Vehicle fuel economy & performance modelling with focus on an engine

Examensarbete för masterexamen

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Type: Examensarbete för masterexamen
Master Thesis
Title: Vehicle fuel economy & performance modelling with focus on an engine
Authors: Kogalur Mallikarjunappa, Shreyas
Abstract: Recently, it has been a growing interest in introducing hybrid electric vehicles in the market. To improve vehicle fuel consumption, a transition is observed from vehicles driven by purely internal combustion engines to hybrid electric vehicles with different levels of electrifications. In this journey, it is very important to consider the match between the engines and the new hybrid electric vehicle configurations. This is because the engine operation would be different in each configuration. Consequently, these engines could be further improved to be well-fitted to the hybrid vehicles. In view of this, a method to integrate engine models with vehicle models is required in the early phases of engine development. This thesis aims to fulfil this gap and implement a modelling method to be able to understand how an engine would work in a new vehicle configuration in the absence of detailed information of different subsystems such as electric machine, vehicle and transmission. The first section involves understanding the 48V battery system, P2 Hybrid Electric Vehicle concepts and engine model calibration. With the knowledge acquired, the second phase of the thesis involves calibrating the engine model in GT-POWER against latest measurement data that was received from a test rig at Volvo Cars. After the engine model calibration, the third phase includes modelling the Volvo XC60 vehicle along with all its subsystems in GT-SUITE software. Upon understanding each subsystem, multiple engine performance maps are extracted from the engine model to represent the engine in the vehicle model. Subsequently, based on the driving cycles, simulations are performed to extract the vehicle fuel consumption for different cases. Different subsystems and technologies are varied to assess the sensitivity of the modular vehicle. On comparing all the different cases, a critical observation on two interesting technologies is made i.e. cylinder deactivation and P2 hybrid electrification. The effects of cylinder deactivation and P2 hybrid electrification are comparable in WLTC; however, the benefit of P2 hybrid is significantly higher than that of cylinder deactivation in other driving cycles including NEDC and aggressive driving cycles. Moreover, there is a reduction in the benefit of cylinder deactivation at the presence of electrification. This observation is valid for all the studied driving cycles for instance, the cylinder deactivation benefit is very low in a really aggressive driving cycle and at the presence of electrification. Furthermore, a smaller electric machine is included in P0 hybrid vehicle configuration to assess the impact of Start-Stop feature alone on the vehicle’s fuel consumption. In terms of performance test of the vehicle, an acceleration test of the vehicle from stand still to 100km/h is conducted. The engine-vehicle model is fairly accurate and performs this test in 7s as compared to the reality of 6.95s.
Keywords: Energi;Transport;Hållbar utveckling;Farkostteknik;Energiteknik;Energy;Transport;Sustainable Development;Vehicle Engineering;Energy Engineering
Issue Date: 2018
Publisher: Chalmers tekniska högskola / Institutionen för mekanik och maritima vetenskaper
Chalmers University of Technology / Department of Mechanics and Maritime Sciences
Series/Report no.: Examensarbete - Institutionen för mekanik och maritima vetenskaper : 2018:58
Collection:Examensarbeten för masterexamen // Master Theses

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