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Optimal control and design of hybrid-electric vehicles.
Degree: 2009, ETH Zürich
The goal of this thesis is to develop novel model-based methods for optimal control and optimal design of hybrid electric vehicles. Two different approaches are used when designing the energy management strategy for two types of parallel hybrid electric vehicles. For the full parallel hybrid a pure mathematical approach is used while an approach derived from optimal sizing studies is used to design the energy management strategy for the torque-assist parallel hybrid. The optimal control problem associated with the energy management in a full parallel hybrid is solved explicitly for a simplified model. The solution of the optimal control problem shows how optimal energy management strategies are derived and that the solution yields simple rules depending on vehicle parameters. Furthermore, a causal, real-time control strategy including anti-windup is presented. The novel energy management for the torque-assist hybrid shows that the gear shifting control can be separated from the torque split control. The energy management strategy utilizes the gear shifting strategy for control of the energy flows while the torque split strategy is given by a simple rule. Results show that the proposed energy management strategy achieves a fuel consumption within 1% from the global optimum for most driving cycles. Furthermore, the results are not sensitive to limitations and energy losses associated with gear shifting. Both the full and the torque-assist parallel hybrid vehicles are optimized with respect to the component dimensions. The overall power-to-weight ratio is kept constant while the hybridization ratio is optimized and investigated for the full hybrid and the torque-assist hybrid. The study shows the non-intuitive result that the need for hybridization is larger in the torque-assist hybrid than in the full hybrid. The simplicity of the torque-assist hybrid allows the optimal hybridization ratio to be found using a very simple and computationally cheap rule. The objective of this rule is to minimize the total CO2 emissions of the vehicle, while maintaining its drivability at a constant level. The starting point is an analysis in which the optimal energy management strategy is found for eight typical driving cycles using dynamic programming. Analyzing these results, a simple yet powerful rule-based method is proposed that allows choosing the sizes of the combustion engine and of the electric motor such that the CO2 emissions are very close to the minimum value, i.e., with a deviation of less than 1% for most driving cycles. In the last chapter of this thesis the focus is on the dynamic programming algorithm. Issues related to the implementation of the dynamic programming algorithm for optimal control of a one-dimensional dynamic model is investigated. A study on the resolution of the discretized state space emphasizes the need for careful implementation. A novel method is presented to treat numerical issues appropriately. In particular, the method deals with numerical problems that arise due to high gradients in the optimal…
Advisors/Committee Members: Guzzella, Lino, Egardt, Bo.
Subjects/Keywords: MATHEMATICAL MODELING IN ENGINEERING AND TECHNOLOGY; CONTROL (MECHANICAL ENGINEERING); HYBRID VEHICLES (VEHICLE ENGINEERING); OPTIMALE REGELUNG (MATHEMATISCHE KONTROLLTHEORIE); OPTIMAL CONTROL (MATHEMATICAL CONTROL THEORY); REGELUNG UND STEUERUNG (MASCHINENBAU); HYBRIDFAHRZEUGE (FAHRZEUGTECHNIK); MODELLRECHNUNG IN TECHNIK UND INGENIEURWESEN; info:eu-repo/classification/ddc/621.3; info:eu-repo/classification/ddc/620; Electric engineering; Engineering & allied operations
to Zotero / EndNote / Reference
APA (6th Edition):
Sundström, O. (2009). Optimal control and design of hybrid-electric vehicles. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/16642
Chicago Manual of Style (16th Edition):
Sundström, Olle. “Optimal control and design of hybrid-electric vehicles.” 2009. Doctoral Dissertation, ETH Zürich. Accessed October 21, 2019.
MLA Handbook (7th Edition):
Sundström, Olle. “Optimal control and design of hybrid-electric vehicles.” 2009. Web. 21 Oct 2019.
Sundström O. Optimal control and design of hybrid-electric vehicles. [Internet] [Doctoral dissertation]. ETH Zürich; 2009. [cited 2019 Oct 21].
Available from: http://hdl.handle.net/20.500.11850/16642.
Council of Science Editors:
Sundström O. Optimal control and design of hybrid-electric vehicles. [Doctoral Dissertation]. ETH Zürich; 2009. Available from: http://hdl.handle.net/20.500.11850/16642