E-KERS Energy Management Crucial to Improved Fuel Economy

The operation of a conventional passenger car is characterised by increasing or maintaining the kinetic energy, when accelerating or cruising the vehicle, and reducing the kinetic energy by using the brakes. While the energy taken by the friction brakes to slow the vehicle is dissipated into heat, the introduction of Kinetic Energy Recovery Systems (KERS) has permitted the recovery of part of the braking energy. This reduces the amount of energy needed from the internal combustion engine (ICE). The contribution reviews the latest developments in electric KERS (E-KERS), with emphasis to round trip efficiency wheels to wheels and electrification of the powertrain. The contribution considers the opportunity to connect the E-KERS traction battery to other electric machines, such as an electrically assisted turbocharger (E-TC) connected to a motor/generator unit, or an electric water pump (EWP), to further optimise the vehicle operation. The electrically assisted TC permits a reduced turbo-lag and the recovery of the extra energy at the TC turbine. The EWP permits to reduce the inertia of the cooling system precisely operated for a faster warm-up and better steady state conditions. The vehicle energy management permitted by the E-KERS and the electrification is concluded to represent a fundamental step to improve the fuel economy of today’s passenger cars.