Combined design and control optimization of hybrid vehicles

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

Convex relaxations in the optimal control of electrified vehicles

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

Toward Holistic Energy Management Strategies for Fuel Cell Hybrid Electric Vehicles in Heavy-Duty Applications

The increasing need to slow down climate change for environmental protection demands further advancements toward regenerative energy and sustainable mobility. While individual mobility applications are assumed to be satisfied with improving battery electric vehicles (BEVs), the growing sector of freight transport and heavy-duty applications requires alternative solutions to meet the requirements of long ranges and high payloads. Fuel cell hybrid electric vehicles (FCHEVs) emerge as a capable technology for high-energy applications. This technology comprises a fuel cell system (FCS) for energy supply combined with buffering energy storages, such as batteries or ultracapacitors. In this article, recent successful developments regarding FCHEVs in various heavy-duty applications are presented. Subsequently, an overview of the FCHEV drivetrain, its main components, and different topologies with an emphasis on heavy-duty trucks is given. In order to enable system layout optimization and energy management strategy (EMS) design, functionality and modeling approaches for the FCS, battery, ultracapacitor, and further relevant subsystems are briefly described. Afterward, common methodologies for EMS are structured, presenting a new taxonomy for dynamic optimization-based EMS from a control engineering perspective. Finally, the findings lead to a guideline toward holistic EMS, encouraging the co-optimization of system design, and EMS development for FCHEVs. For the EMS, we propose a layered model predictive control (MPC) approach, which takes velocity planning, the mitigation of degradation effects, and the auxiliaries into account simultaneously

Cost of ownership-efficient hybrid electric vehicle powertrain sizing for multi-scenario driving cycles

During the last decade, hybrid electric vehicles have gained a presence in the automotive market. On the streets, in motorsports and in society, hybrid electric vehicles are increasingly common. Many manufacturers have become involved in hybrid electric vehicles, while others have hybrid electric vehicle projects in development. Thus, there is already a great variety of hybrid electric vehicles in production, from small microhybrid vehicles to range extenders. Although there are some hybrid electric vehicles designed for urban driving or luxury segments of the market, most of the market share is aimed to the same kind of use and driving, resulting in potentially subsized or oversized hybrid systems that could lead to inefficient use of the vehicle's fuel-saving capabilities in many situations. The present work studies the influence of the sizes of the powertrain components (i.e. the engine, the motor and the battery) on the fuel economy under different assumptions: city driving, highway driving and mixed driving. The utilized framework permits the calculation of the theoretically optimum powertrain sizes assuming a particular target. Different drivers and different traffic conditions are also evaluated. Finally, a long-term cost evaluation is carried out to estimate the optimal sizes of the hybrid electric vehicle powertrain as functions of the type of use of the vehicle throughout its life cycle.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work has been supported by Conselleria de Educacio Cultura i Esports de la Generalitat Valenciana through Project GV/2013/044 AECOSPH.Luján, JM.; Guardiola, C.; Pla Moreno, B.; Reig, A. (2016). Cost of ownership-efficient hybrid electric vehicle powertrain sizing for multi-scenario driving cycles. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 230(3):382-394. doi:10.1177/0954407015586333S382394230

Adaptive energy management for hybrid power system considering fuel economy and battery longevity

The adoption of hybrid powertrain technology brings a bright prospective to improve the economy and environmental friendliness of traditional oil-fueled automotive and solve the range anxiety problem of battery electric vehicle. However, the concern of the battery aging cost is the main reason that keeps plug-in hybrid electric vehicles (PHEV) from being popular. To improve the total economy of PHEV, this paper proposes a win-win energy management strategy (EMS) for Engine-Battery-Supercapacitor hybrid powertrains to reduce energy consumption and battery degradation cost at the same time. First of all, a novel hierarchical optimization energy management framework is developed, where the power of internal combustion engine (ICE), battery and super capacitor (SC) can be gradationally scheduled. Then, an adaptive constraint updating rule is developed to improve vehicle efficiency and mitigate battery aging costs. Additionally, a control-oriented cost analyzing model is established to evaluate the total economy of PHEV. The quantified operation cost is further designed as a feedback signal to improve the performance of the power distribution algorithm. The performance of the proposed method is verified by Hardware-in-the-loop experiment. The results indicate that the developed EMS method coordinates the operation of ICE, driving motor (DM) and energy storage system effectively with the fuel cost and battery aging cost reduced by 6.1% and 28.6% respectively compared to traditional PHEV. Overall, the introduction of SC and the hierarchical energy management strategy improve the total economy of PHEV effectively. The results from this paper justify the effectiveness and economic performance of the proposed method as compared to conventional ones, which will further encourage the promotion of PHEVs.</p

