EV race gathers pace01 January 2011
Ryan Borroff finds out if the concepts electric vehicles for the 2010s are mere flights of fancy or will have a bearing on the future.
If 2010 showed us anything, it's that the race between car manufacturers to develop their own electric cars or even spin off their own electric vehicle (EV) brands is frenetic. Automakers are working quickly to develop their own EVs, with the help of the supply chain. However, except in a few cases, there is currently no clean slate from which to work, meaning the ultimate goal of designing an affordable electric vehicle, with comparable performance to an IC-powered vehicle, is compromised.
Concept cars, though once mere flights of fancy, are now more likely to be test prototypes for future products, particularly in the accelerated world of EV develop- ment. Commonly, suppliers are tasked with helping automakers incorporate electric drivetrains into existing vehicles or to use as many existing components as possible.
EV concept designs are moving rapidly into production, while legislation and regulations struggle to keep up; which means the opportunity to develop a fully optimised electric driveline – with little or no compromise – is elusive.
Peugeot's EX1 concept – first seen at last year's Paris Motor Show – is an advanced high-performance prototype that has notched up a number of EV performance records. Constructed of carbon fibre, the concept incorporates a lightweight, low-friction, single-pinion electric power steering (EPS) system from Nexteer Automotive.
The company had to work quickly – it had just one day – to install the system, a task that was not without some challenges.
"The steering geometry [on the EX1] was completely different to the production vehicle we are supplying, which meant it required different connection points," explains Paul Poirel, Nexteer Automotive's chief product engineer, Europe.
"The first consequence of this was that the steering ratio – the number of degrees that you turn the steering wheel to turn the wheels, was completely changed – from 17 degrees [at the steering wheel] on the production vehicle, to 12 degrees on the concept to achieve the same one degree wheel movement.
"There was a drastic increase on the required steering input from the driver, so we needed to increase the assist level of the concept's steering system. As there was no time to come up with a prototype motor with increased output, we had to use an existing motor, which meant we had to play with the different calibrations in the software to get the most out of it. This was a difficult balancing act, because you have to be careful not to add instability into the system and end up with undesirable steering wheel oscillation, which would have been the consequence."
For now, there seems little future for PSA's EX1 beyond more record breaking. But, as Neil Heslington, managing director of Zytek Automotive, explains, in the new frontier of EVs all lessons learned
are valuable. "Developing an EV prototype has to give us some genuine insight into, or a definite way forward for, a series vehicle," he points out. "That means you have to make the prototype reflect the work you have to do to get it into production. EVs have moved from being conceptual, as in 'what would an EV look like' or 'how would it perform', to 'how do we make a genuine EV alternative to a combustion car?'"
Zytek Automotive has taken the electric smart fortwo from prototype to 1,500 example series production and now operates the production cell at Daimler's smart plant. "In the case of the electric smart, the drivetrain was designed to be a replacement for the IC engine. It sits in a near identical manner in the rear sub frame. So, from a production installation perspective, it was straightforward," says Heslington.
Ultimately, with technology dictating the way cars are constructed, the opportunity for optimising EV design will be dependent on fundamentally changing the way cars are built. In its T.25 and electric T.27 cars, Gordon Murray Design has done this, which meant that Zytek's involvement in the T.27 development, if not entirely clean sheet, was close. "On most EV concepts, battery packaging is a huge consideration. It's a trade-off between energy versus weight and cost," comments Heslington. "The integration of the driveline systems – motor, power, electronics and so on – is very important. As we designed the T.27 battery, we've been able to optimise it to work with the motor and the inverter, and minimise weight and optimise performance. The T.25 lends itself very well to adopting EV technology."
For now, suppliers understand that maximising the performance of the driveline systems is paramount to future EV success. Six suppliers – Valeo, Leroy-Somer, Johnson Controls, GKN, Michelin and Leoni – have joined forces to develop a fully optimised electric driveline.
Focusing on economy, performance and weight reduction, each member of the consortium will work to develop every component from common specifications, so that the chance of developing a fully efficient EV is possible.
BMW is already on the way. Its Megacity car – which should arrive in 2013 – is one example of a second wave of EVs that will be constructed differently, in order to optimise performance. A clean sheet design from carbon-fibre reinforced plastic and aluminium, the Megacity will have a reduced part count and should be cheaper to build, though not cheap to buy.
Such innovation should mean that the next generation of EVs will be a more exciting, and enticing, proposition for car buyers when the advantages of EV ownership outweigh the lifestyle compromises. For city dwellers at least.
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