Formula E car

Formula E to test the limits of electric transport

Ten cities around the world will play host to an experiment to use racing to push electric vehicle design as Formula E takes to the streets later this year.

In the spring of 2011 Jean Todt of Formula One’s organising body FIA said it was time for the organisation to look at a type of race that would showcase technologies designed to deal with the environmental problems of motor transport. In September of this year, the 11 teams with all-electric open-wheeled race cars will head to one of the most polluted cities on Earth – Beijing – to kick off the first series of Formula E.

Unlike the distinctly petrol-headed F1 series, the cars will not roar as they rev up their engines. Although nowhere near as quiet as a Prius running around back streets on its electric engine, and more in line with a petrol-driven car passing at 70mph, the cars are expected to emit no more than 80dbA of noise as they charge past the finish line at speeds up to 225km/h. It will be way down from the ear-splitting 140dBA of F1 vehicles.

In a ‘burnout’ demonstration on an LA street last year, most of the noise came from the tyres as they slid on the road. As it revved up to leave a rubber stain on the streets, the engine noise was more reminiscent of a washing machine’s spin cycle and that was only when the driver put his foot down.

At a launch event last year, racing driver Lucas di Grassi said he noticed the difference with electric vehicles compared to conventional petrol-driven racers immediately: “The first thing you notice is the absence of vibration and noise, not when the car is running but when still or at low speed. You can hear what the car is doing... what the suspension is doing.”

But di Grassi stressed that in many other ways, Formula E cars, which go into full trials over the summer, will behave similarly to their petrol-driven counterparts. “Overall, the driving techniques will be very similar. Drivers who are good in Formula 1 will be good in Formula E.”

Urban street racing

Because of its showcase potential and Formula E Holdings chief Alejandro Agag’s belief that the electric car belongs in urban areas, the races will not be on long, remote, purpose-built courses. Instead, each of the ten races will be along city streets – sealing off parts of central London, for example, next June. Because of the disruption to busy city centres, practice, qualification and racing will take place in one day.

“If you make a mistake in practice it’s really going to hamper your weekend. So it’s going to favour those drivers that make no mistakes and at the same time are able to be quick straight out of the box,” says Sam Bird, one of the drivers for the Virgin Racing team.

Spectators close to the pits will get a clear view of one of the key problems that plagues electric vehicles: range. The battery is not big enough to keep the car running for the full duration of a race let alone practice and qualifying as well. At 30kWh and a maximum weight of 200kg, the battery capacity is limited to about half that of the base Tesla Model S road car, which has a range of 335km under normal driving conditions. A Formula E race will last around an hour.

One solution would be to swap batteries in and out during a pit stop, using similar techniques to those developed by failed Israeli company Better Place for road vehicles. However, the organisers claim safety concerns make a swappable battery difficult to implement. It would probably also increase vehicle weight – the battery is already a significant contributor at about a quarter of the total weight of vehicle and driver. The battery itself is twice as heavy as the maximum amount of petrol that an F1 car can carry over the entire course of a race. Thanks to the battery, a Formula E car is around 20 per cent heavier than an F1 car.

If the battery were scaled up to cover an entire race, it could easily soak up at least a third of the total weight and slow the vehicle down even further. Because of this, Formula E has gone for an approach reminiscent of endurance races such as Le Mans. Formula E is, after all, about the endurance of the technology.

Roughly halfway through the race, drivers will pull into the pits, clamber out and run over to another, fully charged car. After around 30 seconds of safety checks – drivers will not be allowed to perform the fast starts that were common in Le Mans endurance racing – the driver can re-enter the race and, with luck, take the car to the finish line.

 

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Pit-stop charging

Because everything is completed in one day, cars will have to charge in the pits whenever possible to ensure they can make it through the entire event. In keeping with the technology showcase element of Formula E, the safety car will be recharged wirelessly using systems supplied by Qualcomm’s Halo division. Keen to promote the wireless charging technology through Formula E, Qualcomm’s venture finance operation has put money into the championship.

Halo uses inductive charging technology to allow a car to charge while sitting on a powered pad instead of having to be plugged into the mains supply. Qualcomm claims the technology can deliver up to 20kW – about a tenth of the maximum power that the engine can draw from the battery during the practice and qualifying sessions – so that a battery could in principle be charged from empty in around 90 minutes.

To begin with, teams will use conventional wired charging connections but Qualcomm says it will make the Halo charger available to teams in the second season.

Like F1, Formula E teams will base their cars to some extent on standardised components built by companies such as McLaren, Renault and Williams. However, the standardisation is more to do with cost than trying to create a more level playing field – teams have greater latitude in picking components than their F1 counterparts if they feel they have the technology and expertise to do so. But the FIA is keen to ensure that it can get off to a good, competitive start by providing teams with the core components needed to ensure one well-financed group does not walk away with the championship and to prove the concept of electric racing with a low number of variables. During the first season, teams will use a car designed by French firm Spark Racing Technology. Drayson Racing expects to move to its own car design in 2015.

The battery design has been put together by Williams, which is using a currently undisclosed battery chemistry, although the choices are largely between variants of nickel metal hydride or lithium-polymer – the latter presents greater safety issues in an environment where sparks could be flying. Explosive chemistries and high-energy densities tend to go hand in hand in battery technology, although some researchers believe there are less flammable options waiting to be discovered.

McLaren Electronics Systems is no stranger to providing standardised components to racing teams. The company already produces the electronic control units (ECUs) that every F1 car now needs to have. The FIA chose to standardise on a single engine-controlling computer to reduce the software burden on teams. Now, individual teams only have access to parameters that they can use to trade off performance variables, although the FIA and McLaren are looking at ways in which the ECUs might support customised tasks so that teams can innovate further.

In Formula E, McLaren’s role expands to the ‘engine’ – the motor-generator unit (MGU). Cars can have one or two MGUs. At just over 25kg each they are so much lighter than a battery that using two is an option. However, teams are restricted on where they can fit them: they can only connect them to the rear axle. As a synchronous motor design, the MGU is capable of much higher torque and control than a petrol motor and also helps with braking when the motor shifts to being a part-time electric generator. The synchronous motors are controlled electronically – magnets on the stator help force the rotor to move under processor control. This allows for a much higher degree of acceleration and, conversely, braking.

Racegoers can expect to see a fair amount of wheel spin, especially as drivers are not allowed the luxury of traction control. But a quiet form of racing could need a bit of screeching to get going when the rubber doesn’t quite hit the road firmly enough.

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