Thermal Management of Electrified Vehicles—A Review

Vehicle electrification demands a deep analysis of the thermal problems in order to increase vehicle efficiency and battery life and performance. An efficient thermal management of an electrified vehicle has to involve every system of the vehicle. However, it is not sufficient to optimize the thermal behavior of each subsystem, but thermal management has to be considered at system level to optimize the global performance of the vehicle. The present paper provides an organic review of the current aspects of thermal management from a system engineering perspective. Starting from the definition of the requirements and targets of the thermal management system, each vehicle subsystem is analyzed and related to the whole system. In this framework, problems referring to modeling, simulation and optimization are considered and discussed. The current technological challenges and developments in thermal management are highlighted at vehicle and component levels

Multi-Disciplinary Optimisation of Road Vehicle Chassis Subsystems

Two vehicle chassis design tasks were solved by decomposition-based multi-disciplinary optimisation (MDO) methods, namely collaborative optimisation (CO) and analytical target cascading (ATC). A passive suspension system was optimised by applying both CO and ATC. Multiple parameters of the spring and damper were selected as design variables. The discomfort, road holding, and total mass of the spring–damper combination were the objective functions. An electric vehicle (EV) powertrain design problem was considered as the second test case. Energy consumption and gradeability were optimised by including the design of the electric motor and the battery pack layout. The standard single-level all-in-one (AiO) multi-objective optimisation method was compared with ATC and CO methods. AiO methods showed some limitations in terms of efficiency and accuracy. ATC proved to be the best choice for the design problems presented in this paper, since it provided solutions with good accuracy in a very efficient way. The proposed investigation on MDO methods can be useful for designers, to choose the proper optimisation approach, while solving complex vehicle design problems

Eco-Driving Strategy Implementation for Ultra-Efficient Lightweight Electric Vehicles in Realistic Driving Scenarios

This paper aims to provide a quantitative assessment of the effect of driver action and road traffic conditions in the real implementation of eco-driving strategies. The study specifically refers to an ultra-efficient battery-powered electric vehicle designed for energy-efficiency competitions. The method is based on the definition of digital twins of vehicle and driving scenario. The models are used in a driving simulator to accurately evaluate the power demand. The vehicle digital twin is built in a co-simulation environment between VI-CarRealTime and Simulink. A digital twin of the Brooklands Circuit (UK) is created leveraging the software RoadRunner. After validation with actual telemetry acquisitions, the model is employed offline to find the optimal driving strategy, namely, the optimal input throttle profile, which minimizes the energy consumption over an entire lap. The obtained reference driving strategy is used during real-time driving sessions at the dynamic driving simulator installed at Politecnico di Milano (DriSMi) to include the effects of human driver and road traffic conditions. Results assess that, in a realistic driving scenario, the energy demand could increase more than 20% with respect to the theoretical value. Such a reduction in performance can be mitigated by adopting eco-driving assistance systems

Shoot-tips vitrification protocol for red chicory (Cichorium intybus L.) lines

Shoot tips from in vitro stock plants of red chicory ‘Rosso di Chioggia’ line were cryopreserved by one-step vitrification. After two days of cold-hardening on hormone-free MS medium and loading for 30 min in a mixture of 2 M glycerol and 0.4 M sucrose at 25°C, shoot tips were dehydrated with PVS2 vitrification solution at 0°C for 60 min and plunged directly into liquid nitrogen. The post-thaw survival of shoot tips was achieved 79% when was cultured on recovery medium containing 0.5 mM BA. Observed regrowth, after six weeks of culture in the same medium composition, was 100%. Rooted cryopreserved microshoots showed good quality when transferred to the greenhouse. Preliminary results proved that the genetic fidelity of the cryopreserved line was maintained. The same vitrification protocol was then applied to three other red chicory lines, ‘Rosso di Treviso precoce’, ‘Rosso di Treviso tardivo’ and ‘Castelfranco’. A simple and effective protocol for the cryopreservation of red chicory shoot tips has been successfully developed as a result of this study