| 1. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Electro-thermal Control of Modular Battery using Model Predictive Control with Control Projections
- 2015
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 48:15, s. 368-375
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a novel model predictive control algorithm to achieve voltage regulation and simultaneous thermal and SOC balancing of a modular battery using limited future load information. The modular battery is based on multilevel converter (MLC), which provides a large redundancy in voltage synthesis and extra degree-of-freedom in control. The proposed algorithm is based on orthogonal decomposition of controller into two components, one for voltage control and the other for balancing control. The voltage control decisions are made using a simple minimum norm problem whereas the balancing control decisions are made in two stages. The first stage computes a balancing control policy based on an unconstrained LQ problem and the second stage enforces constraint on control actions via projection on a time-varying control constraint polytope. The control algorithm shows promising performance in a simulation study of a four cell modular battery. The performance and the simplicity of the control algorithm make it attractive for real-time implementation in large battery packs.
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| 2. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Evaluating the Potential for Cell Balancing Using a Cascaded Multi-Level Converter Using Convex Optimization
- 2012
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823168 ; 3, s. 100-107
-
Konferensbidrag (refereegranskat)abstract
- The modeling and design of an active battery cell balancing system using Multi- Level Converter (MLC) for EV/HEV/PHEV is studied. The MLC allows to independently switch ON/OFF each battery cell in a battery pack . This extra degree-of-freedom (DoF) can be exploited to optimally use each cell in order to balance among them the temperature and state-of- charge (SoC). This study has shown that the constrained convex optimization based control policy, exploiting the extra DoF of MLC, gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. Thus, the MLC has promising potential to offer extra benefit of achieving cell balancing while being simultaneously used as a motor driver.
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| 3. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Feasibility Issues of using Three-Phase Multilevel Converter based Cell Balancer in Battery Management System for xEVs
- 2013
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823434 ; 46, s. 390-397
-
Konferensbidrag (refereegranskat)abstract
- The use of a three-phase multilevel converter (MLC) as an integrated cell balancer and motor driver is investigated for three-phase AC applications in EVs/HEVs/PHEVs. The paper analyzed an issue of additional battery losses caused by the flow of reactive and/or harmonic power from each power cell of the three-phase MLC battery system. The paper also investigates the size of shunt capacitor required for compensation of the losses to acceptable level. This study concludes that the size of the required capacitor is too big for the vehicle application unless some other active compensation is used as well. Another practical way to employ the MLC as a cell balancer is to use it in a cascaded connection with the conventional three-phase two-level voltage source inverter however it may not be a cost-effective solution either due to high component count.
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| 4. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Load Management of Modular Battery using Model Predictive Control: Thermal and State-of-Charge Balancing
- 2016
-
Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 25:1, s. 47-62
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal and state-of-charge (SOC) imbalance is well known to cause non-uniform ageing in batteries. This paper presents the electro-thermal control of a multi-level converter (MLC) based modular battery to address this issue. The modular battery provides a large redundancy in synthesizing terminal voltage, which gives extra degrees-of-freedom in control on cell level. There are multiple tightly coupled control objectives including the simultaneous thermal and SOC balancing as well as battery terminal voltage control. The main purpose of this paper is to devise an electro-thermal control scheme for cases where full future driving information is not accessible. The control scheme is based on decomposition of controller into two orthogonal components, one for voltage control and the other for balancing control. This problem decomposition enables the application of constrained linear quadratic model predictive control scheme to solve the balancing problem elegantly. The control scheme is thoroughly evaluated through simulations of a four cell modular battery. The results show that a rather short prediction horizon is sufficient to achieve robust control performance.
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| 5. |
- Altaf, Faisal, 1982, et al.
(författare)
-
On Thermal and State-of-Charge Balancing using Cascaded Multi-level Converters
- 2013
-
Ingår i: Journal of Power Electronics. - : The Korean Institute of Power Electronics. - 1598-2092. ; 13:4, s. 569-583
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the simultaneous use of a multi-level converter (MLC) as a DC-motor drive and as an active battery cell balancer is investigated. MLCs allow each battery cell in a battery pack to be independently switched on and off, thereby enabling the potential non-uniform use of battery cells. By exploiting this property and the brake regeneration phases in the drive cycle, MLCs can balance both the state of charge (SoC) and temperature differences between cells, which are two known causes of battery wear, even without reciprocating the coolant flow inside the pack. The optimal control policy (OP) that considers both battery pack temperature and SoC dynamics is studied in detail based on the assumption that information on the state of each cell, the schedule of reciprocating air flow and the future driving profile are perfectly known. Results show that OP provides significant reductions in temperature and in SoC deviations compared with the uniform use of all cells even with uni-directional coolant flow. Thus, reciprocating coolant flow is a redundant function for a MLC-based cell balancer. A specific contribution of this paper is the derivation of a state-space electro-thermal model of a battery submodule for both uni-directional and reciprocating coolant flows under the switching action of MLC, resulting in OP being derived by the solution of a convex optimization problem.
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| 6. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Performance Evaluation of Multilevel Converter based Cell Balancer with Reciprocating Air Flow
- 2012
-
Ingår i: IEEE Vehicle Power and Propulsion Conference. - 9781467309530 ; , s. 706-713
-
Konferensbidrag (refereegranskat)abstract
- The modeling and design of an active battery cell balancing system using Multilevel Converter (MLC) for EV/HEV/PHEV is studied under unidirectional as well as reciprocating air flow. The MLC allows to independently switch ON/OFF each battery cell in a battery pack. The optimal policy (OP ) exploiting this extra degree-of-freedom can achieve both temperature and state-of-charge (SoC) balancing among the cells. The OP is calculated as the solution to a convex optimization problem based on the assumption of perfect state information and future driving. This study has shown that OP gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. It is also shown that using reciprocating flow for OP gives no significant benefit. Thus, reciprocating flow is redundant for MLC-based active cell balancing system when operated using OP.
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| 7. |
- Altaf, Faisal, 1982, et al.
(författare)
-
Simultaneous Thermal and State-of-Charge Balancing of Batteries: A Review
- 2014
-
Ingår i: IEEE Vehicle Power and Propulsion Conference, 27-30 October 2014, Coimbra Portugal.
