Renault KERS analysis
Kinetic Energy Recovery Systems (KERS) is one of the biggest technical challenges of the season and also one of the biggest unknowns. Renault bring us up to speed with this exciting new technology...
What is KERS?
It’s a system whereby the goal is to store the energy produced under braking in a reservoir (either batteries or flywheel) in order to release it under acceleration. The 2009 technical regulations state that KERS should not deliver power in excess of 60kW, which is equivalent to around 80 horsepower, when the driver presses a button on the steering wheel. He cannot use more than 400kJ per lap.
Is there only one way to recover the energy and reuse it?
When the 2009 KERS system was being conceived, the engineers had a choice between two different approaches. The first consisted of using a carbon flywheel in a vacuum linked via a CVT transmission to the differential. This system stores the mechanical energy, offers a big storage capacity and has the advantage of being independent from the gearbox. However, to be driven precisely, it requires some powerful and bulky actuators, and lots of space. The second option was to rely on an electrical motor, which works by charging the batteries under braking and releasing the power on acceleration.
Which choice did Renault go with and how does the system work?
Renault chose to go with the electrical solution, as did most other teams. The system consists of three important parts:
An electric motor (MGU: Motor Generator Unit) situated between the fuel tank and the engine, linked directly to the crankshaft of the V8 to deliver additional power.
Some latest generation ion-lithium batteries (HVB: High Voltage Battery Pack) capable of storing and delivering energy rapidly.
A control box (KCU: KERS Control Unit), which manages the behavior of the MGU when charging and releasing energy. It is linked to the car’s standard electronic control unit.
What were the main challenges encountered during the development of the system?
Firstly, it was necessary to deal with the weight and volume of the system, which adds considerable weight in comparison with the 2008 car. This means there is less ballast available for the engineers to redistribute in order to balance the chassis. Also, the cooling of the batteries is of great importance and it was necessary to develop a specific system for them.
Where are the batteries situated?
They are positioned under the fuel tank. Some teams have chosen to place them under the driver’s legs or in the sidepods, but Renault opted against this as it felt these solutions presented more problems.
Does the MGU have to be positioned between the engine and the fuel tank?
No. It’s possible to situate it parallel to the gearbox in the rear of the car. So it’s connected straight to the rear wheels and releases its power through the differential.
Will Renault be the only team to use this system with this set-up?
No, the team will provide its KERS system to another team this season.
Why are most teams behind schedule in the development of their systems?
The development timescale was very tight: the system had to be developed in just 18 months and so the number of advanced projects and preliminary studies have been limited. Some teams have suffered from this and may have chosen solutions that are difficult to develop. There has also been the safety of the drivers and mechanics to consider which has required extensive safety training. Finally, the factories have had to install special testing rigs and implement further personnel training.
Will KERS produce more competitive racing?
Not necessarily. If all the teams use KERS, they will use it in the same way, in the same places, at the same times, and so there will be no advantage. On the other hand, not having the system will be an enormous handicap.
Has F1 already helped this technology progress in terms of its relevance to the wider world?
The development of electrical motors capable of delivering 80 horsepower for minimum space and weight while operating in a very harsh environment represents a significant step forward in the world of energy recovery.