Electric vehicles accelerate

Mitsubishi Motors Corporation is accelerating work on electric-vehicle research.

Following quickly on production of the small-car Colt EV test vehicle, the carmaker has developed an electric version of the high-performance Lancer Evo IX.

Engine, transmission, fuel tank and other mechanical parts are gone. Instead, four independent electric motors, each developing 50kW, drive each wheel.

The in-wheel motors are powered by a pack of 24 lithium-ion batteries housed in the floor of the car. The new motor uses a hollow donut construction, which locates the rotor outside the stator instead of inside as in conventional electric motors.

Mitsubishi says this design makes it easier to raise power and torque. Each motor is rated at 518-Nm torque. The higher torque removes the need for a speed-reducer unit, eliminating weight and improving power-transmission efficiency, says the company.

The structure also allows the brake mechanism to fit inside the motor which fits neatly inside the wheel housing. Inverters front and rear control the motors.

Mitsubishi says this new arrangement overcomes the difficulties presented by the steering components and makes the motors suitable for fitting to front wheels and use in four-wheel-drive vehicles.

The Lancer Evo MIEV has a kerb weight of 1590kg, compared with 1410kg for the conventional car.

But Mitsubishi says it still achieves a speed of 180kph and, in normal town and highway running, the vehicle has a range of 250km.

Mitsubishi sees this technology as the basis for the next generation of electric vehicles with the MIEV concept used in hybrid and fuel-cell vehicles. It is still early days in the development cycle but the vehicle has already been certified to operate on public roads so it can be tested in actual conditions.

The development programme aims to raise performance and reduce weight and size, with 2010 targeted for production.

By then the company aims to be marketing high-performance electric, hybrid and fuel-cell vehicles that deliver not only superior environmental performance but also maintain the performance and manoeuvrability of petrol-engined vehicles.