The power requirements imposed on an active vibration isolation system are quite important to the overall system design. In order to improve the efficiency of an active isolation system we analyze different feedback control strategies which will provide electrical energy regeneration. The active isolation system is modeled in a state-space form for two different types of actuators: a piezoelectric stack actuator and a linear electromagnetic (EM) actuator. During regenerative operation, the power is flowing from the mechanical disturbance through the electromechanical actuator and its switching drive into the electrical storage device (batteries or capacitors). We demonstrate that regeneration occurs when controlling one or both of the flow states (velocity and/or current). This regenerative control strategy affects the closed loop dynamics of the isolator which sees its damping reduced. / Master of Science

The high price of batteries in working machines with electric drives offer a potential for investment in energy-saving hydraulic systems. The decentralized power network opens up new approaches for hydraulic- and hybrid circuits. In addition, the regeneration of energy can be used at any point of the machine. For the example of an excavator arm drive with a double cylinder two compact hydraulic circuits are presented, which relieve a central hydraulic system.

Este trabalho aborda a aplicação de uma máquina elétrica síncrona do tipo tubular linear de ímãs permanentes em um sistema de suspensão semiativa. O uso de amortecedores eletromagnéticos lineares em sistemas de suspensão não é uma ideia nova, mas a maioria dos trabalhos publicados sobre este assunto concebem soluções ativas e negligenciam as semiativas, sobretudo com estudos experimentais. Nesta pesquisa é discutido um modelo dinâmico eletromecânico acoplado de um sistema de suspensão semiativa, considerando um amortecedor eletromagnético linear e também apresentando dados experimentais. Leis da mecânica clássica e do eletromagnetismo são aplicadas para descrever o sistema que combina teoria de vibrações e máquinas elétricas. Um modelo virtual com vários subsistemas foi implementado no ambiente MATLABR /Simulink/Simscape para associar equações e simular o desempenho global. Para o caso passivo, os resultados numéricos e experimentais validam os parâmetros e confirmam a funcionalidade do sistema e a metodologia proposta. Simulações e testes experimentais para o caso semiativo são consistentes, mostrando uma melhoria na transmissibilidade de deslocamento, em relação ao modo passivo, e a possibilidade de regeneração de energia. / This work addresses the application of a tubular linear permanent magnet synchronous machine working as a damper for a semi-active suspension system. The use of linear electromagnetic dampers in suspension systems is not a new idea. However, most published papers on this subject outline active solutions and neglect semi-active ones, above all, with experimental studies. Here a dynamic mechanicalelectromagnetic coupled model for a semi-active suspension system is reported. This is in conjunction with a linear electromagnetic damper and also presents experimental data. Classical laws of mechanics and electromagnetics are applied to describe a dynamic model combining vibration and electrical machines theories. A multifaceted MATLABR /Simulink/Simscape model was implemented to incorporate equations and simulate global performance. For the passive case, numerical and experimental results validate the parameters and confirm system function and the proposed methodology. Simulation and practical results for the semi-active case are consistent, showing an improvement in the displacement transmissibility and the possibility of energy regeneration.

The high price of batteries in working machines with electric drives offer a potential for investment in energy-saving hydraulic systems. The decentralized power network opens up new approaches for hydraulic- and hybrid circuits. In addition, the regeneration of energy can be used at any point of the machine. For the example of an excavator arm drive with a double cylinder two compact hydraulic circuits are presented, which relieve a central hydraulic system.

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Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17555号 / 工博第3714号 / 新制||工||1566(附属図書館) / 30321 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 中部 主敬, 教授 牧野 俊郎, 教授 小森 悟 / 学位規則第4条第1項該当

<p>The electrification trend affecting off-road vehicles is paving the way toward dedicated electrified hydraulic actuation systems. Although traditional centralized fluid power architectures are still utilized in many applications for low cost, power density, and reliability, nowadays emission policy results in an increasing interest in developing electro-hydraulic actuator (EHA) solutions. EHAs enable non-throttling actuation and energy recuperation during overrunning loads, leading to higher transmission efficiency and lower fuel consumption. These features in energy efficiency make EHAs competitive in meeting emission regulations compared to conventional hydraulic solutions.</p> <p>The key challenge in developing the EHA solution comes from the high cost and space requirements, especially for the adoption of self-contained EHAs in mobile applications. In this study, two architectures for the EHA are proposed, a closed-circuit architecture and an open-circuit one, to determine the most practical and efficient configuration. The most effective open-circuit architecture with distributed concepts is further investigated for implementation, which requires less modification of the mechanical structures and performs more efficiently than the closed-circuit alternative. The proposed EHA is driven by an electro-hydraulic unit (EHU) consisting of a variable-speed electric motor and a fixed-displacement hydraulic pump, which is relatively cost-effective. A novel hydraulic configuration is proposed, which allows the EHA to cover full-speed operating ranges in four quadrants. </p> <p>To verify the EHA design, the behavior of the proposed system should be predicted prior to costly experiments and demonstrations. For this purpose, an integrated simulation model is developed based on the lumped parameter approach in the Amesim environment. The model includes the electric system, the hydraulic system, and the mechanism to be implemented, which are capable of flexible analysis of functionality, efficiency, and thermal performance.</p> <p>In this work, a dedicated test rig for EHA testing is developed. The test rig can help verify EHA performance, test the control algorithm, and diagnose errors before implementing the system on real applications. The experimental results from the test rig also validate the simulation model. An independent load drive of the test rig allows testing all possible  loading conditions of the proposed EHA, thus demonstrating the energy performance in four quadrants. Thermal behavior is investigated with long duty cycles to determine the need for additional cooling equipment. After the validation of the hydraulic configuration, a power electronics setup is added to the test rig, which allows to drive the EHA system with the novel designed EHUs. Validation on the test platform paves the way for implementation in a vehicle. </p> <p>As a final step, the proposed EHA system is implemented in a reference vehicle, a Case New Holland TV380 skid steer loader. A novel designed EHU is adopted to drive the system for technology demonstration. The energy savings capacity of the EHA is investigated in comparison to the baseline measurements of the traditional open-center hydraulic architecture. The impressive savings from the reduction of throttling losses and energy recovery guide the possible commercialization of such EHAs in mobile hydraulic applications. The controller design of the implemented EHA system is investigated with the aim of improving the dynamic performance, e.g., reducing damping oscillation. Basic power management strategies are also studied to integrate EHA with the power train of current hydraulic machines. Regarding future work, based on this research but not within the scope of this study, the proposed EHA system can be adopted with different types of prime movers, such as axial piston machines as the hydraulic part of an EHU. Furthermore, the design approach proposed in this study can help resize the EHA system for other applications with different loading conditions and power requirements, and the energy savings capability can be further investigated. With this, a comprehensive market analysis will be performed for the commercialization of EHA. </p>

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