-
Konferensbidrag (refereegranskat)abstract
- The battery pack lifetime is severely affected by the State-of-Charge (SOC) and thermal imbalance among its cells, which is inevitable in large automotive batteries. In this review paper, the need of simultaneous thermal and SOC balancing is emphasized. Thermal and SOC balancing are two tightly coupled objectives. However, we argue here that it is possible to achieve these simultaneously by using a balancing device that enables the non-uniform use of cells, optimally using the brake regeneration phases and load variations in the drive cycle, and exploiting cell redundancy in the battery pack. The balancer must provide extra degree-of-freedom in control by distributing a large battery pack into smaller units to enable an independent cell/module-level control of a battery system.
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| 8. |
- Berbyuk, Viktor, 1953, et al.
(författare)
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Optimal Kinematic Design of Gantry Parallel Robot
- 2005
-
Ingår i: Proc. of IDETC/CIE2005 ASME2005 International Design Engineering Technical Conferences & Computer and Information in Engineering Conference: 5th International Conference on Multibody Systems, Nonlinear Dynamics, and Control (MSNDC), September 24-28, 2005, Long Beach, California, USA, Volume 1, Paper DETC2005-84397, 2005.. ; 1, s. Paper DETC2005-84397
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses some issues of optimal kinematic design of parallel robot with 3 degrees of freedom. Robot performs translational gantry type motion with a large workspace. The structures nominal kinematics is identical to the Linear Delta Robot, the difference being the way which the links are organized. In order to yield a design of the Gantry Parallel Robot with a large workspace volume and good kinematic properties, multi-criteria optimization is used. The objective functions comprise a space utilization index and the inverse conditioning number of the Jacobian matrix. Three different geometrical layouts of the robot are examined and the Pareto optimality between the objective functions is found for several different cases. Pareto-optimal curves showing the relationship between the workspace size and the manipulability are presented as a tool for the designer. The obtained results give a good overview of the kinematic properties of the Gantry Parallel Robot that can be used for designing the parallel structures for various applications.
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| 9. |
- Egardt, Bo, 1950, et al.
(författare)
-
Electromobility Studies Based on Convex Optimization DESIGN AND CONTROL ISSUES REGARDING VEHICLE ELECTRIFICATION
- 2014
-
Ingår i: IEEE Control Systems. - 1066-033X. ; 34:2, s. 32-49
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a framework to study design tradeoffsin the search for electromobility solutions based on approximatemodeling of the power flows in the powertrain as afunction of component sizes. An important consequence ofthe modeling assumptions is that the optimal energy managementand component sizes can be computed simultaneouslyin a convex program, which means that competingdesigns can be evaluated in an objective way, avoiding theinfluence of a separate control system design. The fact thatthe optimization problem is convex allows large problemsto be solved with moderate computational resources, whichcan be exploited by, for example, running optimizationsover very long driving cycles. The problem formulationalso admits design decisions for the charging infrastructureto be included in the optimization.
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| 10. |
- Hu, Xiaosong, 1983, et al.
(författare)
-
Comparison of Three Electrochemical Energy Buffers Applied to a Hybrid Bus Powertrain with Simultaneous Optimal Sizing and Energy Management
- 2014
-
Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 15:3, s. 1193-1205
-
Tidskriftsartikel (refereegranskat)abstract
- This paper comparatively examines three different electrochemical energy storage systems (ESSs), i.e., Li-ion battery, supercapacitor, and dual buffer, for a hybrid bus powertrain operated in Gothenburg, Sweden. Existing studies focus on comparing these ESSs in terms of either general attributes (e.g., energy density and power density) or their implications to the fuel economy of hybrid vehicle with a heuristic/non-optimal ESS size and power management strategy. This paper adds four original contributions to the related literature. First, the three ESSs are compared in a framework of simultaneous optimal ESS sizing and energy management, where the ESSs can serve the powertrain in a most cost-effective manner. Second, convex optimization is used to implement the framework, which allows the hybrid powertrain designers/integrators to rapidly and optimally perform integrated ESS selection, sizing, and power management. Third, both hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV) scenarios for the powertrain are considered, in order to systematically examine how different the ESS requirements are for HEV and PHEV applications. Finally, a sensitivity analysis is carried out to evaluate how price variations of the on-board energy carriers affect the results and conclusions.
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| 11. |
- Hu, Xiaosong, 1983, et al.
(författare)
-
Energy efficiency analysis of a series plug-in hybrid electric bus with different energy management strategies and battery sizes
- 2013
-
Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 111, s. 1001-1009
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is concerned with the tank-to-wheel (TTW) analysis of a series plug-in hybrid electric bus operated in Gothenburg, Sweden. The bus line and the powertrain model are described. The definition and the calculation method of the recuperation and fuel-to-traction efficiencies are delineated for evaluating the TTW energy conversion. The two efficiencies are quantified and compared for two optimization-based energy management strategies, in which convex modeling and optimization are used. The impact of downsizing the battery on the two efficiencies is also investigated.
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| 12. |
- Hu, Xiaosong, 1983, et al.
(författare)
-
Longevity-conscious dimensioning and power management of the hybrid energy storage system in a fuel cell hybrid electric bus
- 2015
-
Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 137, s. 913-
-
Tidskriftsartikel (refereegranskat)abstract
- Energy storage systems (ESSs) play an important role in the performance and economy of electrified vehicles. Hybrid energy storage system (HESS) combining both lithium-ion cells and supercapacitors is one of the most promising solutions. This paper discusses the optimal HESS dimensioning and energy management of a fuel cell hybrid electric bus. Three novel contributions are added to the relevant literature. First, efficient convex programming is used to simultaneously optimize the HESS dimension (including sizes of both the lithium-ion battery pack and the supercapacitor stack) and the power allocation between the HESS and the fuel cell system (FCS) of the hybrid bus. In the combined plant/controller optimization problem, a dynamic battery State-of-Health (SOH) model is integrated to quantitatively examine the impact of the battery replacement strategy on both the HESS size and the bus economy. Second, the HESS and the battery-only ESS options are systematically compared in the proposed optimization framework. Finally, the battery-health-perceptive HESS optimization outcome is contrasted to the ideal one neglecting the battery degradation (assuming that the battery is durable over the bus service period without deliberate power regulation).
