Innovative Zero-Emissions Braking System: performance analysis and energy consumption optimization

The following Master's Thesis discusses the analysis of a braking system, designed by the IEHV research group as an alternative and environmentally friendly solution to traditional friction brakes. The idea arose from the need to completely reduce the emissions of the braking system of an electric vehicle: traditional brakes, in fact, produce dust emissions due to the consumption of the pads; regenerative braking (RB) allows a considerable reduction in emissions but not enough to reach zero-pollutants. In the first part of the thesis, a brief analysis is proposed on the efficiency of regenerative braking as a function of the State of Charge (SoC) of the battery and its impact on dust emissions. Therefore, an innovative solution called Zero-Emissions Driving System (ZEDS) is proposed for replacing conventional brakes with the goal of zero-emissions. Such a system proposes a series system between an electric motor (in-wheel motor) and the brake. The latter has a geometry such that it houses magnetorheological fluid (MRF) inside it, which can change its viscous properties according to the magnetic field passing through it. It is thus an electro-actuated brake, capable of generating a magnetic field passing through the fluid and developing braking torque. In this way, the brake system does not work by friction and can be considered a green system in its own right. The second part focuses on describing a 1D simulation model built on Matlab Simulink to simulate the dynamics of a vehicle, equipped with four wheels, each having a ZEDS system mounted. The model is able to simulate the 1D motion of an electric vehicle and reproduce the operations of major components such as ZEDS and the battery pack according to a specific driving cycle. The goal is to obtain initial results that could testify the feasibility of the system, while complying with safety and regulation requests. Nullifying pollutant emissions is not the only purpose of the study carried out, as the ZEDS system, being fully electro-actuated, has allowed the design of a control logic capable of optimizing the energy consumption of the whole vehicle. Such a control system, described in the third part of the thesis, is able to coordinate and manage the operation of the four ZEDSs according to their working conditions. Specifically, it monitors parameters, such as SoC, which directly impacts RB efficiency, MRF temperature (which must necessarily be within a predefined range to ensure proper brake operation), battery temperature, and in-wheel motor temperatures, and acts to optimize total energy consumption. This logic was implemented in the Simulink model, returning results that testified to its efficiency .