Hybrid Vehicular System Research Articles

Modified multiport Luo converter integrated with renewable energy sources for electric vehicle applications

Purpose Growing concerns about the depletion of fossil fuels and global awareness about the environmental pollution motivate the automobile industries to search for an alternative transportation system such as hybrid vehicular systems, plug-in hybrid vehicular systems and electric vehicular systems. To have carbon emission-free environment, these electric vehicles use renewable sources, such as solar and fuel cell, as primary source of supply. As these renewable sources are intermittent in nature, an energy buffer such as battery or super capacitor is required for the smooth supply and regulation of load power. The current electric vehicle systems use multistage power electronic converters for energy transfer. Therefore, this paper aims to propose a modified multiport converter based on Luo topology. Design/methodology/approach The suggested converter is developed based on Luo topology using voltage lift technique. Findings Most of the research presents buck boost converter as power electronic interface in electric vehicle applications. Whereas the converter proposed in this paper is based on Luo topology. It exhibits the features of single stage conversion between the input output ports, with less ripple, high efficiency, fewer components and centralized control for effective power management. Originality/value The presented converter can work in all possible modes such as buck and boost modes independently or simultaneously during various operating conditions of electric vehicles. During buck/boost mode, the primary source PV (Photovoltaic) in the converter provides the required power for the vehicle and charges the secondary source, i.e. battery, whereas during boost mode the battery supplies the sufficient power to load.

Simulation of a hybrid vehicle powertrain having direct methanol fuel cell system through a semi-theoretical approach

Different operating scenarios can be used in a hybrid system based on a direct methanol fuel cell (DMFC) and a battery. In this paper, a DMFC system model is integrated into a model formed for a hybrid vehicular system that consists of a battery, a DMFC stack and its auxiliary equipments; and the model is simulated in Matlab/Simulink environment using a quasistatic approach. An algorithm for the energy management of the system is also developed considering the state of charge (SOC) of the battery. In the DMFC system model, the current and empirical data for the polarization curves as well as methanol crossover and water crossover rates are taken as the input parameters, whereas the stack voltage, the remaining methanol in the fuel tank, and the power demand of auxiliary equipments are taken as the output parameters. In this model, the methanol consumption, and the water and CO2 production are found applying mass balances for each component of the system. The results of the simulations help to give more insights into the operation of a DMFC based hybrid system.

Power Management Optimization of a Fuel Cell/Battery/Supercapacitor Hybrid System for Transit Bus Applications

In this paper, the optimization of a power management strategy of a fuel cell/battery/supercapacitor hybrid vehicular system is investigated, both offline and in real time. Two offline optimization algorithms, namely, dynamic programming and Pontryagin's minimum principle, are first compared. The offline optimum is used as a benchmark when designing a real-time strategy, which is an inevitable step since the offline optimum is not real-time capable and is oriented only toward minimizing hydrogen consumption, which may result in the unnecessary overloading of the battery. The design and optimization of the real-time strategy makes use of a multiobjective genetic algorithm while taking into account, apart from hydrogen consumption, other important factors, such as the slow dynamics of the fuel cell system and minimizing the battery power burden. As a result, the real-time strategy is found to consume slightly more hydrogen than the offline optimum; however, it dramatically improves system durability.

Parallel combination of FC and UC for vehicular power systems using a multi-input converter-based power interface

Fuel cells (FC) are widely recognized as one of the most promising technologies to meet future power requirements of vehicular applications. However, a FC system combined with an energy storage system (ESS) can perform better for vehicle propulsion as considering several points. As the additional ESS can fulfill the transient power demand fluctuations, the FC system can be downsized to fit the base power demand without facing peak loads. Besides, braking energy can be recovered by the ESS. Interfacing of traction drive requirements with characteristics and modes of operation of on-board generation units and ESSs calls for suitable power electronic converter configuration. In this paper, a FC/UC hybrid vehicular power system using a multi-input converter-based power interface is proposed. The applied power interface topology ensures the active power sharing and DC link voltage stabilization for the hybrid vehicular system. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB®, Simulink® and SimPowerSystems® environments.

