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| 2. |
- Murgovski, Nikolce, 1980, et al.
(författare)
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Convex optimization of charging infrastructure design and component sizing of a plug-in series HEV powertrain
- 2011
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902661937 ; 18:PART 1, s. 13052-13057
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Konferensbidrag (refereegranskat)abstract
- With the topic of plug-in HEV city buses, this paper studies the highly coupled optimization problem of finding the most cost efficient compromise between investing in onboard electric powertrain components and installing a charging infrastructure along the bus line. The paper describes how convex optimization can be used to find the optimal battery sizing for a series HEV with fixed engine and generator unit and a fixed charging infrastructure along the bus line. The novelty of the proposed optimization approach is that both the battery sizing and the energy management strategy are optimized simultaneously by solving a convex problem. In the optimization approach the power haracteristics of the engine-generator unit are approximated by a convex, second order polynomial, and the convex battery model assumes quadratic losses. The paper also presents an example for a specific bus line, showing the dependence between the optimal battery sizing and the number of charging stations on the bus line.
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| 3. |
- Alverhed, Elin, et al.
(författare)
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Autonomous last-mile delivery robots: a literature review
- 2024
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Ingår i: European Transport Research Review. - 1867-0717 .- 1866-8887. ; 16:1
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Forskningsöversikt (refereegranskat)abstract
- This literature review investigates how self-driving autonomous delivery robots (ADRs) impact last-mile deliveries, add value to the logistics and transport industry, and contribute to creating competitive business models. Autonomous vehicles are still a developing technology and ADRs could possibly be one of the solutions to the last-mile problem, in particular in cities and for urban freight with an increasing number of parcels to deliver. Last-mile delivery is also changing as e-commerce and more demanding customers emerge. Such development, however, faces challenges regarding infrastructure, externalities such as CO2 emissions, and shorter delivery-time requirements. This review, focused on ADRs, reveals four major themes (operations, infrastructure, regulations, and acceptance) through which we explain the barriers and benefits of using ADRs for last-mile deliveries. The review shows that the operations of ADRs can impact last-mile deliveries by lowering costs, optimising the use of time, and reducing externalities. The review also shows that the foundation of last-mile infrastructure would have to change if ADRs are to be used to a greater extent. Regulations for ADRs are still not yet in place, which makes the market somewhat confused. The acceptance of ADRs in society is another challenge because the innovation of ADRs is still new and unfamiliar. Altogether, the use of ADRs for last-mile deliveries shows great potential, based on the promising results of the articles reviewed. However, most studies on ADRs have been theoretical in nature, such as models, which highlights the need for real-world case studies and implementations.
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| 4. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Optimization Based Design of Heterogeneous Truck Fleet and Electric Propulsion
- 2016
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Ingår i: Proceedings, ITSC. IEEE 19th International Conference on Intelligent Transportation Systems (ITSC), November 1-4, 2016, Rio de Janeiro, Brazil. - 9781509018895 ; , s. Art no 7795575, Pages 328-335
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Konferensbidrag (refereegranskat)abstract
- Many researches have been focused on vehicle routing problem during past decades where subject vehicles are previously fully designed and ready to start operation. Further, extensive studies have been done on powertrain design irrespective of the routes where the vehicle is going to be employed. In the present paper, we try to define a new branch of problems where the vehicle design, in particular its propulsion system and loading capacity, is treated simultaneously with the routing problem. The focus is on optimization based design of heterogeneous electric truck fleet to perform a prescribed task with a lowest cost on an available set of routes. The approach is illustrated in a simple case study problem. It is shown that long heavy combination vehicles are energy-efficient but not cost-optimal on short routes.
