Hybrid Electric Traction Research Articles

Pareto front analysis of a multiobjective MPC-based EMS for a series hybrid electric tractor

Pareto front analysis of a multiobjective MPC-based EMS for a series hybrid electric tractor

MPC-based EMS for a Series Hybrid Electric Tractor

MPC-based EMS for a Series Hybrid Electric Tractor

Design of distributed hybrid electric tractor based on axiomatic design and Extenics

Led by the goals of energy saving and low emissions, tractors need more efficient operations under complex farmland working environments. The powertrain architecture of the tractor has a significant influence on the performance. Therefore, the research on the innovative design of the tractor powertrain architecture can improve the efficiency, energy saving, and environmental protection effects. Based on the creative design method of Axiomatic Design (AD) and Extenics, this paper conducts an innovative design analysis of the powertrain architecture of distributed hybrid electric tractor (DHET). Firstly, AD is used to perform the hierarchical analysis of the tractor powertrain architecture design. Then according to the design content, the design matrix (DM) is established, and the matrix is transformed to extract the 3 × 3 coupling contradiction matrix. Finally, the application of Extenics solves the contradictions in the innovative design of the tractor powertrain architecture. Simulation and prototype experiments have proved that DHET has the advantages of energy saving and emission reduction. This paper analyzes the innovative design of DHET's powertrain architecture, which can provide a theoretical basis and method support for the product's innovative design.

Comparative Analysis of Hybrid Electric Architectures for Specialized Agricultural Tractors

In this work, a comparative numerical analysis between the performance of a conventional specialized orchard tractor and those of three different hybrid electric tractor configurations is presented. The aim was to compare several powertrain configurations in the same working scenarios derived from field measurements. Peak power capabilities and endurance were numerically tested with specific load scenarios involving both transportation mission profiles and field activities with external implements powered through the power take off of the tractor. The proposed hybrid architectures were configured with the same battery-based energy storage system to perform the comparison with the same energy storage capabilities. Two parallel, two series and one electro-hydraulic hybrid configuration were modeled and tested through simulations. The parallel ones excelled in peak power performance, whereas the series configurations had the highest fuel savings. The electro-hydraulic configuration was proposed as an alternative able to allow for a downsized engine but also for the introduction of the Continuously Variable Transmission (CVT) functionality, which is always an interesting feature for such working machines.

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.

An intelligent energy management strategy for an off‐road plug‐in hybrid electric tractor based on farm operation recognition

Due to the growing emergence of vehicle electrification, agricultural tractor developers are launching hybrid powertrains in which energy management strategy (EMS) assumes a prominent role. This work mainly aims at developing an EMS for a plug-in hybrid electric tractor (PHET) to minimise fuel consumption and increase the operating range. The developed off-road PHET power sources are composed of a biogas-fuelled Internal Combustion Engine Generator (Bio-Gen), a photovoltaic system, and a battery pack. To control the power flow among different sources, a two-layer EMS is formulated. In this regard, initially, the farm operating mode is recognised by means of classification of a working cycle's features. Then, a control strategy based on a multi-mode fuzzy logic controller (MFLC) is employed to manage the power flow. At each sequence, the classifier identifies the farm operation condition and accordingly activates the relative mode of the MFLC to meet the requested power from the Bio-Gen. The performance of the proposed EMS has been evaluated based on three real-world typical agricultural working cycles. The results demonstrate the successful performance of the proposed intelligent EMS under farm conditions by maintaining the energy sources' operation in a high-efficiency zone which can lead to the extension of the working range and decrease fuel consumption.

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.

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.

Design, Development, and Evaluation of a PV_Bio-Gen Range Extender for an Off- Road Electric Tractor

Transformation from fossil fuels to clean energy is necessary due to the stricter environmental protection policies. Hence, replacing conventional vehicles by electric vehicles (EVs) and renewable energy based vehicles would be as solutions in advance. However, some constraints are raised, e.g., low energy density of renewable energy sources and recharging time of batteries. Among various alternatives renewable sources, photovoltaic (PV) and biofuels seem to be more available in farm applications. The objective of this research is to retrofit an existing electric tractor into a series hybrid electric through the use of a PV system and a biogas fueled engine generator set (Bio-Gen). Moreover, some field measurements are carried out to define typical working cycles for farm hybrid vehicle application. Considering these points, the modeling, simulation and developing of an Extended- Range Solar Assist Plug-In Hybrid Electric Tractor (E-RSAPHT) are presented in this paper. Due to multi-power sources, a heuristic control strategy is developed to increase the operating time. Experimental results showed that the proposed system could improve energy autonomy and fuel efficiency. For typically evaluated toolbars, the operation ranges of the trailer, boom-type sprayer, and water-pump system were found up to 7.3, 8.7, and 14 hours, which correspond to a working range extended up to 292, 255, and 320% compared to the base system, respectively. The analysis illustrated that even for a 2100 kg electric farm vehicle, a downsized 4.4 kW Bio-Gen allows the hybrid electric system to supply the power demand compared to the conventional system by using the internal combustion engine (ICE).

