Chalmers Open Digital Repository

Välkommen till Chalmers öppna digitala arkiv!

Här hittar du:

  • Studentarbeten utgivna på lärosätet, såväl kandidatarbeten som examensarbeten på grund- och masternivå
  • Digitala specialsamlingar, som t ex Chalmers modellkammare
  • Utvalda projektrapporter

Enheter i Chalmers ODR

Välj en enhet för att se alla samlingar.

Senast inlagda

Metod för livscykelanalys för produkter tillverkade av Swedish Electro Magnets, SEM
(2023) Johansson, Jim; Pettersson, Emil; Chalmers tekniska högskola / Institutionen för industri- och materialvetenskap; Chalmers University of Technology / Department of Industrial and Materials Science; Hammersberg, Peter; Hammersberg, Peter
This report is about the development and function testing of a simplified life cycle analysis (LCA) methodology and a corresponding tool for SEM (Swedish Electro Magnets), developed using commonly available software in the Microsoft office suite. This work is done using a real case of the XPI (extreme pressure injector) stator-injector as reference, reporting on the conclusions from the test analysis. Since the main goal of the study was to develop a calculation tool, this study includes much information about how the tool was developed from the steps of Lifecycle analysis (LCA). While the results from example use of the tool have not been verified against real measured data, the tool follows the standard methodology for LCA and provides results deemed as reasonable. The stator-injector is manufactured in Åmål by SEM and is an important component of the fuel injection system for Scania truck engines. The commercial automotive industry is constantly working to reduce their environmental impact and this study is intended to help SEM identify which part of the product lifecycle is the most damaging to the environment. It is also meant to provide tools for further development of SEM products from an environmental perspective. The results from this study show that almost all emissions come from the usage of the stator-injector during its service life and that improvements in this area should be prioritised for further development. Some of the most important observations include that there is room for reduction of emissions on a per piece basis in the production, but that in the development phase the most important goal should be to increase efficiency as the absolute majority of emissions are generated during use. However, there are still possibilities for improvements in the areas of packaging and transport. The accuracy of the developed tool is highly dependent on the quality of the input data and should be considered carefully before use. The tool does however produce results roughly in line with expectations and does identify a problem area which should be prioritised for further development. This study was conducted at the department of Industrial and Material Science at Chalmers University of Technology.
Modeling and Simulation of Soft Switching in Traction Inverter
(2023) Lu, Kuang; Gandla, Lakshmi Priya; Chalmers tekniska högskola / Institutionen för elektroteknik; Lundberg, Stefan
In this thesis, two soft switching inverter topologies the Active Clamped Resonant DC Link Inverter (ACRDCLI) and theAuxiliary Resonant Commutated Pole Inverter (ARCPI) are designed. Their performance is compared with the Hard Switched Inverter (HSI) in simulations. In order to ensure the balance of the soft switching resonant circuit and to achieve a certain reference current, the parame ters of the circuit components are selected according to the references and modified appropriately. The load is modelled as a Permanent Magnet Synchronous Machine (PMSM) equivalent circuit and the parameters are taken from the Finite Element Method (FEM) data based on a fixed operating point. The total power losses in the switches are calculated based on the loss profile in Piecewise Linear Electrical Circuit Simulation (PLECS). Hysteresis current control and Space Vector Pulse Width Modulation (SVPWM) are used to control the current of the ACRDCLI and the ARCPI respectively. Two different state machines have also been designed to ensure the proper operation of the two soft switching topologies. The same control method is used for two HSIs as a control group to have a fair comparison. By simulating each topology under the similar conditions it can be concluded that each topology can output similar power and the total losses in two soft switching topologies are reduced by 18% compared to HSI, especially in switching losses by 98% at 33 kHz switching frequency. Due to the circuit complexity and poor Total Harmonic Distortion (THD) perfor mance of the ACRDCLI only the ARCPI is further analysed for different switching frequencies and current operating points. At high switching frequency of 80 kHz the THD value for the ARCPI is 0.286 % and for the HSI the THD is 0.366 %. With increasing switching frequency the THD for the ARCPI is smaller than the HSI and the ACRDCLI. The ARCPI gives the maximum efficiency of 97.57 % at 25 kHz switching frequency. Compared to the HSI there is an efficiency improvement of 1.71 % with the ARCPI at high switching frequency.
Improved noise map accuracy by using GPS acquired vehicle speeds: study of predicted equivalent noise levels using the Nord96 and Nord2000 models
(2022) Kondic, Marija; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Forssén, Jens; Forssén, Jens
