Downsizing potential of wheel brakes in electric vehicles

In most cases of daily driven trips electric vehicles allow to cover decelerations up to 0.3 g only through regenerative braking. The usage of the conventional friction brake is massively reduced. Nowadays classic performance criteria are still the foundation of dimensioning friction brakes. These performance criteria include driving down mountain passes and consumer tests like sequenced stoppings. Since with a fully charged or not conditioned battery, regenerative braking is not possible. The recuperative braking system officially is not part of the service brake and is switched off during the test maneuvers. A vehicle with an electric powertrain that offers a competitive driving range must be equipped with a heavy battery and therefore has a higher overall mass compared to a vehicle with an internal combustion engine with comparable performance. With higher overall weight, the conventional friction brake has to be dimensioned larger to fulfill the same decelerating requirements. The conclusion is that with today's way of dimensioning electric vehicle with less use of brakes must have larger brakes. The paper analyzes the potential of downsizing wheel brakes in electric vehicles. It will regard methods, which could avoid the overheating of smaller dimensioned wheel brakes while driving down mountain passes. The number of the sequenced stoppings of the consumer tests will be reduced. Self-developed thermal models of disc brakes with different materials are added to the vehicle models. Furthermore, models of constant energy sinks are implemented to the electric powertrain. The objective is to analyze the effect of regenerative braking and reduced requirements for the design of wheel brakes.