A Model-Based Design Approach for a Parallel Hybrid Electric Tractor Energy Management Strategy Using Hardware in the Loop Technique

Recent developments in emissions regulations are pushing Non-Road Mobile Machineries manufacturers towards the adoption of more efficient solutions to reduce the amount of pollutants per unit of work performed. Electrification can be a reasonable alternative to traditional powertrain to achieve this goal. The higher complexity of working machines architectures requires, now more than ever, better design and testing methodologies to better integrate electric systems into mechanical and hydraulic layouts. In this work, the attention focused on the use of a Hardware in the Loop (HIL) approach to test performance of an energy management strategy (called load observer) developed specifically for an orchard tractor starting from field characterization. The HIL bench was designed to replicate a scaled architecture of a parallel hybrid electric tractor at mechanical and electrical level. The vehicle behavior was simulated with a personal computer connected on the CAN BUS network designed for the HIL system. Several tasks were simulated starting from data gathered during field measurements of a daily use of the machine. Results showed good performance in terms of load split between the two power sources and stability of the speed control although the variability of the applied load

study of a hardware in the loop bench for an electrified working vehicle

n/

Micro-scale modeling of Lithium-ion battery

Good energy density, long lifetime, high capacity and high voltage make Lithiumion batteries the most widespread energy storage systems, suitable for several fields of application. Nevertheless, usage leads to cell degradation which mainly results in capacity and power fade. Degradation phenomena are the result of the interaction between mechanical and electro-chemical mechanisms, which are reviewed in this paper. Lithium-ion batteries store and deliver electric energy by means of ions transport between anode and cathode through the electrolyte. The active material of the electrodes consists of micrometer particles which can host lithium ions through insertion/extraction processes. These processes are modelled as diffusion-mechanical problem, since the lithium concentration gradient within the particle due to ions diffusion generates internal stresses in analogy with a temperature gradient. The model in this work, usually referred as diffusion induced stress (DIS), can predict the stresses in the active material particles which are the driving force for damage, pulverization, exfoliation and crack propagation. Indeed, the damage induced by the insertion/extraction processes explains the capacity reduction over charge/discharge cycles: a critical issue for batteries lifetime

study and identification of the thermo electric behavior of lithium ion batteries for electric vehicles

Abstract In this paper, the study and the modeling of a lithium-ion battery cell is presented. A programmable electronic load was laboratory designed and realized in order to reduce the cost of the total equipment. The testing system is supplemented with a commercial programmable power supply. This dedicated laboratory equipment can be used to apply cycles according to user defined current profiles. Some tests were performed on the battery cell. The acquired data allowed to carry out the battery modeling and the parameters identification procedure. Finally, the mechanical and the thermal phenomena to which a battery is subjected are presented and discussed

working cycle requirements for an electrified architecture of a vertical feed mixer vehicle

Abstract In the last years, the need for lower pollutant emissions has become one of the most discussed topic worldwide. Governments establish stricter regulations almost yearly in order to push the industry towards more efficient machines or, at least, lower harmful gas emissions. Agriculture is experiencing the same trend with strict regulations which force manufacturers to the massive use of diesel engine exhaust after-treatment systems. At the same time, industries are considering other options that can satisfy regulations and also add functionalities to their products. This research wants to show the results of the study which led to the first electric prototype of a self-propelled vertical feed mixer. A methodological approach in collaboration with an Italian feed mixer wagons manufacturer, allowed to characterize the traditional machine in all its working conditions leading to the necessary requirements for the design of the final electric architecture

multibody simulation of a small size farming tracked vehicle

Abstract In this paper, the Multibody (MTB) model of a small size tracked vehicle for farming applications is shown. These machines may encounter several working scenarios in their operating life when equipped with different working tools. Moreover, they are used in unstructured environments that are very difficult to predict in terms of terrain conditions and slope. Depending on these factors, the actual tractive force may vary a lot requiring often a high number of field tests to qualify the vehicle performance. The numerical model built in MSC ADAMS, wants to be a software environment where several working conditions can be exploited considering the dynamic properties of the vehicle. This work focuses on the global kinematic behavior, considering the difference between imposed motion laws and the actual one

Shape Influence of Active Material Micro-Structure on Diffusion and Contact Stress in Lithium-Ion Batteries