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| 13. |
- Hu, Xiaosong, 1983, et al.
(författare)
-
Optimal Dimensioning and Power Management of a Fuel Cell/Battery Hybrid Bus via Convex Programming
- 2015
-
Ingår i: IEEE/ASME Transactions on Mechatronics. - 1083-4435 .- 1941-014X. ; 20:1, s. 457-468
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is concerned with the simultaneous optimal component sizing and power management of a fuel cell/battery hybrid bus. Existing studies solve the combined plant/controller optimization problem for fuel cell hybrid vehicles (FCHVs) by using methods with disadvantages of heavy computational burden and/or suboptimality, for which only a single driving profile was often considered. This paper adds three important contributions to the FCHVs-related literature. First, convex programming is extended to rapidly and efficiently optimize both the power management strategy and sizes of the fuel cell system (FCS) and the battery pack in the hybrid bus. The main purpose is to encourage more researchers and engineers in FCHVs field to utilize the new effective tool. Second, the influence of the driving pattern on the optimization result (both the component sizes and hydrogen economy) of the bus is systematically investigated by considering three different bus driving routes, including two standard testing cycles and a realistic bus line cycle with slope information in Gothenburg, Sweden. Finally, the sensitivity of the optimization outcome to the potential price decreases of the FCS and the battery is quantitatively examined.
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| 14. |
- Johannesson, Lars, 1979, et al.
(författare)
-
A comparison of stochastic optimal control laws for a parallel hybrid vehicle
- 2006
-
Ingår i: Proceedings of the 8th International Symposium on Advanced Vehicle Control, Taipei, Taiwan.
-
Konferensbidrag (refereegranskat)abstract
- This paper studies the properties of stochastic optimal control laws for hybrid vehicles, derived using stochastic dynamic programming with a Markov Chain as a drive behavior model. The focus of the study is on establishing how complex the Markov Chain model needs to be in order to achieve good performance. Moreover, a simple robustness analysis is done in order to examine how a control law, optimized with data from one city, performs when evaluated in a city with a considerably different drive behavior. The results indicate that it is sufficient to use a Markov Chain model with only power demand as the sole variable in the Markov state. Furthermore the simulation results show a remarkable robustness for the fuel consumption of the derived controllers when evaluated on a new drive behavior.
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| 15. |
- Johannesson, Lars, 1979, et al.
(författare)
-
A Novel Algorithm for Predictive Control of Parallel Hybrid Powertrains based on Dynamic Programming
- 2007
-
Ingår i: Fifth IFAC Symposium on Advances in Automotive Control.
-
Konferensbidrag (refereegranskat)abstract
- A novel algorithm for predictive control of parallel hybridvehicle powertrains is presented. The algorithm uses informationfrom GPS and digital maps to schedule the use of the energy bufferalong the planned route. The algorithm is based on dynamicprogramming and achieves close to the theoretical minimalconsumption when simulated on measured drive data. For simulatedroutes with a topographic profile that contains large hills thefuel consumption savings compared to a competitive non predictivecontroller are 6%. For simulated routes with a more moderatetopographic profile the savings are between 2-3% and for routeswith completely flat topographic profile the savings are onlybetween 0.5-2
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| 16. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Approximate Dynamic Programming Applied to a Four Quadrant Transducer Series-Parallel Hybrid Electric Bus
- 2009
-
Ingår i: European Control Conference, ECC 2009, Budapest, Hungary, 23-26 August 2009. - : IEEE. - 9783952417393 ; , s. 4846-4851
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an Approximate Dynamic Programming scheme that, based on the assumption of perfectly known future driving, efficiently solves the optimal power split in a Series-Parallel hybrid powertrain. The scheme combines two ideas to reduce the computational load of the dynamic programming. First, the cost-to-go function is approximated using piecewise linear functions on a sparse grid. Secondly, by using precalculated maps, the iterations performed in the dynamic programming are reduced to simple table lookups and linear interpolation. The approximation scheme is simulated on a Four Quadrant Transducer Series-Parallel Hybrid Electric Bus. In the simulations the approximation scheme is able to find a sufficiently good approximation of the optimal control trajectory.
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| 17. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Approximate Dynamic Programming Applied to Parallel Hybrid Powertrains
- 2008
-
Ingår i: Proceedings of the 17th IFAC World Congress, 2008.
-
Konferensbidrag (refereegranskat)abstract
- The extra degree of freedom offered in hybrid electric vehicles have inspired manyresearchers to formulate and solve optimal control problems of various kinds. This paper presentsan Approximate Dynamic Programming scheme that efficiently solves the optimal power splitbetween the internal combustion engine and the electric machine in parallel hybrid powertrains.Gear switches and switches between hybrid and pure electric mode are formally treated. Thescheme combines two ideas to reduce the computational time of the iterations performed inthe dynamic programming. First, the value function is approximated using piecewise linearfunctions on a sparse grid. Secondly, by using model approximation the iterations performed inthe dynamic programming are reduced to solving scalar quadratic problems. In the simulationsthe approximation scheme is able to find a good approximation of the optimal control trajectory.
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| 18. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Assessing the Potential of Predictive Control for Hybrid Vehicle Powertrains using Stochastic Dynamic Programming
- 2007
-
Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 8:1, s. 71-83
-
Tidskriftsartikel (refereegranskat)abstract
- The potential for reduced fuel consumption of Hybrid Electric Vehicles by the use of predictive powertrain control was assessed on measured drive data from an urban route with varying topography. The assessment was done by evaluating the fuel consumption using three optimal controllers, each with a different level of information access to the driven route. The lowest information case represents that the vehicle knows that it is being driven in a certain environment, e.g. city driving, and that the controller has been optimized for that type of environment. The second highest information level represents a vehicle equipped with a GPS combined with a traffic flow information system. In the highest information level the future power demand is completely known to the control system, hence the corresponding optimal controller results in the minimal attainable fuel consumption. The study showed that good performance, 1-3% from the minimal attainable fuel consumption, can be achieved with the lowest information case, with a time invariant controller that is optimized to the environment. The second highest information level results in less than 0.2% higher consumption than the minimal attainable on the studied route. This means that it is possible to design a predictive controller based on information supplied by the vehicle navigation system and traffic flow information systems that can come very close to the minimal attainable fuel consumption. A novel algorithm that uses information supplied by the vehicle navigation system was presented. The proposed algorithm results in a consumption only 0.3% from the minimal attainable consumption on the studied route.