The noise maps in Sweden have always been constructed with the Nord 96 calculation model using the signposted speeds. This project investigates the limitations of this model, as well as what differences arise when the signposted speeds are exchanged for the real recorded vehicle speeds. In this case, the GPS acquired speeds were used. Different steps in the Nord 96 calculation model that could influence the changes in the noise maps were addressed, as well as the differences between the Nord 96 and Nord 2000 models. The influence of the percentage of heavy vehicles, different vehicles categories and importance of the acceleration of vehicles is investigated. The main goal of this paper was to investigate the possibility of creating a set of measures to be used as a correction for the current calculation model. This investigation is conducted on the subject area consisting of Kävlinge, Furulund, Löddeköpinge, and Björnstorp area. The Kävlinge area is closely investigated and the individual streets are analysed for the purpose of detecting the causes of sound pressure level differences on a small scale. Significant results were obtained, showing that difference in noise level can be up to ± 5 dB in some street segments, which is detectable by human ears. The correction of the current model is concluded not to be possible by just taking the average SPL difference for different street types and speed limits, thus the further investigation is needed.
Auralization of road traffic scenes: Investigating perceived effects of heavy vehicle proportion
(2022) Zhou, Yun; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Forssén, Jens; Forssén, Jens
For vehicles with internal combustion engines, the main types of noise when driving are tyre-road noise and propulsion noise. According to the Nord 2000 model, light and heavy vehicles have different noise levels and spectrum at different speeds. In urban traffic scenes, the number of light and heavy vehicles varies, and people may perceive the scenes differently even if they have the same equivalent A-weighted level (LAEq) but various proportions of light and heavy vehicles. To investigate the effect of the proportion of heavy vehicles on human psychological perception, the noise signals of five individual vehicles (two heavy and three light) at different speeds were auralized based on the combined model proposed in the LISTEN project and applied to compose eight traffic scene signals containing different proportions of heavy vehicles. These signals are used in the listening test where participants were asked to make category judgments and paired comparisons. The results of the category judgment part of the listening test showed that the signals containing heavy vehicles were indeed more disturbing than the signal only consisting of light vehicle noise, and scoring higher in loudness, sharpness and roughness. However, the stress and annoyance felt by the participants when listening to the signals did not increase with the proportion of heavy vehicles in the signal. From the paired comparison part of the test, it can be found that for heavy vehicles, participants felt more disturbed by the lower speed signals when the perceived loudness of the signals was constant. As for the plausibility of the traffic scene signals created, all eight signals scored similarly, between 5 and 6 on a scale of plausibility, which means that the traffic scene signals created are somewhat plausible, but still need to be improved.
Covariance and coherence matching for binaural room impulse responses; implementation and evaluation of rendering methods using different-order ambisonics
(2022) Hedlund , Elin; Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Chalmers tekniska högskola / Institutionen för arkitektur och samhällsbyggnadsteknik (ACE); Ahrens, Jens; Ahrens, Jens
Rendering binaural room impulse responses with the use of spherical microphone arrays and sets of head-related transfer functions minimize required measurements but will however exhibit a difference in perception due to, among other things, spherical harmonic truncation. By utilizing the spatial perceptually relevant interaural cues, the similarity to a directly measured BRIR could be enhanced. In this thesis, two different methods for rendering binaural room impulse responses with different-order Ambisonics are employed to evaluate and compare the similarity between the generated BRIRs and directly measured counterparts using an artificial head and torso recording. Both methods utilize inter-aural cues within the inter-aural coherence and covariance matrix, respectively, in order to process the diffuse part of the BRIR. The results show an improvement for the covariance matrix framework compared to the coherence matching method, even for rendering employing first-order Ambisonics. A pilot study in the form of an informal listening test was conducted to investigate the perceived similarity between the generated and measured BRIRs. The results of the listening test indicate that an increased spatial resolution due to higher-order Ambisonics will enhance the perceived similarity, while also displaying varying results depending on rendering method. However, a more extensive listening test would be beneficial. The findings indicate that the covariance framework with even higher-order Ambisonics would further optimize the quality and perceived similarity.