Tuesday, 30 September 2014
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Electric formula: inside the Formula E racing car

Ellie Zolfagharifard looks at the electric drivetrain at the heart of next year’s Formula E Championship  

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At top speed, the SRT_01E can hit an estimated 225km/hr

If you’ve ever been in an electric race car, you’ll know that the almost instant torque and acceleration can be just as breath-taking as the gas-guzzling roar of a Formula One engine. But to die-hard fans, electric racing can be a hard sell. Without the thunder of the internal combustion engine and the reek of gasoline, many race goers say the sport just isn’t the same.

That’s a view that the new FIA Formula E Championship is hoping to change next year. The first all-electric auto racing series will start September 2014 and run through to June 2015. Ten teams, each with two drivers, will compete against each other over the course of an hour, racing through the streets of some of the world’s most impressive cities, including London, Berlin, Rome and Rio de Janeiro.

All teams will be required to use a common chassis being developed by Renault together with Spark Racing Technologies. Named Sark-Renault SRT_01E Formula E, it will feature technology from a range of different companies, many of whom are also involved in Formula One. Earlier this month, the Formula E racing car was unveiled at the Frankfurt motorshow providing a better look at what we might expect.

Once the championship has got of the ground, the organisers will make Formula E an open series in its second year. This means that each team will be free to develop its own car,
with whatever configuration of electric motors, batteries and charging systems that they believe will give them the biggest advantage in the race.

‘It is going to be brilliant seeing these cars racing through the centres of iconic cities’ said Peter van Manen, managing director of McLaren Electronic Systems, whose group has provided the electric motor, transmission and electronics for all the first-year cars. ‘Electric motors produce almost instant torque and acceleration delivering both performance and efficiency. We can look forward to some exciting racing.’

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Both motor and control unit come from McLaren, with the system claimed to have the highest power-to-weight ratio of any automotive motor

The motor and power electronics began development four years ago and have been the focus of intensive research and testing ever since. The electric motor drives the rear wheels of the racing car via a four-speed sequential gearbox. The motor is much smaller than an internal combustion engine at only 26kg and provides more than 250hp. Torque delivery is almost instant, giving the powertrain extremely fast acceleration.

According to McLaren, the electric system has the highest power-to-weight ratio of any automotive motor in the world. When the driver takes his foot off the pedal, the electric motor acts as a generator, providing engine braking and charging the battery at the same time. The motor turns at speeds up to 17,500rpm, which is similar to that of the V8 Formula One engines.

‘Elite racing cars are extremely intelligent these days, they are transmitting vast streams of data back to team engineers and their torque and energy use is controlled using sophisticated ECUs [engine control units],’ said van Manen. ‘The Formula E cars will be no different, giving the teams both data and the capacity to implement unique race set-ups and strategies.’ 

The energy for the electric motor comes from lithium-ion batteries — the same technology that is used in laptop computers — which are located behind the driver within the carbon safety cell. The flow of energy between the battery pack and the electric motor is controlled by motor-control electronics. All of the electrical systems operate at very high voltages, up to 800V.

The electric motor and controller provides a better power to weight performance than any other automotive electric motor in the world today according to van Manen. ‘That makes it unique,’ he said. ‘The challenge for any new racing design is delivering performance, while ensuring quality and safety, in too short a time. Formula E is no exception.’

The electric motor and control electronics are evolutions of the parts originally created for the McLaren P1 hybrid sportscar. In the P1, however, the electric motor supplements performance and efficiency of the turbocharged internal combustion engine. The engine control unit that manages the powertrain is the same unit that controls all the IndyCar engines
in the US, but with different software.

The group has already conducted thousands of miles of motor testing in the lab ahead of the season. It claims to have so far clocked up the equivalent of two seasons of racing in testing. According to van Manen, the biggest challenge with the electric motor and control electronics has been managing the heat and high voltages. Making things smaller means little thermal mass and so heat-sink design and cooling needs careful attention. 

‘We did this with clean system architecture, good design, thorough testing and by using proven parts and technology, whenever possible,’ said van Manen, who added that the engine’s range was a major limitation.

‘Batteries are still heavier than a tank of petrol or diesel and so the number of miles the car can race is less than more conventional open-wheel racing cars, he said. ‘In the first year of racing, drivers will switch cars halfway through the race to spice it up. Battery efficiency and range is improving all the time and we will see faster and wireless charging emerge in the future, so range will progressively increase.’

Van Manen said fans could expect to get closer to the action in the upcoming season. Acceleration and braking with be severe, testing drivers’ skill and nerve. The powertrain has its own characteristic sound, which Van Manen says is in fact very loud and just as exhilarating an the noise of a combustion. If all goes to plan, Formula E, could be just what the automotive industry needs to convince the wider public that electric cars can be both sustainable and exciting.

