Components

Major EV Components

An electric vehicle is composed of four major components:

            Electric motor

            Batteries

            Controller

            Charger

There are also four major categories of support hardware for the EV system:

            Interface hardware

            Control and safety circuitry

            Auxiliary power

            Monitoring

EV History - The first really successful electric automobile was the carriage built by William Morrison of Des Moines, Iowa, in 1890.

Morrison's car used high, spoked wagon wheels to negotiate the rutted roads of America, and an innovative guidance system which included patented rack-and-pinion steering.

Morrison's car was capable of running for 13 consecutive hours at 14 mph. Much of the car's success, however, was attributable to the promotional efforts of Harold Sturges, secretary of the American Battery Company.

This is better than most modern golfcarts

FACT: we don't buy much oil from Saddam/Iraq (% of US oil imports from Iraq fluctuated from 3-9% since 1997, zero from1990-97).

As far as equating gasoline consumption with oil profits in Iraq. About 25% of our imports are from the Persian Gulf currently. About 90% of our oil is imported.

The most current alternatives to the internal combustion engine (ICE):

1. Ultra Low Emissions Vehicles (ULEV)

2. Zero Emission Vehicles (ZEV)

ULEV ~ are equipped with emissions controls that release roughly 45lbs of carbon monoxide per 12,000 miles.

ZEV ~ produce no tailpipe emissions

~ include vehicles powered by

- Electricity (EVs)

- Flywheels

- Hydrogen Fuel Cells

- CNG

EV uses electricity stored in batteries to power one or more electric motor.

- when recharging simply plug in from the convenience of home

- no fuel, combustion, exhaust or evaporative emission system

- Almost maintenance free

- Emissions associated with EV charging are extremely low

Recharge via ~ coal and oil fired power plants

nuclear

hydroelectric

solar

wind power

The golden haze (smog) caused by our love affair with the ICE car will have long lasting effects. The number of vehicles and miles traveled are increasing yearly, despite stringent standards to improve tailpipe emissions. Scientist predicts that our increase reliance on the automobile could increase pollution levels to 40% by the year 2010. In California where the car is considered a necessity, ICE vehicles account for 90% of carbon monoxide, 77% of nitrous oxides and 55% of reactive organic gasses. In addition, green house gasses such as carbon dioxide are expected to increase approximately 33% by the year 2010.

The following list describes the potential health risks associated with these emissions.

CARBON MONXIDE - is an odorless and colorless gas which is highly poisonous. CO can reduce the bloods ability to carry oxygen and aggravate lung & heart disease.

SULFUR OXIDES (Sox) and SULFUR DIOXIDE (So2) When combined with water vapor in the air SO2 is the main contributor of acid rain.

NITROUS OXIDES (NOx) and NITROGEN DIOXIDE (NO2) These chemical are the yellowish brown haze seen over dirty cities. When combined with oxygen from the atmosphere, NO becomes NO2, a poisonous gas that can damage lung tissue.

HYDROCARBONS (HC) this group of pollutants containing Hydrogen and Carbon. Hydrocarbons can react to form ozone. Some (HCS) are carcinogenic and others can irritate mucous membranes.

OZONE (03) this is the with haze or smog seen over many cities ozone is formed in the lower atmosphere when NMOG and NOX react with heat and sunlight ozone can irritate the respiratory system, decrease lung function and aggravate chronic lung disease such as asthma.

CARBON DIOXIDE (CO2) - CO2 is a naturally occurring gas in the atmosphere and is a necessary ingredient of the ecosystem. In large quantities it can allow more light to enter the atmosphere than can escape. The excess heat from the trapped light can lead to the green house effect and global warming.

The overall mix of power plants in the US is 55% coal, 9% natural gas and 4% oil. The other 32% include nuclear power and renewable energy sources such as hydroelectric, solar, wind and geothermal.

In California where over half of the states pollution comes from ICE vehicles, the overall mix of power plants is one of the cleanest in the country. In fact natural gas facilities in California emit 40 times less NOx than existing coal plants in the Northeast. Renewable sources such as hydro, solar, wind and geothermal produce a respectable share of electricity generated in California. Many EV critics remain skeptical because of such finding of Californias mix of power plants is relatively clean compared to that in the rest of the country

Several studies have concluded that improvements in air quality can be achieved by plugging-in to EVs. EVs are significantly cleaner over the course of 100,000 miles than ICE cars.

