Electrical Cars/Vehicles Dr. Khaled Awasa By: Saliba Nail Madanat & Abdullah Sultan Dalain Introduction - An Electric car is an alternative fuel automobile that use electric motors and motors controllers for propulsion, in place of more common propulsion methods such as the internal combustion engine (ICE). Electric cars are specifically a variety of electric vehicle created or adapted for use in the road. Electric cars are commonly powered by on-board battery packs, and as such are battery electric vehicles (BEVs). History of Electric Cars 1- Early Years (1890 – 1930):- In 1895, Americans began to devote attention to electric vehicles. Early electric vehicles, such as the 1902 Wood's Phaeton, where little more than electrified horseless carriages and surreys. The Phaeton had a range of 18 miles, a top speed of 14 mph, and cost 2000$. The invention of the electric starter by Charles Kettering in 1912 eliminated need for the hand crank to start internal combustion engine & in this year an electric roadster sold for 1790$, while a Gasoline car sold for 650$. 2- The middle years (1930-1990):- The first battronic electric truck was delivered to the Potomac Edison Company in 1964. This truck was capable of speeds of 25 mph, a range of 62 miles, and a pay-load of 2500 pounds. During this time, Sepring-Vanguard produced over 2000 "CitiCars". These cars has a top speed of 44 mph, and a range of 50-60 miles. Another company was Elcar Corporation, it had a top speed of 45 mph, a range of 60 miles, and cost between 4000$ & 4500$. In 1975, the United States Postal Service purched 350 electric delivery jeeps from the American Motor Company to be used in a test program. These jeeps had a top speed of 50 mph, and a range of 40 miles. 3- The Modern Generation of Electric Vehicles (1990 – 2010):- in this duration, Chevrolet S-10 pickup truck, converted by U.S. Electricar. It was powered by dual alternating current motors and lead acid batteries. It had a range of about 60 miles and could be recharged in less than 7 hours. An early 1990s vehicle was the Ford Ecostar utility van with an alternating current motor and sodium sulfur batteries. The top speed was 70 mph and it had a range of 80 to 100 miles. The Toyota RAV4 was a five-passenger sport utility vehicle with a range of about 95 miles, a 1,000-pound NiMH batteries, a top speed of 79 mph, acceleration from 0 to 50 mph in 13 seconds, and a payload of 785 pounds. BMW also came out with the Mini E in a limited numbers of states. The Mini E was a two-passenger hatchback with a range of about 120 miles with its 575-pound lithium ion batteries, a top speed of 81 mpg, acceleration from 0 to 50 mph in 8 seconds, and a payload of 354 pounds. 4- Today’s Generation of Electric Vehicles (2011 to Present):- Today’s electric vehicle technology can really be broken down into four technologies: • Hybrid electric vehicle • Battery electric vehicle (BEV) • Plug-in hybrid electric vehicle (PHEV) • Extended-range electric vehicle (EREV). Advantages:1- No Gas required, some electric cars have a battery range of 40 miles without any Gas consumption. 2- Electricity is much cheaper than Gas, and you can plug the car into any outlet of the proper voltage. 3- Electric cars give off no emissions, they are better than hybrids in this because the are 100% free of pollutants. 4- Safety is a big concern with these vehicles. However the fluid batteries actually take impact better than a fully made gas car, and can help even more in the event of an accident. Disadvantages:1- Electric car batteries are not cheap, a 40 miles range vehicle sells for around 30000$. 2- These car make no silence, so people won't hear if one of this cars is coming and an accident could occur. 3- Most of the batteries of electric cars are slowly charged, it take you hours to fully charge them. 4- Mostly have a range of less than 25 miles and the top speed of most models is 60 mph, but this will improve in the future. Differences Components 1- Motor:- Generally the brushless DC motor is used. - Simpler to maintain, more durable, smaller. - 85%-90% more efficient. - Able to self start. 2- Controller:- Control the BLDC motor. - Increase efficiency, reliability and extended battery life time. 3- Charger:- It contains a plug that connects electric vehicle batteries to an electrical source, providing the batteries with electrical energy. 4- DC/DC Converter:- Recharges the battery through DC converter. - The Iota DLS-55 is the most common option. 5- Contactors:- This is like a big ON switch, powering up the drive circuit when we turn the key. - The Nafeng ZJW400A is an economical option, or the Gigavac GX14 is a higher powered option. 