Hydraulic Hybrid Technology Review – Perspectives and Benefits of its Implementation on Public Transportation Vehicles

IC engines amount to 25% in global energy consumption, which is mostly due to their massive share in road transport of approximately 99%. The motivation for development of fuel efficient vehicle propulsion systems arises from strong dependence of the transportation sector on fossil fuels and the need for a rapid response to the global warming challenge. Hybridization has, globally, proven its capabilities in enhancing the powertrain efficiency and is the only technology offering significant breakthroughs in near and mid-term. While there are a number of approaches, Hydraulic Hybrid Technology (HHT) has been lately utilized as an alternative power source for vehicles. HHT gives unique advantages for easy and cost-effective implementation in current production vehicles as well as an aftermarket solution. It seems to be the replacement for expensive, bulky and environmentally hazardous battery technology. Hydraulic energy conversion and storage provide exceptional power density and efficiency making them ideally suited for regenerative powertrain design. It is particularly efficient in city traffic conditions, characterized by frequent stops, coasting and long idling periods. Additionally, emissions are reduced, particularly at idling and low speeds, compared to conventionally powered vehicles. While HHT is still in the prototype and simulation stage, this paper reviews current state-of-the-art

A general real-time control approach of intrusion response for industrial automation systems

Intrusion response is a critical part of security protection. Compared with IT systems, industrial automation systems (IASs) have greater timeliness and availability demands. Real-time security policy enforcement of intrusion response is a challenge facing intrusion response for IASs. Inappropriate enforcement of the security policy can influence normal operation of the control system, and the loss caused by this security policy may even exceed that caused by cyberattacks. However, existing research about intrusion response focuses on security policy decisions and ignores security policy execution. This paper proposes a general, real-time control approach based on table-driven scheduling of intrusion response in IASs to address the problem of security policy execution. Security policy consists of a security service group, with each type of security service supported by a realization task set. Realization tasks from several task sets can be combined to form a response task set. In the proposed approach, first, a response task set is generated by a nondominated sorting genetic algorithm (GA) II with joint consideration of security performance and cost. Then, the system is reconfigured through an integrated scheduling scheme where system tasks and response tasks are mapped and scheduled together based on a GA. Furthermore, results from both numerical simulations and a real-application simulation show that the proposed method can implement the security policy in time with little effect on the system

Energy management in plug-in hybrid electric vehicles: recent progress and a connected vehicles perspective

Plug-in hybrid electric vehicles (PHEVs) offer an immediate solution for emissions reduction and fuel displacement within the current infrastructure. Targeting PHEV powertrain optimization, a plethora of energy management strategies (EMSs) have been proposed. Although these algorithms present various levels of complexity and accuracy, they find a limitation in terms of availability of future trip information, which generally prevents exploitation of the full PHEV potential in real-life cycles. This paper presents a comprehensive analysis of EMS evolution toward blended mode (BM) and optimal control, providing a thorough survey of the latest progress in optimization-based algorithms. This is performed in the context of connected vehicles and highlights certain contributions that intelligent transportation systems (ITSs), traffic information, and cloud computing can provide to enhance PHEV energy management. The study is culminated with an analysis of future trends in terms of optimization algorithm development, optimization criteria, PHEV integration in the smart grid, and vehicles as part of the fleet

Parallel hydraulic pressure assist/work circuit hybrids for automated side loader refuse vehicles

