Ultracapacitors

Nowadays, no electrochemical energy system presents a competitive operation if compared with internal combustion engine, which is the reason for combining electrochemical energy systems to obtain a hybrid energy storage system. This paper presents a fuel cell-battery-ultracapacitor system for vehicle application. The objective of this paper is to present the Energetic Macroscopic Representation (EMR) of the multisource power system. I.

ABSTRACT Ultracapacitors are an alternative storage element to deal with the power requirements of autonomous electric vehicles. This is possible because ultracapacitors can deliver large amount of power in short periods of time and their shelf life is longer than other conventional storage elements. For designing a high performance electric vehicle capable to run a quarter of a mile in 10 seconds, it was decided to use several modular ultracapacitors that have lower voltage levels than motors requirements. In these conditions, it is needed an efficient DC-DC converter which can manage the required power and energy to be delivered to electric motors, assuring the needed voltage and current levels. This work shows a design of a DC-DC converter that interface ultracapacitors and motors in a high performance electric vehicle. This design was possible by performing a power loss analysis, a component calculation and a simulation validation.

The fuel economy and all-electric range (AER) of hybrid electric vehicles (HEVs) are highly dependent on the on-board energy-storage system (ESS) of the vehicle. Energy-storage devices charge during low power demands and discharge during high power demands, acting as catalysts to provide energy boost. Batteries are the primary energy-storage devices in ground vehicles. Increasing the AER of vehicles by 15% almost doubles the incremental cost of the ESS. This is due to the fact that the ESS of HEVs requires higher peak power while preserving high energy density. Ultracapacitors (UCs) are the options with higher power densities in comparison with batteries. A hybrid ESS composed of batteries, UCs, and/or fuel cells (FCs) could be a more appropriate option for advanced hybrid vehicular ESSs. This paper presents state-of-the-art energy-storage topologies for HEVs and plug-in HEVs (PHEVs). Battery, UC, and FC technologies are discussed and compared in this paper. In addition, various hybrid ESSs that combine two or more storage devices are addressed. Index Terms-Battery, energy storage, fuel cell (FC), hybrid electric vehicles (HEVs), plug-in HEVs (PHEVs), ultracapac-itor (UC).

PWM or Pulse Width Modulation based control of
power electronic circuits is most common method used for
controlling output voltage of bidirectional converter. Various
modes of operation of bidirectional converter is discussed. A low
cost micro-controller board, Arduino, has been used to
implement the PWM control technique thus avoiding the need
for complex hardware circuitry. MATLAB/SIMULINK is used
to design the bidirectional converter.

Fuel cell (FC) application in vehicular technology has gained much popularity since the past few years. Typically, fuel Cell Hybrid Electric Vehicle (FCHEV) consists of fuel cell, battery and/or ultracapacitor (UC) as the power sources. The power converter is integrated to the power sources to form the hybrid FC system. This helps to compensate the drawback of individual power sources. Apart from the technical efficiency of power sources itself, the performance of an FCHEV is governed by the efficiency of power electronics and associated controller. In this paper, a state-of-the-art of vehicle classification is reviewed, in which the focus is placed on the deployment of fuel cell, battery, ultracapacitor and flywheel. The configurations used in FCHEV, followed by the updated power converter topologies, are also discussed. The topologies are categorized and discussed according to the power stages and control techniques used in the configurations. Then, multiple stages conversion and single stage topologies are described chronologically. The advantages and disadvantages of each topology, safety standards, current situation and environmental impact of FCHEV are also discussed. In addition, the current development of FCHEV, challenges and future prospects are also elaborated. The rapid growth of FC based research and technology has paved great prospects for FCHEVs in the near future, with the prediction of the competitive cost of hydrogen as compared to gasoline.

