Nazih Moubayed

Parameter identification of the lead-acid battery model

The lead-acid battery, although known since strong a long time, are today even studied in an intensive way because of their economic interest bound to their use in the automotive and the renewable energies sectors. In this paper, the principle of the lead-acid battery is presented. A simple, fast, and effective equivalent circuit model structure for lead-acid batteries was implemented. The identification of the parameters of the proposed lead-acid battery model is treated. This battery model is validated by simulation using the Matlab/Simulink Software.

Design and Implementation of Space Vector Modulation-Based Sliding Mode Control for Grid-Connected 3L-NPC Inverter

This paper presents a closed-loop space vector modulation (SVM)-based sliding mode controller (SMC) for a three-level grid-connected neutral point clamped (3L-NPC) inverter. The nonlinear SMC based on Gaos reaching law has been designed to control the grid current and inject desired amount of active and reactive power into the network. Due to using single dc source at the NPC inverter dc bus, neutral point voltage is controlled through redundant switching states and instantaneous dc voltage feedback integrated into SVM technique. Meanwhile, there is no external voltage controller involved, thus no associated fine tuning issues are existed. The performance of the proposed hybrid controller to inject a desired active/reactive power to the grid is investigated through external perturbations such as change in the line current amplitude/phase shift, ac voltage fluctuation, as well as dc voltage variation. Full converter state-space model was developed and simulated. Experimental results are provided to verify the fast dynamic performance, low content of line current THD%, and good voltage balancing of dc bus capacitors of the NPC inverter.

Three-level neutral-point-clamped inverters in transformerless PV systems — State of the art

Nowadays, the three-level neutral point clamped (3L-NPC) inverter has become more attractive among multilevel inverters topologies, especially in transformerless grid connected photovoltaic systems. Due to the unbalance between the two DC load-side capacitor voltages, the development and improvement of such topology were important topics in recent studies. New structures were derived focusing on better distribution of losses, increasing efficiency, decreasing the switching devices losses and the conduction losses. For this reason, seven derived topologies are discussed in this paper and compared among the conventional inverter. In addition, a part of this study focuses on modifying modulation techniques in order to comply with the neutral point fluctuation problem. Several carrier-based PWM and space vector modulation techniques are considered, discussed and compared.

Fuel flow control of a PEM Fuel Cell with MPPT

In this paper, a Fuel Cell (FC) Maximum Power Point Tracking (MPPT) with fuel flow optimization is developed. The aim of this study is to extract the maximum power from a FC at different fuel flow rates and to protect the FC from over-current and voltage collapses across terminals. The system is composed of a tracker with a buck converter able to change the impedance and therefore the FC power. In order to illustrate our approach, simulation results show the behavior of the tracker at different fuel flow rates and verify the concept of maximum power tracking.

Sliding Mode Fixed Frequency Current Controller Design for Grid-Connected NPC Inverter

In this paper, a fixed-frequency pulsewidth modulation (PWM) based on sliding-mode current controller is designed and applied to a utility interface three-phase/wire/level neutral-point-clamped inverter. The proposed design methodology of the sliding-mode control is based on a constant switching frequency operation and on Gaos reaching law that allows chattering compensation. The aim of the controller is to inject a controlled active power from renewable energy sources into the grid while controlling the power factor and minimizing supply current harmonics. Moreover, the dc-link voltages across the split capacitors are controlled with a simple proportional-integral (PI) regulator. Experimental results show the advantages of the proposed control algorithm in terms of fast dynamic response, low voltage ripple on the dc bus, low current Total Harmonic Distortion, and robustness toward external perturbations from the dc and ac sides; moreover, a comparison with a PWM-PI current controller is presented.

Sliding-mode current control design for a grid-connected three-level NPC inverter

Three-level neutral point clamped (NPC) inverter topologies are becoming more and more the interest of studies, especially in grid connected systems, due to their advantages compared to other multilevel inverters. Synchronization with an AC source remains a challenge ring current injection to the grid. In order to enhance the performance and the immunity of such grid connected inverters, a sliding mode current controller based on Gaos reaching law has been designed in this paper, and then applied to a three-wire three-level NPC inverter to have a unity power factor system. A PI regulator has been also employed to deal with the split DC-capacitors voltage unbalance problem. Robustness towards external disturbances was verified through simulations using MATLAB.

Comparison between different control methods of a solar energy conversion system

In the context of renewable energy, this study treats the case of the conversion of solar energy, which is one part of non pollutant energy, to electrical one. Maximizing methods of the generated power is discussed in this paper. Thus, the case of solar panel is studied and a comparison between the ‘perturb and observe’ control method and the ‘incremental conductance’ control method in order to maximize the output power are given, analyzed and discussed.

Power electronics interface configurations for hybrid energy storage in hybrid electric vehicles

This paper presents a study of different converter topologies used in the design of hybrid electric vehicle drive trains with emphasis on the power electronic interface for a battery/ultracapacitor hybrid energy storage pack. Each of the topologies proposed in literature has its own advantages and disadvantages, thus choosing an appropriate topology depends greatly on the specified application, design and operation requirements. Several aspects have to be considered to obtain a reliable comparison among different power converter topologies.

Health status and diagnosis of batteries in renewable energy systems: An overview

A battery is a device that converts chemical energy directly to electrical one. In the context of renewable energy, the purpose of using batteries is to store the generated power from solar panels, wind turbines or from other renewable energy sources. In this paper, an overview of the batteries used in green energy systems is discussed. The health status of these batteries is treated. Finally, an overview of the current methods using in the diagnosing of the lead acid batteries degradation is also given and discussed.

Maximum Power Point Tracking With Reactant Flow Optimization of Proton Exchange Membrane Fuel Cell

In this paper, a fuel cell (FC) maximum power point tracking (MPPT) with fuel flow optimization is presented. The aim of this study is to extract the maximum power from a FC at different fuel flow rates and to protect the FC from over-current and voltage collapse across terminals. The system is composed of a tracker with a buck converter able to change the output impedance of the FC and therefore its power. In order to illustrate our approach, the tracker is simulated by using both static and dynamic FC models to describe the FC response. Simulation results show the behavior of the tracker at different fuel and oxidant flow rates and verify the concept of maximum power tracking.