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The rate in the electrification of vehicles has risen in recent years. With intensified development more and more attention is paid to the noise and vibration in such vehicles especially from the EDU (Electric Drive Unit). In this paper the main NVH simulation process of a high-speed E-axle up to 30,000 rpm for premium class vehicle application is presented. The high speed, high-power density and lightweight design introduces new challenges. Benchmarking of different EDUs and vehicles leads to targets which can be used at the early stage of development as subsystem targets. This paper shows the CAE methodology which can be used to verify the design and guarantee the target achievement. Using CAE both source and structure can be optimized to improve the NVH behavior.

Gear trains applied to automotive transmissions and combustion engines are potential excitation sources of undesired whine noise. Consequently, the prediction of gear whine issues in an early stage of the product development process is strongly requested. Beside the actual excitation mechanism which is closely related to the gear's transmission error, the vibratory behavior (e.g. resonances) of other affected components like shafts, bearings and housing plays an important role in terms of structure borne noise transfer. The paper deals with gear contact models of different degree of detail, which are embedded in a multi-body dynamics (MBD) environment. Since gear meshing frequency and their harmonics may easily reach up to 5 kHz or even 10 kHz, applied gear contact models must be highly efficient with respect to calculation performance. Otherwise, major requirements of the development process in terms of process time can not be satisfied as is the case with FEA-based contact models.

Efficient integration of mechanics and microelectronics components is nowadays a must within the automotive industry in order to minimize integration risks and support optimization of the entire system. We propose in this work a cross domain co-simulation platform for the efficient analysis of mechatronic systems. The interfacing of two state-of-the-art simulation platforms provides a direct link between the two domains at an early development stage, thus enabling the validation and optimization of the system already during modeling phase. The proposed cross-domain co-simulation is used within our TEODACS project for the analysis of the FlexRay technology. We illustrate using a drive-by-wire use case how the different architecture choices may influence the system.

Recently, hybrid and fully electric drives have been developing widely in variety, power and range. The new reliable simulation approaches are needed, in order to meet the defined NVH targets of these systems and implementing CAE methods for front loading, Design Validation Process (DVP). This paper introduces the application of a novel NVH analysis workflow on an electric vehicle driveline including both electromagnetic and mechanical excitations for an absolute evaluation of the NVH performance. At first, the electromagnetic field is simulated using FEM method to extract the excitations on the stator, rotor bearings as well as the drive torque. Then, the multibody dynamic model of the driveline is built-up, driven by this torque. The effect of eccentricity and skew angle of rotor in electromagnetic excitations are shown.

This paper presents a simulation environment and methodology for noise and vibration analyses of a driven rear axle in a bus application, with particular focus on medium to high frequency range (400 Hz to 3 kHz). The workflow demonstrates structure borne noise and sound radiation analyses. The fully flexible Multi-Body Dynamics (MBD) model - serving to cover the actual mechanical excitation mechanisms and the structural domain - includes geometrical contacts of hypoid gear in the central gear and planetary gear integrated at hubs, considering non-linear meshing stiffness. Contribution of aforementioned gear stages, as well as the propeller shaft universal joint at the pinion axle, on overall axle noise levels is investigated by means of sensitivity analysis. Based on the surface velocities computed at the vibrating axle-housing structure the Wave Based Technique (WBT) is employed to solve the airborne noise problem and predict the radiated sound.

Advanced powertrain test, which is simulating real road load condition, was performed on the dynamic test bed. This cutting edge system can reproduce real road resistance based upon the vehicle dynamic model and wheel slip model. This wheel slip function is simulating the real behavior of the powertrain wheel as close as possible at each wheel independently. Additionally, low inertia of dynamometer motor themselves is another advantage for this purpose. This test bed is capable of testing all kinds of 2WD and 4WD powertrain configuration regardless of transmission type. Also, vehicle configuration can be mounted and tested on this test bed with small addition of supporting system alternatively. For the application, a four wheel drive powertrain was mounted on the test bed and driveline noise and vibration behavior such as transfer rattling noise and tip in/out shock were reproduced on this test bed.

The demand for high efficiency powertrains in automotive engineering is further increasing, with hybrid powertrains being a feasible option to cope with new legislations. So far hybridization has only played a minor role for L-category vehicles. Focusing on an exemplary high-power L-category on-road vehicle, this research aims to show a new development approach, which combines longitudinal dynamic simulation (LDS) with “Design of Experiments” (DoE) in course of hybrid electric powertrain development. Furthermore, addressing the technological aspect, this paper points out how such a vehicle can benefit from 48V-hybridization of its already existing internal combustion powertrain. A fully parametric LDS model is built in Matlab/Simulink, with exchangeable powertrain components and an adaptable hybrid operation strategy. Beforehand, characterizing decisions as to focus on 48V and on parallel hybrid architecture are made.