Application of fuel cell (FC) in power generation requires efficient power converters and controllers for hybridization of energy storage devices. This paper presents the control technique in a fuel cell and ultracapacitor hybrid system to eliminate the slow dynamic problem of FC. The control technique involves a linear quadratic regulator and proportional integral (LQR-PI) controller, where the FC boost converter and the UC bidirectional converter are controlled using a double-loop PI controller and a voltage-mode LQR controller, respectively. The simulation with different types of load was performed to compare the performance of the proposed controller with both PI and LQR controllers. The results revealed that the LQR-PI controller had better overshoot and undershoot responses (7.37% and 6.43%, respectively) than the proportional integral controller (11.47% and 11.42%, respectively) and linear quadratic regulator (23.87% and 21.5%, respectively). The energy sharing performance was verified through variation in load resistance and disturbances in bus voltage. The voltage recovery time of LQR-PI controller was slightly higher (200 ms) than that of the LQR controller (23.8 ms) and, however, lower than that of the PI controller (300 ms). The results revealed that the proposed controller is efficient for load voltage as well as load current fluctuations.

This study presents an original control algorithm for a hybrid energy system with a renewable energy source, namely, a polymer electrolyte membrane fuel cell (PEMFC) and a photovoltaic (PV) array. A single storage device, i.e., a supercapacitor (ultracapacitor) module, is in the proposed structure. The main weak point of fuel cells (FCs) is slow dynamics because the power slope is limited to prevent fuel starvation problems, improve performance and increase lifetime. The very fast power response and high specific power of a supercapacitor complements the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The energy in the system is balanced by d.c.-bus energy regulation (or indirect voltage regulation). A supercapacitor module functions by supplying energy to regulate the d.c.-bus energy. The fuel cell, as a slow dynamic source in this system, supplies energy to the supercapacitor module in order to keep it charged. The photovoltaic array assists the fuel cell during daytime. To verify the proposed principle, a hardware system is realized with analog circuits for the fuel cell, solar cell and supercapacitor current control loops, and with numerical calculation (dSPACE) for the energy control loops. Experimental results with small-scale devices, namely, a PEMFC (1200 W, 46 A) manufactured by the Ballard Power System Company, a photovoltaic array (800 W, 31 A) manufactured by the Ekarat Solar Company and a supercapacitor module (100 F, 32 V) manufactured by the Maxwell Technologies Company, illustrate the excellent energy-management scheme during load cycles.

This paper proposes a perfect energy source supplied by a polymer electrolyte membrane fuel cell (PEMFC) as a main power source and storage devices: battery and supercapacitor, for modern distributed generation system, particularly for future fuel cell vehicle applications. The energy in hybrid system is balanced by the dc bus voltage regulation. A supercapacitor module, as a high dynamic and high power density device, functions for supplying energy to regulate a dc bus voltage. A battery module, as a high energy density device, operates for supplying energy to a supercapacitor bank to keep it charged. A FC, as a slowest dynamic source in this system, functions to supply energy to a battery bank in order to keep it charged. Therefore, there are three voltage control loops: dc bus voltage regulated by a supercapaci-tor bank, supercapacitor voltage regulated by a battery bank, and battery voltage regulated by a FC. To authenticate the proposed control algorithm, a hardware system in our laboratory is realized by analog circuits and numerical calculation by dSPACE. Experimental results with small-scale devices (a PEMFC: 500-W, 50-A; a battery bank: 68-Ah, 24-V; and a supercapacitor bank: 292-F, 30-V, 500-A) corroborate the excellent control principle during motor drive cycle.

Modern fuel-cell (FC) vehicles (such as cars, buses, tramways, trains, or aircrafts) arose from an infusion of research money by several research agencies, including the U.S. Department of Energy (DOE), the Istituto Motori of Italian National Research Council (CNR), the French National Center for Scientific Research (CNRS), the French National Railways Company (SNCF), the ALSTOM Company, the Japan Railway Technical Research Institute, and so forth. The aim of this research is to study, analyze, and test energy-efficient and environmentally friendly traction systems.

One of the main problems in autonomous electric vehicles is the energy storage, because of the use of low capacity batteries with low power delivery. This work shows a way to deal with the energy storage problem on a high performance electric vehicle capable to run a quarter of a mile in 10 seconds. The concept design of the system combines different storage technologies, ensuring the appropriate power delivery to the motors during the short time needed. In order to achieve this goal, it is necessary to determine the optimum size of each storage element to guarantee the vehicle high performance. This work proposes a methodology for evaluating different characteristics of ultracapacitors and batteries, such as mass, volume and cost. After determining the amount of the storage technologies, it is possible to make an optimal power management in the vehicle, that combined with the control of the motors improves the performance of the electric vehicle.

