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Advance CAE Methods for NVH Development of High Speed Electric Axle

AVL LIST GmbH-Mehdi Mehrgou, Julian Pohn, Bernhard Graf, Christoph Priestner
AVL Software and Functions Gmbh-Mathias Deiml
  • Technical Paper
  • 2020-01-1501
To be published on 2020-06-03 by SAE International in United States
By developing more electric vehicles more and more focus are to the noise and vibration from Electric Drive unit. Here a high-speed E-axle for premium class vehicle is being developed up to 30,000 rpm, with high power density and lightweight design which introduce new challenges. Benchmarking of different E-axle and vehicles lead to targets which can be used at the begin of development as subsystem targets. This paper shows first how these targets like tonal noise can be simulated. Then the CAE method is used to optimize the source and structure to improve the NVH. Different aspects like torque ripple, electric whine, gears whine and mounting are discussed.
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Root Cause Analysis and Structural Optimization of E-Drive Transmission

AVL LIST GmbH-Thomas Resch
AVL-AST d.o.o.-Borislav Klarin, Ivan Grozdanovic, Denis Pevec
  • Technical Paper
  • 2020-01-1578
To be published on 2020-06-03 by SAE International in United States
We face a growing demand for so-called eAxles (electric axle drive) in vehicle development. An eAxle is a compact electric drive solution for full electric vehicles (and P4 hybrids) with integrated electric machine and transmission. The transmission can be rather simple using fixed gear with cylindrical gear steps but increasing demands on power and speed range as well as efficiency increase its complexity with planetary stages or switchable gear steps. Such an electro-mechanic system has different behavior than the classical ICE-driven powertrains, for example regarding NVH, where high frequency and tonal noise from gear whining and electro-magnetic excitation is an important comfort issue that needs to be understood and controlled. As knowledge base for such drives is currently low, development needs to be supported by methodologies, which are not only on high predictive level for NVH responses, but also allow a detailed understanding and insight into the causes and reasons of a certain behavior to identify noise effects and to accelerate learning for such systems. In addition, such methods should lead to the possibility to…
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HEV Evaluation in Simulation Phase Based on Predicted Sound Behavior

AVL LIST GmbH-Paco Langjahr, Markus Resch, Bernhard Graf
  • Technical Paper
  • 2020-01-1511
To be published on 2020-06-03 by SAE International in United States
Grown interest in complex modern Hybrid Electric Vehicle (HEV) concepts has raised new challenges in the field of NVH. The switch between Internal Combustion Engine (ICE) and Electric Motor (EM) at low speeds produces undesirable vibrations and a sudden raise of noise levels that affects the sound quality and passenger comfort achieved by the close-to-silent electric powertrain operation. Starting the ICE in the most suitable driving situation to create a seamless transition between driving modes can be the key to minimize the NVH quality impact in driver and passenger’s perception in HEVs. To integrate this important aspect in the early stages of the development and design phase, simulation technologies can be used to address the issue. By analyzing NVH measurements, the different noise components of the vehicle operation can be separated into ICE-related noise, EM-related noise and driving noise. To achieve highest system flexibility, these noise components can be synthesized, providing an integral NVH assessment tool that can be adapted to different driving conditions. ICE and EM noise are simulated using additive synthesis of an…
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Simulation Process for the Acoustical Excitation of DC-Link Film Capacitors in Highly Integrated Electrical Drivetrains

