Dimensioning of a permanent magnet synchronous machine for electric vehicles according to performance and integration requirements

Finding the optimum design of electrical machines for a certain purpose is a time-consuming task. First results can be achieved, however, with scaling known machine designs in length and turns per coil by means of analytical equations, while scaling in diameter requires finite element analysis (FEA), since electromagnetic properties change significantly. In this paper, the influence of diameter, length and turns per coil on the torque, power and efficiency of a permanent magnet synchronous machine (PMSM) are investigated in a sensitivity analysis. Furthermore, their impact on energy consumption in different drive cycles and different vehicle types is outlined. A highway car and a city car are compared in a highway cycle, a city cycle and the Worldwide Harmonized Light Vehicle test Cycle. The results describe significant differences in energy consumption for different machine designs in one application but also between different applications. This highlights the necessity to decide whether or not the powertrain should be optimized for a single purpose or for universal use.

Analysis of the NOx storage behaviour during cold start of modern SCR flow-through substrates and SCR on-filter substrates

Selective catalytic reduction (SCR) systems are the state-of-the-art technology to reduce nitrogen oxide emissions (NOx) of modern diesel engines. The system behaviour is well understood in the common temperature working area. However, the system properties below light-off temperature are less well known and offer a wide scope for further investigations. Vehicle measurements show that under specific conditions during cold start, NOx can be partially stored and converted on on-filter and flow-through SCR catalysts. The purpose of this work was in a first step to analyse the main influence parameters on the NOx storage behaviour. Therefore, synthetic gas test bench measurements have been carried out, varying the gas concentrations, temperature, and gas hourly space velocity (GHSV). These investigations showed that the NOx storage effect strongly depends on the NH3 level stored in the catalyst, GHSV, the adsorbed water (H2O) on the catalyst, and the temperature of the catalyst. Further influence parameters such as the gas composition with focus on carbon monoxide (CO), short-chain hydrocarbons and long-chain hydrocarbons have been analysed on a synthetic gas test bench. Depending on operating conditions, a significant amount of NOx can be stored on a dry catalyst during the cold start phase. The water vapor from the combustion condenses on the cold exhaust pipe during the first seconds, or up to a few minutes after a cold start. As the water vapor reaches the surface of the catalyst, it condenses and adsorbs onto it, leading to a sudden temperature rise. This exothermal reaction causes the stored NOx to be desorbed, and furthermore it is partially reduced by the NH3 stored in the catalyst.

Systematic synthesis and multi-criteria evaluation of transmission topologies for electric vehicles

The focus on the expansion of the electrification of vehicles becomes stronger. Thus, the development process of powertrains of those cars needs to be more dynamic to react to the new challenges. One way to accelerate the development is to automate predevelopment and evaluation at an early stage. An automated method to synthesize transmission topologies and pre-design gears for the generated topologies for electric vehicles is presented within this paper. The method contains two internal evaluations—one after the topology synthesis and the second after the initial design of the gears. The results of the method are gear ratios and gear data for the single transmission steps of each topology. The inputs and boundary conditions can be easily changed and fitted to specific requirements for all use-cases. Here, the process is explained, and the methods' results are validated using state-of-the-art passenger vehicle transmission. As for electric trucks, no state-of-the-art electric powertrains exist; the method is subsequently applied to find topologies for a heavy-duty truck. Extracts of the results are presented. The application for trucks is carried out within the publicly funded research project “Concept ELV2”. In general, the method is capable of synthesizing transmissions for any given vehicle and motor combination.

Methods for modeling the steering wheel torque of a steer-by-wire vehicle

Unlike electromechanical steering systems, steer-by-wire systems do not have a mechanical coupling between the wheels and the steering wheel. Therefore, a synthetic steering feel has to be generated to supply the driver with the necessary haptic information. In this paper, the authors analyze two approaches of creating a realistic steering feel. One is a modular approach that uses several measured and estimated input signals to model a steering wheel torque via mathematical functions. The other approach is based on an artificial neural network. It depends on steering and vehicle measurements. Both concepts are optimized and trained, respectively, to best fit a reference steering feel obtained from vehicle measurements. To carry out the analysis, the two approaches are evaluated using a simulation model consisting of a vehicle, a rack actuator, and a steering wheel actuator. The research shows that both concepts are able to adequately model a desired steering feel.

