Porsche reveals 4WD electric Boxster 25 | 05 | 2011
PORSCHE IS INCHING closer to launching electric variants of its Boxster after the German sportscar company wowed journalists at the Michelin Challenge Bibendum in Berlin. Porsche revealed electric-powered rear and four wheel-drive variants of the Porsche Boxster E roadster.
Porsche was demonstrating its Boxster E prototypes to a wide audience of representatives from politics, industry, trade and research at this global forum for sustainable mobility in the German capital.
The technology in the Boxster E follows similar ground-breaking initiatives; the 911 GT3 R Hybrid race car, 918 Spyder super sports car and 918 RSR concept.
The Boxster E prototypes are being used as part of the “Model Region Electro-Mobility Stuttgart” 1 large-scale trial to explore the everyday practicality of all-electric vehicles and how they are used, especially in terms of driving and battery charging.
What the researchers at Porsche are looking for is an understanding of the requirements that will shape tomorrow’s products, the future direction of Porsche Intelligent Performance and how to integrate electric vehicles into the infrastructure.
Thanks to its design as a mid-engine sports car, the Porsche Boxster is the ideal vehicle platform for conducting realistic trials with electric-drive systems. The open-top two-seater car is very light, enabling the new components that are the electric motor, battery and high-voltage technology to be accommodated within the vehicle in a crash-proof way.
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Together with the low drag, this reduces driving resistance for optimal range. Also of importance for a Porsche sports car, even one that is electrically-driven, is the high driving dynamics potential, not least as a consequence of the balanced axle-load distribution intrinsic to the mid-engine design.
The four-wheel-drive Boxster E is an all-electric vehicle without any additional combustion engine on board. Propulsion is provided by two independent electric motors with constant mesh gearboxes that act on the front and rear axles. The rear drive unit — comprising motor and transmission, together with the power electronics for controlling the electric motor — is located where the manual transmission and exhaust system are accommodated in the conventional Boxster.
In the front end, the space vacated by the 64-litre fuel tank, now redundant, is occupied by the second drive unit. The power electronics unit in the adjacent luggage compartment serves the front axle electric motor. The Boxster E thereby features all-wheel drive without mechanical transmission of power.
To ensure maximum driving stability and traction, a central electric control unit looks after the synchronisation of the two electric motors and controls the drive torque distribution to the front and rear axle.
The two electric motors develop a total power output of 180 kW and a maximum total torque of 540 Nm at a maximum engine speed of approximately 12,000 rpm. That means that the two electric motors in tandem deliver significantly higher drive power than what is available from present day hybrid vehicle electric power units.
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As well as the all-electric drive of the Boxster E producing zero tailpipe emissions, it also offers a completely new form of Porsche driving pleasure. Maximum torque of the electric drive kicks in virtually from the first turn of the engine. The Boxster E moves almost silently while at the same time developing powerful propulsion from the very outset.
The two motors enable the two-seater to sprint to 62mph in 5.5secs from a standing start. Its top speed, limited to 124mph is achieved without any gear change at all – whether automatic or manual.
The high power output of the two motors offers a second advantage: it means more recovered power is available because more energy can be recovered during braking. This increases efficiency of the drive unit.
In the case of the two other Boxster E models with rear wheel drive there is no front electric motor, therefore delivering a power output of 90 kW and a rated torque of 270 Nm. This model can sprint from a standing start to 62mph in 9.8secs, with a top speed of 93mph.
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Jim McGill