Concept of an electromechanical brake-by-wire system for battery-electric vehicles

Brake-by-wire systems have received more and more attention in the recent years, but a closer look on the available systems shows, that they have not reached full by-wire level yet. Most systems are still using hydraulic connections between main cylinder and the brake calipers on at least one axle to ensure functional safety. Mostly, this is the front axle, since the front brakes have to convert more kinetic energy during braking manoeuvers due to the dynamic wheel load shift. Electromechanical actuators are currently used for rear brake systems in hybrid brake-by-wire applications solely, since a loss of the front brake calipers can lead to severe conditions and control loss of the vehicle during braking. Further, the higher mass of battery-electric vehicles (BEVs) leads to much higher braking forces on both axles, so the electromechanical calipers on the market are no longer suitable. This article presents a concept for a brake-by-wire system for a battery electric vehicle, which features electromechanical brake actuators on all corners with a fail-safe architecture. The proposed system supports braking ratios up to z = 100% for vehicles with a total mass of maximum 3.5 tons. Besides the mechanical design of the actuator, the power electronics are taken into account too and the behavior is investigated through dedicated simulation.