Croatian start-up set to begin production of electric hypercar

Rimac Automobili unveiled its Concept_One at the Frankfurt Motor Show in September last year and took first production orders for the vehicle at last week’s Top Marques Monaco event, for scheduled delivery in early 2014.

The Concept One has a claimed total power output of 1088bhp and 3800Nm of motor torque, which compares with 1184bhp for the Bugatti Veyron Super Sport — officially the world’s fastest production car.

The range of the vehicle is 600km in normal driving mode, although the company admits this drops to between 140–180km in race mode. It can accelerate from 0–100kph in 2.8 seconds, to an electronically limited top speed of 305kph.

For the electric powertrain, the car uses four 250kW liquid-cooled permanent magnet motors controlled by Rimac’s ‘all wheel torque vectoring system’.

The powertrain is divided into the front and rear sub-systems coupled to two symmetrical motor-controller-reduction-gearbox units.

This enables control of each wheel independently in both directions thousands of times each second, as Rimac’s mechanical engineer Boris Tarnovski explained to The Engineer.

‘The driver can choose between a neutral and safe (under-steer oriented) set-up — alternatively, if the driver has more skills and confidence, an over-steer set-up can be chosen.

‘This feature is not a technological gimmick, it also improves safety since electric motors can react much faster compared to traditional stability control systems (ESP), which use hydraulic brakes in order to influence the vehicle stability. Together with the very low centre of gravity, extremely high torque available almost from zero RPM and the lack of shift interruptions, the Concept_One delivers a completely new driving experience.’

The battery pack consists of 1400 LifePO4 (lithium-iron-phosphate) cells with a combined capacity of 92kWh.

‘One of the most difficult tasks was the energy storage — we had to find a way to get as much power and energy as possible, and still keep the package small, light and efficient, Tarnovski said. ‘Our battery-module architecture has evolved during the development through many stages and redesigns, and was then optimised during lab and real-world tests in prototypes until we were satisfied.’

An active battery management system (A-BMS) monitors and balances each cell separately, while the thermal management system works to keep the ideal conditions for long battery life and optimal performance.

Tarnovski said 90 per cent of the production process will be done at the Rimac Automobili factory, near Zagreb.