According to a Northeast States for Coordinated Air Use Management, EVs result in significant reductions of carbon monoxide, greenhouse gasses and ground level ozone in the region with magnitudes cleaner than even the cleanest ULEV. In the next 15 years, aging coal plants will be replaced by modern natural gas fired plants. This improvement alone will reduce power plant emission significantly. Controlling emissions from several hundred power plants are much easier than controlling the emission from 187 million ICE vehicles.

The US environmental protection agency estimates that tailpipe emission increase 25% for every 10,000 miles traveled. As a gasoline car ages, their engine, catalytic converter and other emission control devices become less efficient. The cleanest a gas car will ever be is the day it rolls off the assembly line.

The Electric Power Resource Institute estimated that this country has the ability to support 50 million EVs without building any more power plants another study puts this number close to 20 million. Even so, 20 million EVs is only 10 percent of todays fleet of 187 million cars.

New cars entering the market are not necessarily the cleanest either. The hottest vehicles on the market are SUV which now account for 40% of all new car sales. These guzzlers are driving up this countrys demand for imported oil, decreasing overall fuel efficiency and increasing emissions.

The deterioration of emission control systems on ICE vehicles can increase emission up to 90% To deal with the increased emissions state government have adapted emission inspection programs with varied degree of success

Twenty million EVs each with 100,000 miles on the odometer, would reduce CO2 emissions in this country by 500 million tons without building more power plants

EVs will have a considerable impact on reducing air pollution improving fuel efficiency and reducing the overall dependency on foreign oil. As power plants improve efficiency and turn to cleaner fuels such as natural gas and zero emission sources, EVs will continue to be the best solution toward attaining clean air.

Pulse Width Modulation

A moderately low-cost form of drive for controlling DC motors makes use of one of several types of power transistors. These transistors are switched rapidly on and off in a technique known as Pulse Width Modulation (PWM). Hence the term PWM drive .

An transistor acts as a gate to allow a precise amount of current to flow to the motor. As this gate is rapidly switched on and off, the amount of current which flows is dependent upon the ratio between On time and Off time. The larger this ratio is, the more current will flow. The lower the ratio, the less current will flow. Since the transistor is pulsed, the technique is known as pulse width modulation.
Through feedback systems, this PWM technique can also precisely control the voltage allowed to generate the armature field of the motor, and thus the speed is controlled.

Figure 1 shows three different PWM signals. Figure 1a shows a PWM output at a 10% duty cycle. That is, the signal is on for 10% of the period and off the other 90%. Figures 1b and 1c show PWM outputs at 50% and 90% duty cycles, respectively. These three PWM outputs encode three different analog signal values, at 10%, 50%, and 90% of the full strength. If, for example, the supply is 9V and the duty cycle is 10%, a 0.9V analog signal results.
Fig 1a

A control circuit turns one (or more) solid state power switches in rapid succession. These switches (transistors, SCR's, IGBT's, MOSFETS) have no moving parts - nothing to wear out. The amount of time that the are on when compared to the amount of time that they are off determines how much curent a motor sees. This ratio is called "duty cycle". A controller at 10% power would be on 1 unit of time and off for 9 moter time units. The length of these time units are
based on the switching frequency.

You can simulate this at home with a light switch.

1. Turn on the light and count to "1".
2. Then turn off the light and count th "3"
3. Repeat 1, then 2.

You have just created a controller working at 25% duty cycle with a switching frequency of about 1/4 Hz. A light switch is a mechanical device and will wear out quickly doing this hence the solid state components. Also in order for the power to appear smoothly the swtiching frequency is typically thousands of Hz.

This is the BASICS of controller operation!

- The electric motor performs the same function as an engine, It is a prime mover. Its converts energy into mechanical motion.

- The batteries are both the gas tank and fuel in an electric vehicle.

- The controller is an electronic device that controls the flow of electricity from the batteries to the motor.

- The charger is another electronic device. Its job is to replenish the batteries after their energy has been consumed by the motor in operation.

- Interface hardware involves mechanical devices that fit the electric propulsion machinery to the vehicle itself.

- Control and Safety equipment are a variety of components that add control and safety features to the electric drive.

- Auxiliary loads and 12V power. Horn, headlights, windshield wipers, turn signals, brake lights and many other electrical devices are designed to work on 12VDC.

- Monitoring equipment. Instrumentation and other indicators enable the operator to monitor the operation of the electric propulsion system.