Within gear pair development, the simulation of loaded transmission error, line of action and summarized mesh point are crucial information in design optimization as well as reliability, NVH and efficiency prediction. These properties and variables are difficult to evaluate and are usually only assessed through proxy-variables such as unloaded transmission error or contact pattern assessment. Alternatively, large design loops can be generated when prototypes are produced to directly assess the results of reliability, NVH and efficiency and simulation models updated to the results, but not directly calibrated. This work will showcase an advanced test facility with the unique capabilities to evaluate all gear contact types (including hypoid, beveloid, cylindrical and spiral) under loaded conditions while assessing position and force data that can be used to validate simulation models directly and enhance design development.

The rate in the electrification of vehicles has risen in recent years and, despite that electric vehicles are quiet, NVH remains a major requirement of vehicle development. The typical NVH issues are gear whine from the gearbox, noise from the E-machine or electromagnetic whine, as well as the noise from the inverter, and noise from inverter harmonics effect on E-machine. Simulation methodologies and CAE workflows are being enhanced to contribute to electric drive systems development. Front loading in the concept and layout design phase are necessary to avoid significant NVH issues at the end of development. The authors previously presented a workflow for combining the electric and mechanical noise for electric drives for the concept and layout design phases. This paper shows an application of the formerly presented workflow for NVH simulation and validation of a system with an Interior Permanent Magnet (IPM) E-machine.

This paper presents a methodology for numerical investigation of a full flexible balancer drive together with engine and crank train under realistic operating conditions where shaft dynamics, gear contact and rattle impacts, gear root stresses and friction losses in bearings and gear interaction are taken into account and can be balanced against each other to achieve the design criteria. Gear rattle is driven by the speed fluctuation of the crank train, the resistance torque (mainly friction), shaft inertia and the backlash in the gears. The actual trend to engine downsizing and up-torqueing increases the severity to rattle as engines are running on higher combustion pressures. This increases torque and speed fluctuation, which makes the detailed investigation in this torque transfer even more demanding. A common method to reduce gear rattle is the usage of so-called scissors gears.

Today, the number of downsized engines with two or three cylinders is increasing due to an increase in fuel efficiency. However, downsized engines exhibit unbalanced interior sound in the range of their optimal engine speed, largely because of their dominant engine orders. In particular, the sound of two-cylinder engines yields half the perceived engine speed of an equivalent four-cylinder engine at the same engine speed. As a result when driving, the two-cylinder engine would be shifted to higher gears much later, diminishing the expected fuel savings. This contribution presents an active in-car sound generation system that makes a two-cylinder engine sound like the more familiar four-cylinder engine. This is done by active, load-dependent playback of signals extracted from the engine vibration through a shaker mounted on the firewall. A blind test with audio experts indicates a significant reduction of the engine speed when shifting to a higher gear.

In recent years, the use of high-power inverters has become increasingly prevalent in vehicles applications. With the increasing number of electric vehicle models comes the need for efficient and reliable testing methods to ensure the proper functioning of these inverters. One such method is the use of Hardware-in-the-Loop (HiL) environments, where the inverter is connected to a simulated environment to test its performance under various operating conditions. HiL testing allows for faster and more cost-effective testing than traditional methods and provides a safe environment to evaluate the inverter's response to different scenarios. Further, in such an environment, it is possible to specifically stimulate those system states in which conflicts between the lines arise regarding the ideal system parametrization. By combining HiL testing with design-of-experiments and modelling methods, the propulsion system can hence be optimized in a holistic manner.

This work presents a physical model that calculates the efficiency maps of the inverter-fed Permanent Magnet Synchronous Machine (PMSM) drive. The corresponding electrical machine and its controller are implemented based on the two-phase (d-q) equivalent circuits that take into account the copper loss as well as the iron loss of the PMSM. A control strategy that optimizes the machine efficiency is applied in the controller to maximize the possible output torque. In addition, the model applies an analytical method to predict the losses of the voltage source inverter. Consequently, the efficiency maps within the entire operating region of the PMSM drive can be derived from the simulation results, and they are used to represent electric drives in the system simulation model of electric vehicles (EVs).

Encapsulations of E-drive systems are gaining importance in electric mobility, since they are simple measure to improve the noise behavior of the drive. Current experimental evaluation methods however pose substantial challenges for the test personnel and are associated with considerable effort in both time and cost. Evaluating the encapsulation on an e-drive test bed, for example, requires a functional e-drive and test bed resources. Evaluations in the vehicle on the other hand make objective assessments difficult and are subject to increasingly limited availability of prototype vehicles fit for NVH testing. To overcome these challenges, AVL has developed a new experimental evaluation method for the NVH efficiency of e-drive encapsulations. In this method, the e-drive is freely suspended in a semi-anechoic chamber and its structure is excited using shakers while the radiated noise with and without encapsulation is measured.