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Vehicle Conceptualisation, Compactness, and Subsystem Interaction: A network approach to design and analyse the complex interdependencies in vehicles
KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.ORCID iD: 0000-0001-9518-0056
2023 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The conventional approach to vehicle design is restrictive, limited, andbiased. This often leads to sub-optimal utilisation of vehicle capabilities and allocated resources and ultimately entails the repercussions of designing andlater on an using an inefficient vehicle. To overcome these limitations, it is important to gain a deeper understanding of the interaction effects at component,subsystem, and system level. In this thesis, the research is focused on identifying appropriate methods and developing robust models to facilitate the interaction analysis.

To scrutinise and identify appropriate methods, criteria were developed.Initially, the Design Structure Matrix (DSM) and its variations were examined.While DSM proved to be fundamental for capturing interaction effects,it lacked the ability to answer questions about the structure and behaviour ofinteractions and to predict unintended effects. Therefore, network theory wasexplored as a complementary method to DSM which was capable of providing insights into interaction structures and identifying influential variables.

Subsequently, two criteria were established to identify subsystems significant to interaction analysis: high connectivity to other subsystems and multidisciplinary composition. The traction motor was observed to satisfyboth criteria as it had higher connectivity with other subsystems and was composed of multiple disciplines. Therefore, a detailed model of an induction motor was developed to enable the interaction analysis.

The induction motor model was integrated into a cross-scalar design tool.The tool employed a two-step process: translating operational parametersto motor inputs using Newtonian equations and deriving physical attributes,performance characteristics, and performance attributes of the motor. Comparing the obtained performance characteristics curve against existing studiesvalidated the model’s reliability and capabilities. The design tool demonstrated adaptability to different drive cycles and the ability to modify motor performance without affecting operational parameters. Thus validating the capability of the design tool to capture cross-scalar and intra-subsystem interaction effects. To examine inter-subsystem interaction, a thermal model of an inverter was developed, capturing temperature variations in the power electronics based on motor inputs. The design tool successfully captured interaction effects between motor and inverter designs, highlighting the interplay with operational parameters.

Thus, this thesis identifies methods for interaction analysis and develops robust subsystem models. The integrated design tool effectively captures intra-subsystem, inter-subsystem, and cross-scalar interaction effects. The research presented contributes to the overarching project goal of developing methods and models that capture interaction effects and in turn serve as a guiding tool for designers to understand the consequences of their design choices.

Abstract [sv]

Det konventionella tillvägagångssättet för fordonsdesign är restriktiv, begränsat och partiskt. Detta leder ofta till en suboptimal användning av fordonets kapacitet och tilldelade resurser och innebär i slutändan att konsekvenserna blir att använda ett ineffektivt fordon. För att övervinna dessa begränsningar är det viktigt att få en djupare förståelse för interaktionseffekterna på komponent-, delsystem- och systemsnivå. I denna avhandling fokuserar forskningen på att identifiera lämpliga metoder och utveckla robusta modeller för att underlätta interaktionsanalysen.

För att granska och identifiera lämpliga metoder utvecklades kriterier. Till att börja med undersöktes Design Structure Matrix (DSM) och dess variationer. Medan DSM visade sig vara grundläggande för att fånga interaktionseffekter, saknade den förmågan att besvara frågor om interaktionsstrukturer och beteende samt förutsäga oavsiktliga effekter. Därför utforskades nätverksteori som en kompletterande metod till DSM, vilket kunde ge insikter i interaktionsstrukturer och identifiera inflytelserika variabler.

Därefter etablerades två kriterier för att identifiera delsystem som är betydelsefulla för interaktionsanalysen: hög anslutning till andra delsystem och mångdisciplinär sammansättning. Dragkraftmotorn observerades uppfylla båda kriterierna eftersom den hade högre anslutning till andra delsystem och var sammansatt av flera discipliner. Därför utvecklades en detaljerad modell av en induktionsmotor för att möjliggöra interaktionsanalysen.

Induktionsmotormodellen integrerades i ett tvärskaligt designverktyg. Verktyget använde en tvåstegsprocess: att översätta operativa parametrar till motorinsatser med hjälp av Newtons ekvationer och härleda fysiska egenskaper, prestandakaraktäristik och prestandaattribut hos motorn. Jämförelse av den erhållna prestandakaraktäristikkurvan med befintliga studier validerade modellens tillförlitlighet och förmågor. Designverktyget visade anpassningsbarhet till olika körcykler och förmågan att modifiera motorprestanda utan att påverka operativa parametrar. Detta validerade designverktygets förmåga att fånga tvärskaliga och intra-subsystem interaktionseffekter. För att undersöka inter-subsysteminteraktion utvecklades en termisk modell av en inverter, som fångade temperaturvariationer i kraftelektroniken baserat på motorns styrning. Designverktyget fångade framgångsrikt interaktionseffekter mellan motor- och inverterdesign och belyste samspelet med operativa parametrar.