This paper presents the utilization of a PEM fuel cell as a main power source in a distributed generation system, particularly for future electric vehicle applications. One of the main weak points of the fuel cell is its time constants dominated by 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, recognized as a fuel starvation phenomenon. Therefore, to employ a PEM fuel cell in dynamic applications, the electrical system must have at least an auxiliary power source to improve system performance when electrical loads at a dc bus demand high energy in a short time. The possibilities to use a supercapacitor or battery bank as an auxiliary source with a fuel cell main source is presented in detail. The very fast power response and high specific power of a supercapacitor or high specific energy of battery can complement the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The studies of two hybrid power systems for vehicle applications: a fuel cell/battery and a fuel celli supercapacitor hybrid power sources are explained. Experimental results in laboratory authenticate that energy storage devices can assist the fuel cell to meet the vehicle power demand and help achieve a better performance.

A new hybrid energy storage system is proposed in this paper based on partial power processing concept. Unlike the conventional designs, the proposed HESS processes only a portion of the vehicle power through the interfacing DC/DC converter. The new concept reduces the converter losses, enables the full usage of stored energy in the storage units and provides stable DC bus voltage irrespective of the operating conditions. The interfacing converter is only active when there is a need to supply power from the ultra-capacitors (UC). The regenerative braking energy is captured by both the UC, and the battery via the bidirectional converter. The proposed topology is analyzed, simulation and experimental results are presented in the paper to confirm the validity and the effectiveness of the proposed system.

This paper proposes a high-power high-energy dc distributed generation system supplied by a polymer electrolyte membrane fuel cell (PEMFC) as a main power source and storage devices: battery and supercapacitor, for future fuel cell vehicle applications. The energy in hybrid system is balanced by the dc bus voltage regulation. The principle is based on frequency approach that the FC dynamics are limited to avoid fuel starvation problems and the battery dynamics are also limited to reduce its stress. As a result, the hybrid power source will increase its lifetime. To authenticate the proposed control algorithm, a hardware system in our laboratory is realized by analog circuits and numerical calculation by dSPACE. Experimental results with small-scale devices (a PEMFC: 500-W, 50-A; a battery bank: 68-Ah, 24-V; and a supercapacitor bank: 292-F, 30-V, 500-A) corroborate the excellent control principle during motor drive cycle. Index Terms-Converters, current control, energy conversion, energy management, hydrogen, oxygen, polymer electrolyte membrane fuel cell (PEMFC).

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. Index Terms-Hybrid power source, peak load shaving, polymer electrolyte membrane fuel cell (PEMFC), power electronics, power system control, supercapacitor.

In this work, simultaneous energy regeneration and motion control for robot manipulators with brushless motors is considered. The robot has a number of semi-active joints connected to ultracapacitors, while the remaining joints are fully-active, powered from constant-voltage power supplies. A three-phase inverter is used to apply voltage to each motor, and the space vector pulse width modulation technique is used to generate voltage commands for the inverter. A PI controller is used to generate voltage commands for the inverter based on reference currents. A method is developed to obtain actual torque based on the desired torque generated by a virtual controller, which can be any suitable robot motion control algorithm, for instance inverse dynamics. A novel optimization approach is used to generate reference currents that maximize the amount of regenerative energy stored in the ultracapacitor and motor inductance subject to the torque demanded by the virtual controller. An explicit solution is found for the optimal current references and it is shown that the well-known choice of a zero direct current component in the direct-quadrature frame is sub-optimal relative to our energy optimization objective. A simulation using a 2-link planar manipulator with one active and one semi-active joint is used to illustrate the results.

In this work, simultaneous energy regeneration and motion control for robot manipulators with brushless motors is considered. The robot has a number of semi-active joints connected to ultracapacitors, while the remaining joints are fully-active, powered from constant-voltage power supplies. A three-phase inverter is used to apply voltage to each motor, and the space vector pulse width modulation technique is used to generate voltage commands for the inverter. A PI controller is used to generate voltage commands for the inverter based on reference currents. A method is developed to obtain actual torque based on the desired torque generated by a virtual controller, which can be any suitable robot motion control algorithm, for instance inverse dynamics. A novel optimization approach is used to generate reference currents that maximize the amount of regenerative energy stored in the ultracapacitor and motor inductance subject to the torque demanded by the virtual controller. An explicit...

