Influence of a CVT on the fuel consumption of a parallel medium-duty electric hybrid truck

Hybrid electric vehicles are being developed to reduce the pollutant emissions and the fossil-fuel consumption of transportation. Innovative technologies are inserted to improve the performance of hybrid vehicles, including trucks and buses. Thereby, trends towards gear shifting automation motivate the research on replacing a discrete conventional Automated Manual Transmission (AMT) with a Continuously Variable Transmission (CVT). Theoretically, such a transmission enables better operation points of the thermal engine, and therefore a reduction of its fuel consumption and emissions. However, the conventional (hydraulic actuated) CVT efficiency during quasi-stationary operation is typically lower than the efficiency of a classical discrete gearbox, which leads to higher fuel consumption. This paper is focused on the study of the interests of a CVT for a medium-duty Hybrid Electric Truck (HET). The complete model and control of CVT-based and AMT-based HET are described in a unified way using Energetic Macroscopic Representation (EMR). These models are transformed to backward-models to be computed by the Dynamic Programming Method (DPM). Such a method leads to define the (off-line) optimal energy management strategies for a fair comparison of both hybrid trucks. For the studied driving cycle, the hybridization allows a fuel saving of 10% with an AMT and 3% with a CVT. The fuel consumption is higher for the CVT-based HET in comparison with the AMT-based HET due to the lowest efficiency of the CVT (85%) compared to the AMT (around 92%). However, future (on-demand) CVTs with an increased efficiency could be a solution of interest to reduce the fuel consumption of such applications. The developed method can be used to test these new CVTs, other vehicles or other driving cycles

Real-time backstepping control for fuel cell vehicle using supercapacitors

A key issue of real-time applications is ensuring the operation by taking into account the stability constraints. For multisource vehicles, stability is impacted by the multisource interactions. Backstepping control ensures stable control for most classes of nonlinear systems. Nevertheless, no backstepping control in real time has been yet proposed for multisource vehicles. The objective of this paper is to apply the backstepping control to a multisource vehicle with fuel cell and supercapacitors for real-time implementation. A distribution criterion is used to allocate energy between sources. Experimental results demonstrate that the developed backstepping control can be implemented in real-time conditions. The supercapacitors can thus help the fuel cell to meet the requirements of the load with a guarantee of system stability. © 1967-2012 IEEE

Flexible simulation of an electric vehicle to estimate the impact of thermal comfort on the energy consumption

The energy consumption of electric vehicles depends on the traction energy but also on the thermal comfort energy. Some studies lead to the estimation of this energy consumption from real measurements on different driving and climatic conditions. However, those results rely on a large number of vehicle tests, which is time consuming. Moreover, the impacts of the different subsystems cannot be differentiated in such global studies. A flexible simulation tool can help to analyze the impact of the different parts of a vehicle. This paper proposes a multi-physical parametrized model of an electric vehicle including the traction and comfort subsystems. A flexible model of a Renault Zoe is developed thanks to the energetic macroscopic representation. This model is validated by experimental tests of the real vehicle. Then, the impact of the HVAC (heating, ventilation, and air conditioning) subsystem is studied for different driving cycles and climatic conditions. In very cold conditions, the use of the HVAC subsystem represents an increase of up to 248% of the total energy consumption, compared to summer conditions

Energetic Macroscopic Representation and inversion-based control of a CVT-based HEV

A Continuous Variable Transmission (CVT) is introduced in the simulation model of a Hybrid Electric Vehicle (HEV). The CVT-based vehicle simulation and its control are deduced from the Energetic Macroscopic Representation (EMR). Simulations are provided to show the interest of the CVT in term of fuel consumption

Project-Based Master on Intelligent Electric Vehicles

International audienceA new master degree on Intelligent Electric Vehicles is proposed at University of Lille 1, France. Indeed, industrial companies in transportation system are moving on more electrified vehicles. As transversal skills are required for transportation applications, this Master degree is organized in a progressive way and on a project-based philosophy

An Energy-Flow Based Methodology - Application to hybrid vehicles

A new methodology is presented, based on energy-flow analysis on systems. The aim is to obtain a representation of energy flows between the various sources of a complex system, via energy storage devices connected together with electrical and mechanical converters. Coupling elements can be added to allow the connection of various subsystems. From such a representation, inversion rules lead to the establishment of a maximal control structure that allow an easy identification of the controls needed for the considered system. From this methodology, application example will be given, related to hybrid vehicles

Energetic Macroscopic Representation and PSIM® simulation: application to a DC/DC converter input filter stability

Simulation is a key issue in the design of control electrical systems. Simulation packages using component library, such as PSIM®, are very useful to achieve this goal. The simulation model is thus easily built from the system topology (structural model). But the deduction of the control scheme is more difficult, because a functional model is more suitable. Some graphical descriptions, such as EMR (Energetic Macroscopic representation) are recently been developed to help the user in the control scheme design. But they are generally associated with functional software, such as Matlab-Simulink®. In this paper, a structural modeling software is combined with a functional modeling method. An original and new control of a DC/DC converter is taken as an example

Automatic Driving Cycle Generator for Electric Vehicles

International audienc

An Energetic Based Method Leading to Merged Control Loops for the Stability of Input Filters

In most of applications, power converters are controlled to allow their output current/voltage to follow the required reference values. For DC/DC and DC/AC converters, the control must take into account their input voltage, which must be rejected. In such conditions, the converters can be modeled as negative impedance, causing the instability of their feeding 2nd order input filter. This paper presents an original method for the stabilization of the input filter. A merged control scheme is defined using an Energetic based method. A first control scheme is defined to control the output current. A second independent control scheme is defined to control the filter stability. Both control loops are merged using a weighing criterion. Simulation results are provided and the stability issue is discussed

Comparison of continuous and discrete variable transmissions for parallel HEVs

Parallel Hybrid Electric Vehicles (HEVs) with Discrete and Continuous Variable Transmissions (DVT and CVT) are studied. A common Energetic Macroscopic Representation (EMR) is developed for both kinds of parallel HEVs. Then, a common control structure is deduced from this EMR. Optimization-based Energy Management Strategies (EMSs) are developed. Simulation results are provided and comparison between Parallel HEVs with CVT and DVT are presente