汽车专业毕业设计翻译battery-electric-vehicle.doc

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BATTERY ELECTRIC VEHICLE

ABSTRACT
BATTERY ELECTRIC VEHICLE

Petroleum amazes us every day – its prices simply keep rising and rising. It is almost impossible to predict if you will be able to keep driving your car as you used to, in the future. Most people are already shortening their vacations and holiday trips to save a little more gas and polls report that many people are already cutting back on their everyday expenses in order to pay for their gas.
Adhering to gas saving tips has been useful up until now for some, but just as people adjust to the new prices, the prices rise again! Luckily, there is a solution that can help you cut down your gas expenses and save money no matter how high gas prices rise. The interest in these types of vehicles has risen within the past few years, not only because they do not need a lot of gas, but also because they are environment-friendly – a big concern now that global warming has become such an immediate threat. After all, who wouldn’t want a car that is cheap to travel with and keeps the environment green and the air clear? Most people would – as long as they can afford the initial investment: electric cars!

Battery electric vehicle
The battery electric vehicle, or BEV, is a type of all-electric vehicle that uses chemical energy stored in rechargeable battery packs. As electric vehicle, it employs electric motors and motor controllers instead of internal combustion engines (ICE’s). Some confusion arises because the industry often refers to BEV’s when it means electric cars. ("Battery electric vehicles" including commercial vehicles in addition to passenger cars.)
PRINCIPLE OF OPERATION

How do electric cars work?
First, an electric car is powered by an electric motor, compared to old-fashioned cars that contain a gasoline engine. From the outside, it is almost impossible to tell whether a car is electric or powered on gasoline. However, when you are driving the car, you will get a few hints – for example, the engine is very silent. The main difference appears when you open the hood and get a glimpse of the electric engine, which is powered by a controller, and the rechargeable batteries, that are used to power the controller.

A typical electric car, this one has some particularly snazzy decals. This vehicle is owned by Jon Mauney.

This electric vehicle began its life as a normal, gasoline-powered 1994 Geo Prism!.

Here are the modifications that turned it into an electric car:

v The gasoline engine, along with the muffler, catalytic converter, tailpipe and gas tank, were all removed.
v The clutch assembly was removed. The existing manual transmission was left in place, and it was pinned in second gear.
v A new AC electric motor was bolted to the transmission with an adapter plate.
v An electric controller was added to control the AC motor.
v
The 50-kW controller takes in 300 volts DC and produces
240 volts AC, three-phase. The box that says "U.S. Electricar" is the controller.
v A battery tray was installed in the floor of the car.
v Fifty 12-volt lead-acid batteries were placed in the battery tray (two sets of 25 to create 300 volts DC).
v Electric motors were added to power things that used to get their power from the engine: the water pump, power steering pump, air conditioner.
v A vacuum pump was added for the power brakes (which used engine vacuum when the car had an engine).

The vacuum pump is left of center.
The shifter for the manual transmission was replaced with a switch, disguised as an automatic transmission shifter, to control forward and reverse.

An automatic transmission shifter is used to select forward
and reverse. It contains a small switch, which sends a signal to the controller.
A small electric water heater was added to provide heat.

The water heater
A charger was added so that the batteries could be recharged. This particular car actually has two charging systems -- one from a normal 120-volt or 240-volt wall outlet, and the other from a magna-charge inductive charging paddle.

The 120/240-volt charging system

The Magna-Charge inductive paddle charging system
The gas gauge was replaced with a volt meter.

The "gas gauge" in an electric car is either a simple volt meter or a more sophisticated computer that tracks the flow of amps to and from the battery pack.
Everything else about the car is stock. When you get in to drive the car, you put the key in the ignition and turn it to the "on" position to turn the car on. You shift into "Drive" with the shifter, push on the accelerator pedal and go. It performs like a normal gasoline car.

