Ultracapacitor Research Articles

Experimental Verification of a Double-Input Soft-Switched DC–DC Converter for Fuel Cell Electric Vehicle With Hybrid Energy Storage System

In the drivetrain of a fuel cell (FC)-powered electric vehicle, double-input converter plays a critical role by transferring the power from battery and FC to an ultracapacitor (UC) during acceleration and from UC to the battery during braking. As the battery and FC have unregulated low voltage, the converter should provide a high-voltage gain as well as an efficient power conversion. In this article, a double-input three-level converter composed of buck-boost-half-bridge modules is proposed for automotive applications. The proposed converter can supply the load in the absence of FC or battery. The converter takes advantage of active clamp configuration in terms of reducing the voltage stress across switches and providing soft-switching performance. Consequently, the converter's overall performance in terms of switching losses and cost can be considerably improved. The switching scheme doubles the effective switching frequency, which, in turn, reduces the size of the boost inductors to enhance power density. The operational characteristics of the converter and comparison with state-of-the-art converters are given in this article. Finally, a 4-kW, 100-kHz prototype using gallium nitride switches is implemented to validate the proposed concept.

A Hybrid Energy Storage System for Dual-Motor Driven Electric Vehicles

To satisfy the high power requirements for accelerating, climbing or running at high speeds, dualmotor driven electric vehicle (EV) is becoming more and more popular. To reduce the high-power influence to the battery life, a hybrid energy storage system (HESS) for dual-motor driven EV is proposed in this paper. Compared with conventional HESS, the proposed method is suitable for dual-motor driven EV, by the additional ultra-capacitor (UC). Different modes of the HESS are able to be realized, and the overall efficiency can be optimized. Moreover, no DC/DC converter is needed in this method, and the cost and the control complexity are reduced. The topology of the HESS is firstly proposed and the working principle is analyzed. The simulation is established to validate the proposed method.

Plasmonic optical trapping of nanoparticles with precise angular selectivity.

In this paper, a plasmonic trapping scheme including a polystyrene nanoparticle with gold cap and a metal tip tweezers was proposed. We numerically investigated the optical trapping behavior of the metal tip to this asymmetric particle. The results show that the metal tip can capture the particle at the position of the gold cap due to the strong plasmonic interaction, while other positions of the particle cannot be captured by metal tip. Furthermore, the trapping angle of the nanoparticle can be adjusted by changing the incident wavelength. Precisely controlling the trapping angle of the nanoparticles in our study has important potential applications of optical tweezers, such as in single molecule manipulation.

Olfactometric Comparison of the Volatile Insecticide, Metofluthrin, Through Behavioral Responses of Aedes albopictus (Diptera: Culicidae).

Testing behavioral response to insecticidal volatiles requires modifications to the existing designs of olfactometers. To create a testing apparatus in which there is no chemical memory to confound tests, we detail the technical aspects of a new tool with design influences from other olfactometry tools. In addition, this new tool was used to evaluate a novel formulation of metofluthrin for use as an outdoor residual treatment. After sourcing materials to prioritize glass and metal construction, a modular wind tunnel was developed that hybridizes wind tunnel and olfactometer specifications. Volatile contaminants were removed by strong ultraviolet light within the chamber before and between trials. Repellent trials were conducted with an experimental formulation of metofluthrin and a commercial formulation of esfenvalerate, prallethrin, and piperonyl butoxide (Onslaught Fast Cap) against Aedes albopictus (Skuse). Toxicant vapors were delivered with attractants from a lure with behavioral responses scored 20 min post-exposure. Upwind attraction to the attractant lure and the Onslaught Fast Cap plus lure resulted in 90 and 75% capture, respectively. In contrast, metofluthrin vapors resulted in less than 10% attraction, while also causing repellency, disorientation, knockdown, and mortality effects. Our findings demonstrated that an inert modular wind tunnel was functional for mitigating toxic secondary exposures of spatial repellents amidst complex behavioral analysis in mosquitoes. The resulting observations with formulated metofluthrin positively reinforce the merit of transitioning metofluthrin into expanded roles in mosquito management.

