that the subjects tend to satisfy the desires of fantasy consolidating the characterization of higher education institutions as conception of universal ideas.
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