BMW reveals drive details of its first FE contender
BMW has revealed some details pertaining to the drivetrain of its first Formula E car, which will make its racing debut on Saturday 15 December at the Season 5 opener in Ad Diriyah.
At the heart of its iFE.18, which is being run by the BMW i Andretti Motorsport Team is the Racing eDrive01, which BMW says brings together expertise from both BMW’s motorsport and BMW’s electric ‘i’ brand.
Development of the drivetrain began in early 2017 with pre-development for production drive systems, and was produced in the same facilities as the next generation of BMW’s roadgoing i series drives, which meant it benefited from the expertise of production engineers in the areas of manual and mechanical manufacturing of electric motors and their components. By mid 2017 the first concepts of the Racing eDrive 01 were on the test stand, allowing many rounds of optimisation and refinement to be completed during extensive bench testing by the time it came to the roll out of the iFE.18 in April 2018.
The powertrain itself is made up of three main components, the electric motor, the cooling system and the inverter. All of these components have been designed to offer maximum efficiency, the highest possible energy density and in the lightest and most compact design possible, which meant that BMW had to turn to state-of-the-art materials, technologies and processes.
The electric motor is made up of three parts: the rotor, the stator and the casing. BMW says that in order to keep weight to a minimum while retaining the necessary strength, the rotor has supports made of fibre composites, while innovative materials such as special thermally-conductive resins, titanium and ceramic are used to give the motor a high gravimetric energy density.
This motor is cooled by a ‘virtually 360°’ cooling geometry in an additively manufactured aluminium case, and has been extensively optimised using CFD to ensure that ‘pressure loss is minimal and maximum efficiency is guaranteed.
Finally, the inverter, which converts the direct current from the McLaren Applied Technologies-supplied battery into the alternating current which is required by the motor, is housed in a casing partially made from fibre composites. Inside the inverter meanwhile are multiple MOSFETS (metal-oxide-semiconductor field-effect transistors) with cutting edge silicon carbide technology used for the semiconductors. This means that the inverter achieves very high dielectric strength but minimal energy losses and compact size.
All this innovation means that compared to the drive BMW uses in its roadgoing i3, the Racing eDrive 01 is 50 per cent lighter and 66 per cent smaller, but offers twice the torque density and engine speed, and four times the energy density.