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| 5. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Sensitivity Analysis of Optimal Energy Management in Plug-in Hybrid Heavy Vehicles
- 2017
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Ingår i: 2017 2nd IEEE International Conference on Intelligent Transportation Engineering (ICITE). - 9781509062737 ; , s. 320-327
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Konferensbidrag (refereegranskat)abstract
- Optimal energy management strategies of hybrid vehicles are computationally expensive when considering the entire trip ahead rather than a short upcoming horizon. Considering the entire representative trip is already needed in concept design stages of the vehicle. In order to come up with an appropriate design while minimizing the total ownership cost the energy management strategies must already be used together with early concept evaluations. To investigate the possibility of replacing the optimal energy management with simpler approaches, here, the sensitivity of optimal solution to some of vehicle parameters and traffic flow is studied. It is seen that a simpler approach, i.e. an instantaneous optimization, can be used, in case of smooth traffic flow, since the gain of optimal strategy in reduction of operational cost is less than 4% for different vehicle hardware setup and for selected representative driving cycle. Dynamic programming is used as a solution method for finding the optimal strategy.
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| 6. |
- Ghandriz, Toheed, 1982, et al.
(författare)
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Transportation-mission-based Optimization of Heterogeneous Heavy-vehicle Fleet Including Electrified Propulsion
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:11
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Tidskriftsartikel (refereegranskat)abstract
- Commercial-vehicle manufacturers design vehicles to operate over a wide range of transportation tasks and driving cycles. However, certain possibilities of reducing emissions, manufacturing and operational costs from end vehicles are neglected if the target range of transportation tasks is narrow and known in advance, especially in case of electrified propulsion. Apart from real-time energy optimization, vehicle hardware can be meticulously tailored to best fit a known transportation task. As proposed in this study, a heterogeneous fleet of heavy-vehicles can be designed in a more cost- and energy-efficient manner, if the coupling between vehicle hardware, transportation mission, and infrastructure is considered during initial conceptual-design stages. To this end, a rather large optimization problem was defined and solved to minimize the total cost of fleet ownership in an integrated manner for a real-world case study. In the said case-study, design variables of optimization problem included mission, recharging infrastructure, loading--unloading scheme, number of vehicles of each type, number of trips, vehicle-loading capacity, selection between conventional, fully electric, and hybrid powertrains, size of internal-combustion engines and electric motors, number of axles being powered, and type and size of battery packs. This study demonstrated that by means of integrated fleet customization, battery-electric heavy-vehicles could strongly compete against their conventional combustion-powered counterparts. Primary focus has been put on optimizing vehicle propulsion, transport mission, infrastructure and fleet size rather than routing.
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| 7. |
- Groot, Jens, 1980, et al.
(författare)
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Energy storage system optimisation of a plug-in HEV
- 2008
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Ingår i: International Journal of Electric and Hybrid Vehicles. - 1751-4088. ; 1:3, s. 319-331
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the optimisation of the energy storage system of a parallel hybrid plug-in car. The objective is to study how the electric driving range is influenced by factors such as package volume and auxiliary power consumption. Simulation and optimisation are used to find the most cost effective battery arrangement for specified electric driving range, volume, power and lifetime requirements. Two battery technologies, NiMH and Li-ion, are included in the simplified case study. The result indicates that the battery cost and size are highly dependent on the required electric driving range. It is found that a 3±5km electric driving range is possible with a minor cost increase. An electric driving range of 15±25km is possible, but results in a more bulky, and much more costly, battery system. It is important to point out that the results are not general. The electric driving range can be significantly extended by decreasing the roll and/or the air resistance.