6- Batteries:- The batteries that are used for electric cars are rechargeable. -How does it work ? When the pedal is pushed; the controller gathers energy from the battery. Controller delivers the appropriate amount of electrical energy to the motor. Then the electrical energy transformers to mechanical energy. So, wheels turn an vehicle move. -In the Electric Cars, the main Power Electronics component is DC/DC Converter:In electric engineering, a DC to DC converter is a category of power converters and it is an electric circuit which converts a source of direct current (DC) from one voltage level to another, by storing the input energy temporarily and then releasing that energy to the output at a different voltage. The storage may be in either magnetic field storage components (inductors, transformers) or electric field storage components (capacitors). DC/DC converters can be designed to transfer power in only one direction, from the input to the output. However, almost all DC/DC converter topologies can be made bi-directional. A bi-directional converter can move power in either direction, which is useful in applications requiring regenerative braking. The most common DC/DC converters can be grouped as follows: 1. NON-ISOLATED CONVERTERS The non-isolated converters type is generally used where the voltage needs to be stepped up or down by a relatively small ratio (less than 4:1). And when there is no problem with the output and input having no dielectric isolation. There are five main types of converter in this nonisolated group, usually called the buck, boost, buck-boost, Cuk and charge-pump converters. The buck converter is used for voltage stepdown, while the boost converter is used for voltage step-up. The buckboost and Cuk converters can be used for either step-down or step-up. The charge-pump converter is used for either voltage step-up or voltage inversion, but only in relatively low power applications. 2. ISOLATED CONVERTERS Usually, in this type of converters a high frequency transformer is used. In the applications where the output needs to be completely isolated from the input, an isolated converter is necessary. There are many types of converters in this group such as Half-Bridge, Full-Bridge, Fly-back, Forward and Push-Pull DC/DC converters. All of these converters can be used as bi-directional converters and the ratio of stepping down or stepping up the voltage is high. 3. ELECTRIC VEHICLE CONVERTERS REQUIREMENTS In case of interfacing the Fuel Cell, the DC/DC converter is used to boost the Fuel Cell voltage and to regulate the DC-link voltage. However, a reversible DC/DC converter is needed to interface the SCs module. A wide variety of DC-DC converters topologies, including structures with direct energy conversion, structures with intermediate storage components (with or without transformer coupling). However some design considerations are essential for automotive applications: Light weight, High efficiency, Small volume, Low electromagnetic interference, Low current ripple drawn from the Fuel Cell or the battery, The step up function of the converter, Control of the DC/DC converter power flow subject to the wide voltage variation on the converter input. Each converter topology has its advantages and its drawbacks. For example, The DC/DC boost converter does not meet the criteria of electrical isolation. Moreover, the large variance in magnitude between the input and output imposes severe stresses on the switch and this topology suffers from high current and voltage ripples and also big volume and weight. A basic interleaved multichannel DC/DC converter topology permits to reduce the input and output current and voltage ripples, to reduce the volume and weight of the inductors and to increase the efficiency. These structures, however, can not work efficiently when a high voltage step-up ratio is required since the duty cycle is limited by circuit impedance leading to a maximum step-up ratio of approximately 4. Hence, two series connected step-up converters would be required to achieve the specific voltage gain of the application specification. A fullbridge DC/DC converter is the most frequently implemented circuit configuration for fuel-cell power conditioning when electrical isolation is required. The full bridge DC/DC converter is suitable for high-power transmission because switch voltage and current are not high. It has small input and output current and voltage ripples. The full-bridge topology is a favorite for zero voltage switching (ZVS) pulse width modulation (PWM) techniques.