Formula E car specifications

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Top speed:

220km/h A
Acceleration: 0 to 100 in three seconds
Power: 180KW
Weight: 780kg
Gearbox: Two gears
Batteries: Lithium ion
Voltage: 800V
Range: 25 minutes
Charging time: 90 minutes


Readers' comments (13)

  • Why not have replaceable battery packs to be replaced in the pit stops to extend the range and hence race time?

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  • Capacitive live charging of cars while car is running is an innovative new method of charging cars from road while car is running part from inductive charging of cars in pits.we do not need any coils buried in the road for live battery charging .This is a very innovative simple idea .only some aluminium foils and rubber insulation are needed to install this in road .I developed this idea a year ago .kindly contact if anyone is interested in this idea vinodkrajan@yahoo.com

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  • Formula E must serve - if nothing else - to accelerate the roll-out of long-range, high-energy-density (lithium) battteries. Rapid recharging and conductive charging etc will sadly take he pressure off - but it is primarily..almost exclusively - the failure/refusal of major carmakers to mass-produce next-gen long-range(200+ miles) cells that is still preventing mass adoption of electric.
    Speed is a range/energy density issue too.

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  • Electric cars are the future and the sooner that there is more development the better. Almost instant torque is the key that will make this an exiting sport. I feel that a new race series will help develop the technology and show motor sport fans that this is the way forward.

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  • I personally can't wait for this series, being a Motorsport competitor and an Electrical Engineer I will get intrest out of both aspects of the sport. Who knows it may well be my sport of Rallying next :-)
    I don't know why they have to race through our cities though! Whats wrong with keeping the sport to the many motorsport venues this country has? and teaching our youth that the place for fast cars, speed and thrills is at these proper motorsport venues and NOT on our roads.

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  • A very positive method of promoting and improving electric vehicles. The point being missed above is that Major Manufacturers are planning to market hydrogen fueled electric vehicles as soon as they can. H2 fueled cars provide all the benefits of being electric, with the range of a normal vehicle. Cost being the major hold-up, along with lack of fuel stations and eventually the cost of H2 fuel.
    Complete change is needed to move to the hydrogen economy, Distributed Generation of energy, and hydrogen production with a hydrogen vehicle on a leaseholder ownership basis will effectively lower the cost of electricity, heating gas and vehicle fuel to offset the higher costs of the installation and vehicle. See Global Hydrogen Ambassadors on LinkedIn

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  • The cars are at last catching up with the electric racing motorcycles like in the 1900's . This year the electric bikes lapped the Isle of man TT course at over 100 mph average speed. Again battery life limited the race distance but the interesting part was how the rider managed his electrical energy use to make the best use of battery v ditance. The hare and the tortoise syndrome which gave a good result.
    I do not understand why the technical description of the electric car states that there is a 4 speed gearbox in the transmission yet the race car blurb say 2 gears. Also why there are two drivers per race then it states that the drivers swap cars in the middle of the race. A bit strange that.

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  • Two drivers, two cars each. Not difficult.

  • In that case why not just run two short races ?- like the Americans do which means two massed starts which is more exciting than pitstops deciciding the outcome of the race .
    Alternatively make changing the fuel cells part of the pit stop. That will exercise the engineers minds into designing fast change , man handlable fuel cell design , its what we do with our cameras - one battery in use and another charged up battery ready to insert when required - we don't carry two cameas less expensive too although I appreciate it creates jobs for the car manufacturers.

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  • Is this a car race, or a pitstop race? This is the question for the developers. 180kW of stored energy is not enough, and battery power will require pit changes, even with KERS. Simply stated the power to weight to range ratio just does not make sense for a race venue, YET. Good start up idea!

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  • It involves a pit stop unique to Formula E. According to FIA, a pit stop will involve a change of car. When the battery runs out, the driver will make a pit stop, then run 100 metres to climb into a recharged car.

  • Give them a flippin chance folks. This is an emerging technology so it will be far from perfect on day 1.

    I would suggest that running races on street circuits is more about promoting the concept than actually challenging F1. Whilst the 'noise' is supposed to be loud, I doubt it will come close to a V8 at full chat which is a good thing on street tracks.

    I do agree with the idea of changing batteries rather than cars but then again, emerging technology syndrome, the ability to swap an 800V power unit safely during a race is probably not there yet but it will come, as will the mileage. Bearing in mind that only a few years ago the mileage of electric cars were counted in double, not treble figures.

    And it's a common fallacy that F1 or motorsport in general churns out new ideas and inventions, the cars are usually used as test beds for manufacturer developed ideas, many of them having been around for years. Many of the great strides in automotive technology have been thanks to the development of the humble ECU (Electronic Control Unit as far as I'm aware) which has enabled stuff like ABS and EFi am amongst many others.

    The idea of two races is also much more appealing, the concept works well in Superbikes. A breakdown or crash in one race doesn't mean the weekends a complete write off, it gives the lower formula's race time in front of interested spectators, and the whole event becomes a complete day out instead of a single, 90 minute event.

    There again the FIA are quite mad anyway, why would they listen to us, after all we only pay them to hold the event!

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