Shell Eco-marathon Competition Research Articles

Implementation of Optimized Regenerative Braking in Energy Efficient Driving Strategies

In this paper, determination of optimized regenerative braking-torque function and application in energy efficient driving strategies is presented. The study investigates a lightweight electric vehicle developed for the Shell Eco-Marathon. The measurement-based simulation model was implemented in the MATLAB/Simulink environment and used to establish the optimization. The optimization of braking-torque function was performed to maximize the recuperated energy. The determined braking-torque function was applied in a driving strategy optimization framework. The extended driving strategy optimization model is suitable for energy consumption minimization in a designated track. The driving strategy optimization was created for the TT Circuit Assen, where the 2022 Shell Eco-Marathon competition was hosted. The extended optimization resulted in a 2.97% improvement in energy consumption when compared to the result previously achieved, which shows the feasibility of the proposed methodology and optimization model.

Vehicle Model-Based Driving Strategy Optimization for Lightweight Vehicle

In this paper, driving strategy optimization for a track is proposed for an energy efficient battery electric vehicle dedicated to the Shell Eco-marathon. A measurement-based mathematical vehicle model was developed to simulate the behavior of the vehicle. The model contains complicated elements such as the vehicle’s cornering resistance and the efficiency field of the entire powertrain. The validation of the model was presented by using the collected telemetry data from the 2019 Shell Eco-marathon competition in London (UK). The evaluation of applicable powertrains was carried out before the driving strategy optimization. The optimal acceleration curve for each investigated powertrain was defined. Using the proper powertrain is a crucial part of energy efficiency, as the drive has the most significant energy demand among all components. Two tracks with different characteristics were analyzed to show the efficiency of the proposed optimization method. The optimization results are compared to the reference method from the literature. The results of this study provide an applicable vehicle modelling methodology with efficient optimization framework, which demonstrates 5.5% improvement in energy consumption compared to the reference optimization theory.

Model of a prototype vehicle powered by a hybrid hydrogen system

The paper presents a physical mathematical model of the movement of a prototype vehicle equipped with an electric drive system powered by two sources of hydrogen fuel cell and supercapacitors. The model is based on the analysis of the forces acting on the vehicle during motion, taking into account both resistance to motion and propulsion. The model also considers the flow of electrical energy from two sources: a hydrogen fuel cell and supercapacitors, taking into account energy buffering. The aim of the model was to develop a tool to analyse fuel consumption at different control strategies of energy flow in a vehicle. The paper also presents the results of model identification for the Hydros prototype vehicle developed at Lublin University of Technology for the Shell Eco Marathon competition. Model validation was performed for a selected run during the 2019 London competition. High agreement of the model with the results of the actual vehicle was obtained.

Comparative analysis of the hybrid power system topology for a high efficiency prototype vehicle

The paper presents a comparative analysis of three solutions of the power supply topology of a high-efficiency hybrid vehicle. The analysis was carried out for the Hydros prototype vehicle developed at the Lublin University of Technology for the Shell Eco Marathon competition. This vehicle is driven by an electric motor powered by two energy sources: hydrogen fuel cells and supercapacitors, allowing temporary energy buffering. Three variants of the mutual connection of the two energy sources to a single receiver were analysed, taking into account the voltage converter systems between the individual components of the system. The aim of these analyses was to determine the most energy-efficient solution.

An Ultra-Efficient Lightweight Electric Vehicle—Power Demand Analysis to Enable Lightweight Construction

A detailed analysis of the power demand of an ultraefficient lightweight-battery electric vehicle is performed. The aim is to overcome the problem of lightweight electric vehicles that may have a relatively bad environmental impact if their power demand is not extremely reduced. In particular, electric vehicles have a higher environmental impact during the production phase, which should be balanced by a lower impact during the service life by means of a lightweight design. As an example of an ultraefficient electric vehicle, a prototype for the Shell Eco-marathon competition is considered. A “tank-to-wheel” multiphysics model (thermo-electro-mechanical) of the vehicle was developed in “Matlab-Simscape”. The model includes the battery, the DC motors, the motor controller and the vehicle drag forces. A preliminary model validation was performed by considering experimental data acquisitions completed during the 2019 Shell Eco-marathon European competition at the Brooklands Circuit (UK). Numerical simulations are employed to assess the sharing of the energy consumption among the main dissipation sources. From the analysis, we found that the main sources of mechanical dissipation (i.e., rolling resistance, gravitational/inertial force and aerodynamic drag) have the same role in the defining the power consumption of such kind of vehicles. Moreover, the effect of the main vehicle parameters (i.e., mass, aerodynamic coefficient and tire rolling resistance coefficient) on the energy consumption was analyzed through a sensitivity analysis. Results showed a linear correlation between the variation of the parameters and the power demand, with mass exhibiting the highest influence. The results of this study provide fundamental information to address critical decisions for designing new and more efficient lightweight vehicles, as they allow the designer to clearly identify which are the main parameters to keep under control during the design phase and which are the most promising areas of action.