AVL LIST GmbH-Julian Pohn
BMW Group-Maximilian Herrnberger, Jakob Bonart, Roland Lichtinger
  • Technical Paper
  • 2020-01-1500
To be published on 2020-06-03 by SAE International in United States
The advancing electrification of the powertrain is leading towards new challenges in the field of acoustics. Film capacitors used in power electronics are a potential source of high-frequency interfering noise since they are exposed to voltage harmonics. These voltage harmonics are caused by semiconductor switching operations that are necessary to convert the DC voltage of the battery into three-phase alternating current for the electrical machine. In order to predict the acoustic characteristics of the DC-link capacitor at an early stage of development, a multiphysical chain of effects has to be addressed to consider electrical and mechanical influences. In this paper, a new method to evaluate the excitation amplitude of film capacitor windings is presented. The corresponding amplitudes are calculated via an analytical force based on electromechanical couplings of the dielectric within film capacitors. As a next step, these calculated excitation amplitudes can be used in a FE simulation by applying volumetric strains on capacitor windings. This allows to consider the structural dynamic properties of different capacitor geometries. In order to lower the computational costs, a…
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The Prospect and Benefits of Using the Partial-Averaged Navier-Stokes Method for Engine Flows

AVL LIST GmbH-Branislav Basara, Zoran Pavlovic
Texas A&M University-Sharath Girimaji
  • Technical Paper
  • 2020-01-1107
To be published on 2020-04-14 by SAE International in United States
This paper presents calculations of engine flows by using the Partially-Averaged Navier Stokes (PANS) method (Girimaji [1]; [2]). The PANS is a scale-resolving turbulence computational approach designed to resolve large scale fluctuations and model the remainder with appropriate closures. Depending upon the prescribed cut-off length (filter width) the method adjusts seamlessly from the Reynolds-Averaged Navier-Stokes (RANS) to the Direct Numerical Solution (DNS) of the Navier-Stokes equations. The PANS method was successfully used for many applications but mainly on static geometries, e.g. Basara et al. [3]; [4]. This is due to the calculation of the cut-off control parameter which requires that the resolved kinetic energy is known and this is usually obtained by suitably averaging of the resolved field. Such averaging process is expensive and impractical for engines as it would require averaging per cycles. A recently published work on PANS (Basara et al. [5]) opens a prospect of more cost-effective engine calculations. This new PANS approach solves the additional equation for a total resolved turbulent kinetic energy which enables continuous (in situ) update of the…
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A Modular Gasoline Engine Family for Hybrid Powertrains: Balancing Cost and Efficiency Optimization

AVL LIST GmbH-Wolfgang Schoeffmann, Michael Howlett, Alois Fuerhapter, Paul Kapus, Christoph Sams, Helfried Sorger
  • Technical Paper
  • 2020-01-0839
To be published on 2020-04-14 by SAE International in United States
The electrification of the powertrain is a prerequisite to meet future fuel consumption limits, while the internal combustion engine (ICE) will remain a key element of most production volume relevant powertrain concepts. High volume applications will be covered by electrified powertrains. The range will include parallel hybrids, 48V- or High voltage Mild- or Full hybrids, up to Serial hybrids. In the first configurations the ICE is the main propulsion, requiring the whole engine speed and load range including the transient operation. At serial hybrid applications the vehicle is generally electrically driven, the ICE provides power to drive the generator, either exclusively or supporting a battery charging concept. As the ICE is not mechanically coupled to the drive train, a reduction of the operating range and thus a partial simplification of the ICE is achievable. The paper shows the advances on a modular powertrain technology approach with different combinations of ICE, electrification and transmission variants, based on an engine family architecture with common parts, machining and assembly concepts, as well as the feasibility to integrate different…
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FCEV Performance Assessment - Electrochemical Fuel Cell and Battery Modelling on Vehicle Level

