Juan P. Torreglosa

Predictive Control for the Energy Management of a Fuel-Cell–Battery–Supercapacitor Tramway

This paper evaluates a hybrid powertrain based on fuel cell (FC), battery, and supercapacitor (SC) for the “Urbos 3” tramway, which currently operates powered by SC in the city of Zaragoza, Spain. Due to the dynamic limitations of the main energy source, a proton-exchange-membrane (PEM) FC, other energy secondary sources (ESSs), battery and SC, are needed to supply the vehicle power demand. Moreover, these energy sources allow the energy recovery during regenerative braking. The different sources are connected to a dc bus through dc-dc converters which adapt their variable voltages to the bus voltage and allow the control of energy flow between the sources and the load. The components of the hybrid tramway have been modeled in Matlab/Simulink and are based on commercially available devices. The energy management system used in this work to achieve a proper operation of the energy sources of the hybrid powertrain is based on predictive control. Simulations for the real cycle of the tramway show the suitability of the proposed powertrain and control strategy.

Control strategies for high-power electric vehicles powered by hydrogen fuel cell, battery and supercapacitor

Problems relating to oil supply, pollution, and green house effects justify the need for developing of new technologies for transportation as a replacement for the actual technology based on internal combustion engines (ICE). Fuel cells (FCs) are seen as the best future replacement for ICE in transportation applications because they operate more efficiently and with lower emissions. This paper presents a comparative study performed in order to select the most suitable control strategy for high-power electric vehicles powered by FC, battery and supercapacitor (SC), in which each energy source uses a DC/DC converter to control the source power and adapt the output voltage to the common DC bus voltage, from where the vehicle loads are supplied. Five different controls are described for this kind of hybrid vehicles: a basic control based on three operation modes of the hybrid vehicle depending on the state of charge (SOC) of the battery (operation mode control); a control strategy based on control loops connected in cascade, whose aim is to control the battery and SC SOC (cascade control); a control based on the technique of equivalent fuel consumption, called equivalent consumption minimization strategy (ECMS); and two based on control techniques very used nowadays, the first one of them is a fuzzy logic control and the second one is a predictive control. These control strategies are tested and compared by applying them to a real urban street railway. The simulation results reflect the optimal performance of the presented control strategies and allow selecting the best option for being used in this type of high-power electric vehicles.

Application of cascade and fuzzy logic based control in a model of a fuel-cell hybrid tramway

This paper presents a model for a fuel cell (FC)-battery powered hybrid system for the Metro-Centro tramway (400kW) from Seville, Spain. Modeling of each component, implemented in MATLAB/SIMULINK environment, is briefly presented. Polymer Electrolyte Membrane (PEM) FC and Ni-MH battery models are designed from commercial available components. Two control strategies are presented and tested for the energy management of the hybrid system: cascade and fuzzy logic. The objective of both strategies is to manage the primary (PEM FC) and secondary (battery) energy source to supply the power requirements of the tramway forcing the FC to work around its maximum efficiency point and maintaining the battery state of charge (SOC) in a desired level.

Operation mode control of a hybrid power system based on fuel cell/battery/ultracapacitor for an electric tramway

This paper focuses on describing a control strategy for a real tramway, in Zaragoza (Spain), whose current propulsion system is to be replaced by a hybrid system based on fuel cell (FC) as primary energy source and batteries and ultracapacitors (UCs) as secondary energy sources. Due to its slow dynamic response, the FC needs other energy sources support during the starts and accelerations, which are used as energy storage devices in order to harness the regenerative energy generated during brakings and decelerations. The proposed energy management system is based on an operation mode control, which generates the FC reference power, and cascade controls, which define the battery and UC reference powers in order to achieve a proper control of the DC bus voltage and states of charge (SOC) of battery and UC. The simulations, performed by using the real drive cycle of the tramway, show that the proposed hybrid system and energy management system are suitable for its application in this tramway.

Control based on techno-economic optimization of renewable hybrid energy system for stand-alone applications

Control focused on optimizing the lifecycle costs of a stand-alone hybrid system.Combination of renewable sources, battery and hydrogen systems.The modeling includes the electric models of the components.The system assures reliable electricity support for stand-alone applications. This paper presents an Energy Management System (EMS) for hybrid systems (HS) composed by a combination of renewable sources with the support of different storage devices (battery and hydrogen system) that allow its operation without the necessity of grid connection (i.e. a stand-alone system).The importance of the proposed EMS lies in taking into account economic issues that affect to the decision of which device of the HS must operate in each moment. Linear programming was used to meet the objective of minimizing the net present value of the operation cost of the HS for its whole lifespan. The total operation costs depend largely on the reposition costs of its components. Instead of considering predefined reposition years for each component and calculate their net present cost from them (as is commonly considered in other works), in this work it was proposed to use lifetime degradation models - based on the well-known statement that the lifetime depends on the hours of operation and the power profiles that the components are subjected to- from which the repositions are made to check how they affect to the cost calculation and, consequently, to the EMS performance.The behavior of the proposed control is checked under a long term simulation, in MATLAB-Simulink environment, whose duration is the expected lifespan of the HS (25 years). A conventional state-machine EMS is used as a case study to validate and compare the results obtained. The results demonstrate that the proposed HS and EMS combination assures reliable electricity support for stand-alone applications subject to different techno-economic criteria (generation cost and sustenance of battery SOC and hydrogen levels), achieving to minimize the operation cost of the system and extend their lifespan.

Control strategies of a fuel-cell hybrid tramway integrating two dc/dc converters

This paper compares two control strategies of a fuel cell (FC)-battery powered hybrid system integrating two dc/dc converters for the Metro-Centro tramway (400 kW) from Seville, Spain. Besides, modeling of each component is briefly presented. These models have been implemented in MATLAB/SIMULINK environment. A Polymer Electrolyte Membrane (PEM) FC is used in this work. The FC model characteristics are selected from a Nuvera 127 kW PEM FC. Two PEM FCs connected in parallel operate as primary energy source and a group of Ni-MH battery supplements the output of the FC during tramway acceleration or whenever else needed and provides regenerative braking energy recapture capability. Finally, the simulation results of both control configurations (Cascade and States Control Strategies) are presented for the real driving cycle of the tramway. The results demonstrate the hybrid system capability to meet appropriate driving cycle in both cases.

GESTION DE ENERGIA PARA TRANVIA HIBRIDO BASADO EN PILA COMBUSTIBLE, BATERIA Y SUPERCONDENSADOR

This paper describes the confi guration, modelling and control of a new hybrid propulsion system for the Zaragoza tramway.The new tramway confi guration is composed by a Proton-Exchange- Membrane Fuel-Cell (PEM FC) as main energy source and a Li-ion battery and an Ultra-Capacitor (UC) as energy storage systems. Thus, the battery supports to the FC during the starting and absorbs the power generated by the regenerative braking. Otherwise, the UC, which is the element with the fastest dynamic response, acts mainly during power peaks which are beyond the operation range of the FC and battery. The FC, battery and UC provide with DC/DC converters which allow their connection to the DC bus and control the energy exchange. The new energy management system described is composed by three control loops in cascade for the FC converter and two control loops for the battery and UC. This control system has been evaluated for the real driving cycle of the tramway. The results show how the control system is valid for its application in this hybrid system.