Siemens has developed a hybrid drive system for rubber-tired gantry (RTG) cranes that drastically reduces their fuel consumption. The hybrid crane uses ultracapacitors to store energy that is regenerated when a container is lowered or during braking, and reuses this energy to assist the engine later on. The main goal of this thesis is improving the crane's energy management strategy. This is the system that optimizes the fuel cost by controlling in real time how and when the two available power sources of the hybrid crane are used.

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 and a long-term storage system, 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. 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 dynamic optimization 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 a SC module (100 F, 32 V). Experimental results validate the excellent control algorithm during load cycles.

This paper presents the utilization of energy storage device composed of 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 flatness properties for fuel cell/supercapacitor hybrid power source. Utilizing the flatness principle, we propose simple solutions to the hybrid energy management and stabilization problems. To authenticate the proposed control laws, a test bench is realized in laboratory. The control algorithm (energy and current control loops) is digitally implemented by dSPACE controller DS1103. Experimental results with small-scale devices (a PEMFC: 500 W, 50 A, 10 V; and a supercapacitor bank: 250 F, 32 V, 500 A) substantiate the excellent performance during load cycles.

Absrract-This paper presents a new control algorithm for utilizing rEM fuel cell and supercapacitors for automotive system. A PEM fueI cell is operated as a directional main power source connected to 42 V dc bus (PowerNet) by boost converter, and supercapaciton is controlled as a fast bidirectional auxiliary power source connected to de bus by a 2-quadrant de/de converter. The system employs a 500 W PEM fuel cell and a supercapacitive storage device, composed of six components (3,SOO F, 2.S 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 de bus hetween the main and auxiliary sources.

This paper presents a control strategy for employing PEM fuel cell, known as slow dynamic device, as main power source and supercapacitors, known as high dynamic storage elements, as auxiliary power source for dc distributed system. The main point is to regulate the dc bus, and the important constraint is to avoid speedy operation of fuel cell current. Therefore, fuel cell is simply operating in almost steady state conditions in order to ensure a good synchronization between fuel (hydrogen and oxygen) flow and fuel cell current and to lessen mechanical stresses. The proposed control is based, first, on the regulation of the dc bus voltage through the control of the power delivered by the supercapacitors, and second, on the control of the supercapacitor voltage by the operating of the fuel cell. To validate control algorithms, hardware system is realized by analogical current loops and digital voltage loops (dSPACE). Experimental results, with a ZSW PEM 500 W, 12.5 V, 40 A fuel cell and a SAFT 292 F, 30 V, 400 A supercapacitor module for a 42 V dc distributed network, confirm system operations.

Electric vehicles (EV) demands for greater acceleration, performance, and vehicle range in pure electric vehicles plus mandated requirements to further reduce emissions in hybrid electric vehicles (HEV) increase the appeal for combined on-board energy storage systems and generators. This paper deals with a multiple input DC-DC power converter devoted to combine the power flowing of multi-source on energy systems. The multi-source is composed of (i) a fuel cell system as a prime power demands, (ii) super capacitor banks as energy storage devices for high and intense power demands, (iii) superconducting magnetic energy storage system (SMES), (iv) multiple input DC-DC power converter, (v) a three phase inverter-fed permanent magnet synchronous motor as a drive. In this system, It is used super capacitor banks and superconducting magnetic energy replaces from the battery system. The modeling and transient performance simulation is effective for reducing transient influence caused by sudden charge of effective load. The main purpose of power electronic converters is to convert the DC power output from the fuel cell and other to a suitable AC voltage, which can be connected to electric loads directly (PMSM). The fuel cell and other output is connected to the DC-DC converter, which regulates the DC link voltage. Keywords: Fuel Cell system, superconducting magnetic energy storage (SMES), multiple input DC-DC power converter ultracapacitor tank and FLC.