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| 19. |
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| 20. |
- Johannesson, Lars, 1979
(författare)
-
Development of a Time invariant Stochastic Model of a Transport Mission
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report a continuous state space markov process is identified from drive data collected in central Gothenburg. The drive behavior is modeled as a time invariant markov process with acceleration and velocity as the markov states. The acceleration is modeled as beta distributed with the beta parameters dependent on previous acceleration and velocity. The model is verified by comparing simulated velocities and accelerations with the measurements. The simulations show that the model is able to reproduce most of the behavior exhibited in the measurements. It is therefore concluded that the beta distribution is a good modeling choice for a markov process that describes the time invariant distribution of acceleration and velocity.
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| 21. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Gantry Tau – A New Parallel Kinematic Robot
- 2004
-
Ingår i: Proceedings of the 4th Chemnitz Parallel Kinematics Seminar, (Ed.: Reimund Neugebauer), April 20-21, 2004, Verlag Wissenschaftliche Scripten. - 3937524053 ; , s. 731-734
-
Konferensbidrag (refereegranskat)abstract
- A new parallel structure, the Gantry Tau, is introduced. The structure provides 3 degrees of freedom translational motion with a large workspace. The structures nominal kinematics is identical to the Linear Delta robot. In order to yield a design of the Gantry Tau with a large workspace volume and good kinematic properties, multi-criteria optimization is used. Different geometrical layouts are examined and the Pareto optimality between the objective functions is found.
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| 22. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Gantry-Tau – A New Three Degrees of Freedom Parallel Kinematic Robot
- 2003
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the last decades, an increasing attention has been paid to the study of different parallel structure mechanisms and their applications, mainly triggered by Stewart that presented an aircraft simulator system. Parallel structure features provide big advantages in potential applications. For example, parallel robots may give higher speed and acceleration, higher static and dynamic accuracy and higher stiffness than what is possible with the industrial robots used today. A typical limitation with many of the paral-lel structures is that their workspace is small com-pared to the serial structures. This paper presents a new parallel structure, the Gantry-Tau, which pro-vides 3 degrees of freedom (DOF) translational mo-tion with a large workspace. The structure of the ro-bot is patented by ABB. The Gantry-Tau robot is a six link parallel kinematic structure with the links configured according to 3-2-1. The 3-2-1 notation refers to how many links form each resulting kine-matic cluster of the robot. Orientational DOF of the robot could be provided by a decoupled system. For a conventional 3 DOF serial gantry ro-bot two of the actuators contribute to the moving mass. The Gantry-Tau can be constructed with ex-ceptionally low moving mass since the actuators are stationary and the structure has inherently high stiff-ness. The structure is thus ideal for many applications with demands on high accelerations, for instance for the pick and place operations. The nominal inverse and direct kinematics of the structure are developed and optimization is used to find a construction of Gantry-Tau with maximum workspace volume.
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| 23. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Including a battery state of health model in the hev component sizing and optimal control problem
- 2013
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902823434 ; , s. 398-403
-
Konferensbidrag (refereegranskat)abstract
- This paper studies convex optimization and modelling for component sizing and optimal energy management control of hybrid electric vehicles. The novelty in the paper is the modeling steps required to include a battery wear model into the convex optimization problem. The convex modeling steps are described for the example of battery sizing and simultaneous optimal control of a series hybrid electric bus driving along a perfectly known bus line. Using the proposed convex optimization method and battery wear model, the city bus example is used to study a relevant question: is it better to choose one large battery that is sized to survive the entire lifespan of the bus, or is it beneficial with several smaller replaceable batteries which could be operated at higher c-rates?
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| 24. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Look-ahead Vehicle Energy Management with Traffic Predictions
- 2015
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 48:15, s. 244-251
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a vehicle energy management system that uses information about upcoming topography and speed limits along the planned route to schedule the speed and the gear shifts of a heavy diesel truck. The proposed control scheme divides the predictive control problem into two layers that operate with different update frequencies and prediction horizons. The focus in the paper is on the top layer that plans the vehicle speed in a convex optimization problem leaving the gear decision to be optimized in the lower layer in a dynamic program. The paper describes how predictive information of the movement pattern of surrounding vehicles can be incorporated into the convex optimization of the vehicle speed by using a moving time window constraint.
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| 25. |
- Johannesson, Lars, 1979
(författare)
-
On Energy Management Strategies for Hybrid Electric Vehicles
- 2006
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid electric vehicles are characterized by the existence of an electric energy buffer in the powertrain. Compared to a conventional vehicle the existence of the buffer means an extra degree of freedom in the powertrain. The driver's request for a specific power demand can thus be met by a combination of power from the primary power unit and power from the electric buffer. Furthermore, when the vehicle is braking, energy can be regenerated and stored in the buffer.The subject of this thisis is the control of the load distribution between the power sources in the hybrid electric powertrain. The control problem is to choose at every moment the distribution of power from the electric buffer and primary power unit that minimizes the fuel consumption and emissions in the long run. To solve this problem the efficiency characteristics of the components in the powertrain must be considered. The problem is complicated due to that the future driving is largely unknown. This uncertainty of the future driving makes it difficult from a fuel efficiency viewpoint to compare taking energy from the buffer with taking energy from the fuel tank. In this thesis this problem is handled by using a model based information perspective. The controller is derived by Stochastic Dynamic Programming using a simple model of the powertrain and a Markov process model of the future driving. The resulting controller minimizes the expected fuel consumption with respect to the Markov process model of the future driving. In cooperation with Volvo Cars a controller supplied by Volvo Cars is compared with a controller that is derived with Stochastic Dynamic Programming on drive data collected in Gothenburg. When simulated on the Gothenburg drive data the controller derived with Stochastic Dynamic Programming reduces the fuel consumption by 5\%.The model based information perspective is used to study which type of information that should be supplied to the controller. This thesis investigates if information from GPS and digital maps can be used to schedule the use of the buffer so that fuel consumption reductions are achieved. A novel algorithm for predictive control of the power distribution in parallel hybrid vehicle powertrains is presented. The algorithm is based on dynamic programming and can be used when the future route is known to the controller. In simulations the algorithm achieves close to the theoretical minimum fuel consumption.
