Phatiphat Thounthong

Control Strategy of Fuel Cell and Supercapacitors Association for a Distributed Generation System

This paper proposes an innovative control strategy for a voltage-regulated dc hybrid power source employing polymer electrolyte membrane fuel cell as the main energy source and supercapacitors as the auxiliary power source for a distributed generation system. This strategy is based on a standard dc link voltage regulation, which is simpler than standard state machines used for hybrid source control, and free of chattering problems. Its originality lies in using only the storage device for supplying the energy required to achieve the dc link voltage regulation. Therefore, the main source of the hybrid system is considered as a standard load, working only in regenerative braking, to keep the storage device charged. The general structure of the studied system, the control principle of the hybrid source, the realization of the experimental bench, and the experimental validation are all presented.

Comparative Study of Fuel-Cell Vehicle Hybridization with Battery or Supercapacitor Storage Device

This paper studies the impact of fuel-cell (FC) performance and control strategies on the benefits of hybridization. One of the main weak points of the FC is slow dynamics dominated by a temperature and fuel-delivery system (pumps, valves, and, in some cases, a hydrogen reformer). As a result, fast load demand will cause a high voltage drop in a short time, which is recognized as a fuel-starvation phenomenon. Therefore, to employ an FC in vehicle applications, the electrical system must have at least an auxiliary power source to improve system performance when electrical loads demand high energy in a short time. The possibilities of using a supercapacitor or a battery bank as an auxiliary source with an FC main source are presented in detail. The studies of two hybrid power systems for vehicle applications, i.e., FC/battery and FC/supercapacitor hybrid power sources, are explained. Experimental results with small-scale devices (a polymer electrolyte membrane FC of 500 W, 40 A, and 13 V; a lead-acid battery module of 33 Ah and 48 V; and a supercapacitor module of 292 F, 500 A, and 30 V) in a laboratory authenticate that energy-storage devices can assist the FC to meet the vehicle power demand and help achieve better performance, as well as to substantiate the excellent control schemes during motor-drive cycles.

Control Algorithm of Fuel Cell and Batteries for Distributed Generation System

This paper intends to propose a novel control algorithm for utilizing a polymer electrolyte membrane fuel cell (PEMFC) as a main power source and batteries as a complementary source, for hybrid power sources for distributed generation system, particularly for future electric vehicle applications. The control, which takes into account the slow dynamics of a fuel cell (FC) in order to avoid fuel (hydrogen and air) starvation problems, is obviously simpler than state machines used for hybrid source control. The control strategy lies in using an FC for supplying energy to battery and load at the dc bus. The structure is an FC current, battery current, and battery state-of-charge (SOC) cascade control. To validate the proposed principle, a hardware system is realized by analogical circuits for the FC current loop and numerical calculation (dSPACE) for the battery current and SOC loops. Experimental results with small-scale devices (a 500 W PEM FC and 33 Ah, 48 V lead-acid battery bank) illustrate the excellent control scheme during motor drive cycles.

Analysis of Supercapacitor as Second Source Based on Fuel Cell Power Generation

This paper presents the utilization of a supercapacitor as an auxiliary power source in a distributed generation system, composed of a polymer electrolyte membrane fuel cell (PEMFC) as the main energy source. The main weak point of fuel cells (FCs) is slow dynamics because one must limit the FC current slope in order to prevent fuel starvation problems, to improve its performance and lifetime. The very fast power response and high specific power of a supercapacitor can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The FC and supercapacitor characteristics are clearly presented. Experimental results with small-scale devices (supercapacitor bank: 292-F, 30-V, 400-A; PEMFC: 500-W, 40-A) illustrate excellent performance during a motor drive cycle.

Modeling and Control of Fuel Cell/Supercapacitor Hybrid Source Based on Differential Flatness Control

Fuel-cell vehicles (FCVs) with energy storage (ES) device(s) could result in improved lifetime, performance, fuel economy, and reduced cost. This paper presents the utilization of an ES device consisting of a supercapacitor bank for future electric vehicles with a hydrogen fuel cell (FC) as the main power source. The study mainly focuses on the innovative control law based on the flatness properties for a FC/supercapacitor hybrid power source. Utilizing the flatness principle, we propose simple solutions to the hybrid energy-management and stabilization problems. A supercapacitor module, as a high dynamic and high-power density device, functions to supply energy to regulate the dc-bus energy. The FC, as a slower dynamic source in this system, functions by supplying energy to keep the supercapacitor module charged. To ensure energy-efficient operation of the FC stack, the output current ripple of the FC stack is minimized by parallel boost converters with an interleaving switching technique for a high-frequency ripple by the supercapacitor for a low-frequency ripple. To authenticate the proposed control laws, a test bench is realized in the laboratory. The control algorithm (energy and current control loops) is digitally implemented by dSPACE controller DS1103. Experimental results with small-scale devices (a proton exchange membrane FC (PEMFC) of 500 W, 50 A, and 10 V and a supercapacitor bank of 250 F, 32 V, and 500 A) substantiate the excellent performance during load cycles.