Siemens has developed a hybrid drive system for rubber-tired gantry (RTG) cranes that drastically reduces their fuel consumption. The hybrid crane uses ultracapacitors to store energy that is regenerated when a container is lowered or during braking, and reuses this energy to assist the engine later on. The main goal of this thesis is improving the crane's energy management strategy. This is the system that optimizes the fuel cost by controlling in real time how and when the two available power sources of the hybrid crane are used.

One of the main problems in autonomous electric vehicles is the energy storage, because of the use of low capacity batteries with low power delivery. This work shows a way to deal with the energy storage problem on a high performance electric vehicle capable to run a quarter of a mile in 10 seconds. The concept design of the system

A combination of battery and ultracapacitor as a hybrid energy storage system (HESS) for an electric vehicle (EV) can result in better acceleration performance, reduced battery charge-discharge cycle and longer driving range. This paper presents a new converter design combining triple-halfbridge (THB) and boost half-bridge (BHB) converters in a batteryultracapacitor HESS. The BHB converter is used to compensate the voltage variation of the ultracapacitor. A power management system is proposed to control the power of battery and ultracapacitor, to supply the demanded power of an EV. This paper describes the operation of the proposed converter using a simplified ∆-type primary-referred equivalent circuit. This paper also shows the simulation results verifying the fast dynamic response of the proposed power management system for the proposed HESS, with minimal current stress.

This paper presents an original control algorithm for a hybrid energy system with a renewable energy source: a photovoltaic (PV) array and a wind turbine (WD). A single storage device, a supercapacitor (SC) module, is in the proposed structure. The very fast power response and high specific power of a SC complements the insufficient power output of the main sources to produce the compatibility and performance characteristics needed in a load. To verify the proposed principle, a hardware system is realized with analog circuits and with numerical calculation (dSPACE) for the energy control loops. Experimental results with small-scale devices, namely, a wind turbine generator (500 W), a photovoltaic array (800 W, 31 A) manufactured by the Ekarat Solar Company and a SC module (100 F, 32 V), illustrate the excellent energy-management scheme during load cycles.

This paper presents a system using a supercapacitor storage device to smoothen the output power fluctuation of a variable-speed wind generator. This kind of system is a multiconverter structure and exhibits nonlinear behavior. In this paper, a nonlinear control algorithm based on the flatness properties of the system is proposed. Utilizing the flatness principle, we propose simple solutions to the energy-management and stabilization problems. To authenticate the proposed control laws, a test bench is realized in the laboratory. The control algorithm is digitally implemented by dSPACE controller DS1104. Experimental results with small-scale devices (a wind generator of 500 W and a supercapacitor bank of 100 F, 32 V, and 500 A) corroborate the superb performance during load cycles.

A renewable energy hybrid power plant, fed by photovoltaic (PV) source with a supercapacitor (SC) storage device and suitable for distributed generation applications, is proposed herein. The PV is used as the main generator and the supercapacitor functions as an auxiliary source for supplying the deficiency power (transient and steady-state) from the PV. For high power applications, 4-phase parallel boost converters and 4-phase parallel bidirectional converters are implemented for the PV converter, and a storage device, respectively. A mathematical model (reduced-order model) of the PV, and supercapacitor converters is described for the control of the power plant. Using the nonlinear approach based on the flatness property, we propose a simple solution to the optimization, stabilization, and robustness problems in the hybrid power system. This is the key innovative contribution of this research paper. The prototype small-scale power plant studied was composed of a PV array (0.8 kW) and a supercapacitor module (100 F). Experimental results authenticate the excellent control algorithm during load cycles.

This paper presents the utilization of a supercapaci-tor 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.

This paper reports the preliminary experimental evaluation of a four wheel motors series hybrid prototype equipped with an internal combustion engine coupled to a generator and an energy recovery system (batteries plus ultracapacitors). The paper analyses global efficiency (energy dissipated to overcome the dissipative forces on energy dissipated in fuel), autonomy in electric configuration, and the efficiency of the regenerative braking system. The tests were carried out in a test cell equipped with a chassis dynamometer. The tests were performed according to the current regulated procedures. A constant speed test was performed in order to evaluate the autonomy of the vehicle in the electric configuration. The results show that the real tank to wheels efficiency is about 30% for HOST as a series hybrid and 79% for HOST as an electric vehicle.

