Your Selections

University of Ljubljana
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.
new

Performance Evaluation of an Electric Vehicle with Multiple Electric Machines for Increased Overall Drive Train Efficiency

University of Ljubljana-Mario Vukotić, Damijan Miljavec
University of Rome Niccolò Cusano-Laura Tribioli, Daniele Chiappini
Published 2019-10-07 by SAE International in United States
Proposed solutions for electric vehicles range from the simple single-motor drive coupled to one axle through a mechanical differential, to more complex solutions, such as four in-wheel motors, which ask for electronic torque vectoring. Main reasons for having more than one electric machine are: reduction of the rated power of each motor, which most likely leads to simplification and cost reduction of all the electric drive components; increased reliability of the overall traction system, enhancing fault tolerance ability; increase of the degrees of freedom which allows for control strategy optimization and efficiency improvement. In particular, electrical machines efficiency generally peaks at around 75% of load and this usually leads to machine downsizing to avoid operation in low efficiency regions. The same output performance can be achieved by using two or more electrical machines, rather than only one, of smaller size and running them at unequal load - one of the machines at higher load and the other(s) at lower load.In this paper, the performance of an electric vehicle with multiple electric machines is analyzed to…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Magnetostrictive and Magnetic Sources of Noise in the Electric Motors

University of Ljubljana-Janko Slavic, Gregor Cepon, Miha Boltezar
Domel d.o.o.-Janez Luznar
Published 2016-06-15 by SAE International in United States
In electric motors the working torque results from the magnetic forces (due to the magnetic field). The magnetic forces are also a direct source of structural excitation; further, the magnetic field is an indirect source of structural excitation in the form of magnetostriction. In the last decade other sources of structural excitation (e.g. mechanical imbalance, natural dynamics of the electric motor) have been widely researched and are well understood. On the other hand, the excitation due to the magnetic forces and magnetostriction is gaining interest in the last period; especially in the field of auto-mobility.Due to the broadband properties of the magnetic field (e.g. Pulse-Width-Modulation(PWM), multi-harmonic excitation), the direct structural excitation in the form of magnetic forces is also broadband. It is important to understand the broadband content of this excitation with regards to the broadband structural response which results in the broadband noise of the electric motor. This research presents an experimental approach to the characterization of the magnetic forces due to PWM excitation.The magnetostrictive excitation has long been researched in the time-domain, only.…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Crank-Angle Resolved Modeling of Fuel Injection, Combustion and Emission Formation for Engine Optimization and Calibration on Real-Time Systems

University of Ljubljana-Tomaz Katrasnik
AVL LIST GmbH-Christoph Poetsch
Published 2016-04-05 by SAE International in United States
The present work introduces an innovative mechanistically based 0D spray model which is coupled to a combustion model on the basis of an advanced mixture controlled combustion approach. The model calculates the rate of heat release based on the injection rate profile and the in-cylinder state. The air/fuel distribution in the spray is predicted based on momentum conservation by applying first principles. On the basis of the 2-zone cylinder framework, NOx emissions are calculated by the Zeldovich mechanism. The combustion and emission models are calibrated and validated with a series of dedicated test bed data specifically revealing its capability of describing the impact of variations of EGR, injection timing, and injection pressure. A model based optimization is carried out, aiming at an optimum trade-off between fuel consumption and engine-out emissions. The findings serve to estimate an economic optimum point in the NOx/BSFC trade-off. The real-time capability of the model is proven by running a vehicle drivecycle simulation coupled to an aftertreatment system on HiL hardware.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Accelerated Fatigue and Modal Parameter Identification of Lightweight Structures

SAE International Journal of Materials and Manufacturing

University of Ljubljana-Janko Slavic, Martin Cesnik, Miha Boltezar
  • Journal Article
  • 2014-01-2095
Published 2014-06-30 by SAE International in United States
Car components are exposed to the random/harmonic/impact excitation which can result in component failure due to vibration fatigue. The stress and strain loads do depend on local stress concentration effects and also on the global structural dynamics properties. Standardized fatigue testing is long-lasting, while the dynamic fatigue testing can be much faster; however, the dynamical changes due to fatigue are usually not taken into account and therefore the identified fatigue and structural parameters can be biased. In detail: damage accumulation results in structural changes (stiffness, damping) which are hard to measure in real time; further, structural changes change the dynamics of the loaded system and without taking this changes into account the fatigue load in the stress concentration zone can change significantly (even if the excitation remains the same).This research presents a new approach for accelerated vibration testing of real structures. The new approach bases on phase locked harmonic excitation and can be used for identification of natural frequencies and damping while the damage due to vibration is being accumulated. At the same time a…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Comprehensive Study on Different System Level Engine Simulation Models

University of Ljubljana-Tomaz Katrasnik
AVL LIST GmbH-Johann C. Wurzenberger
Published 2013-04-08 by SAE International in United States
Engine simulation can be performed using model approaches of different depths in capturing physical effects. The present paper presents a comprehensive comparison study on seven different engine models. The models range from transient 1D cycle resolved approaches to steady-state non-dimensional maps. The models are discussed in the light of key features, amount and kind of required input data, model calibration effort and predictability and application areas. The computational performance of the different models and their capabilities to capture different transient effects is investigated together with a vehicle model under real-life driving conditions. In the trade-off field of model predictability and computational performance an innovative approach on crank-angle resolved cylinder modeling turned out to be most beneficial. It covers a high level of physical based approaches needed in early development phases and it runs in real-time as needed to support calibration in late development phases.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Real-Time Capable, System-Level Simulation With Integrated Pollutant Formation and Exhaust Aftertreatment Modeling