The test-bed research of a low power low-temperature PEM fuel cell

The article presents the results of testbed research of Horizon H-300 PEM Fuel Cell. It is a Polymer Electrolyte Membrane Fuel Cell (PEMFC) which reaches 300 Watt output power. It is a power source for hyper-light prototype vehicles taking part in the Shell Eco-Marathon competition. The aim of the research was to develop the load characteristics of a PEM type cell. The tests were carried out in a steady state of operation and included developing the characteristics of the output voltage concerning the load current. The current load was carried out by a programmable electronic load with the ability to accurately determine the load current. It also allows for measuring the output voltage. The tests were carried out in the load current range 0.2 - 7A, which is a significant range of the cell’s operating parameters which is used in the vehicle. During the tests, hydrogen consumption was also measured at individual points of the cell’s operation using a flow meter. This has also allowed the development of the characteristics of fuel consumption and power generated by the cell. The developed characteristics are presented in this article. A linear characteristic of power and fuel consumption in the function of the current loading on the cell was obtained for practically the whole range of the tested loads. Also, the specific fuel consumption is linearly dependent on the load power, and the lowest values (in the example the highest efficiency) were obtained at the lowest value of load power.

Strength analysis of the drive wheel hub of a hydrogen-powered prototype hyper-light vehicle

This article presents a strength analysis of the rear wheel hub of the prototype vehicle for the Shell Eco-Marathon competition. Due to only one wheel in the vehicle’s driving axle, all drive components and the wheel are subjected to higher loads. Therefore, the rear hub must withstand the loads generated by the rear part of the vehicle and the powertrain. The aim of the paper was to develop a hub with the minimum possible weight while fulfilling the strength conditions. The low weight of the hub is particularly important because of the efforts to achieve the highest possible efficiency of the drive system, which generates less energy loss and the ability to travel a longer distance on the same amount of fuel. The article presents the developed three-dimensional model of the hub. The suitable materials for the individual elements that are parts of the whole hub were selected. The three-dimensional model was tested to strength analysis using the finite element method with the use of Abaqus® software. The developed calculation mesh as well as the assumptions and boundary conditions of the modelling carried out are presented. The results of the simulation tests, which are the basis for further design work are also described.

Driving strategy for minimal energy consumption of an ultra-energy-efficient vehicle in Shell Eco-marathon competition

The paper focuses on the different driving strategies (driving cycles) for minimisation of the energy consumption of an ultra-energy-efficient electric vehicle developed by students for Shell Eco-marathon competition. The vehicle runs on hydrogen fuel and completes a set track with a 1420 m length and zero vertical deviation which is used for the 2019 European edition of the contest. A dynamic simulation model of the vehicle is developed taking into account vehicle resistance forces. A simplified model of the propulsion system is also described and used in the simulation. The propulsion system consists of a hydrogen fuel cell with a 1 kW rated power output, electric motors, electric converters, motor controllers and transmission. Furthermore, a strategy overview is proposed by which the vehicle complies with all necessary strategy limitations deriving from the competition rules. The various driving strategies, that comply with the competition average speed and differ from one another by the number of motors and transmission ratio, are simulated. The optimisation is done by changing the maximal and the minimal no-load speeds of the vehicle. A comparison of the energy usage is therefore conducted based on these strategies and the optimal one is chosen. In conclusion, additional driving strategies are proposed, in case more vehicle manoeuvrability or simpler driving style are desired during the race.

Developing of automatic lap counting system for electric vehicle at Shell Eco-marathon competition

The article shows the development of a closed circuit track counting system made from a prototype electric car that was specifically developed for the Shell Eco Marathon. The system records the laps made by transmitting and receiving radio waves (RF). The entire electronic system was built on the Arduino microcontroller platform and one-way radio frequency transceiver modules. The design of the system was developed using Catia V5 3D modeling software. Additive technology was used to reduce the mass of the system.

Vehicle’s energy efficiency via pilot work’s efficiency in Shell Eco-marathon competition

Shell Eco-marathon is a competition about energy efficiency and the first thing one have to do, is to design and build lightweight, aerodynamic vehicle with fine mechanical transmission and tires with low rolling resistance. Depending on power unit type, there is a need of perfect way of transforming chemical or electrical energy to mechanical one. In addition, almost every team develops their own driving strategy, applied by the pilot in the competition. Doing this, in the best way they can do, most competitors decide before-mentioned is the maximum, but if one can look to the vehicle plus the pilot like a system, there is more possibilities for improving the efficiency of that system. This paper includes analysis of vehicle control functions and specific organizational distribution and design of vehicle’s controls, in accordance with the capabilities of the pilot.