Därmed identifierar denna avhandling metoder för interaktionsanalys och utvecklar robusta delsystemmodeller. Det integrerade designverktyget fångar effektivt intra-subsystem-, inter-subsystem- och tvärskaliga interaktionseffekter. Den presenterade forskningen bidrar till det övergripande projektets mål att utveckla metoder och modeller som fångar interaktionseffekter och i sin tur fungerar som ett vägledande verktyg för designers att förstå konsekvenserna av sina designval.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2023. , p. 77
Series
TRITA-SCI-FOU ; 2023:51
Keywords [en]
Subsystem interaction, Interaction effects, Design Structure Matrix, Network theory, Cross-scalar design tool, Induction motor, Inverter.
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
URN: urn:nbn:se:kth:diva-337391ISBN: 978-91-8040-717-5 (print)OAI: oai:DiVA.org:kth-337391DiVA, id: diva2:1801723
Presentation
2023-10-24, Hugin, Teknikringen 8, Stockholm, 10:00 (English)
Supervisors
Note

QC 231003

Available from: 2023-10-03 Created: 2023-10-02 Last updated: 2023-10-09Bibliographically approved
List of papers
1. A Holistic Design Approach to the Mathematical Modelling of Induction Motors for Vehicle Design
Open this publication in new window or tab >>A Holistic Design Approach to the Mathematical Modelling of Induction Motors for Vehicle Design
2023 (English)In: Procedia CIRP, 2023, Vol. 119, p. 1246-1251Conference paper, Published paper (Refereed)
Abstract [en]

In early-stage vehicle design, there is a significant lack of knowledge about the impact of design requirements on the design of subsystems, theresulting knock-on effects between subsystems and the vehicle’s overall performance. This leads to a sub-optimal vehicle design with increaseddesign iterations. To mitigate this lack of knowledge, a cross-scalar design tool consisting of an induction motor model is presented in this paper.The tool calculates the motor’s attributes, namely its volume, mass, and the performance it can deliver to satisfy a given drive cycle’s requirements.This is achieved by breaking down the drive cycle requirements into motor parameters from which the various power losses are derived. Thesekey losses are then utilised to develop the torque/speed curve. Furthermore, it is proposed that the motor’s attributes can be used to design othersubsystems and consequently analyse their interaction effects. For example, the motor’s attributes can be used to design regenerative brakes andconsequently analyse their influence on brake wear, lifetime, and energy savings. Thus, the design tool enables the design of efficient vehicles withminimised design iterations by analysing the influence of design requirements on the subsystem’s design and the consequent interaction effectsamong the subsystems and on the vehicle’s overall performance.

Series
Procedia CIRP, ISSN 2212-8271
Keywords
Early-stage design; Design tool; Subsystem Interaction; Induction Motor Model
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-337384 (URN)10.1016/j.procir.2023.02.193 (DOI)2-s2.0-85169913726 (Scopus ID)
Conference
The 33rd CIRP Design Conference, Sydney, Australia, May 17-19, 2023
Note

QC 20231002

Available from: 2023-10-02 Created: 2023-10-02 Last updated: 2023-11-02Bibliographically approved
2. Passive cooling modelling on train electronic systems
Open this publication in new window or tab >>Passive cooling modelling on train electronic systems
(English)Manuscript (preprint) (Other academic)
Abstract [en]

With the advent on Silicon Carbide (SiC) semiconductors in electric traction several benefits become possible, includingthe possibility to switch from active cooling systems to passive ones. In order to understand the temperature distributionand variation of passive cooling systems a conjugate heat transfer problem has to be solved, where the conduction ina solid is coupled with the convection of the fluid flowing past the solid. These problems have reasonable solutions forsteady state simulations, but not for transient conditions like the ones encountered in regular operation of rail vehicles.In this paper, two analytical models are derived to model the temperature distribution and variation, and the modelsare validated against the results obtained from numerical simulations in two different cases. In parallel, an electricmotor model is used to derive the power losses in the converter, defining the heat flow to be dissipated. Finally, thecomplete model is tested for realistic drive cycles where the driving operational conditions define both the power lossesto be dissipated and the free flow speed due to the vehicle speed. Results indicate that the developed model is ableto successfully capture the temperature variations during the different stages of the drive cycle; During accelerationphases, for instance, the power losses increase drastically while lower speeds lead to larger temperature surges.Moreover, the model is able to capture the temperature distribution over the length of the power electronics component.The result is a simple analytical model that can derive the temperature variations within the power electronics withreasonable accuracy and much faster computation times compared to non-steady state numerical simulations.

Keywords
Passive cooling, IGBT, Inverters, Trains, Coupling
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-337387 (URN)
Note

QC 20231004

Available from: 2023-10-02 Created: 2023-10-02 Last updated: 2023-10-04Bibliographically approved
3. Analyzing interaction effects in a vehicle model using network theory
Open this publication in new window or tab >>Analyzing interaction effects in a vehicle model using network theory
2021 (English)In: Resource Efficient Vehicles Conference, rev2021, 2021Conference paper, Published paper (Other academic)
Abstract [en]

The vehicle industry is moving towards developing more sustainable and efficient solutions. This movement towards sustainable and efficient solutions brings up the need to develop and integrate new subsystem technologies that are beneficial for the overall vehicle system. However, introducing new technology into an existing vehicle architecture may have knock-on effects on the dependent subsystems. Furthermore, there can be a bias towards the existing technological solutions as a large part of the architecture is developed pertaining to the established solutions. Therefore, sufficient knowledge is required to understand the level of impact the interdependencies, both direct and indirect, can have at a subsystem level and at the overall vehicle system level. To address and assess these interdependencies that arise during the conceptual design phase, a bottom-up design model is proposed. The model, utilizing network theory could represent each subsystem as nodes and their interaction effects on each other as edges. Thus, the interaction effects between different subsystems and their complex influence on the overall vehicle system are considered. This model could serve to evaluate an optimal solution in terms of functional density and economic benefits thus providing the opportunity to avoid any unintended negative indirect effects. Furthermore, it could help in identifying the technological limits in the current vehicle system and thus, identifying the areas that can be developed to further enhance the vehicle system performance. The method of implementation, its advantages, disadvantages, applications, and challenges in implementation are discussed.

National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-300752 (URN)
Conference
Resource Efficient Vehicles Conference, rev2021
Note

QC 20211027

Available from: 2021-09-02 Created: 2021-09-02 Last updated: 2023-10-02Bibliographically approved

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Abburu, Sai Kausik

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