Electrochemical-mechanical modelling is a key issue to estimate the damage of active material, as direct measurements cannot be performed due to the particles nanoscale. The aim of this paper is to overcome the common assumptions of spherical and standalone particle, proposing a general approach that considers a parametrized particle shape and studying its influence on the mechanical stresses which arise in active material particles during battery operation. The shape considered is a set of ellipsoids with variable aspect ratio (elongation), which aims to approximate real active material particles. Active material particle is divided in two domains: non-contact domain and contact domain, whether contact with neighbouring particles affects stress distribution or not. Non-contact areas are affected by diffusion stress, caused by lithium concentration gradient inside particles. Contact areas are affected simultaneously by diffusion stress and contact stress, caused by contact with neighbouring particles as a result of particle expansion due to lithium insertion. A finite element model is developed in Ansys™APDL to perform the multi-physics computation in non-spherical domain. The finite element model is validated in the spherical case by analytical models of diffusion and contact available for simple geometry. Then, the shape factor is derived to describe how particle shape affects mechanical stress in non-contact and contact domains

Analysis of a Parallel Hybrid Electric Tractor for Agricultural Applications

The field of Non-Road Mobile Machineries (NRMM) is now more than ever considering the adoption of electric systems to reduce the amount of pollutant emissions per unit of work. However, the intensity and complexity of the tasks performed by a working machine during its life is an obstacle to the widespread adoption of electric systems. Specific design solutions are required to properly split the power output of the hybrid powertrain among the different loads (wheel, power take off, hydraulic tools, etc.). In this work, a performance analysis between a traditional agricultural tractor and a proposed hybrid electric architecture of the same vehicle is shown. The comparison was performed on a set of tasks characterized on a real orchard tractor which were used to build the input signals of two different numerical models: one for the traditional diesel architecture and the other for the hybrid electric solution. The two models were tested with the same operating tasks to have a one to one comparison of the two architectures. Peak power capabilities of the hybrid solution and performance of the Load Observer energy management strategy were investigated to validate the feasibility of the proposed solution

Numerical Performance Investigation of a Hybrid eCVT Specialized Agricultural Tractor

The need for highly efficient agricultural machineries is increasing the interest of the research community and of industrial manufacturers towards the use of integrated electric systems in combination with traditional powertrain elements. In this work, a hybrid electric tractor with electric continuously variable transmission (eCVT) capabilities was studied to investigate their performance in comparison with that of traditional diesel-powered tractor designs. This hybrid electric configuration can be classified as a power-split architecture that aims to combine the best characteristics of both the simpler parallel and the series hybrid layout while minimizing their main drawbacks. An eCVT configuration can allow for optimizing the diesel operating point with respect to the current working conditions, and achieving peak power performance and energy saving with relatively small electric machines. The proposed hybrid eCVT (HeCVT) tractor architecture was studied using a numerical model that allowed for developing two different control strategies: a charge depleting mode enabling the driver to use full power for the most power-intensive scenarios and a charge sustaining mode developed to optimize efficiency and battery use along an entire work day. To test the proposed architecture, several tasks derived from experimental field measurements on a specialized agricultural tractor were used. HeCVT results were compared with a numerical model of the traditional tractor validated by these experimental data. The HeCVT tractor showed good performance in terms of peak power capabilities using a downsized diesel engine, and consistent fuel savings were obtained according to typical daily working scenarios

Thermo magnetic {FEM} simulation of a {PM} synchronous motor with input data from telemetry driving cycles

Abstract Nowadays, the requirements to reduce greenhouse gas emissions and to provide a healthy and more habitable environment, has led to the development of several sustainable alternative for eco-mobility. Since the improvement of internal combustion engine has reached a steady state point in terms of overall efficiency, the increasingly stringent requirements imposed by international normative standards are leading automotive companies to find other alternatives to reduce pollution. Thanks to the exponentially growth of power electronics, the huge interest on research of high energy and power density batteries and the more integration of the embedded systems, the central role of the electric drive has taken over on most of vehicles applications. The wide use of permanent magnets synchronous motors for electric vehicles application has rapidly spread out, thanks to their capability to provide high torque and efficiency with low weight and size. Since the natural behaviour of permanent magnets to demagnetize under severe conditions, both coupled thermal and magnetics, the necessity to understand and predict the phenomena is mandatory. This paper carries out a performance analysis in duty cycle, given by real CAN and GPS readings in a studied pathway, with discussion of numerical and graphic technical evaluations. Finite element software has also been used for coupled electromagnetic and thermal calculation to set the magnets working point and establish the temperature distribution within the motor itself during the whole thermal transient. A particular overview is done on the dependence of material used and different cooling solutions adopted