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| 8. |
- Hellgren, Jonas, 1974
(författare)
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A Methodology for the Design of Cost Effective Hybrid Vehicles
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with system design of cost effective hybrid and fuel cell vehicles. Today (2004) the major disadvantages of these vehicles are increased complexity and component costs. However, the decrease in cost of electrical components and the environmental concern make these vehicles more and more competitive. To make hybrid and fuel cell vehicles cost effective, a sensible system design plays a decisive role. Configuring, choosing, sizing and energy management of vital powertrain components determine how cost effective a system is. The powertrain is the system in a vehicle that develops and transmits traction power. A cost effective powertrain system is both fuel efficient and cheap in component cost. On the road and in the showroom today, hybrid vehicles are powered by both a small gasoline engine and an electric machine. By using the electric machine in combination with an energy buffer, braking energy can be regenerated. Thanks to the power assisting buffer, the engine can also be smaller in size. Energy management is a specific and crucial problem in hybrid vehicles; it determines how power is distributed between the buffer and the primary power unit. The primary power unit can be a combustion engine, a fuel cell or a high capacity battery. A computer tool THEPS has been developed by the author. THEPS uses simulation and optimization to propose a powertrain concept from requirements and conditions. An example of a requirement is the desired top speed of the vehicle. Some conditions are fuel price and interest rate. The approach is to regard the output from a simplified vehicle model as a function of design variables. Characteristics defined by the design variables are: type of powertrain, type and size of vital components and directives for the energy management. The intention is to minimize the operating cost of the vehicle, i.e. the sum of component, fuel and component wear cost. An evolutionary algorithm is utilized for optimization. For the complex nonlinear optimization problem, which exists in THEPS, such an algorithm is suitable because the solution space contains numerous local minima and is discontinuous. Another contribution is a library including powertrain models. The library is developed in the modeling language Modelica and includes models that are more detailed than the models used by THEPS. The objective with the library is to analyze hybrid powertrains proposed by THEPS. The thesis also describes the development of a scaled, hybrid electric, model car prototype. The primary power unit of the model car is a lead-acid battery and the buffer of the model car is a high-power super capacitor. Traction and steering of the car are radio remote controlled. Three case studies using THEPS are also included. In the first case study a powertrain is adapted to an existing city bus route in the Swedish city of Göteborg. The second case study deals with a waste disposal truck and the third case study deals with a taxi car. The case studies indicate that new powertrain technologies can be competitive from a cost perspective, in some applications, already at present time. It is for example reasonable to equip heavy vehicles running in urban areas with hybrid powertrains. The case studies also indicate that hybrid and/or fuel cell cars can be a more cost effective choice than conventional cars in a near future (2015). Another indication is that it will not be clear for a customer which powertrain concept to choose. The reason is that many cost effective powertrain concepts will be offered. The best choice will depend on the application.
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| 9. |
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| 10. |
- Hellgren, Jonas, 1974, et al.
(författare)
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A Systematic Way of Choosing Driveline Confriguration and Sizing Components in Hybrid Vehicles
- 2000
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Ingår i: 2000 Future Transportation Technology Conference, August 21-23, 2000, in Costa Mesa, California, USA, 2000.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Energy saving in general and less polluting vehicles in specific, become more and more urgent topics. One reason is that, in a world where the demand for fast transportation is increasing, the risk of global warming is a fact. Hybrid Vehicles (HV:s) are proposed as a more environmentally friendly candidate than conventional vehicles. Nowadays, there are numerous different types of HV:s and the components can, in theory, be sized in infinite ways. There is no simple answer to how to choose driveline configuration and size components in a HV. This paper describes one method, Driveline Synthesis (DS), that systematically presents a suitable driveline, on the basis of demands and conditions. Examples of demands are driving cycle and emission free zones. Some conditions are fuel price, tax on pollution and discount rate. The most suitable driveline is defined as the most cost effective. Total cost is defined as the sum of: cost of components, fuel cost, cost of external energy and cost of pollution. Genetic algorithms are used as an optimization method.Two major types of drivelines are compared in a case study, a conventional bus with a diesel engine and automatic transmission versus a series hybrid bus with different types of primary power units (diesel engine or fuel cell) and storage devices (super capacitor or NiMH battery). DS gives reasonable answers but needs further validation and development. One conclusion from the work is that the most suitable driveline configuration depends very much on demands, conditions and present technology, i.e. HV:s are only preferable to conventional vehicles under special circumstances.
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