Here are some interesting statistics:
v The range of this car is about 50 miles (80 km).
v The 0-to-60 mph time is about 15 seconds.
v It takes about 12 kilowatt-hours of electricity to charge the car after a 50-mile trip.
v The batteries weigh about 1,100 pounds (500 kg).
v The batteries last three to four years.
To compare the cost per mile of gasoline cars to this electric car, here's an example. Electricity in North Carolina is about 8 cents per kilowatt-hour right now (4 cents if you use time-of-use billing and recharge at night). That means that for a full recharge, it costs $1 (or 50 cents with time-of-use billing). The cost per mile is therefore 2 cents per mile, or 1 cent with time-of-use. If gasoline costs $1.20 per gallon and a car gets 30 miles to the gallon, then the cost per mile is 4 cents per mile for gasoline.
Clearly, the "fuel" for electric vehicles costs a lot less per mile than it does for gasoline vehicles. And for many, the 50-mile range is not a limitation -- the average person living in a city or suburb seldom drives more than 30 or 40 miles per day.
To be completely fair, however, we should also include the cost of battery replacement. Batteries are the weak link in electric cars at the moment. Battery replacement for this car runs about $2,000. The batteries will last 20,000 miles or so, for about 10 cents per mile.

Comparison with internal combustion vehicles
§ Purchase cost
Batteries are usually the most expensive component of electric cars, though the price per kilowatt-hour of energy capacity has fallen in recent years for the more recently introduced technologies such as lithium-ion and lithium-polymer, as would be expected for any new technology. Older technologies such as lead-acid have become more expensive due to increase in materials cost, particularly lead, driven by demand for use in powered bicycles (particularly in China and India) and in uninterruptible power supplies to support small computer systems. Since the late 1990s, advances in battery technologies have been driven by skyrocketing demand for laptop computers and mobile phones, with consumer demand for more features, larger, brighter displays, and longer battery time driving research and development in the field. The electric vehicle marketplace has reaped the benefits of these advances, but the cost per unit of energy capacity still favors older, heavier, less efficient technologies.
Some batteries can be leased or rented instead of bought (see Think Nordic). In 1947, in Nissan's first electric car, the batteries were removable so that they could be replaced at filling stations with fully charged ones.
§ Running costs
Electric car operating costs can be directly compared to the equivalent operating costs of a gasoline-powered vehicle. A liter of gasoline contains about 8.9 kW·h of energy. To calculate the cost of the electrical equivalent of a liter of gasoline, multiply the utility cost per kW·h by 8.9. Because automotive internal combustion engines are only about 20% efficient, then at most 20% of the total energy in that liter of gasoline is ever put to use.
A car powered by an internal combustion engine at 20% efficiency, getting 8 L/100 km (30 mpg), will require (8.9*8)*0.20 = 14.2 kW·h/100 km. At a cost of $1/L, 8 L/100 km is $8 per 100 km. A battery electric version of that same car with a charge/discharge efficiency of 81%, and charged at a cost of $0.10 for kW·h would cost (14.2/0.81)*0.10 = $1.75 per 100 km, or would be paying the equivalent of $0.22/L. The Tesla uses about 13 kW·h/100 km, the EV1 used about 11 kW·h/100 km.
Servicing costs should be lower for an electric car. The movie “Who Killed the Electric Car “shows a comparison between the parts that require replacement in a gasoline powered car and the EV1 (none), stating that they bring the cars in every 5,000 miles, rotate the tires, fill the windshield washer fluid and send them back out again. Even brakes require less maintenance because of the regenerative braking, the same as with a hybrid.
Electric cars using lead-acid batteries require replacement of the battery pack on a regular basis, while internal combustion engines can last the life of the vehicle, with routine repairs. Lithium-ion and NiMH batteries typically last the life of the vehicle. No Toyota Prius has ever needed their NiMH battery replaced from wear and tear.
§ Energy efficiency
An electric car's efficiency is affected by its charging and discharging efficiencies. A typical charging cycle is about 85% efficient, and the discharge cycle converting electricity into mechanical power is about 95% efficient, resulting in 81% of each kW·h is put to use. The electricity generating system in the USA loses 9.5% of the power transmitted between the power station and the socket, and the power stations are 33% efficient in turning the calorific value of fuel at the power station to electrical power. Overall this results in an efficiency of 0.81*0.3=24.2% from fuel in to the power station, to power into the motor of the EV.
Production and conversion electric cars typically use 10 to 23 kW·h/100 km (0.17 to 0.37 kW·h/mi). Approximately 20% of this power consumption is due to inefficiencies in charging the batteries. Tesla Motors indicates that the well to wheels energy consumption of their li-ion powered vehicle is 10.9 kW·h/100 km (0.176 kW·h/mi). The US fleet average of 10 L/100 km (23 mpg US) of gasoline is equivalent to 96 kW·h/100 km (1.58 kW·h/mi) and the 3.4 L/100 km (70 mpg US) Honda Insight uses 32 kW·h/100 km (0.52 kW·h/mi) (assuming 9.6 kW·h per liter of gasoline), so hybrid electric vehicles are relatively energy efficient, and battery electric vehicles are much more energy efficient.
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Ø A 2001 DOE estimate calculates a battery powered EV at 7¢/kW·h can be driven 69 kilometers (43 mi) for a dollar and at $0.33/L ($1.25/USG) a gasoline vehicle will go 29 kilometers (18 mi). At $3.75/USG that is less than 10 kilometers (6.2 mi).