One of the main problems in autonomous electric vehicles is the energy storage, because of the use of low capacity batteries with low power delivery. This work shows a way to deal with the energy storage problem on a high performance electric vehicle capable to run a quarter of a mile in 10 seconds. The concept design of the system

This paper presents a new control strategy for dc-link stabilization that use supercapacitors (SC) as the energy storage unit. A three-port isolated converter based on a dual active bridge topology is presented, and a reduced-order mathematical model of the system is described for power plant control. Using a nonlinear control approach based on the flatness property, we propose a simple solution to dynamic and stabilization problems in the power electronics systems. The controller design parameters are independent of the operating point at which interactions between the dc main substation, loads and energy storage unit are taken into account by the controller. Furthermore, high dynamics in the disturbance rejection are achieved, which is the key contribution described in this paper. To validate the proposed method, a hardware system is modeled using digital estimation with a DS1103 dSPACE controller platform. We analyze a prototype small-scale network that uses a 1 kW six-pulse rectifier as a dc substation and a 250 F, 32 V supercapacitor bank (by Maxwell Technologies Inc.) as an energy storage substation. Finally, the utility of the control algorithm is validated using experimental results measured during load cycles.

This paper presents a new control approach for dc-link stabilization in weak networks that use supercapacitors (SC) as the energy storage substation. A 4-phase parallel converter with interleaved switching technique is presented as a 2-quadrant SC converter, and a reduced-order mathematical model of the system is described for power plant control. Using a nonlinear control approach based on the flatness property, we propose a straightforward solution to dynamic and stabilization problems in the power electronics systems of networks, which is the key contribution described in this paper. To validate the proposed method, a hardware system is modeled using digital estimation with a DS1104 dSPACE controller platform. We analyze a prototype small-scale network that uses a 700 W six-pulse rectifier as a dc main generator and a 100 F, 32 V SC bank as an energy storage substation. Finally, the utility of the control algorithm is validated using experimental results measured during load cycles.

A renewable energy hybrid power plant, fed by photovoltaic (PV) and fuel cell (FC) sources with a supercapac-itor (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.

A renewable energy hybrid power plant, fed by photovoltaic (PV) and fuel cell (FC) sources with a supercapacitor storage device and suitable for distributed generation applications, is proposed herein. The PV is used as the main generator; the FC acts as a power source, feeding only the insufficiency power (steady-state) from the PV; and the supercapacitor functions as an auxiliary source for supplying the deficiency power (transient and steady-state) from the PV and the FC. Using the nonlinear approach based on the flatness property, we propose a simple solution to the dynamics, optimization, stabilization, and robustness problems in the hybrid power system. This is the key innovative contribution of this research paper. The prototype small-scale power plant studied was composed of a PEMFC system (1.2 kW), a PV array (0.8 kW), and a supercapacitor module (100 F). Experimental results in laboratory authenticate the excellent control algorithm during load cycles.

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.

The present article show the research that led to the design and construction of a bench or arrangement with ultra-capacitors (BUC) that is put into operation with an electronic controller. These modules are powered by photovoltaic solar energy -responsible for the supply and supply of electric current- to increase the autonomy in a lighting system. Describes the performance of the ultracapacitors in series and parallel circuit, in order to determine the energy stored in the bank, to integrate it to the electronic controller in charge of the load, provision, visualization and adjustment of the passage of the energy current solar photovoltaic to BUC and the load made up of Leds. Storage of the Ragone diagram is fulfilled; which by means of the BUC is able to supply -in a short time- high energy density, contrary to the rechargeable battery used that is responsible for delivering for a longer time lower density of electric energy.

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.

This paper presents a fuzzy control law based on differential flatness approach for distributed dc generation (nonlinear system) supplied by a fuel cell (FC) (main source) and supercapacitor (auxiliary source). The main technical feeble point of FCs is slow dynamics because the power slope is limited to prevent fuel starvation problems, improve performance and increase lifetime. The very fast power response and high specific power of a supercapacitor complements the slower power output of the main source to produce the compatibility and performance characteristics needed in a load. The energy in the system is balanced by dc bus energy regulation (or indirect voltage regulation). A supercapacitor module functions by supplying energy to regulate the dc bus energy. The FC, as a slow dynamic source in this system, supplies energy to the supercapacitor module in order to keep it charged. Using the intelligent fuzzy control law based on the flatness property, we propose straightforward solutions to hybrid energy management, dynamic and stabilization problems. 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 power plant (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 load cycle.

