Kinetic Energy Recovery System (KERS)
I recently had a conversation with someone about Formula 1 and at one point we talked about KERS, recovering energy during braking. Then I promised him to make a post on this subject. Kinetic Energy Recovery Systems (KERS) was introduced to Formula 1 in 2009 and not used anymore from 2013. Currently a lot of Roadcars are using this system and that again shows a piece of technology which, thanks to F1, can be found now in the ''normal'' cars.
Kinetic Energy Recovery Systems or KERS works on the basic principle of thermodynamics that states, Energy can neither be created nor destroyed, but it can be converted from one form to another.
How drivers use(d) KERS
The driver can dose the use of KERS himself, which means he can use it several times per lap, as the regulations stipulate that the release must be completely under the driver's control. To give an example: KERS creates a power boost of up to 6.67 seconds per lap and which contains a maximum of 60 kW (81.67 hp). As soon as the driver crosses the start/finish line, this 6.7 second time limit is automatically reset.
This is how KERS works
In the charging phase during braking kinetic energy from the rear brakes (1) is captured by an electric alternator/motor (2), controlled by a central processing unit CPU (3), which then charges the batteries (4).
The task of the KERS system is to store the energy obtained during braking. In 2009 the riders did have an extra button that provides them with a boost of around 80 horsepower. The energy would be stored in a battery during braking, but Williams used a flywheel for this. The boost may not exceed 60KW or 400KJ per lap in 2009. At the time KERS was introduced to F1, there were only 4 teams using it: Renault, BMW, Ferrari and McLaren. Further in the season, it was Renault and BMW that stopped to use KERS early. This was because they did not see the added value of it, since the entire system weighs 35 Kilo and they had problems with space in the car. The location of the main KERS components at the base of the fuel tank reduces fuel capacity by around 15kg, enough to influence race strategy, particularly at circuits where it was previously possible to run just one stop. The system also requires additional radiators to cool the batteries. So I can understand why they made this decision.
McLaren Mercedes has been developing their own KERS for over two years. In 1999, McLaren created the KERS system. In 1999, Mario Illien designed a technology for Mercedes that recovered energy lost while braking by using hydraulic fluid pressure. It would have given the car a 45-bhp boost for four seconds, but it could have been utilized multiple times per lap. For the 2009 season, McLaren developed an electrically powered hybrid powertrain in collaboration with Mercedes.
Safety
After touching the steering wheel and side pod of a BMW F1 car equipped with the KERS prototype in July 2008, a mechanic experienced a significant jolt. The shock was caused by a high-frequency AC voltage between the two contact points, which was traced back to the KERS control unit and intermittent capacitive coupling from the high-voltage network to the 12-volt network after a six-week inquiry. The voltage traveled from the 12-volt network to the steering wheel and back to the control unit via the carbon chassis.
Other recommendations for the development of electric KERS systems emerged from the investigation, in addition to identifying the problem and pointing to remedies. Changes in the control unit's design to avoid capacitive coupling effects, expanded monitoring functions for high frequencies, and a conductive connection of the chassis components to avoid any electric potential are among the solutions found.
KERS in Roadcars
Over the years, several car manufacturers have experimented with KERS for their road cars. Like Volvo, among others. Volvo uses KERS for the XC90 and they estimate that it will improve the fuel economy by 15%. Williams Hybrid Power, a division of the company that owns the Williams Formula 1 team sold the KERS project to a British Automotive company named GKN for £13,5 Million Pounds (€15,3 Million Euro's). They have used this technology in 500 buses in London and Oxford.
Rick