· Carbon dioxide emissions
While electric cars are considered zero-emission-at-tailpipe-vehicles, they cause an increase in electrical generation needs. Generating electricity and providing liquid fuels for vehicles are different categories of the energy economy, with different inefficiencies and environmental harms. A 55% to 99.9% improvement in CO2 emissions takes place when driving an EV over an internal combustion (gasoline, diesel) vehicle depending on the source of electricity. according to the Electric Vehicle Association of Canada, (who sell electric vehicles) CO2 and other greenhouse gas emissions are minimal for electric cars powered from sustainable electricity sources (for example, by solar energy) or for internal combustion engine cars that are run on renewable fuels such as biodiesel.
If the object of the exercise in looking at alternatives to conventional vehicles is to reduce CO2 emissions, then that has to mean using the most carbon-efficient vehicle you can buy. This depends on the source of your grid electricity; a very high percentage of California electricity is from hydropower, while almost all Texas electricity is from coal]. For the "average" US grid, currently a diesel is better than an EV. Most electricity generation in the United States is from fossil sources, and a lot of that is from coal, according to the U.S. Department of Energy. Coal is more carbon-intensive than oil. - The US national grid is under invested and is having trouble meeting even current levels of demand according to the US DOE.
Overall average efficiency from US power plants (33% efficient) to point of use (transmission loss 9.5%), (US DOE figures) is 29.87% . Accepting 90% efficiency for the electric vehicle gives us a figure of only 26.88% overall efficiency. That is lower than the efficiency of an internal combustion engine (Petrol/Gasoline 30% efficient, Diesel engines 45% efficient - Volvo figures). So a diesel would be better if your grid power was coming from a nearly diesel-burning power plant. The actual result depends on different refining and transportation costs getting fuel to a car versus a power plant. Diesel engines can also easily run on renewable fuels, biodiesel, vegetable oil fuel, with no loss of efficiency. Using fossil based grid electricity entirely negates the in vehicle efficiency advantages of electric cars. The major potential benefit of electric cars is allowing diverse renewable electricity sources, including nuclear power, to fuel cars.
A modern TDI PD or common rail type diesel engine vehicle is almost twice efficient when using fossil diesel than an EV running on grid electricity which is mostly from fossil fuel. It can also run on renewable waste vegetable oil fuel, which is viewed as carbon neutral, or low carbon impact if processed into biodiesel, but controversial if new oil is used, because biofuels have been blamed for higher world food prices, (particularly US bio-ethanol) and increased rainforest depletion to grow palm oil. As well as waste oil, new vegetable oil fuels from algae, and forestry waste being piloted in Finland with Nokia venture capital, are new renewable diesel engine fuel sources that are coming on stream.
Electric vehicles did not win the US 'Tour de Sol' competition for greenest car, a VW TDI running on Waste Vegetable Oil did.
· Smog
The Ontario Medical Association announced that smog is responsible for an estimated 9,500 premature deaths in the province each year. Electric cars or plug-in hybrids, especially in emission-free electric mode, could vastly reduce this number.
· Range vs cruising speed
The tradeoff for range against cruising speed is well known for IC vehicles; typically a cruising speed of around 50 mph i