Ricardo Barrero

Energy savings in public transport

Growing pollution levels and traffic congestion in major cities are becoming delicate issues that could be eased by more efficient public transportation systems. To reduce emissions, electric powered vehicles are in use in many cities. Depending on the number of commuters and on the available infrastructure, different types of electric vehicles (battery electric buses, trolley buses, trams, metro, light rail) can be applied. Although these mass transit vehicles enable large reductions in terms of emissions, their energy efficiency could be significantly improved. This improvement can be reached by the hybridization of their drive train with the inclusion of an energy storage system (ESS) for energy recovery purposes [1], [2]. Recent studies have shown that up to 40% of the energy supplied to electrical rail guided current, and power losses, a model of the tram, network, and substations power flow has been developed in a Matlab/ Simulink environment. Results obtained in energy savings at substation level vary from 24iquest27.6% under the same driving profile and auxiliaries load, while at the endof- life (EoL) of supercapacitors, the range varies from 18.1 - 25.1%, depending on the super capacitor module used and the vehicle load.

An Advanced Power Electronics Interface for Electric Vehicles Applications

Power electronics interfaces play an increasingly important role in the future clean vehicle technologies. This paper proposes a novel integrated power electronics interface (IPEI) for battery electric vehicles (BEVs) in order to optimize the performance of the powertrain. The proposed IPEI is responsible for the power-flow management for each operating mode. In this paper, an IPEI is proposed and designed to realize the integration of the dc/dc converter, on-board battery charger, and dc/ac inverter together in the BEV powertrain with high performance. The proposed concept can improve the system efficiency and reliability, can reduce the current and voltage ripples, and can reduce the size of the passive and active components in the BEV drivetrains compared to other topologies. In addition, low electromagnetic interference and low stress in the power switching devices are expected. The proposed topology and its control strategy are designed and analyzed by using MATLAB/Simulink. The simulation results related to this research are presented and discussed. Finally, the proposed topology is experimentally validated with results obtained from the prototypes that have been built and integrated in our laboratory based on TMS320F2808 DSP.

Stationary or Onboard Energy Storage Systems for Energy Consumption Reduction in a Metro Network

This article will compare the benefits and constraints of onboard and stationary energy storage systems (ESS) with the aim of reducing the overall energy consumption on a low DC voltage metro network. A dedicated simulation tool that models a metro line with conventional or hybrid trains and stationary supercapacitor (SC)-based ESSs has been developed for this purpose. The model can simulate the energy exchange among simultaneously running vehicles of a conventional metro line and evaluate the effect of a stationary ESS when installed along the line. Different traffic scenarios are considered for the study: high, moderate, and low traffic volume as this element has a strong influence on the energy exchange among the running vehicles and therefore on the energy available for storage in the ESS. This will eventually determine the energy consumption reduction. This simulation tool is used to study the most convenient ESS alternative for the case of a Brussels metro line. When compared with a conventional metro line, the total energy consumption reduction achieved with stationary ESS varies in function of the traffic conditions, ESS size, and ESS distribution along the line. With efficient metro trains, values of energy savings up to 18.7, 25.1, and 36.4 per cent can be obtained at high, moderate, and low traffic volumes, respectively. In contrast, using onboard ESS on every vehicle, the maximum energy savings achieved vary between 27.3 and 36.3 per cent at high and low traffic volumes, respectively. Results show that even though the energy savings achieved are higher with onboard ESS, the amount of SC cells needed is lower when using stationary ESS. However, benefits such as peak power shaving, voltage drop reductions, and reduced line losses are better attained by onboard ESS.

Analysis and configuration of supercapacitor based energy storage system on-board light rail vehicles

This article will propose different energy storage systems, ranging from 0.91 kWh to 1.56 kWh, suitable for a 30 m long tram. To configure the system regarding energy content, voltage variation, maximum current and power losses, a model of the tram, network and substations power flow has been developed in a Matlab/Simulink environment. Results obtained in energy savings at substation level vary from 24% to 27,6% under the same driving profile and auxiliaries load; while at the end-of-life of super capacitors, the range varies from 18,1% to 25,1% depending on the super capacitor module used and vehicle load. The effect of the power converter between the energy storage system and the pantograph will be evaluated in terms of efficiency and rated power.

Control, analysis and comparison of different control strategies of electric motor for battery electric vehicles applications

Electric motors are key components in all electric drivetrains, particularly battery electric vehicles (BEVs). Consequently, the control strategies of those electric motors play an important role in the development of high performance BEV powertrains. Therefore, this article presents the control design, analysis and comparison of different motor control strategies. In this paper, the most popular control strategies (such as Indirect Field-Oriented Control (IFOC), Hybrid IFOC and PWM voltage scheme, IFOC based on SVPWM, Direct Torque Control (DTC), and DTC based on SVPWM) are designed and analyzed in detail by using Matlab/Simulink. Furthermore, in this research, IFOC based on PWM voltage and PSO is designed to improve the motor efficiency especially at low load conditions. It is shown that the PSO algorithm has the straightforward goal of minimizing the motor losses at any operating condition by selecting the optimal flux. The simulation and experimental results are provided.

A comparative study of different control strategies of On-Board Battery Chargers for Battery Electric Vehicles

On-Board Battery Charger is one of the key components required for the emergence and acceptance of Battery Electric Vehicles (BEVs). The control strategy of the battery charger plays an important role in the development of BEVs. Therefore, the proper selection of this control strategy can significantly improve the performance of the BEVs during charging mode from the grid. In this paper, a comparative study of different control strategies of on-board battery chargers for BEVs is presented. In this research, three control strategies are designed and applied to control the power flow of the on-board battery charger during charging mode from the ac grid. These control strategies are hysteresis current control (HCC), Proportional-Integral Control (PIC) and Proportional-Resonant Control (PRC). These control strategies are designed and analyzed by using MATLAB/Simulink. The simulation and experimental results are provided.

TECHNOLOGICAL SOLUTIONS AIMING AT RECOVERING METRO BRAKING ENERGY: A MULTI-CRITERIA ANALYSIS CASE STUDY

The transport sector, being responsible for a large share of fossil fuels consumption and emissions, mainly CO 2 , is seeking for different ways of reducing their energy consumption and, especially, their dependency on fossil fuels. The purpose of this paper is to present the Multi-Criteria Analysis (MCA) of technological solutions recovering metro braking energy. The MCA PROMETHEE method endorsed to select the most suitable technological solution for the tram and metro network in Brussels. The MCA approach allowed to firstly evaluate the different technologies and afterwards to propose an individual decision to the public transport decision-maker based on the decision problem objectives and the MCA results. Keywords: public transport, metro braking energy, PROMETHEE

Optimization of Propulsion Systems for Series-Hybrid City Busses through Experimental Analysis

This article describes a methodology for the optimization of hybrid propulsion systems combining an onroad measurement campaign with the development of a simulation tool. This methodology has been applied in particular on a series-hybrid city bus. The experimental set-up and the software tool are presented. The measurement setup is based on a National Instruments-cDAQ data acquisition system, containing a real-time programmable embedded processor. The software model is mainly based on the ‘backwards-looking’ or ‘effect-cause’ method which calculates the energy consumed by a vehicle following a predefined driving cycle by going upstream the vehicle components. Experimental as well as simulated results are presented. The developed simulation tool is assessed and refined by means of the experimental data obtained during the thorough on-road measurement campaign. Suggestions for an improved and more efficient power flow control strategy for series-hybrid city busses are given. - Copyright Form of EVS25.sz