This may seem like old news now but I figured I’d do this analysis anyway because it helps me understand these things, and hopefully it helps you too!
In 2014 the FIA allowed F1 teams to use a “powered control system” on the rear brake system as the additional regenerative capabilities of the MGU-K under the current regulations resulted in inconsistent retardation of the rear axle. Not that the teams had a choice as to whether they used such a system, as a conventional hydraulic setup would be incredibly inconsistent and – more importantly – unnatural to the driver. This system is more commonly known as brake-by-wire (BBW)
So what exactly happens when the driver hits the brake pedal?
I wrote this brief study for my physics coursework and I thought it would be suitable for a blog post. As I found out during this write-up, information about KERS is extremely hard to come by as it is a very secretive area of engineering. I’ll have all my references at the bottom but before you read, it is worth mentioning that this is not a truly reliable study. I have done the best I can with the information I have found and I would like to thank Craig Scarborough (@ScarbsF1) for pointing me in the right direction on occasion. Enjoy!
Most hybrid vehicles today utilise a rechargeable electric motor running alongside an Internal Combustion Engine (ICE), which in turn generates the electricity needed to power the aforementioned motor. In terms of satisfying changes needed to combat climate change, hybrid vehicles are arguably a step in the right direction. However all-electric power is an even more sustainable solution but they require an alternative energy source (hybrids use the mechanical movement of an ICE) to generate the electricity needed to power the electric motor.
In years gone by, the Motor-Generator Unit (MGU) has primarily been used to convert currents. However over the past decade this technology has been harnessed to increase the efficiency of vehicles, more specifically road-going vehicles such as cars, buses and lorries. MGUs, in the motoring world, can now be referred to as energy recovery systems, their most common application being in how they recover energy that is normally lost under braking.
Work is done at the brakes (by friction) to slow the vehicle down and this dissipates heat energy as a result of the contact between the brake pad and the braking surface (e.g. a disc). This lost energy can be recovered by inputting a generator into the drive system. When the vehicle is under deceleration, the generator harvests this previously lost energy – it acts as a highly resistive force when generating electricity so less force is needed on the braking surface. Therefore less work is done at the brakes and thus less heat is dissipated. Energy has been recovered from the braking phase which can now be used for other purposes, such as powering an electric motor that provides a drive for the vehicle.
These are the basic principles of the Kinetic Energy Recovery System (KERS). It recovers kinetic energy normally lost under braking, stores it (in a chemical or mechanical energy store) and is then used to power the vehicle during acceleration. KERS is, effectively, a glorified MGU: it is well-known for its use in Formula One over the past five years although the technology has expanded rapidly into road cars and other forms of motorsport.