EYEWIRE ENERGY AND ENVIRONMENT CRISES ARE FAST BECOMING THE BIGGEST problems around the world so, as a consequence, new renewable and clean energy power sources must be considered. One of the prevalent alternative sources of electric power is the fuel cell, discovered by Sir William Grove in 1839. One expects that fuel cell power generation systems will be used in a growing number of areas: in portable applications, in transportation applications , and in stationary power applications, for which fuel cell systems can provide both power and heat with cogeneration efficiencies as high as 80%. Numerous recent works have already highlighted the possibility of using the fuel cell in distributed power generation systems. The fuel cell utilizes the chemical energy of hydrogen (H 2) and oxygen (O 2) to generate electricity without pollution, as shown in Figure 1. The byproducts are simply pure water and heat. There are several types of fuel cells, which are characterized by the employed electrolyte. One of the most promising is the small, lightweight, and relatively easy to build polymer elec-trolyte membrane fuel cell (PEMFC), first used by NASA in the 1960s as part of the Gemini space program. A single cell voltage of the fuel cell is given by Gibb's free energy ΔG and is equal to 1.23 V. This theoretical value is never reached even at no-load. For the rated current, the voltage of an elementary cell is about 0.6-0.7 V. Then a fuel cell is always an assembly of elementary cells that constitute a stack as shown in Figure 2.

This paper reports the preliminary experimental evaluation of a four wheel motors series hybrid prototype equipped with an internal combustion engine coupled to a generator and an energy recovery system (batteries plus ultracapacitors). The paper analyses global efficiency (energy dissipated to overcome the dissipative forces on energy dissipated in fuel), autonomy in electric configuration, and the efficiency of the regenerative braking system. The tests were carried out in a test cell equipped with a chassis dynamometer. The tests were performed according to the current regulated procedures. A constant speed test was performed in order to evaluate the autonomy of the vehicle in the electric configuration. The results show that the real tank to wheels efficiency is about 30% for HOST as a series hybrid and 79% for HOST as an electric vehicle.

We report a methodology to optimize vertically grown carbon nanotube (CNT) ultracapacitor (CNU) geometrical features such as CNT length, electrode-to-electrode separation, and CNT packing density. The electric field and electrolyte ionic motion within the CNU are critical in determining the device performance. Using a particle-based model (PBM) based on the molecular dynamics techniques we developed and reported previously, we compute the electric field in the device,
keep track of the electrolyte ionic motion in the device volume, and evaluate the CNU electrical performance as a function of the aforementioned geometrical features. We show that the PBM
predicts an optimal CNT density. Electrolyte ionic trapping occurs in the high CNT density regime, which limits the electrolyte ions from forming a double layer capacitance. In this regime, the CNU capacitance does not increase with the CNT packing density as expected, but dramatically
decreases. Our results compare well with existing experimental data and the PBM methodology can be applied to an ultracapacitor built from any metallic electrode materials, as well as the vertical CNTs studied here.

The growing demand for energy in the world causes a lot of pressure on the environment and the resources used to supply the energy. To ensure a continuous, more reliable and environmentally friendly energy supply system the world started to develop alternative technologies including photovoltaic panels, wind turbines and hydrogen fuel cells. The hydrogen fuel cell in combination with batteries has also been used in electric vehicles to minimize greenhouse gas emissions and the strain on crude oil. There is however no control applied on the different energy
sources within the electric vehicle system. This project focused on developing a smart controller that would determine the energy source supplying the power demanded by the load. The energy sources
include a hydrogen fuel cell, batteries and super-capacitors. The load for the system was simulated on an electronic load using a scaled profile of the power needed by an electronic motor that could be installed in a vehicle. The results showed that by using a smart controller in the system the motor can operate for a longer time than without the controller. Using a controller therefore resulted in increasing both the lifetime and energy supplying time of the energy sources within the system.