The concept of a hybrid traction power supply system

The growing shortage of energy resources to provide heavy traffic and high-speed traffic necessitates the development of a new power supply scheme for a traction network using sources of distributed generation of electric energy. Application of asymmetric distributed traction power system with the use of distributed generation allows to increase electric energy efficiency of the feed system of rolling stock, reduce its material capacity and increase the reliability of the functioning of the railway system as a whole. The proposed structure of the hybrid electric traction system involves the creation of a new paradigm aimed at ensuring high demands on the voltage and specific power in the traction network, which will allow to improve the quality and safety of the transportation process when increasing the energy performance indicators. This paradigm will allow to form a new philosophy of building traction power systems. The key elements of this philosophy are decentralization of generation and consumption of electric energy, the use of intelligent electric equipment, distributed power supply management in a single information space of the energy process during transportation. The peculiarity of the proposed work is the optimal combination of technological processes of transmission, consumption of electric energy and transportation, taking into account the specific conditions of functioning of the electrified section: points of connection of power sources and their type, profile of the track, schedule of trains, types of rolling stock and equipment. Conceptually, the hybrid traction power system is an electric hub, in which the inputs are generating points, and the output is the power supply system of the rolling stock. The internal structure of the electric power objects of the hub is determined by the type of transformation and accumulation of electric energy and ways of managing these objects in real time.

Development of hybrid electric heavy-duty truck with self-propelled trailer

A new architecture of hybrid drivetrain for tractors and semi-trailers is proposed. The goal is to utilise the maximum capability of the hybrid electric tractor and semi-trailer and to enhance the traction and fuel consumption efficiencies. This drivetrain architecture employs a self-propelled trailer so that the tractive effort is shared between the tractor and the semi-trailer. A comprehensive model of the vehicle, including the drivetrain model, is developed and a fuzzy logic controller (FLC) is used to design the power management system (PMS). Simulation runs of the computer model are performed on two standard driving cycles to evaluate both the traction efficiency and fuel consumption of the proposed hybrid drivetrain architecture. The comprehensive results obtained indicate that the proposed self-propelled trailer drivetrain presents a superior advantage over the non-hybrid drivetrains and also the typical hybrid drivetrain for heavy vehicles.

Thermal Real-Time Monitoring of a Gearbox Integrated IPM Machine for Hybrid-Electric Traction

Aiming to monitor the temperatures of critical components of gearbox integrated interior permanent magnet synchronous machines for hybrid-electric vehicles, we present the development of a real-time lumped parameter thermal network model. To this aim, sensitivity and heat flow path analyses are first carried out to identify the most relevant thermal paths. Next, the influence of the gearbox integration on the temperatures within the electric machine and its consideration in the modeling are investigated. The models are then verified experimentally, showing an accuracy of ±5 K. Finally, challenges and uncertainties of the real-time on-board modeling context are ultimately discussed.

Influence of Machine Integration on the Thermal Behavior of a PM Drive for Hybrid Electric Traction

This paper describes a method for fast identification of the thermal behavior of vehicle integrated electric drives to propose a better understanding of electric machine design tailored to driving cycles. A simple, but satisfactorily accurate, calculation method for the estimation of machine losses, which is an input for the analytic thermal network, in the early design stage is introduced. The analytic models, which are verified using measurement data, are used for parameter and case studies for consideration of the thermal environment, with a focus on the gearbox. The first case study analyzes the influence of the gearbox on the thermal behavior of critical machine components. Aiming to use the gearbox lubricant for cooling the winding heads, an improvement of machine performance using an alternative cooling approach, which cools down the end windings, is shown in the second case study.

Comparing Various PM Synchronous Generators: A Feasible Solution for High-Power, Off-Highway, Series Hybrid, Electric Traction Applications

Different disc-type axial flux permanent magnet (AFPM) generators are designed and compared in this article for a Caterpillar D7E track-type tractor (TTT) electric drive model. The design of several feasible generators with multiple stators and rotors are completed for the given electrical and mechanical specifications and compared with a conventional permanent magnet (PM) generator in terms of power density, torque density, loss distribution, efficiency, heat dissipation, volume, inertia, and weight. Electromagnetic, mechanical, and thermal analyses are also accomplished to finalize the designs. The results reveal the benefits of axial gap PM generators over radial gap generators for a hybrid electric traction application.