Intelligent Model-Based Control of a Standalone Photovoltaic/Fuel Cell Power Plant With Supercapacitor Energy Storage

A renewable energy hybrid power plant, fed by photovoltaic (PV) and fuel cell (FC) sources with a supercapacitor (SC) storage device and suitable for distributed generation applications, is proposed herein. The PV is used as the primary source; the FC acts as a backup, feeding only the insufficiency power (steady-state) from the PV; and the SC functions as an auxiliary source and a short-term storage system for supplying the deficiency power (transient and steady-state) from the PV and the FC. For high-power applications and optimization in power converters, four-phase parallel converters are implemented for the FC converter, the PV converter, and the SC converter, respectively. A mathematical model (reduced-order model) of the FC, PV, and SC converters is described for the control of the power plant. Using the intelligent fuzzy logic controller based on the flatness property for dc grid voltage regulation, we propose a simple solution to the fast response and stabilization problems in the power system. This is the key innovative contribution of this research paper. The prototype small-scale power plant implemented was composed of a PEMFC system (1.2 kW, 46 A), a PV array (0.8 kW), and an SC module (100 F, 32 V). Experimental results validate the excellent control algorithm during load cycles.

Model Based-Energy Control of a Solar Power Plant With a Supercapacitor for Grid-Independent Applications

This paper proposes a design for a renewable-energy hybrid power plant that is fed by a photovoltaic (PV) source with a supercapacitor (SC) storage device and is suitable for distributed generation applications. The PV array is used as the main generator, and the SC functions as an auxiliary source for supplying the (transient and steady-state) power deficiency of the PV array. For high-power applications, four-phase parallel boost converters and four-phase parallel bidirectional converters are implemented as a PV converter and a storage device, respectively. A reduced-order mathematical model of the PV and SC converters is described for the control of the power plant. Using a nonlinear approach based on the flatness property, we propose a simple solution to the dynamic, stabilization, and robustness problems in the hybrid power system. This is the key innovative contribution of this research paper. We analyze a prototype small-scale power plant composed of a 0.8-kW PV array and a 100-F SC module. The experimental results authenticate the excellent control algorithm during load cycles.

Utilizing fuel cell and supercapacitors for automotive hybrid electrical system

This paper presents a new control algorithm for utilizing PEM fuel cell and supercapacitors for automotive system. A PEM fuel cell is operated as a directional main power source connected to 42 V dc bus (PowerNet) by boost converter, and supercapacitors is controlled as a fast bidirectional auxiliary power source connected to dc bus by a 2-quadrant dc/dc converter. The system employs a 500 W PEM fuel cell and a supercapacitive storage device, composed of six components (3,500 F, 2.5 V, 400 A) associated in series. The system control structure is realized by analogical for current loop at high dynamics and digital control (dSPACE) for voltage loop and algorithm. The proposed control, illustrated by experimental results, avoids speedy transition of fuel cell current and is based on the power sharing demanded at the dc bus between the main and auxiliary sources

A New Control Law Based on the Differential Flatness Principle for Multiphase Interleaved DC–DC Converter

This brief presents an innovative control law for a distributed dc generation supplied by a dc power source, here, a fuel cell (FC) generator. Basically, an FC is always connected with a power-electronic converter. This kind of system is a nonlinear behavior. Classically, to control the voltage, the current, or the power in the converter, a linearized technique is often used to study the stability and to select the controller parameters of the nonlinear converter. In this brief, a nonlinear-control algorithm based on the flatness property of the system is proposed. Flatness provides a convenient framework for meeting a number of performance specifications on the power converter. Utilizing the flatness property, we propose simple solutions to the system performance and stabilization problems. Design controller parameters are autonomous of the operating point. To validate the proposed method, a prototype FC power converter (1.2-kW four-phase boost converters in parallel) is realized in the laboratory. The proposed control law based on the flatness property is implemented by digital estimation in a dSPACE 1104 controller card. Experimental results with a polymer electrolyte membrane FC of 1200 W and 46 A in the laboratory corroborate the excellent control scheme.

Analysis of Differential Flatness-Based Control for a Fuel Cell Hybrid Power Source

This paper presents an innovative control law for distributed dc generation supplied by a fuel cell (FC) (main source) and supercapacitor (auxiliary source). This kind of system is a multiconverter structure and exhibits nonlinear behavior. The operation of a multiconverter structure can lead to interactions between the controls of the converters if they are designed separately. Typically, interactions between converters are studied using impedance criteria to investigate the stability of cascaded systems. In this paper, a nonlinear control algorithm based on the flatness properties of the system is proposed. Flatness provides a convenient framework for meeting a number of performance specifications for the hybrid power source. Using the flatness property, we propose simple solutions to hybrid energy management and stabilization problems. The design controller parameters are autonomous of the operating point; moreover, interactions between converters are taken into account by the controllers, and high dynamics in disturbance rejection is achieved. To validate the proposed method, a hardware system is realized with analog circuits, and digital estimation is accomplished with a dSPACE controller. Experimental results with small-scale devices (a polymer electrolyte membrane FC of 1200 W, 46 A and a supercapacitor module of 100 F, 500 A, and 32 V) in a laboratory corroborate the excellent control scheme during a motor-drive cycle.