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| 26. |
- Johannesson, Lars, 1979
(författare)
-
Predictive Control of Hybrid Electric Vehicles on Prescribed Routes
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- At the highest level in the powertrain control system in a hybrid electric vehicle an energy management controller interprets the driver’s pedal actions as a torque that is to be delivered at the powertrain output. The energy management controller distributes this torque between the engine and the electric machines and decides when to change gear and when to turn off the engine for pure electric propulsion. The torque distribution should be done in such a way that the fuel consumption and emissions are minimizedwhile at the same time assuring safe operation of the individual components in the powertrain.It is well known that the performance of the energy management controller depends on how well it is adapted to the driving conditions. By using a Global PositioningSystem (GPS) and a digital map it is possible to develop predictive energy management controllers that adapt to the current and future driving conditions, resulting in close tooptimal performance.Dynamic programming is in some sense ideally suited to the problem since it can handle most practical requirements that can be put on the energy management controller. The disadvantage with dynamic programming is the high computational effort compared to other methods such as the Equivalent Consumption Minimization Strategy (ECMS). Dynamic programming has therefore previously primarily been a method for benchmarking energy management controllers in simulation studies. However, by settling for an approximate solution it is shown in the thesis that the computational effort of dynamic programming can be significantly reduced without a degradation of the performance.A novel predictive control scheme based on dynamic programming is presented. Using a GPS and a digital map the predictive control scheme plans both the charging and discharging of the energy storage system as well as the gear shifts and engine on/off decisions. When evaluated in simulations on a city bus, the fuel savings compared witha non adaptive ECMS controller are between 2-4.5% depending on the bus line. These results are for a powertrain variant that is not sensitive to the engine on/off decisions. When simulating a variant of the powertrain that is sensitive to the engine on/off decisions the savings are between 1-12%.
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| 27. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Predictive energy management of a 4QT series-parallel hybrid electric bus
- 2009
-
Ingår i: Control Engineering Practice. - 0967-0661. ; 17:12, s. 1367-1460
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel predictive control scheme for a Series-Parallel hybrid bus. The proposed scheme uses information from GPS together with a data record of the driving along the bus route to schedule the charging and discharging of the energy storage system. Switching between hybrid and pure electric mode are optimized in a receding horizon scheme based on a prediction model that reflects the uncertainty of the future driving. The benefits of the proposed predictive control scheme are shown by a simulation study on measured driving data along a bus route. The simulations show that the predictive control scheme achieves both lower fuel consumption and better control of the energy storage system than can be achieved with a non-predictive controller.
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| 28. |
- Johannesson, Lars, 1979, et al.
(författare)
-
Predictive energy management of hybrid long-haul trucks
- 2015
-
Ingår i: Control Engineering Practice. - : Elsevier Ltd. - 0967-0661 .- 1873-6939. ; 41, s. 83-97
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel predictive control scheme for energy management in hybrid trucks that drive autonomously on the highway. The proposed scheme uses information from GPS together with information about the speed limits along the planned route to schedule the charging and discharging of the battery, the vehicle speed, the gear, and when to turn off the engine and drive electrically. The proposed control scheme divides the predictive control problem into three layers that operate with different update frequencies and prediction horizons. The top layer plans the kinetic and electric energy in a convex optimization problem. In order to avoid a mixed-integer problem, the gear and the switching decision between hybrid and pure electric mode are optimized in a lower layer in a dynamic program whereas the lowest control layer only reacts on the current state and available references. The benefits of the proposed predictive control scheme are shown by simulations between Frankfurt and Koblenz. The simulations show that the predictive control scheme is able to significantly reduce the mechanical braking, resulting in fuel reductions of 4% when allowing an over and under speed of 5. km/h
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| 29. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Analytic Solutions to the Dynamic Programming sub-problem in Hybrid Vehicle Energy Management
- 2015
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 64:4, s. 1458-1467
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Tidskriftsartikel (refereegranskat)abstract
- The computationally demanding Dynamic Programming(DP) algorithm is frequently used in academic research tosolve the energy management problem of an Hybrid ElectricVehicle (HEV). This paper is focused exclusively on how thecomputational demand of such a computation can be reduced.The main idea is to use a local approximation of the griddedcost-to-go and derive an analytic solution for the optimal torquesplit decision at each point in the time and state grid. Therebyit is not necessary to quantize the torque split and identifythe optimal decision by interpolating in the cost-to-go. Twodifferent approximations of the cost-to-go are considered in thepaper: i) a local linear approximation, and ii) a quadratic splineapproximation. The results indicate that computation time can bereduced by orders of magnitude with only a slight degradation insimulated fuel economy. Furthermore, with a spline approximatedcost-to-go it is also possible to significantly reduce the memorystorage requirements. A parallel Plug-in HEV is considered inthe paper but the method is also applicable to an HEV.
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| 30. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Benefit of Route Recognition in Energy Management of Plug-in Hybrid Electric Vehicles
- 2012
-
Ingår i: Proceedings of the American Control Conference. - : IEEE. - 0743-1619. - 9781457710940 ; , s. 1314-1320
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Konferensbidrag (refereegranskat)abstract
- This paper investigates the benefit of an energymanagement system that autonomously can recognize when aplug-in hybrid electric vehicle is driven along known commutingroutes. The presented route recognition algorithm comparesthe GPS trajectory of the ongoing trip with stored commutingroutes using the well known cross-correlation operation. If aroute is recognized the energy management system switchesfrom a charge depleting charge sustaining discharge strategyto a strategy where the battery discharge rate is adapted to thelength of the recognized route, thereby decreasing the averagedischarge current and the resistive losses.The proposed system is evaluated using simulations onone month of logged commuter driving data. The resultsfor an energy management system based on the equivalentconsumption minimization strategy indicate an overall fuel costreduction of 1.5% compared to an system that only utilize acharge depleting charge sustaining strategy.