Powertrain System Design of Medium-sized Hybrid Electric Tractor

Powertrain System Design of Medium-sized Hybrid Electric Tractor

Plowing Performance Simulation and Analysis for Hybrid Electric Tractor

According to plowing operation characteristics, a case study on a parallel HET (hybrid electric tractor) with the torque combinator is conducted to develop a plowing operation performance simulation system. The mathematical models of drive equilibrium, battery, power combinator and control system are established respectively. A simulation system for evaluating the tractive performance, fuel economy, battery characteristics and controller performance of HET is developed in the environment of MATLAB/Simulink. Simulation results suggest that: in this HET, the output torque and traction vary in a large range with the variations in the operation modes and SOC level of the battery; in the common interval of SOC (0.4~0.7), compared with the traditional tractor, HET can achieve larger output torque with a fuel consumption reduction of 18% ~20% in discharge mode; with the capability of keeping the battery charge-discharge stage stable and guaranteeing the SOC variation in a small range, the controller meets with the requirements of plowing operation and benefits the stability of the tractor power and the extension of battery life cycle.

플러그인 하이브리드 전기 트랙터에서 다양한 작업환경을 고려한 주행전략에 대한 연구

농업용으로 사용되는 소형트랙터 개발의 최근 이슈는 친환경과 높은 연비이다. 소형 트랙터는 비닐 하우스 등 실내에서 작업이 가능하도록 설계 되므로 최근 전기 트랙터에 대한 수요가 증가하고 있다. 그러나 전기트랙터는 배터리 등 전기에너지 저장장치의 용량 및 크기공간의 제약으로 충분한 작업시간과 성능 확보에 한계가 존재한다. 따라서 최근 전기 트랙터와 내연기관 트랙터의 특징을 결합한 플러그인 하이브리드 트랙터에 대한 개발이 진행 중이다. 트랙터는 기본 주행 능력외에 PTO 를 통한 여러 작업을 수행 할 수 있어야 하며, 플러그인 하이브리드 트랙터에서는 각각의 작업에 대한 주행전략이 필요하다. 본 연구에서는 트랙터의 작업 모드를 개발하고 그에 대한 각 작업의 작업시간 능력 등을 확인하였다.

Design, Construction and Evaluation of a Sun-Tracking System on a Mobile Structure

Although using sun-trackers are not mandatory in PV systems, their application improves the efficiency and maximizes daily collected energy. To maximize collected energy from an on-board PV array, on a solar assist plug-in hybrid electric tractor (SAPHT) a sun-tracking system was designed and installed. Considering the mobile structure above the SAPHT, designing a time and date independent sun-tracker was desirable. Using four light dependent resistive sensors a sun-tracking system on a mobile structure was constructed and evaluated. Using the designed sun-tracking system, the experimental tests illustrated that 30% more energy was collected in comparison to that of the horizontally fixed mode. Only 1.8% of all maximized energy is consumed by actuators of the designed tracking system. However, the developed sun-tracking system is robust and inexpensive and showed acceptable performance during experimental tests.

Life-cycle assessment of a Solar Assist Plug-in Hybrid electric Tractor (SAPHT) in comparison with a conventional tractor

The most well-known reason of global warming is equivalent carbon dioxide (CO 2equ) emitted from fossil fuels combustion in on-road and off-road vehicles. An appreciable portion of off-road pollution is allocated to farm implements. All cited studies have shown that renewable based electric vehicles (EVs) decrease petroleum consumption and consequently reduce criteria emissions under nearly all circumstances. Considering this, a Solar Assist Plug-in Hybrid electric Tractor (SAPHT) was designed, constructed and evaluated. This research evaluated the life cycle analysis of SAPHT project and compared the results with that of an internal combustion engine tractor (ICET). The life cycle was analyzed based on economical cost and environmental emissions. The externality of environmental pollutions was calculated to derive the life-cycle costs (LCC). The results showed that substituting each ICET by SAPHT can prevent 14 ton CO 2equ emission to atmosphere annually. Also it prevents a high volume of other emissions such as CO, NO x and PM 10 entering the atmosphere. LCC assessment emphasizes on economical effectiveness of SAPHT rather than ICET at any diesel fuel price, therefore, increasing fuel unit prices leads to more effectiveness. It is concluded that levelized cost of energy (LCE) in €/kW h for ICET is almost twice as that of SAPHT. Some of these advantages for SAPHT are offset in part by high purchase costs, heavy and massive batteries and low operating range.

Evaluation of alternative battery technologies for a solar assist plug-in hybrid electric tractor

This paper looks at the various battery technologies available for use in solar assist plug-in hybrid electric tractors In this context, solar assist plug-in hybrid electric tractors are those that may be used in light-duty agricultural operations. To determine the most suitable battery, four common technologies are analyzed looking at the environmental life-cycle effects and costs.