University of Ljubljana-Tomaz Katrasnik
AVL List GmbH-Johann Krammer, Johann C. Wurzenberger, Sophie Bardubitzki
  • Technical Paper
  • 2011-08-0103
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
Today's diesel engines require a combined design and application of combustion strategies with various aftertreatment devices. A comprehensive simulation approach is presented with the aim to support engine development activities in the virtual environment. Combustion and pollutant production models are applied in a real-time capable engine and vehicle simulation model considering crank-angle-resolved phenomena as well as pollutant conversion in a diesel oxidation catalyst (DOC) combined with urea injection and selective catalytic reduction (SCR). Extended species transport model is applied taking into account an arbitrary number of chemical species and reactions in the entire system.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

The Damage Operator Approach: Fatigue, Creep and Viscoplasticity Modeling in Thermo-Mechanical Fatigue

SAE International Journal of Materials and Manufacturing

University of Ljubljana-Marko Nagode
LMS International-Michael Hack
  • Journal Article
  • 2011-01-0485
Published 2011-04-12 by SAE International in United States
In the last decades the development time of vehicles has been drastically reduced due to the application of advanced numerical and experimental methods. Specifications concerning durability and other functional attributes for every new model improve for every vehicle.In particular, for machines and components under variable multiaxial loading, fatigue evaluation is one of the most important steps in the design process. Appropriate material testing and simulation is the key to efficient life prediction.However, the life of automotive components, power plants and other high-temperature facilities depends mostly on thermo-mechanical fatigue (TMF). This is due to the normally variable service conditions, which contain the phases of startup, full load, partial load and shut-down.Within this context, there are several requirements for making accurate life predictions: a proper material model with material parameters derived from testing, modeling of stress-strain response during cyclic loading, a multiaxial fatigue criterion, a proper damage accumulation model and component testing to evaluate the correlation between life prediction models and experiments.For high temperatures the influence of creep, creep fatigue and viscoplastic stress relaxation have to be…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Crank-Angle-Resolved Real-Time Engine Models for Office Applications

University of Ljubljana-Toma Katrašnik
AVL List GmbH-Johann Krammer, Johann C. Wurzenberger, Peter Bartsch
  • Technical Paper
  • 2010-08-0426
Published 2010-05-19 by Society of Automotive Engineers of Japan in Japan
Modeling and simulation tools are getting more and more important during the development phase of vehicle powertrains. A fully integrated real-time (RT) capable engine and vehicle model used for office applications is presented. Steady state results of the RT engine model are compared to experimental data and 1D high fidelity simulations. In addition Drive Cycles are simulated and results are compared to high fidelity simulations and measurements. The integrated RT engine and vehicle approach simplified the harmonization of engine and vehicle parameters to meet figure requirements on driving performance, fuel consumption and emissions, and speeds up the simulation significantly.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Crank-Angle Resolved Real-Time Capable Engine and Vehicle Simulation - Fuel Consumption and Driving Performance

University of Ljubljana-Tomaz Katrasnik
AVL LIST GmbH-Johann C. Wurzenberger, Peter Bartsch
Published 2010-04-12 by SAE International in United States
The present work introduces a fully integrated real-time (RT) capable engine and vehicle model. The gas path and drive line are described in the time domain of seconds whereas the reciprocating characteristics of an IC engine are reflected by a crank angle resolved cylinder model. The RT engine model is derived from a high fidelity 1D cycle simulation and gas exchange model to support an efficient and consistent transfer of model data like geometries, heat transfer or combustion. The workflow of model calibration and application is outlined and base ECU functionalities for boost pressure, EGR, smoke and idle speed control are applied for transient engine operation. Steady state results of the RT engine model are compared to experimental data and 1D high fidelity simulations for 19 different engine load points. In addition an NEDC (New European Drive Cycle) is simulated and results are evaluated with data from chassis dynamometer measurements. A full load acceleration is simulated with the RT engine model and compared to results of a simple map based engine model. The simulation results…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Energy Conversion Efficiency of Hybrid Electric Heavy-duty Vehicles

University of Ljubljana-Tomaž Katrašnik
Published 2009-06-15 by SAE International in United States
Energy conversion efficiency of parallel and series HEVs was analyzed by combined analytical and simulation approach. Combined approach enables evaluation of energy losses on different energy paths and provides their impact on the fuel economy. The paper quantifies influences of different HEV topologies, power ratios and characteristics of the components, and applied control strategies on the energy conversion efficiency of HEVs. Moreover, the paper reveals characteristics of drive cycles that make possible significant fuel economy enhancement of HEVs. Additionally, impact of drive-away and vehicle propulsion by electric motor at low powertrain loads on the energy conversion efficiency of HEVs is analyzed.
Annotation ability available