Qinglian Ren

Effect of transmission design on Electric Vehicle (EV) performance

The current level of interest in Electric Vehicles (EVs) could hardly be overstated as manufacturers and governments around the world appear to have increased interest at a staggering rate. The resurgence of current interest in the early part of the 21st century has been driven by both political and technological developments, namely a requirement to control global emissions and the emergence of new battery designs with improved specific energy, energy density and rechargability properties.

Controller design for hybrid vehicles — state of the art review

The control problem for a hybrid vehicle powertrain is commonly tackled as an optimal control problem, although this is often used in a general sense as opposed to a strict mathematical definition. The problem may be characterised in many ways depending on the performance objective, the hybrid vehicle model considered, the constraints imposed and the available control actions. However, as a general dynamics and control problem it is clearly not straightforward, and is likely to involve combinations of linear and non-linear elements, discrete and continuous systems, algebraic and dynamical systems.

Effect of geared transmissions on electric vehicle drivetrains

The paper describes some simple modelling to investigate whether there are potential benefits to incorporating a geared transmission in electric vehicle driveline. The overall conclusion is that considerable benefits in energy consumption are available if a continuously variable gearbox system is incorporated; performance improvements of 6 to 19.2% are predicted over a range of European, USA and Japanese driving cycles. Furthermore, the use of a much simpler, two speed gearbox an improve performance significantly — by for example 9.2% over the NEDC cycle — although similar improvements are not predicted over other driving cycles. Overall, the results suggest not only that direct benefits in terms of energy reductions are obtainable, but also that significant reductions in motor and driveline sizing may be an alternative approach to exploiting the introduction of a transmission system.Copyright

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.

Analysis of 3 and 4 branch epicyclic transmission systems for Hybrid Electrical Vehicles using matrix method and TSA tool

This paper is focused on modeling and analysis of 3 and 4 branch epicyclic transmission systems for Hybrid Electrical Vehicles (HEVs) using the matrix method and transmission systems analysis (TSA) tool. The TSA tool is especially developed to analyse such systems. The application of the system to a typical hybrid electric vehicle driveline is modeled and a comparison of the performance characteristics of competing designs is discussed. In addition, the potential benefits of the 4 branch epicyclic system are presented.

Modelling and Analyzing Hybrid Electric Vehicles with Single and Dual Epicyclic Power Split Transmissions

The main aim of this paper is to investigate the performance of hybrid electrical vehicles (HEVs) using single and dual epicyclic power split transmissions (PST). The development of PST has been a crucial feature in the technological success of hybrid driveline vehicles. In this paper, single and twin epicyclic power split transmissions models are analyzed and the relationships of speed and torque of the engine, motor and generator are developed. The models are further extended to include all subsystems and a controller designer to be fitted in a typical hybrid electrical vehicle (HEV). Computer programmes for the analysis of epicyclic transmission based on a matrix method are developed and used. In addition, the performance and control strategy of the new system is presented. Three vehicle models are built-up; namely: traditional ICE vehicle, HEV with single epicyclic gearbox, and HEV with twin epicyclic gearbox. The vehicles are simulated over typical driving cycles. The results focus on fuel consumption comparisons but it is also shown how the single and twin epicyclic gearboxes use the engine and motor generator units differently. The simulations show that the twin epicyclic offers substantial improvements of reduction in energy consumption, though the benefits are sensitive to the driving cycle used.