Numerical Analysis and Modelling of Transmission Systems for Hybrid Electric Vehicles and Electric Vehicles

Interest in hybrid electric vehicles (HEVs) and electric vehicles (EVs) has increased rapidly over recent years from both industrial and academic viewpoints due to increasing concerns about environmental pollution and global oil usage. In the automotive sector, huge efforts have been invested in vehicle technology to improve efficiency and reduce carbon emissions with, for example, hybrid and electric vehicles. This thesis focuses on one design area of these vehicles – the transmission – with the aim of investigating the potential benefits of improved transmissions for HEVs and EVs. For HEVs, a novel transmission developed by Nexxtdrive based on a twin epicyclic design is analysed using a matrix method and its performance is compared with the more common single epicyclic arrangement used successfully in the Toyota Prius. Simulation models are then used to compare the performance of a typical HEV passenger car fitted with these two transmissions over standard driving cycles. The conclusion is that the twin epicyclic offers substantial improvements of up to 20% reduction in energy consumption, though the benefits are sensitive to the driving cycle used. For EVs, most designs to date have used a single fixed ratio transmission, and surprisingly little research has explored whether multi-geared transmissions offer any benefits. The research challenge is whether it is possible to optimise the usage of the electric motor in its region of high efficiency by controlling the transmission. Simulation results of two EV examples confirm that energy consumption benefits are indeed achievable – of between 7 and 14% depending on the driving cycle. Overall, the original aspects of this work – the analysis and modelling the twin epicyclic gearbox; the analysis and modelling the twin epicyclic system in a vehicle and a comparison of the results with single epicyclic system; and the analysis and modelling of EVs with and without a transmission system of varying levels of complexity – have shown that there are worthwhile performance benefits from using improved transmission designs for low carbon vehicles

Performance Analysis of Hybrid and Full Electrical Vehicles Equipped with Continuously Variable Transmissions

The main aim of this paper is to study the potential impacts in hybrid and full electrical vehicles performance by utilising continuously variable transmissions. This is achieved by two stages. First, for Electrical Vehicles (EVs), modelling and analysing the powertrain of a generic electric vehicle is developed using Matlab/Simulink-QSS Toolkit, with and without a transmission system of varying levels of complexity. Predicted results are compared for a typical electrical vehicle in three cases: without a gearbox, with a Continuously Variable Transmission (CVT), and with a conventional stepped gearbox. Second, for Hybrid Electrical Vehicles (HEVs), a twin epicyclic power split transmission model is used. Computer programmes for the analysis of epicyclic transmission based on a matrix method are developed and used. Two vehicle models are built-up; namely: traditional ICE vehicle, and HEV with a twin epicyclic gearbox. Predictions for both stages are made over the New European Driving Cycle (NEDC).The simulations show that the twin epicyclic offers substantial improvements of reduction in energy consumption in HEVs. The results also show that it is possible to improve overall performance and energy consumption levels using a continuously variable ratio gearbox in EVs

The State of the Art in Fuel Cell Condition Monitoring and Maintenance

Fuel cell vehicles are considered to be a viable solution to problems such as carbon emissions and fuel shortages for road transport. Proton Exchange Membrane (PEM) Fuel Cells are mainly used in this purpose because they can run at low temperatures and have a simple structure. Yet to make this technology commercially viable, there are still many hurdles to overcome. Apart from the high cost of fuel cell systems, high maintenance costs and short lifecycle are two main issues need to be addressed. The main purpose of this paper is to review the issues affecting the reliability and lifespan of fuel cells and present the state of the art in fuel cell condition monitoring and maintenance. The Structure of PEM fuel cell is introduced and examples of its application in a variety of applications are presented. The fault modes including membrane flooding/drying, fuel/gas starvation, physical defects of membrane, and catalyst poisoning are listed and assessed for their impact. Then the relationship between causes, faults, symptoms and long term implications of fault conditions are summarized. Finally the state of the art in PEM fuel cell condition monitoring and maintenance is reviewed and conclusions are drawn regarding suggested maintenance strategies and the optimal structure for an integrated, cost effective condition monitoring and maintenance management system

Numerical analysis and modelling of transmission systems for hybrid electric vehicles and electric vehicles

Interest in hybrid electric vehicles (HEVs) and electric vehicles (EVs) has increased rapidly over recent years from both industrial and academic viewpoints due to increasing concerns about environmental pollution and global oil usage. In the automotive sector, huge efforts have been invested in vehicle technology to improve efficiency and reduce carbon emissions with, for example, hybrid and electric vehicles. This thesis focuses on one design area of these vehicles – the transmission – with the aim of investigating the potential benefits of improved transmissions for HEVs and EVs. For HEVs, a novel transmission developed by Nexxtdrive based on a twin epicyclic design is analysed using a matrix method and its performance is compared with the more common single epicyclic arrangement used successfully in the Toyota Prius. Simulation models are then used to compare the performance of a typical HEV passenger car fitted with these two transmissions over standard driving cycles. The conclusion is that the twin epicyclic offers substantial improvements of up to 20% reduction in energy consumption, though the benefits are sensitive to the driving cycle used. For EVs, most designs to date have used a single fixed ratio transmission, and surprisingly little research has explored whether multi-geared transmissions offer any benefits. The research challenge is whether it is possible to optimise the usage of the electric motor in its region of high efficiency by controlling the transmission. Simulation results of two EV examples confirm that energy consumption benefits are indeed achievable – of between 7 and 14% depending on the driving cycle. Overall, the original aspects of this work – the analysis and modelling the twin epicyclic gearbox; the analysis and modelling the twin epicyclic system in a vehicle and a comparison of the results with single epicyclic system; and the analysis and modelling of EVs with and without a transmission system of varying levels of complexity – have shown that there are worthwhile performance benefits from using improved transmission designs for low carbon vehicles.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Numerical analysis and modelling of transmission systems for hybrid electric vehicles and electric vehicles

Interest in hybrid electric vehicles (HEVs) and electric vehicles (EVs) has increased rapidly over recent years from both industrial and academic viewpoints due to increasing concerns about environmental pollution and global oil usage. In the automotive sector, huge efforts have been invested in vehicle technology to improve efficiency and reduce carbon emissions with, for example, hybrid and electric vehicles. This thesis focuses on one design area of these vehicles – the transmission – with the aim of investigating the potential benefits of improved transmissions for HEVs and EVs. For HEVs, a novel transmission developed by Nexxtdrive based on a twin epicyclic design is analysed using a matrix method and its performance is compared with the more common single epicyclic arrangement used successfully in the Toyota Prius. Simulation models are then used to compare the performance of a typical HEV passenger car fitted with these two transmissions over standard driving cycles. The conclusion is that the twin epicyclic offers substantial improvements of up to 20% reduction in energy consumption, though the benefits are sensitive to the driving cycle used. For EVs, most designs to date have used a single fixed ratio transmission, and surprisingly little research has explored whether multi-geared transmissions offer any benefits. The research challenge is whether it is possible to optimise the usage of the electric motor in its region of high efficiency by controlling the transmission. Simulation results of two EV examples confirm that energy consumption benefits are indeed achievable – of between 7 and 14% depending on the driving cycle. Overall, the original aspects of this work – the analysis and modelling the twin epicyclic gearbox; the analysis and modelling the twin epicyclic system in a vehicle and a comparison of the results with single epicyclic system; and the analysis and modelling of EVs with and without a transmission system of varying levels of complexity – have shown that there are worthwhile performance benefits from using improved transmission designs for low carbon vehicles.EThOS - Electronic Theses Online ServiceGBUnited Kingdo