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| 31. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Commuter Route Optimized Energy Management of Hybrid Electric Vehicles
- 2014
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Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 15:3, s. 1145-1154
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Tidskriftsartikel (refereegranskat)abstract
- Optimal energy management of hybrid electric vehicles requires a priori information regarding future driving conditions; the acquisition and processing of this information is nevertheless often neglected in academic research. This paper introduces a commuter route optimized energy management system, where the bulk of the computations are performed on a server. The idea is to identify commuter routes from historical driving data, using hierarchical agglomerative clustering, and then precomputean optimal solution to the energy management controlproblem with dynamic programming; the obtained solution canthen be transmitted to the vehicle in the form of a lookup table. To investigate the potential of such a system, a simulation study is performed using a detailed vehicle model implemented in the Autonomie simulation environment for MATLAB/Simulink. The simulation results for a plug-in hybrid electric vehicle indicate that the average fuel consumption along the commuter route(s) can be reduced by 4%–9% and battery usage by 10%–15%.
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| 32. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Comparing two approaches to precompute discharge strategies for plug-in hybrid electric vehicles
- 2013
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902823434 ; , s. 121-126
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates two alternative approaches to precompute a discharge strategy for the main commuter route of a plug-in hybrid electric vehicle. The first approach is based on the idea of computing a state of charge reference trajectory by solving a convex program; while the second approach utilizes dynamic programming to determine an optimal cost-to-go function. During real-time operation the torque split is decided by an equivalent consumption minimization strategy where the main difference between the two approaches is how the equivalence factor is determined. With the first approach it is adapted to track the state of charge reference trajectory and in the second approach it is given by the partial derivative of the cost-to-go function with respect to state of charge. To evaluate the two approaches a simulation study is performed in the dynamic vehicle modelling software Autonomie using logged commuter driving data. The simulation results indicate no clear difference between the two approaches in terms of fuel economy and battery usage. Both approaches are, however, significantly better than a charge depleting charge sustaining discharge strategy.
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| 33. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Cubic Spline Approximations of the Dynamic Programming Cost-to-go in HEV Energy Management Problems
- 2014
-
Ingår i: 13th European Control Conference, ECC 2014; Strasbourg Convention and Exhibition CenterPlace de BordeauxStrasbourg; France; 24 June 2014 through 27 June 2014. - 9783952426913 ; , s. 1699-1704
-
Konferensbidrag (refereegranskat)abstract
- The energy management problem of a hybridelectric vehicle (HEV) is a non-linear and mixed integeroptimization problem. The problem can be solved with DynamicProgramming (DP), but the algorithm requires the problem tobe gridded in time, states and control signals. To ensure a highaccuracy of the solution the grid must be dense, meaning thatthe cost-to-go can require several megabytes of memory. Thescope of this paper is therefore twofold. The first topic is asensitivity study, where the effect of a sparsely gridded state isinvestigated, both for an HEV and a plug-in HEV (PHEV). Thestudy shows that it is possible to use a sparse grid for an HEV,but not for a PHEV. The second topic and the main contributionis a method to approximate the DP cost-to-go with cubic splines.The results indicate that it is possible to use only a few splines,if the knot points are determined based on the characteristicsof the cost-to-go. Thereby it is possible to significantly reducethe memory requirements, without any noticeable increase insimulated fuel consumption.
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| 34. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Cubic Spline Approximations of the Dynamic Programming Value Function in HEV Energy Management Problems
- 2013
-
Ingår i: Workshop for new energy vehicle dynamic system and control technology.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Energy management of a hybrid electric powertrain is a non-linear and mixed integer optimization problem that often is solved with Dynamic Programming (DP); thus requiring the problem to be gridded both in time, control signals and the states. To ensure a high accuracy of the solution the grid must be dense, meaning that the resulting value function can require several megabytes of memory. The first contribution of the paper is therefore a sensitivity study where the effect of a sparsely gridded state is investigated, both for a hybrid electric vehicle (HEV) and a plug-in HEV (PHEV). The study shows that it is possible to use a sparse grid for an HEV, but not for a PHEV. The second contribution is a method to approximate the DP value function with cubic splines. The results indicate that it is possible to useonly a few splines, if the knot points are determined based on the characteristics of the value function. Thereby it is possible to significantly reduce the memory requirements of the PHEV value function, without any noticeable increase in fuel consumption.
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| 35. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Impact of Trip Length Uncertainty on Optimal Discharging Strategies for PHEVs
- 2010
-
Ingår i: Proceedings of the 6th IFAC Symposium Advances in Automotive Control, Munich; 12 July 2010 through 14 July 2010. - 1474-6670. - 9783902661722 ; 43, s. 55-60
-
Konferensbidrag (refereegranskat)abstract
- When charged from the electric grid, plug-in Hybrid Electric Vehicles can be expected to have an all electric range of 10 - 60 km depending on battery size. In order to minimize the fuel cost it is vital to fully deplete the battery between two charging occasions. However, when driving distances exceeding the electric range it is in many cases energy efficient to turn on the engine at an early stage and blend power from the battery with power from the combustion engine. This paper studies how uncertainties regarding the predicted trip length affect the optimal discharging strategy of a parallel plug-in Hybrid Electric Vehicle. The predicted trip length along an otherwise perfectly known speed profile is modeled as a normally distributed stochastic variable and Dynamic Programming is used to calculate the optimal discharging strategy. Calculations are carried out for varying standard deviations on three different speed profiles. The results indicate that it is possible to decrease the fuel costs with 1-4 % even with relatively little knowledge regarding the future trip length.
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| 36. |
- Larsson, Viktor, 1984, et al.
(författare)
-
Influence of State of Charge Estimation Uncertainty on Energy Management Strategies for Hybrid Electric Vehicles
- 2011
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902661937 ; 18:PART 1, s. 9703-9708
-
Konferensbidrag (refereegranskat)abstract
- This paper studies how the optimal energy management of a hybrid electric vehicle and a plug-in hybrid electric vehicle is affected by uncertain estimates of the battery state of charge. A simple model for the battery dynamics and the state of charge estimation is postulated, inspired by the known characteristics of previously proposed estimation schemes. Based on the assumption that the drive cycle is perfectly known, the effects of state of charge estimation uncertainty is studied by including the estimation uncertainty in the optimization of the energy management strategy. The simulations indicate lower battery usage and higher fuel consumption as the estimation uncertainty increases.