2012 Summer.Includes bibliographical references.Hydraulic hybrids have been a subject of study for some time now and the application of these hybrids to refuse vehicles has been thoroughly explored. There is a lesser known subset of these which are known as pressure assist or work circuit hybrids that have unique potential to the field. Work circuit hybrids operate similar to a parallel hydraulic hybrid in that energy is captured and stored during regenerative braking. These hybrids differ in that the energy is then used to operate the hydraulic cylinders that handle and compact the refuse rather than reaccelerating the vehicle. Work circuit hybrids can be applied to many types of vehicles but the refuse vehicle application is the focus of this study. It was known prior to this study that work circuit hybrids are a potential solution to improve the fuel economy of refuse vehicles. However, prior to this study, the design of a work circuit hybrid had not been outlined in the literature. It was the goal of this thesis to answer the following questions. What are the fuel economy and cost characteristics of an optimized work circuit hybrid, and can an advanced hydraulic work circuit design justify further development towards productization? To answer these questions the study began by exploring, at a high level, the feasibility of work circuit hybrids on refuse vehicles. Then, two automated side loader, 28 cubic yard (21.4 m3), McNeilus Street Force MA refuse vehicles that operate on residential routes throughout Denver's surrounding areas were instrumented to produce drive cycle and hydraulic duty cycle data. This data was used to understand vehicle operation and to validate a reverse facing dynamic model of the stock refuse vehicle. A hybrid model was then produces and used in conjunction with a non-linear optimization algorithm to determine the potential benefit of this technology. This study concluded that a work circuit hybrid providing energy to the arm of a side loader refuse vehicle could achieve a 2.3% reduction in fuel consumption with a 4 year payback period using optimally sized hybrid components. The fuel usage reduction for these hybrids is limited to how well the available energy from regenerative braking is matched with the energy required by the work circuit. For this study, only 16% of the braking energy was utilized due to the selection of vehicle and hydraulic circuit. Work circuit hybrids also enable the use of an idle stop control logic, creating a unique opportunity to combine these two technologies yielding a fuel savings of 21.6% for the same vehicle. There are still some challenges to overcome before this technology can be truly understood. One such challenge is the fact that these hybrids require control of the torque converter lock up clutch and the transmission shifting strategy to make an engine driven configuration feasible. Implementing idle stop may also have hidden challenges including energy losses and emissions issues. However, it is the conclusion of this study that work circuit hybrids do offer a unique set of desired characteristics that warrant further development for future use in the field

Modelagem preliminar de um Sistema Híbrido Solar/Biomassa com Acumulação Hidráulica: Estudo de caso de uma Comunidade Isolada.

Apresenta-se um modelo para qualificar a produção de energia e a disponibilidade de um sistema híbrido Solar/Biomassa com armazenamento hidráulico e sua aplicação na comunidade isolada de Santo Antônio no Estado de Para (Brasil). Para tal fim tem-se desenvolvido um modelo matemático do acumulador hidráulico o qual foi validado com dados experimentais reportados na literatura e finalmente integrado em um modelo maior por meio de uma estratégia de integração e controle com modelos anteriormente desenvolvidos por outros autores para a geração de energia a partir da biomassa por meio de um sistema Gaseificador/MCI, e por meio da radiação solar com a utilização de um sistema Dish/Stirling. Os modelos foram criados e solucionados utilizando o software Simulink® de Matlab®. Observou-se mediante simulação com os modelo que embora a densidade de energia dos acumuladores seja baixa (inferior aos 10 kJ/l) este funciona como uma energia de emergência (back up), graças a sua rápida resposta, quando a fonte renovável primaria que quer ser maiormente aproveitada falhe, promovendo segurança ao sistema. Comprova-se também que os SHE baseados só em fontes renováveis podem ser uma solução para o problema de energia das regiões isoladas, já que se complementam para superar suas desvantagens individuais

The architecture of pneumatic regenerative systems for the diesel engine

For vehicles whose duty cycle is dominated by start-stop operation, fuel consumption may be significantly improved by better management of the start-stop process. Pneumatic hybrid technology represents one technology pathway to realise this goal. Vehicle kinetic energy is converted to pneumatic energy by compressing air into air tank(s) during the braking. The recovered air is reused to supply an air starter, or supply energy to the air path in order to reduce turbo-lag. This research aims to explore the concept and control of a novel pneumatic hybrid powertrain for a city bus application to identify the potential for improvements in fuel economy and drivability. In order to support the investigation of energy management, system architecture and control methodologies, two kinds of simulation models are created. Backward-facing simulation models have been built using Simulink. Forward-facing models have been developed in the GT-POWER and Simulink co-simulation. After comparison, the fully controllable hybrid braking system is chosen to realize the regenerative braking function. A number of architectures for managing a rapid energy transfer into the powertrain to reduce turbo-lag have been investigated. A city bus energy control strategy has been proposed to realize the Stop-Start Function, Boost Function, and Regenerative Braking Function as well as the normal operations. An optimisation study is conducted to identify the relationships between operating parameters and respectively fuel consumption, performance and energy usage. In conclusion, pneumatic hybrid technology can improve the city bus fuel economy by at least 6% in a typical bus driving cycle, and reduce the engine brake torque response and vehicle acceleration. Based on the findings, it can be learned that the pneumatic hybrid technology offers a clear and low-cost alternative to the electric hybrid technology in improving fuel economy and vehicle drivability