ОДНОЗНАЧНІСТЬ-НЕОДНОЗНАЧНІСТЬ ПАРАМЕТРИЧНОЇ ОПТИМІЗАЦІЇ АВТОМОБІЛЬНИХ СИСТЕМ ЗА УМОВ КРИТЕРІЙНОЇ НЕВИЗНАЧЕСНОСТІ

Annotation. The general methodology of parametric optimization of systems is considered for two arbitrary cri-teria simultaneously. The so-called principle of expanding an optimization problem is proposed, which creates the basis for finding guaranteed unambiguous solutions, without resorting to artificial formal means of «collapse» of the two cri-teria into one. It turns out that a very common multiplicative criterion for so-called fair trade-off actually expresses the average geometric basic criteria. It is easy to reduce (lead down) it to additive. Therefore, it is certainly not known, why he should give preference to the arithmetic mean (after the appropriate coordinate) of the dimensions of the primary criteria. There are more subjective and far-fetched than objective and truthful in the criterion of a fair compromise.Perfection is a permanent process — it has a beginning but has no end. In that the new" perfections arise from time to time and each of them definitely use a certain time, then, of course, the process of perfection is a step-by-step process, an endless step to an unattainable ideal. This particular circumstance should be taken into account.Described algorithms for optimal search formally reproduce on a primitive model plane the real process of step-by-step improvement of all man-made - from acceptable to better... There are no examples when something was created immediately unconditionally optimally (and the ideal — at all not recognizable and therefore not embodied). At each step, one of the algorithms regulates minimizing the value of a single criterion, without affecting it, without changing the other. That is why there are no conflicts outside the attractor. Only within the attractor, for which the line (which is a one-dimensional attractor) rules on the model plane, the consistency disappears. Another algorithm combines a series of steps in each of which only one parameter varies, and the gain at the same time has both supporters of one perfection, and supporters of some other perfection. Consequently, there are no conflicts, until the algorithm does not attract the attractor, which this time is an area on a model plane, that is a two-dimensional attractor.Within the attractor, all solutions to the optimization problem is appropriate without a doubt, even advisable to consider completely equivalent. However, in fact, insurmountable subjectivism does not allow us to adhere to this idea (let's say, without the participation of any dictator).Розглядається загальна методологія параметричної оптимізації систем одночасно за двома довільними критеріями. Запропоновано так званий принцип розширення оптимізаційної задачі, який створює засади для пошуку гарантовано однозначних її розв’язків, не вдаючись до штучних формальних засобів «згортання» двох критеріїв в один. Виявляється, дуже поширений мультиплікативний критерій так званого справедливого компромісу насправді виражає середнє геометричне основних критеріїв. Його легко звести до адитивного. І отже достеменно не відомо, чому йому слід надавати перевагу перед, скажімо, середнім арифметичним (після відповідного погодження розмірностей)первинних критеріїв. В критерії справедливого компромісу більше суб’єктивного й надума-ного, ніж об’єктивного і правдивого. Удосконалювання — це перманентний процес: він має початок, але не має кінця. А оскільки «нові» дос-коналості виникають час від часу і з кожної з них певний час обов’язково користають, то, зрозуміло, процес удосконалювання — це покроковий процес, нескінченне крокування до недосяжного ідеалу. І саме цю обставину слід обов’язково брати до уваги. Описані в роботі алгоритми пошуку оптимального формалізовано відтворюють на примітивній модельній площині реальний процес покрокового удосконалення всього рукотворного — від прийнятного до кращого… Не існує прикладів, коли б щось було створено відразу беззастережно оптимально (а ідеальне — взагалі не пізнаване, а отже й не втілюване). На кожному кроці один з алгоритмів регламентує мінімізувати значення якогось одного критерію, не зачіпаючи, не змінюючи іншого. А тому поза атрактором жодних конфліктів не виникає. І тільки в межах атрактора, за який на модельній площині править відтинок лінії (що є одновимірним атрактором), злагода зникає. Інший алгоритм поєднує в собі низку кроків, в кожному з яких змінюється тільки один параметр і зиск при цьому мають як прихильники якоїсь одної досконалості, так і прихильники якоїсь іншої досконалості. Тож не виникає конфліктів, аж допоки алгоритм, знову ж таки, не надибує атрактор, який цього разу є областю на модельній площині, тобто двовимірним атрактором. В межах атрактора всі розв’язки оптимізаційної задачі доречно, доцільно вважати цілком рівноцінними. Проте насправді нездоланний суб’єктивізм не дозволяє пристати на цю думку (без участі якогось диктатора, скажімо)

Experimental Investigation of Ultracapacitor Impedance Characteristics

© 2015 The Authors. Published by Elsevier Ltd. Ultracapacitors (UCs) are being increasingly studied and deployed as a short-term energy storage device in various energy systems including uninterruptible power supplies, electrified vehicles, renewable energy systems, and wireless communication. They exhibit excellent power density and energy efficiency. The dynamic behavior of a UC, however, strongly depends on its impedance characteristics. In this paper, the impedance characteristics of a commercial UC are experimentally investigated through the well-adopted Electrochemical Impedance Spectroscopy (EIS) technique. The implications of the UC operating conditions (i.e., state of charge (SOC) and temperature) to the impedance are systematically examined. The results show that the impedance is highly sensitive to temperature and SOC; and the temperature effect is more significant. The experimental design and multi-condition impedance analysis provides prudent insights into UC system integration, dimensioning, and energy management strategy synthesis in advanced energy systems

Battery States Monitoring and its Application in Energy Optimization of Hybrid Electric Vehicles

L'abstract è presente nell'allegato / the abstract is in the attachmen