Designing Shell Eco Marathon Car Bodies with Solid Work

The Shell Eco Marathon is a world-class car competition for students. Through this competition, students compete to create innovation and creativity in the development of vehicle technology. The final result of this competition is the birth of vehicles that are economical, environmentally friendly, including a lightweight and aerodynamic body. This study aims to produce an urban concept car body design for racing purposes, with several provisions that comply with the Shell Eco Marathon competition regulations, have a low drag coefficient and turbulence value. This research includes research and development (R&D), using the ADDIE development model (Analysis, Design, Development, Implementation, and Evaluation). The test object is the 3D urban concept body shape design. The development of the urban concept body design uses the Solid work 2018 software with a flow simulation feature to analyze 3D urban concept body shape designs. The results of this research and development are (1) the design of the car body shape has met the competition regulations, (2) the drag coefficient value can be achieved at 0.1965, and (3) the value of turbulence intensity can be achieved at 0.133%. The results showed that the development of the urban concept body shape design was as planned.

Development and Application of Advanced Technological Solutions within Construction of Experimental Vehicle

Changing market requirements, pressure to minimize production costs, competition, but also legislative restrictions have an impact on a number of areas, not excluding the automotive industry. Currently, development trends are moving towards the application of advanced technological solutions and materials, with the aim to reduce vehicle‘s weight, increase their strength and safety, and at the same time reduce the emission of vehicles. The Shell Eco Marathon competition is an excellent platform for the implementation of these activities. The main goal of the competition is to support the creative invention of research teams and bring innovative ideas and technical solutions. The scientific article focuses on a detailed analysis of development steps in the construction of experimental vehicles. The results of the research were presented at a competition in London 2019 with successful achievement. This work is a contribution to the design and aerodynamic optimization of the body and at the same time brings new ideas and structural elements to improve the production power unit.

Benefits of using TI6AL4V alloy for connecting rod and crankshaft of a four-stroke ICE

The article presents the process of designing a connecting rod and crankshaft made of titanium alloy Ti6Al4V in accordance with the assumed dimensions. The Engine unit will power a vehicle taking part in the Shell Eco-Marathon competition. The elements were subjected to FEM simulation for static and fatigue strength to check their trouble-free operation. The research has had positive effects, making further modification of the designed parts unnecessary. The energy needed to set in motion elements made of steel and Ti6Al4V alloy was compared, which results in a difference in fuel consumption.

Nafion® Tubing Humidification System for Polymer Electrolyte Membrane Fuel Cells

Humidity and temperature have an essential influence on PEM fuel cell system performance. The water content within the polymeric membrane is important for enhancing proton conduction and achieving high efficiency of the system. The combination of non-stationary operation requests and the variability of environment conditions poses an important challenge to maintaining optimal membrane hydration. This paper presents a humidification and thermal control system, to prevent the membrane from drying. The main characteristics of such a device are small size and weight, compactness and robustness, easy implementation on commercial fuel cell, and low power consumption. In particular, the NTHS method was studied in a theoretical approach, tested and optimized in a laboratory and finally applied to a PEMFC of 1 kW that supplied energy for the prototype vehicle IDRA at the Shell Eco-Marathon competition. Using a specific electronic board, which controls several variables and decides the optimal reaction air flow rate, the NTHS was managed. Furthermore, the effects of membrane drying and electrode flooding were presented.

Optimization of control strategy for a low fuel consumption vehicle engine

The objective of this work is to optimize control strategy of a vehicle which leads to low fuel consumption. A specialized car developed especially to take part in the Shell Eco-marathon competition is considered. At first a general first principle model of the vehicle is discussed, its parameters are tuned taking into account the data obtained experimentally and the model is validated using real measurements. Next, the optimization problem leading to low fuel consumption is discussed. The engine usage continuous-time control strategy is parametrized by means of 4 methods in order to reduce computational complexity. Since the resulting constrained optimization problem is nonlinear, as many as 5 evolutionary algorithms are examined in terms of quality of the final result and computational efficiency. Inefficiency of a classical gradient-based optimization method is demonstrated. Finally, a complete decision system which can act as an autonomous vehicle engine controller is discussed.

