Students at MIT Design Electric Car

by Rich

Wednesday, July 22, 2009 at 11:08 PM EDT

The Toyota Prius hybrid car has been something of a success in the US market (helped, of course, by various tax and other incentives, such as the ability to use HOV lanes in Virginia), and other manufacturers have introduced or are working on hybrid and fully electric vehicles. The Network World web site has an article by Nick Barber, describing a student project at MIT that aim to develop an all-electric vehicle starting from first principles. Their objectives are certainly ambitious enough:

The team’s goal is to build an all-electric car with similar performance capabilities of gasoline-only counterparts, which includes a top speed of about 161 kph, a family sedan capacity, a range of about 320 kilometers and the ability to recharge in about 10 minutes

The fast recharging capability is especially noteworthy, since most current designs envision a recharging period of several hours.

Despite all its drawbacks associated with pollution in general and greenhouse gas emissions in particular, gasoline as a fuel does have one significant advantage: it has a very high energy density. A lot of power can be generated from each kilogram of fuel. So maximizing energy storage and minimizing weight are always challenges for an electric vehicle. The MIT project will use a commercial battery with lithium – iron phosphate cells. These have very low internal resistance, and their chemistry is less volatile than other types of lithium ion cells, which should make them safer in the event of a crash.

The car’s motor is an oil-cooled three-phase AC induction motor, which is quite powerful, generating 250 horsepower, and weighing 138 kg:

It was originally designed to be used in a 15,000 kg electric bus. So when it’s installed in the 2,000 kg car, it should allow it to go from zero to 60 in under nine seconds and achieve a top speed of 100 mph at 12,000 RPMs.

The motor requires a fairly large battery, since it draws 187 kW. Recharging it rapidly is not something you can do with the toaster plugged in:

… in order to charge MIT’s car in about 10 minutes, the team needs 356 volts at 1,000 amps.

In case you are not planning on installing a nuclear power plant in your basement, the batteries can apparently be charged from a standard outlet in 8-10 hours.

This points up an issue that affects all prospective all-electric vehicles: they can only be widely used when there is sufficient infrastructure in place — namely, charging stations — that drivers can travel without an unacceptable risk of being stranded. Still, the same problem had to be overcome initially with gasoline engines; if the vehicles are attractive enough in their own right, the infrastructure will get built.

You can read more about the project, and see some interesting short videos, on the team’s project blog.