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| 37. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Automated Engine Calibration of Hybrid Electric Vehicles
- 2015
-
Ingår i: IEEE Transactions on Control Systems Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 1063-6536 .- 1558-0865. ; 23:3, s. 1063-1074
-
Tidskriftsartikel (refereegranskat)abstract
- We present a method for automated engine calibration, by optimizing engine management settings and power-split control of a hybrid electric vehicle (HEV). The problem, which concerns minimization of fuel consumption under a NOxconstraint, is formulated as an optimal control problem. By applying Pontryagin's maximum principle, this paper shows that the problem is separable in space. In the case where the limits of battery state of charge are not activated, we show that the optimization problem is also separable in time. The optimal solution is obtained by iteratively solving the power-split control problem using dynamic programming or the equivalent consumption minimization strategy. In addition, we present a computationally efficient suboptimal solution, which aims at reducing the number of power-split optimizations required. An example is provided concerning optimization of engine management settings and power-split control of a parallel HEV.
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| 38. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Combined design and control optimization of hybrid vehicles
- 2015
-
Ingår i: Handbook of Clean Energy Systems. - 9781118991978 ; , s. 1-14
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid vehicles play an important role in reducing energy consumption and pollutant emissions of ground transportation. The increased mechatronic system complexity, however, results in a heavy challenge for efficient component sizing and power coordination among multiple power sources. This chapter presents a convex programming framework for the combined design and control optimization of hybrid vehicles. An instructive and straightforward case study of design and energy control optimization for a fuel cell/supercapacitor hybrid bus is delineated to demonstrate the effectiveness and the computational advantage of the convex programming methodology. Convex modeling of key components in the fuel cell/supercapactior hybrid powertrain is introduced, while a pseudo code in CVX is also provided to elucidate how to practically implement the convex optimization. The generalization, applicability, and validity of the convex optimization framework are also discussed for various powertrain configurations (i.e., series, parallel, and series-parallel), different energy storage systems (e.g., battery, supercapacitor, and dual buffer), and advanced vehicular design and controller synthesis accounting for the battery thermal and aging conditions. The proposed methodology is an efficient tool that is valuable for researchers and engineers in the area of hybrid vehicles to address realistic optimal control problems.
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| 39. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Component sizing of a plug-in hybrid electric powertrain via convex optimization
- 2012
-
Ingår i: Mechatronics. - : Elsevier BV. - 0957-4158 .- 1873-4006. ; 22:1, s. 106-120
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel convex modeling approach which allows for a simultaneous optimization of battery size and energy management of a plug-in hybrid powertrain by solving a semidefinite convex problem. The studied powertrain belongs to a city bus which is driven along a perfectly known bus line with fixed charging infrastructure. The purpose of the paper is to present the convexifying methodology and validate the necessary approximations by comparing with results obtained by Dynamic Programming when using the original nonlinear, non-convex, mixed-integer models. The comparison clearly shows the importance of the gear and engine on/off decisions, and it also shows that the convex optimization and Dynamic Programming point toward similar battery size and operating cost when the same gear and engine on/off heuristics are used. The main conclusion in the paper is that due to the low computation time, the convex modeling approach enables optimization of problems with two or more state variables, e.g. allowing for thermal models of the components; or to include more sizing variables, e.g. sizing of the engine and the electric machine simultaneously.
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| 40. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Convex modeling of energy buffers in power control applications
- 2012
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902823168 ; 45, s. 92-99
-
Konferensbidrag (refereegranskat)abstract
- This paper describes modeling steps for presenting energy buffers as convex models in power control applications. Except obtaining the optimal control, the paper also shows how convex optimization can be used to simultaneously size the energy buffer while optimally controlling a trajectory following system. The energy buffers are capacitors and batteries with quadratic power losses, while the resulting convex problem is a semidefinite program. The convex modeling steps are described through a problem of optimal buffer sizing and control of a hybrid electric vehicle. The studied vehicle is a city bus driven along a perfectly known bus line. The paper also shows modeling steps for alternative convex models where power losses and power limits of the energy buffer are approximated. The approximated models show significant decrease in computation time without visible impact on the optimal result.
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| 41. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Convex optimization of charging infrastructure design and component sizing of a plug-in series HEV powertrain
- 2011
-
Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 2405-8963. - 9783902661937 ; 18:PART 1, s. 13052-13057
-
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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| 42. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Convex relaxations in the optimal control of electrified vehicles
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479986842 ; 2015-July, s. 2292-2298
-
Konferensbidrag (refereegranskat)abstract
- When controlling the energy flow in electrified powertrains by means of convex optimization, the typically non-convex set of the original formulation needs to be relaxed to a convex super-set. In this paper we show that when using the backward simulation approach, where vehicle velocity is equal to the reference velocity, the global optimum of the original non-convex problem can be obtained by solving the relaxed convex problem. When vehicle velocity is kept as a state in the problem, in the so called forward simulation approach, we provide a condition for which, when satisfied, an agreement will be achieved between the solutions of the relaxed and the original problem.
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| 43. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Dimensioning and Control of a Thermally Constrained Double Buffer Plug-in HEV Powertrain
- 2012
-
Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467320658 ; , s. 6346-6351
-
Konferensbidrag (refereegranskat)abstract
- This paper describes modeling steps to enable fast evaluation of performance and cost effectiveness of a plugin hybrid electric vehicle. The paper also shows how convex optimization can be used to dimension the vehicle powertrain while simultaneously controlling the energy buffer power. The method allows for optimal control of powertrain components that are subject to thermal constraints. The studied vehicle is a city bus driven along a perfectly known bus line. The bus is equipped with an engine-generator unit and an energy buffer consisting of an ultracapacitor and a battery. The engine generator unit and the energy buffer are modeled with quadratic power losses and are sized for two different charging scenarios. In the first scenario the bus can charge for a couple of seconds while standing still at bus stops, and in the second scenario the bus can charge for a couple of minutes before starting the route. In both scenarios, the ultracapacitor temperature is kept below a certain limit.
