The Electric Car:Tesla Roadster

Written by M.West on October 28, 2006

Tesla RoadsterWhen you put yourself behind the wheel of a high-performance car that costs six figures, you might expect certain things: acceleration that pushes you back into the seat, best of the best stereo equipment, road-hugging handling, the roar of a powerful engine and a hugh budget for the high-octane gas necessary to fuel it.

The Tesla Roadster has almost all of those aspects covered. It’s fast, fancy, handles like a dream and goes like a rocketship, but it’s almost silent and it’ll never burn a bit of gasoline. Tesla’s first production car is also the world’s first high-performance electric car.

Unlike a traditional gasoline-powered car, the Tesla Roadster doesn’t contain hundreds of moving parts. It’s powered by just four main systems:

The Energy Storage System (ESS)
The Power Electronics Module (PEM)
An electric motor
A sequential manual transmission

In place of an internal combustion engine, the Tesla Roadster uses a bank of batteries — the Energy Storage System (ESS). In developing a power source befitting such a high-performance car, Tesla went with technology proven in the laptop computer field — rechargeable lithium-ion batteries. The Roadster contains 6,831 of them. They weigh about 1,000 pounds in total, and Tesla claims that they provide “four to five times the energy-density stores of other batteries”. The batteries fit into 11 sectors with 621 batteries each. A separate computer processor controls each sector to make sure all of the charging and discharging is handled smoothly.

The Power Electronics Module (PEM) is a power inverter and charging system that converts DC power to AC power using 72 insulated gate bipolar transistors (IGBTs). This results in a marked increase in power output compared to first-generation electric cars. Under peak acceleration, the batteries can crank out 200 kW of energy — enough to light 2,000 incandescent light bulbs.

In addition to controlling charge and discharge rates, the Power Electronics Module controls voltage levels, the motor’s RPM (revolutions per minute), torque and the regenerative braking system. This braking system captures the kinetic energy usually lost through braking and transfers it back into the ESS. The efficiency and integration of the battery, PEM and motor systems is between 85 and 95 percent, allowing the motor to put out up to 185 kW of power. Aluminum heat dissipation fins and a rear-mounted ventilation port keep the power transistors from overheating.

The heart of the Tesla Roadster is its 3-phase, 4-pole electric induction motor, which weighs just 70 pounds. Tesla’s claims and independent testing show that the Roadster can reach 60 mph in about four seconds and its speed will top out somewhere around 130 mph. But the Roadster’s performance isn’t just about speed and acceleration. The unique properties of an electric motor give it a huge advantage over a combustion engine in terms of torque, force that tends to rotate or turn things, and power band, the range of operating speeds under which the engine operates efficiently.

The Tesla Roadster can go a lot faster than previous electric cars, but perhaps more importantly, it can go a lot farther. The Roadster’s estimated range is 250 miles on a single charge, at least 100 miles more than General Motors’ EV1, which could go almost 150 miles under optimal conditions.

Most of the hype surrounding the Roadster is about its status as an electric vehicle. But while earlier electric cars tended to be cramped and lacking in features, the Tesla Roadster looks and feels like a sports car. In addition to basics like heated seats, a stereo with CD player, ABS brakes and dual airbags, the Roadster has a few unique features:

A unique PIN to start the car and prevent hot-wiring
A Homelink transceiver you can program to control radio-frequency controlled devices such as your community gate and garage door
A dock connector for your iPod
Electrica lly-controlled door handles (there’s no mechanical lock, which makes it more difficult to break into the car)
Since it’s a convertible, the Roadster comes standard with a soft top. Options include a hard top as well as features like a full leather interior and a satellite navigation system.

Posted Under: Cool Cars,Supercars

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