Roller dynamometer particle immission* measurement

Urban traffic is a significant contributor of particulate matter to the environment (Kessinger et al. in https://www.umweltbundesamt.de/sites/default/files/medien/5750/publikationen/hgp_luftqualitaet_2020_bf.pdf, 2021). Hence, there is a high interest in the measured data of roadside immission measurement station. In the federal state Saxony (Germany), the State Office for Environment, Agriculture and Geology (LfULG) is responsible for supervision of the air pollution. In a joint project, the LfULG, the Leibniz Institute for Tropospheric Research (TROPOS) and the Chair of Combustion Engines and Powertrain Systems of the Technical University of Dresden (Lehrstuhl für Verbrennungsmotoren und Antriebssysteme, LVAS) measured the particulate immission* from a selection of passenger cars in an “environment simulation” Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020). Especially direct injection spark ignition engines, DISI, without particle filter have a high particulate matter emission, depending on the operating condition. However, an increase of the particulate matter immission due to the rising market penetration of DISI engines was not measurable at the immission measurement stations of LfULG. To investigate the effect of vehicle exhaust emission and immission, an experiment was developed to measure particulate matter immission similar to road conditions on a chassis dynamometer. Five used cars with different engines, exhaust after treatment systems and mileage were evaluated regarding their emissions and particulate immissions. Unexpectedly, a high amount of ultrafine particulate matter smaller 100 nm was found during the emission measurements, although the exhaust emissions were completely extracted to the CVS measurement system. It was concluded that these particles were assignable to break and tire wear. This paper summarizes the most important findings, the complete report is available in Weinhold et al. (https://publikationen.sachsen.de/bdb/artikel/36768q, 2020).

Current experimental developments in 48 V-based CI-driven SUVs in response to expected future EU7 legislation

In this paper, we describe experimental developments in an Exhaust Aftertreatment System (EAS) used in a four-cylinder Compression Ignition (CI) engine. To meet the carbon dioxide (CO$$_\mathrm {2}$$ 2 ) fleet limit values and to demonstrate a clean emission concept, the CI engine needs to be further developed in a hybridized, modern form before it can be included in the future fleet. In this work, the existing EAS was replaced by an Electrically Heated Catalyst (EHC) and a Selective Catalytic Reduction (SCR) double-dosing system. We focused specifically on calibrating the heating modes in tandem with the electric exhaust heating, which enabled us to develop an ultra-fast light-off concept. The paper first outlines the development steps, which were subsequently validated using the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Then, based on the defined calibration, a sensitivity analysis was conducted by performing various dynamic driving cycles. In particular, we identified emission species that may be limited in the future, such as laughing gas (N$$_\mathrm {2}$$ 2 O), ammonia (NH$$_\mathrm {3}$$ 3 ), or formaldehyde (HCHO), and examined the effects of a general, additional decrease in the limit values, which may occur in the near future. This advanced emission concept can be applied when considering overall internal engine and external exhaust system measures. In our study, we demonstrate impressively low tailpipe (TP) emissions, but also clarify the system limits and the necessary framework conditions that ensure the applicability of this drivetrain concept in this sector.

Psychoacoustic evaluation of internal combustion engine noises

When buying a car, the acoustic impression of quality of a vehicle drive train is becoming more and more relevant. The perceived sound quality of the engine unit plays a key role here. Due to the nature of individual background noises, that sound quality is negatively influenced. These noise components, which are perceived as unpleasant, need to be further reduced in the course of vehicle development with the identification and evaluation of disruptive noise components in the overall engine noise being a prerequisite for effective acoustics optimization. In particular, the pulsed ticker noise is classified as particularly annoying in Otto DI engines, which is why this article aims to analyze and evaluate the ticking noise components from the overall noise. For this purpose, an empirical formula was developed which can classify the ticking noise components in terms of their intensity. This is purely perception-based and consists of the impulsiveness, the loudness and the sharpness of the overall engine noise. As with other psychoacoustic evaluation scales, the rating was made from 1 (very ticking) to 10 (not ticking). The ticker noise evaluation formula was then verified on the basis of hearing tests with the help of a jury of experts. According to this, it can be predicted precisely in which engine map areas the ticker noise undermines the pleasantness of the overall engine noise.

Cold emission optimization of a diesel- and alternative fuel-driven CI engine

This paper deals with the emission optimization of a compression ignition (CI) engine during cold ambient operation. Hence, in the present study, the effect of different injector nozzle geometries and pilot injection strategies, but also the influence of intake swirl, rail pressure, exhaust gas recirculation (EGR) as well as EGR cooling on the emission behavior during cold run are investigated. Therefore, test bed experiments under steady-state cold conditions are conducted on a state-of-the-art CI single cylinder research engine (SCRE) with approximately 0.5 l swept volume representing the typical passenger car (PC) cylinder size. The cold charge air temperature of down to −8 $$^{\circ }\hbox { C}$$ ∘ C and a low engine coolant and lube oil temperature represent a cold run close to reality. For emulating the higher friction of a typical 4-cylinder PC engine during cold run, the indicated mean effective pressure (IMEP) is increased according to a specifically developed equation and the turbocharger main equation is solved permanently to adjust the gas exchange loss. To take account of a potential future tightening of emission legislation, in addition to limited exhaust gas emissions, non-limited emissions such as carbonyls are measured as well. Since alternative fuels are able to make a significant contribution to the defossilisation of transportation, an oxygen-containing fuel, consisting of 100 % renewable blend components (HVO, ethers and alcohols) and fulfilling the EN 590 legislation is investigated under the same cold conditions in addition to the research on conventional diesel fuel.