Energy management of an FC/UC hybrid vehicular power system using a combined neural network-wavelet transform based strategy

An energy management strategy (EMS) is one of the most important issues for the efficiency and performance of a hybrid vehicular system. This paper deals with a neural network and wavelet transform based EMS proposed for a fuel cell/ultra-capacitor hybrid vehicular system. The proposed method combines the capability of wavelet transform to treat transient signals with the ability of auto-associative neural network supervisory mode control. The main originality of the paper is related with the application of neural network instead of another intelligent control method, fuzzy logic, which is presented in the recent publication of the authors, and the combination of neural network-wavelet transform approaches. Then, the effectiveness comparison of both methods considering one of the most important points in a vehicular system, fuel consumption (or hydrogen consumption), is realized. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB ®, Simulink ® and SimPowerSystems ® environments.

A fuzzy logic based supervisory controller for an FC/UC hybrid vehicular power system

Depending on growing concerns on energy crises and environmental issues, fuel cell (FC) powered electrical vehicles are favored for possible substitute to conventional internal combustion engine (ICE) based vehicular systems. However, the typical power profile of an automobile motor consisting of transients is not suitable for the use of a sole FC system for vehicle propulsion. This shortcoming could be partly overcome by hybridization. Two potential benefits of combining an FC system with an energy storage unit, ultra-capacitor (UC) has been presented in this study. Firstly, the durability of the FC system could be improved because the additional energy source can fulfill the transient power demand fluctuations. Secondly, the ability of the energy storage source to recover braking energy enhances the fuel economy greatly. An important aspect in designing a hybrid power structure is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. An integrated procedure for mathematical modeling and power control strategy design for an FC/UC hybrid vehicle is presented in this paper. A fuzzy logic supervisory controller based power management strategy that secures the power balance in hybrid structure, enhances the FC performance and minimizes the power losses is proposed. The main contribution of this paper apart from the previous studies of the authors is the modeling of the complete FC power system with air supply compressor and the integration of the control of the FC system internal dynamics (especially the oxygen excess ratio) into the overall supervisory control structure to maximize the efficiency and durability. To demonstrate the effectiveness of the proposed power management scheme, simulation studies were performed using MATLAB ®, Simulink ® and SimPowerSystems ® environments by integrating the detailed mathematical and electrical models of the hybrid vehicular system.

A wavelet-fuzzy logic based energy management strategy for a fuel cell/battery/ultra-capacitor hybrid vehicular power system

Abstract Due to increasing concerns on environmental pollution and depleting fossil fuels, fuel cell (FC) vehicle technology has received considerable attention as an alternative to the conventional vehicular systems. However, a FC system combined with an energy storage system (ESS) can display a preferable performance for vehicle propulsion. As the additional ESS can fulfill the transient power demand fluctuations, the fuel cell can be downsized to fit the average power demand without facing peak loads. Besides, braking energy can be recovered by the ESS. This study focuses on a vehicular system powered by a fuel cell and equipped with two secondary energy storage devices: battery and ultra-capacitor (UC). However, an advanced energy management strategy is quite necessary to split the power demand of a vehicle in a suitable way for the on-board power sources in order to maximize the performance while promoting the fuel economy and endurance of hybrid system components. In this study, a wavelet and fuzzy logic based energy management strategy is proposed for the developed hybrid vehicular system. Wavelet transform has great capability for analyzing signals consisting of instantaneous changes like a hybrid electric vehicle (HEV) power demand. Besides, fuzzy logic has a quite suitable structure for the control of hybrid systems. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB®, Simulink® and SimPowerSystems® environments.

Modeling and analysis of an FC/UC hybrid vehicular power system using a wavelet-fuzzy logic based load sharing and control algorithm

Abstract Fuel cell (FC) systems are potentially promising candidates as alternative energy sources for use in vehicular applications. The natural advantages of hybrid power sources may be effectively utilized to improve the efficiency and dynamic response of a vehicular system. Fuel cell (FC) and ultra-capacitor (UC) based hybrid power systems appear to be very promising for satisfying high energy and high power requirements for vehicular applications. In this paper, a FC/UC hybrid vehicular power system using a wavelet based load sharing and fuzzy logic based control algorithm is proposed. While wavelet transforms are suitable for analyzing and evaluating the dynamic load demand profile of a hybrid electric vehicle (HEV), the use of fuzzy logic controller is appropriate for the hybrid system control. The mathematical and electrical models of the hybrid vehicular system are developed in detail and simulated using MATLAB®, Simulink® and SimPowerSystems® environments.