AVL LIST GmbH-Johann C. Wurzenberger, Thomas Glatz
AVL-AST d.o.o.-Davor Rašić, Gregor Tavcar
  • Technical Paper
  • 2020-01-0857
To be published on 2020-04-14 by SAE International in United States
Fuel cell electric vehicles are a promising technology to create CO2- neutral mobility. Model-based development approaches are key to reduce costs and to raise efficiencies. A model on vehicle system level is discussed that balances the need of physical depth and computational performance. The vehicle model comprises the domains of mechanics, electrics, thermodynamics, cooling and controls. Detailed models of the fuel cell and battery are presented as a part of the system model. The models apply electrochemical approaches and spatial resolutions up to 3D. The models of both components are validated via 3D reference simulations showing a seamless parameter transfer between system level and CFD-based simulations. The validity of the vehicle model, including the electrochemical components, is demonstrated by simulating the Toyota Mirai vehicle. Simulation results of an NEDC are compared to measurements. The added value of the high-resolved fuel and battery models is shown by insights gathered from selected WLTP driving phases.
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Evaluation of flow paths due to leakages of flammable liquids by the SPH method. Application to real engines.

AVL LIST GmbH-David Greif
AVL France-Simon Ameye
  • Technical Paper
  • 2020-01-1111
To be published on 2020-04-14 by SAE International in United States
One the most important safety issues for automotive engineering is to avoid any fire due to the ignition of flammable liquids, which may result from leaks. Fire risk is a combination of hot temperature, fast vaporization and accumulation of vapor in a cavity. In IC engines, potentially flammable liquids are fuel and oil. To guarantee safety, no flammable liquids must come into contact hot parts of the engine. Consequently, shields are designed to guide the flow path of possible leakages and to take any flammable liquid out of the hot areas. Simulation is a great help to optimize the shape of the shield by investigating a large number of possible leakages rapidly. Recent breakthroughs in numerical methods make it possible to apply simulations to industrial design concepts. The approach is based on the Lagrangian Smoothed Particle Hydrodynamics (SPH) method. The SPH method is an efficient method to capture the rivulets on highly complex geometries and thus determine the relevance of the design. A new implicit algorithm was developed to make the simulations faster. Preliminary tests…
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Model-Based Brake Disc Temperature Prediction on High Speed Testing Mode and Circuit

AVL LIST GmbH-Mario Oswald, Stefan Kellner
Hyundai & Kia Corp.-PilYoung Jeong
  • Technical Paper
  • 2020-01-0214
To be published on 2020-04-14 by SAE International in United States
A brake is a mechanical device that inhibits the motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by friction energy. Commonly, most brakes use friction between two surfaces pressed together to convert the kinetic energy of the moving object into heat, though other methods of energy conversion may be employed. If braking is repeated or sustained in high load or high-speed conditions, the motion will be unstable and can lead to a loss of stopping power because the disc capability for braking is not enough. These phenomena are generally defined as brake fading. Brake fade is caused by an overheating brake system. This paper describes the thermal modeling and process to predict the disk temperature under a condition which causes the fade characteristics. Also, the model of disc temperature prediction developed with consideration of acceleration and deceleration from the vehicle specification by combining the full vehicle modeling with thermal disc model. The disc temperature model…
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An Integrated View on Automotive SPICE, Functional Safety and Cyber-Security

AVL LIST GmbH-Eric Armengaud
Austrian Institute of Technology (AIT)-Christoph Schmittner
  • Technical Paper
  • 2020-01-0145
To be published on 2020-04-14 by SAE International in United States
Automotive domain has seen safety engineering at the forefront of the industry’s priorities for the last decade. Therefore, additional safety engineering efforts, design approaches and well-established safety processes have been stipulated. Today many connected and automated vehicles are available and connectivity features and information sharing is increasingly used. This increases the attractiveness of an attack on vehicles and thus introduces new risks for vehicle cyber-security. Thus, just as safety became a critical part of the development in the late 20th century, the automotive domain must now consider cyber-security as an integral part of the development of modern vehicles. Aware of this fact, the automotive industry has therefore recently taken multiple efforts in designing and producing safe and secure connected and automated vehicles. As the domain geared up for the cyber-security challenges, they leveraged experiences from many other domains, but nevertheless, must face several unique challenges. For that aim, the domain invested efforts in the development of industry standards to tackle automotive cyber-security issues and protect their assets. The joint working group of the standardization organizations…