Exercise 1. Answer the questions

Text

Electric vehicles (or “EVs”) run at least partially on electricity. There

are two basic types of EVs: all-electric vehicles (AEVs) and plug-in hybrid electric vehicles (PHEVs).

All-electric vehicles (AEVs) run only on electricity. They receive electricity by plugging into the grid and store it in batteries. They consume

no petroleum-based fuel and produce no tailpipe emissions. AEVs include Battery Electric Vehicles (BEVs) and Fuel Cell Electric Vehicles (FCEVs). In addition to charging from the elec- trical grid, both types are charged in part by regenerative braking, which generates electricity from some of the energy normally lost when braking.

Most AEVs have all-electric ranges of 80 to 100 miles, while a few luxury models have ranges up to 250 miles. When the battery is depleted, it can take from 30 minutes (with fast charging) up to nearly a full day (with Level 1 charging) to recharge it, depending on the type of charger and bat- tery.

Plug-in hybrid electric vehicles (PHEVs) offer both a gasoline or die- sel engine and an

electric motor. PHEVs run on electricity for shorter ranges (6 to 40 miles), then switch over to an

internal combustion engine running on gasoline when the battery is depleted. The flexibility of PHEVs allows drivers to use electricity as often as possible while also being able to fuel up with gasoline if needed. Powering the vehicle with electricity from the grid reduces fuel costs, cuts petroleum consumption, and reduces tailpipe emissions compared to conventional vehicles.

An electric vehicle’s drive mechanism is mainly constituted of the following three parts: car motor, motor controller, car batteries.

Basically, all cars run on the principle of conversion of energy from one form to another. In a traditional gasoline car, the chemical energy stored in the fuel is converted into kinetic energy by the internal combus- tion engine, releasing byproducts in the form of combustion emissions. Whereas in an electric car, the electromechanical energy from the batteries is converted first into electrical energy and then into kinetic energy re- quired for driving the car.

Car motor: The accelerator pedal in these cars is connected to a po- tentiometer (variable resistor). The potentiometer sends an appropriate electric signal to the motor controller corresponding to the amount by which the pedal is pressed. If the pedal is not pressed, no signal is transmit- ted. If the pedal is grounded or fully pressed, maximum signal is transmit- ted. Thus, the motor will deliver maximum power. The car motor may be a DC or an AC motor. DC motors are easy to maintain, more efficient and also allow greater acceleration. The motor can deliver between 20,000 watts to 30,000 watts of power.

Motor controller: This device is a link between the car batteries and the actual motor. It receives the controlling signal from the potentiometer connected to the accelerator pedal. It will transmit the battery voltage to the motor depending on this input signal.

Car batteries: Car batteries can be simple lead-acid batteries or the more sophisticated and long lasting NiMH batteries. These batteries will be between 96 to 192 volts for a typical DC motor. The battery charging mechanism in an electric car is of prime importance. It monitors the volt- age, amperage and battery temperatures to avoid battery damage by over- heating. A typical battery can be fully charged in 3-4 hours via hard wired charging docks built specially for this purpose.

Exercise 1. Answer the questions

1. What is an electric vehicle?

2. What types of EVs are there?

3. Which EV type is more environmentally friendly: AEV or PHEV? Why?

4. Are AEVs suitable for long-distance travel?

5. Do EVs run on the principle of energy conversion?

6. What are the main parts of the EV drive mechanism?

7. What is the function of the potentiometer in the EV motor?

8. Why is the battery charging mechanism of prime importance in

EVs?