Design and energy efficiency analysis of a pure fuel cell vehicle for Shell eco racer

The target of Shell Eco-marathon competition of vehicle is to drive a fixed distance with the lowest quantity of fuel. To win the competition, the fuel cell-powered propulsion system needs to be ultra efficient since the fuel cell system and transmission system are the key effects on the performance of the fuel cell-powered propulsion system. In this study, a high-efficiency fuel cell propulsion system has been designed and integrated in a prototype vehicle to participate the Shell Eco-marathon Asia 2018 race. To achieve that, the vehicle dynamic is modeled to make the selection of the key components, and some experiments have been conducted to obtain the properly vehicle driving strategy. Based on the results of vehicle dynamic analysis, a high specific power proton-exchange membrane fuel cell (PEMFC) stack with 1000 W and a high-performance direct current (DC) brushless motor (1000 W) are selected to build the propulsion system of the Shell Eco-marathon vehicle. Based on the experimental result, the racing time (1300-1440 seconds) and varied range of racing speed (23-27 km/h) are selected as the driving strategy. Finally, the efficiency of the fuel cell-powered vehicle is analyzed. In the race at the year of 2018, the designed vehicle won the first place.

Determination of the rolling resistance coefficient of pneumatic wheel systems

The basic resistance during moving objects that are equipped with a circular system is rolling resistance. In objects powered by muscle power, such as: bicycles, wheelchairs, mobile machines, shelves and storage trolleys, the problem of rolling resistance limitation is more important than in the case of structures powered by engines characterized by a significant excess of driving force relative to the sum of resistance forces. Research is being carried out on limiting the rolling resistance force, however, there is a lack of methods for measuring this parameter in the actual operating conditions of devices with a drive system without a drive unit. In the article for research, an innovative method was used of measuring the rolling resistance coefficient of objects equipped only with the rolling chassis of accordance with the patent application P.424484 and a test device compatible with the patent application P.424483. The study involved a pneumatic wheel commonly used in wheelchairs, the use of which gains popularity with increased interest in the construction of electric or diesel vehicles with low energy demand. Examples of such vehicles are available during the Shell Eco-marathon competition. The study was financed from the means of the National Centre for Research and Development under LIDER VII programme, research project no. LIDER/7/0025/L-7/15/NCBR/2016.

Electric Car Chassis for Shell Eco Marathon Competition: Design, Modelling and Finite Element Analysis

The increasing demand for energy efficient electric cars, in the automotive sector, entails the need for improvement of their structures, especially the chassis, because of its multifaceted role on the vehicle dynamic behaviour. The major criteria for the development of electric car chassis are the stiffness and strength enhancement subject to mass reduction as well as cost and time elimination. Towards this direction, this work indicates an integrated methodology of developing an electric car chassis considering the modeling and simulation concurrently. The chassis has been designed in compliance with the regulations of Shell Eco Marathon competition. This methodology is implemented both by the use of our chassis load calculator (CLC) model, which automatically calculates the total loads applied on the vehicle’s chassis and by the determination of a worst case stress scenario. Under this extreme stress scenario, the model’s output was evaluated for the chassis design and the FEA method was performed by the pre-processor ANSA and the solver Ansys. This method could be characterized as an accurate ultrafast and cost-efficient method.

Development of a Coreless Permanent Magnet Synchronous Motor for a Battery Electric Shell Eco Marathon Prototype Vehicle

Abstract This paper describes the development of an in-wheel Coreless Permanent Magnet Synchronous motor designed and built for the participation of the Aero@UBI team in Shell Eco-Marathon competition where a low power and highly efficient motor was needed. The design of the motor for this competition is presented and the adopted concepts explained. The conjunction of the concepts embedded in the design made this motor one of a kind. The use of Litz wire and a single wave winding turn allow the possibility to configure the motor’s constant. The model used in the motor’s design is presented. The motor was built, and the experimental tests data are given for the motor. The motor was tested with two different controllers and the results show the high efficiency of the presented motor.

AERODYNAMICS ASSESSMENT USING CFD FOR A LOW DRAG SHELL ECO-MARATHON CAR

Having a small car running with low power can be achieved by reducing the aerodynamics drag, rolling resistance and mechanical frictions between the moving parts. The Shell Eco-Marathon competition held around the world with events in Europe, USA and Asia shows every year new techniques and ideas to reduce the power needed to drive the car. The record of over 3400 km on the equivalent of a single litre of fuel is an indication of how car can run efficiently. The problem with these low drag cars is the driver perception about the shape of the car. Although the tear drop shape is known as having the minimum drag, practically this shape cannot be used due to size and packaging limitations in addition to the safety issue. In this work, a low drag concept car is proposed using initial CAD design. The concept car is examined using a commercial CFD software by simulating the airflow around car. The spatial distribution of the pressure and velocity vectors are utilized to improve the car shape and to achieve a low drag force coefficient while keeping the down force at its minimum value. By changing the car front, underneath and rear shapes, it was possible to reduce the drag coefficient from 0.430 for the baseline to 0.127 for the final design, while meeting the competition regulations.