Brake-By-Wire Coming To Formula E

5 months ago by 6

Formula E London Eprix 2016

Formula E London Eprix 2016

Formula E cars could feature brake-by-wire systems as early as the 2018/19 season.

The current generation of the electric single-seater harvests energy under braking from the rear axle via its electric motor, but this is a basic system with predetermined values rather than one that tailors the amount of energy being regenerated.

Introducing a brake-by-wire system would allow greater electronic control of the rear brakes that improves the feel for the drivers and maximises regen.

Formula E Putrajaya Eprix 2015

Formula E Putrajaya Eprix 2015

Teams view such an ‘active braking’ system as one of the key technologies needed in the series, especially with qualifying power increasing from 200kW to 250kW and race power rising from 170kW to 200kW in 2018/19.

DS Performance technical manager Xavier Mestelan-Pinon described brake-by-wire as “the big new thing” for Formula E, while Faraday Future Dragon Racing technical manager Nicolas Maduit said he was sure “there will be some active braking system” for 2018/19.

“It could be close to what we see in the World Endurance Championship,” Maduit added.

German braking specialist LSP has already built an active braking system, known as IBSe, which can control brake pressure by axle or on each wheel.

Professor Burkhard Goschel, president of the FIA’s Electric and New Energies Championships Commission, said a brake-by-wire system was achievable but a final decision is yet to be taken.

“We can do it, yes,” he said. “It is under investigation at the moment on how we go into this.”

Goschel said the FIA had “ideas” on how to improve efficiency and “make the series more dynamic”.

He added: “This could include a front axle in the future so it gives totally different energy management.”

Future technologies divisive

Harvesting energy from the front-axle and introducing torque vectoring – the process of having one motor power each wheel, and being able to manipulate how much power is delivered to each wheel at any time – are among Formula E’s most divisive talking points.

Formula E

“It is far too early to talk about a [front] motor,” said Maduit. “I think this could come in for 2021/22, possibly.

“I think the regulations and roadmap needs to move on but it needs to be careful on costs also.

“We need to see what is happening in the car industry. Electric technology is moving fast and we need to match it and stay relevant.”

Formula E frontrunner Lucas di Grassi added: “I would also use an electronic differential on the back and one motor for each wheel to control the acceleration, because this makes much more sense for an electric vehicle.

“We will see what the future holds but we need to try and look at a closer timeframe for these to come in.”

Goschel said torque vectoring would “make life easier for the driver” and as it could constitute a driver aid would require serious discussion.

“If a car is going like it is on rails, it is not so exciting,” he said. “So we should take care of this point.”



6 responses to "Brake-By-Wire Coming To Formula E"

  1. Ct200h says:

    Seems like these cars should have a front motor generator to capture brake energy thru the front wheels. Regen from the rears only is super tricky as regen varies based on soc and temps .
    A small frt motor or in wheel motors could give strong braking And capture

  2. jdbob says:

    When the state of charge is low or high there is less regen available and you often hear the engineer tell the driver to change the brake bias. This apparently changes how much friction braking occurs between front and rear axle. So is this change done mechanically now? I had assumed it was already done electrically.

    1. pjwood1 says:

      Thanks. After watching FE rear ends coming out as they go into turns, bias issues make sense. Few amateur drivers fool with brake bias, some in rain. You don’t want those “rears locking up”. Hence, a wire solution which is already practiced where brake regen is found in street cars. I always thought the rear bias in the Volt was awesome because, of all the street cars I’ve owned, no other had less front dive.

      Manufacturers use things like heavy front brake bias, and excessive negative camber in rear tires, to keep the public safe. That doesn’t mean it’s ideal for comfort, speed, or wear.

    2. Terawatt says:

      I’m pretty sure it’s hydraulic, like on any street-legal car, not mechanical.

      Brake bias is forward on basically all cars. When you brake, weight is shifted forwards and there is a lot more over the front axle than the rear one, unless the car has extremely rear-biased weight distribution to begin with. But the brake bias also affects the balance of the car, and thus how easy it is to control under braking. In a race car the right compromise demands much more driver skill but stops faster than in a street car, but even a race car benefits from being – relatively – easy to drive.

      Of course many other factors affect handling too, so there is no such thing as an optimal brake bias that is right regardless of other factors. The state of the tires, track temperature, how much rubber has been laid down, ambient temperature and humidity… and car setup such as dampers (compression and rebound), spring stiffness, ride height, aero, camber and caster all influence handling. If the racing sims I have played are any indication, it is pretty hard to get right and nearly all combinations of settings are terrible..!

      (Many may be unfamiliar with the terms camber and caster, but everyone is familiar with the *concepts*. The supporting wheels kids use to learn to bike have huge negative camber – they lean inwards vertically so the top of the tire is closer to the centre of the bike, as viewed from behind, than the bottom of the tire. Caster on the other hand is about where the (vertical) axle around which the steering wheels pivot is placed, relative to the center of the wheel. A shopping cart has extreme caster, which makes the wheels turn to align themselves with the direction in which you push the cart.)

      1. Terawatt says:

        I realize my attempt to explain caster wasn’t very good, and I completely forgot about toe, which is also very important..!

        Here’s from someone who understands this much better than I do:

  3. Martin Winlow says:

    Heavens! I’ve already got this on my i-MiEV!

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