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| 44. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Engine on/off control for dimensioning hybrid electric powertrains via convex optimization
- 2013
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 62:7, s. 2949-2962
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel heuristic method for optimal control of mixed-integer problems that, for given feasible values of the integer variables, are convex in the rest of the variables. The method is based on Pontryagin's maximum principle and allows the problem to be solved using convex optimization techniques. The advantage of this approach is the short computation time for obtaining a solution near the global optimum, which may otherwise need very long computation time when solved by algorithms guaranteeing global optimum, such as dynamic programming (DP). In this paper, the method is applied to the problem of battery dimensioning and power split control of a plug-in hybrid electric vehicle (PHEV), where the only integer variable is the engine on/off control, but the method can be extended to problems with more integer variables. The studied vehicle is a city bus, which is driven along a perfectly known bus line with a fixed charging infrastructure. The bus can charge either at standstill or while driving along a tramline (slide in). The problem is approached in two different scenarios: First, only the optimal power split control is obtained for several fixed battery sizes; and second, both battery size and power split control are optimized simultaneously. Optimizations are performed over four different bus lines and two different battery types, giving solutions that are very close to the global optimum obtained by DP.
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| 45. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Filtering driving cycles for assessment of electrified vehicles
- 2013
-
Ingår i: Workshop for new energy vehicle dynamic system and control technology.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a method for pre-filtering driving cycles that are to be used for assessment of electrified vehicles. The method ensures that the vehicle may exactly follow the filtered velocity demanded by the driving cycle. Employing convex optimization, the method also allows optimal velocity shaping that minimizes the amount of wasted energy. We illustrate the method by an example of performance assessment of a hybrid electric bus in a series powertrain topology.
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| 46. |
- Murgovski, Nikolce, 1980, et al.
(författare)
-
Optimal battery dimensioning and control of a CVT PHEV powertrain
- 2014
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 63:5, s. 2151-2161
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents convex modeling steps for the problem of optimal battery dimensioning and control of a plug-in hybrid electric vehicle with a continuous variable transmission. The power limits of the internal combustion engine and the electric machine are approximated as convex/concave functions in kinetic energy, whereas their losses are approximated as convex in both kinetic energy and power. An example of minimizing the total cost of ownership of a city bus including a battery wear model is presented. The proposed method is also used to obtain optimal charging power from an infrastructure that is to be designed at the same time the bus is dimensioned.
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| 47. |
- Ni, Lei, et al.
(författare)
-
Vehicle Lateral Motion Control with Performance and Safety Guarantees
- 2016
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 49:11, s. 285-290
-
Konferensbidrag (refereegranskat)abstract
- This paper explores the use of Model Predictive Control (MPC) techniques to solve vehicle lateral motion control problem on highway scenarios. In particular, the problem of autonomously driving a vehicle along a desired path is formulated, where safety constraints and performance levels must be guaranteed for all possible road curvatures within a con [pact set. Safety constraints are translated into a maximum lateral deviation and orientation error w.r.t. a desired path, while performance requirements are formulated in terms of bounded lateral acceleration and velocity. Preliminary simulation results ahoy that the designed controller is capable of delivering acceptable performance at the cost of limited online computational costs. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
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| 48. |
- Nilsson, Magnus, et al.
(författare)
-
ADMM applied to energy management of ancillary systems in trucks
- 2015
-
Ingår i: American Control Conference. - 0743-1619. - 9781479986842 ; 2015-July, s. 3459-3466
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates how recently endorsed methods in distributed optimization can be exploited in the energy-management problem for heavy trucks, with focus on improved control of ancillary systems. The justification for investigating this is because it may offer higher modularity and integrity to the development process of vehicle models. This paper assumes an indirect approach for solving the optimal control problem. For simplicity, a multi-level control hierarchy is also assumed, where prediction and integer decisions are planned at a higher level, while real-time decisions take place at a lower level. This allows the higher level to deliver an estimate of optimal costates to the lower level. Convex models of ancillary components allow the problem to be formulated as a second-order cone program at the lower level, which can be reformulated as an exchange problem suitable for distributed control. The exchange problem is solved using the alternating direction method of multipliers with proximal message passing, which returns a solution with the same fuel economy as that from dynamic programming. Convergence properties are briefly discussed, where the most notable conclusion is that warm start gives a significant improvement on the convergence rate, supporting practical feasibility of the distributed approach.
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| 49. |
- Nilsson, Magnus, et al.
(författare)
-
Assessing the potential of prediction in energy management for ancillaries in heavy-duty trucks
- 2014
-
Ingår i: 2014 European Control Conference, ECC 2014. - : Institute of Electrical and Electronics Engineers Inc.. - 9783952426913 ; , s. 1693-1698
-
Konferensbidrag (refereegranskat)abstract
- The degree of importance of prediction in the control of ancillary systems for conventional heavy-duty trucks is investigated, with focus on fuel economy. An optimal control law that utilizes prediction is compared with a suboptimal causal control law. The incentive for this investigation is that the suboptimal control law is less complex to develop and implement for the considered system. The results are not general since only a limited amount of ancillary systems have been modeled, only two different drive cycles have been evaluated and simplified mathematical component models for a specific test truck have been used in the optimization problem. Nevertheless, preliminary results from this investigation indicate that simple suboptimal control laws can yield close to the same improvements in fuel efficiency as a predictive controller, when compared to a baseline control law. Tuning complexity is expected to rise when more ancillaries are included in the energy management problem. This can be a valid argument to incorporate prediction in future work.
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| 50. |
- Nilsson, Magnus, 1978, et al.
(författare)
-
Combined platooning and energy management with high integrity
- 2015
-
Ingår i: International Conference on Energy Efficient Vehicles (ECEEV).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The message of this contribution is a control hierarchy and formulation of the energy management problem that allows combined platooning and energy management to be solved with distributed algorithms, thereby providing high integrity to individual vehicles in the platoon. This could be of interest to investigate further for high-integrity multi-vendor cooperative driving in the future, since most approaches to energy management today relies on optimization in one form or the other.
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