• Energy Research

Electrochemical capacitors, called supercapacitors (SCs) or ultracapacitors, are devices conveniently used for embedded electrical energy management owing to their huge capacitance, low internal resistance and flexible control through power electronic conversion. This paper proposes a main power supply of hybrid Wind Generator (WG)–SC within the train station for feeding the traction onboard SC through specified limited feeding transit durations. Onboard SCs provide the train with the requested start–up self–energy. The hybrid WG–SCs system is an environmental–friendly source that enables the independency on national grid and guarantees an efficient bidirectional power transfer for energy management with enhanced dynamic performance. Therefore, the dynamic modelling and the experimental analysis of the modern hybrid WG–SCs used for managing the charge/discharge operation of SCs at Unity Power Factor (UPF) mode are presented. For this purpose, the Port–Controlled Hamiltonian (PCH) methodology is deduced and explicitly presented. Simulation results, via MATLAB™, reveal that the proposed PCH control methodology can be successfully implemented to ensure acceptable system dynamic behavior. Numerical results are validated with experimental measurements to investigate the significance of the PCH approach for the energy management operation in eco-tractions.

AbstractThis paper presents the modelling and control strategies based on PI and nonlinear sliding mode controllers of a hybrid fuel cell/supercapacitor source. It is composed of a Polymer Electrolyte Membrane Fuel Cell (PEMFC 500W) and a supercapacitor stack (800W) as a main and an auxiliary sources respectively, to supply the load requirements in the transient and steady states. A classical PI controller has been adapted to control DC bus voltage and to determine the FC's reference current. Due to the fast response in the transient state and its ability to work with a constant or variable frequency, a sliding mode controllers have been used to control the SC and FC currents through boost and DC-DC bidirectional converters, respectively. The simulation results underMatlab/Simulink showed that the proposed control strategies managed and controlled successfully the hybrid system and satisfied the load requirements with a stable and robust performances.

Abstract This paper presents a control strategy for hybrid power source based on fuel cell (FC) as the main power source and battery/supercapacitor (SC) as auxiliary power sources for electric vehicle application. In this study, a Battery and SC are auxiliary devices associated with the FC to ensure the power reversibility in the drive train. The FC, Battery, and SC are connected to the DC bus throughout an interleaved boost converter (IBC) and two interleaved bidirectional converters (IBDC) respectively. The paper proposes the control strategy based on power frequency splitting to avoid FC starvation problem, reduce the battery stress and improve the fuel economy of FC. The detail of the control strategy is presented and an Energetic Macroscopic Representation (EMR) is used to develop the whole system. The simulation results are presented to validate the proposed method in the hybrid system.

AbstractFuel cells are a promising new alternative energy resource in distributed generation and electric vehicle applications. However, usually a fuel cell has slow response due to the dynamic of its auxiliaries. To optimize the fuel cell system performances, an appropriate controller that can regulate the power flow and automatically adjust the converter output voltage is needed. In this paper, Authors suggest and introduce such converter. Our approach consists in designing and managing the control of a non- isolated DC/DC converter with high voltage ratio coupled to a fuel cell stack in transport application. The proposed converter consists of two cascade stages non-isolated DC/DC converters. The first stage is an interleaved boost converter and the second is a floating-interleaving boost. The choice of each converter is based on the efficiency of the converter with high voltage ratio and small input current undulations. The control of both converters is ensured by hybrid duel loop control that contains a voltage loop with a linear PI controller and a fast current loop with a non-linear sliding controller. The simulation of the proposed control under load step variation is performed under Matlab-Simulink environment and gives interesting results. This paper presents and comments the introduced device and discusses the obtained results.

AbstractSolar cell is one of the crucial components in photovoltaic systems. Silicon solar modules are widely used in the Photovoltaic (PV) industry. The silicon PV electrical performance is described by its current–voltage (I–V) characteristic, which is as function of the device used and material properties. This study provides a comparison between a simplified PV-cell and module model and its parameterization, guaranteeing that the I–V characteristic curves fit with the typical points given by manufacturers’ datasheets and experimental data. The PV performance study is carried out as function of the junction temperature and insolation. This contribution gives an overview over PV module defects and degradation.

Wind turbines proliferation in industrial and residential applications is facing the problem of maintenance and fault diagnosis. Periodic maintenances are necessary to ensure an acceptable life span. The aim of this work is to develop theoretical tools to diagnose the failure or the malfunction of the doubly-fed induction generator (DFIG). The diagnosis method is based on the impedance spectroscopy which is used for the diagnosis of batteries, fuel cells, and electrochemical systems. This first attempt for using this method to the diagnosis of the DFIG provides good results for the detection of the grounding connection, short circuit and stator resistance variation.

Mainstream power-conditioning devices such as boost converters are frequently utilized for developing a compatible interface between a fuel cell, electrical storage, and high power loads. The conventional power stage comprising a unique boost converter suffers from low efficiency and poor reliability due to excessive power losses, particularly in high-power applications. Additionally, the presence of high ripple contents can reduce the lifespan of the fuel cell itself. With this background, this paper proposes and experimentally validates a physical components-assisted equivalent power-sharing strategy between parallel-coupled boost converters (PCCs) that is subjected to a wide spectrum of low-voltage–high-power conditions. The operation of PCCs is bottlenecked by several practical limitations, such as the presence of inner circulating currents (ICCs) and stability issues associated with the equivalent sharing of power. To overcome these limitations, a module of reverse blocking diodes is suggested to avoid ICCs between the PCCs. Further, an equalization filter is properly placed to improve the equivalent power-sharing capability. The proposed strategy is theoretically assessed in a MATLAB/Simulink environment with a 6 kW proton exchange membrane fuel cell (PEMFC) as the main power source. A scaled-down laboratory setup consisting of an 810 W PEMFC stack, an electronic load, three boost converters, and a filter circuit is then designed and critically evaluated. A consistent agreement is observed between the experimental findings and the simulation results under realistic operating conditions.