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Exploring the potential of camber control to improve vehicles' energy efficiency during cornering
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.ORCID iD: 0000-0002-4048-3452
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.ORCID iD: 0000-0001-8928-0368
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.ORCID iD: 0000-0002-1426-1936
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2018 (English)In: Energies, E-ISSN 1996-1073, Vol. 11, no 4, article id 724Article in journal (Refereed) Published
Abstract [en]

Actively controlling the camber angle to improve energy efficiency has recently gained interest due to the importance of reducing energy consumption and the driveline electrification trend that makes cost-efficient implementation of actuators possible. To analyse how much energy that can be saved with camber control, the effect of changing the camber angles on the forces and moments of the tyre under different driving conditions should be considered. In this paper, Magic Formula tyre models for combined slip and camber are used for simulation of energy analysis. The components of power loss during cornering are formulated and used to explain the influence that camber angles have on the power loss. For the studied driving paths and the assumed driver model, the simulation results show that active camber control can have considerable influence on power loss during cornering. Different combinations of camber angles are simulated, and a camber control algorithm is proposed and verified in simulation. The results show that the camber controller has very promising application prospects for energy-efficient cornering.

Place, publisher, year, edition, pages
MDPI AG , 2018. Vol. 11, no 4, article id 724
Keywords [en]
Camber, Cornering, Energy saving, Magic formula
National Category
Energy Systems
Identifiers
URN: urn:nbn:se:kth:diva-227632DOI: 10.3390/en11040724ISI: 000434703400035Scopus ID: 2-s2.0-85044506343OAI: oai:DiVA.org:kth-227632DiVA, id: diva2:1205689
Note

QC 20180515

Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2024-03-15Bibliographically approved
In thesis
1. Improving energy-efficiency of electric vehicles by over-actuation: Du som saknar dator/datorvana kan kontakta mnybacka@kth.se för information
Open this publication in new window or tab >>Improving energy-efficiency of electric vehicles by over-actuation: Du som saknar dator/datorvana kan kontakta mnybacka@kth.se för information
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

As the concerns regarding environmental pollution, climate change and the fossilfuel crisis have grown, electric vehicles (EVs) have attracted a great deal of attention. However, for EVs to be more competitive compared with internal combustion engine vehicles (ICEVs), their driving range needs to be increased. Therefore,energy-efficient control of EVs is considered to be a very important research field.

Electrification of actuators for EVs makes decentralized driving systems possible,such as systems providing individual wheel torque, individual wheel steering andindividual wheel camber control. Electrified vehicle actuators can provide morecontrol possibilities than the normal control of motion in the longitudinal and thelateral direction. EVs equipped with these kinds of actuators are thereby overactuated and more advanced motion controls focusing on energy-efficiency andvehicle directional stability can be realised.

The research objective of the work presented in this doctoral thesis was the exploration of energy-efficient control methods for over-actuated EVs. In order toevaluate the contribution of different control strategies to energy saving, modelsfor energy loss during driving, especially during cornering, were developed. Both alinear tyre model with a camber effect and a non-linear tyre model with a cambereffect were studied. The powertrain efficiency based on a motor efficiency map ofin-wheel motors, was considered.

On the basis of vehicle dynamics with a linear tyre model, camber’s contributionto tyre slip loss reduction during cornering and the corresponding contributionof direct yaw moment control (DYC) when neglecting the powertrain losses werestudied and compared. The results show that camber control can reduce the tyreslip loss significantly and DYC in this case has a small contribution to tyre slip lossreduction. Using a non-linear tyre model, a camber controller based on the lateralacceleration was developed, the effectiveness of this controller was evaluated andthe results show a promising energy saving.

In addition, to investigate the influence of the powertrain losses, a DYC for energyefficiency considering a motor efficiency map was proposed. While satisfying thesame cornering demand, by actively distributing the wheel torques using DYC forenergy-efficiency, the overall energy-efficiency during non-safety-critical manoeuvres could be improved.

Since there might be a higher risk of accidents when applying DYC for energyefficiency in safety-critical manoeuvres, a DYC for safety was developed based ona stability judgement considering the yaw rate and slip angle. To handle this compromise, a switching principle for alternating between DYC for energy-efficiencyand DYC for stability was then proposed. Furthermore, a method for designing arule-based DYC for energy-efficiency was developed to reduce the calculation task and thereby enable real-time implementation.

This research has resulted in an increased understanding of how to improve energyefficiency using different actuators in an over-actuated EV. Different ways in whichover-actuation of EVs can improve the energy-efficiency are presented and analysed in this thesis. Altogether, potential energy loss reductions (up to 22% usingcamber control) for the studied vehicles and manoeuvres have been found usingthe developed methods. Even though the actual improvement will depend on theconsidered vehicle, actuators and driving conditions, the methodology presented inthis thesis can be applied to other vehicles and driving situations.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2020. p. 76
Series
TRITA-SCI-FOU ; 2020:09
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-272045 (URN)978-91-7873-494-8 (ISBN)
Public defence
2020-05-08, Live-streaming: https://kth-se.zoom.us/j/69854468785, Stockholm, 09:00 (English)
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Supervisors
Note

QC 20200416

Available from: 2020-04-16 Created: 2020-04-15 Last updated: 2022-06-26Bibliographically approved

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Sun, PeikunStensson Trigell, AnnikaDrugge, LarsJerrelind, JennyJonasson, Mats

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