Implementation of an on-line multi-objective particle swarm optimization controllers gains self-adjusted of FC/UC system devoted for electrical vehicle

In the context of ameliorating the electrical vehicle dynamic, this paper suggests an on-line control based on multi-objective Particle-Swarm-Optimization (MOPSO). This control is applied to Fuel Cell (FC)/Ultra-Capacitor (UC) vehicle in order to enhance the dynamic system and to reduce fuel consumption. The traction system, comprising a permanent magnet synchronous motor (PMSM) as well as the main power source and the auxiliary energy device, is controlled using PI controllers. The regulators’ gains are adjusted by an energy management system based on off-line PSO, in the first step and on-line MOPSO in the second one. In order to demonstrate the effectiveness of the two proposed approaches, a New York City cycle profile is implemented as the reference speed of the vehicle model. Theoretical analysis and outcomes display that the on-line self-adjusted PI regulators by MOPSO established on the Integral Absolute Error (IAE) index contributes better to the power management system than conventional regulators based on the same index.

Studies of voltage stabilization and balancing systems in energy storage modules based on supercapacitors

Supercapacitors come under different names and scientific nominations as Ultracapacitors (UCs) or double layer capacitors, or electrochemical capacitors, they are considered as promising technological devices used for storing energy in the field of energy storage systems. They are able to deliver high power and enable high load currents in addition their ability to bridge power gaps. As we will notice, they have fast yet complicated charging/discharging mechanism interpretations. This paper will provide an overview on different equivalent circuits of a supercapacitor, and will highlight the concept of unbalanced series of connected ultracapacitors and different options in rectifying such unbalance. The balancing of supercapacitors connected in series can come in different modes passive or active and maybe hybrid. A comparison between the different modes will be executed using MATLAB/Simulink and results will be shown based on the economical and performance perspectives.

Comparison of the capacity factor of stationary wind turbines and weather-routed energy ships in the far-offshore

Offshore wind energy technology has developed rapidly over the last decade. It is expected to significantly contribute to the further increase of renewable energy in the global energy production in the future. However, even with floating wind turbines, only a fraction of the global offshore wind energy potential can be harvested because grid-connection, moorings, installation and maintenance costs increase tremendously as the distance to shore and the water depth increase. Thus, new technologies enabling harvesting the far offshore wind energy resource are required. To tackle this challenge, mobile energy ship concepts have been proposed. In those concepts, electricity is produced by a water turbine attached underneath the hull of a ship propelled by the wind using sails. It includes an on-board energy storage system since energy ships are not grid-connected. Thus, the ships route schedules could be dynamically optimized taking into account weather forecast in order to maximize their capacity factors (CF). The aim of this study is to investigate how high the capacity factors of energy ships could be when using weather-routing and compare them to that of stationary wind turbines that would be deployed in the same areas. To that end, a modified version of the weather-routing software QtVlm was used. Velocity and power production polar plots of an energy ship that was designed at LHEEA were used as input to QtVlm. Results show that capacity factors over 80% can be achieved with energy ships and stationary offshore wind turbines deployed in the North Atlantic Ocean.

Circuit Modeling of Coaxial-Cable Baluns in Microstrip-Mounted, High-Power, Very-High-Frequency Amplifiers [Application Notes

Baluns have been studied for several decades. They have been used in antennas as unbalanced-to-balanced signal convertors and have sometimes taken on the role of impedance transformers. Apart from their use in antennas, baluns can be found across a variety of applications, ranging from mixers and samplers to power dividers and amplifiers. Good reviews of the most common balun types can be found in [1]-[3]. Because technology limits the maximum v age that can be applied to a transistor, the plest way for a component vendor to in power capabilities is to increase the c This can be done by connecting ma sistor units in parallel, which in tur decrease of the transistor input imp power increases. Currently, laterall transistor modules for very-high-freq with 1-kW output power, have a roughly 1 impedance [4]-[6] . A further increase in power cap bilities will cause an additional drop in input impedance, which eventual forming standard 50-Ω impedanc mes quite difficult and forces designers to es with groups of two transistors and drive them dentially, effectively placing them in series. Baluns play a critical role in this process by preserving symmetry between the transistors, maximizing obtainable power, and relaxing the criteria for the transformation network by halving its transformation ratio, yielding novel types of baluns [7]-[9].

Full-Scale Physical Simulator of All SiC Traction Motor Drive With Onboard Supercapacitor ESS for Light-Rail Public Transportation

This article deals with the design and laboratory implementation of a full-scale physical simulator of an all-silicon carbide (SiC) traction motor drive for light-rail transit systems (LRTS) with onboard supercapacitor energy storage system (ESS). It consists of a pulsewidth modulation (PWM) rectifier representing the 750 V dc catenary line, a three-phase two-level PWM traction inverter to drive a three-phase squirrel-cage traction motor, a flywheel coupled to the motor shaft to represent the dynamic behavior of the transportation vehicle, a loading generator connected to the grid via a dc-link converter with active front-end, and a supercapacitor ESS containing a bidirectional dc–dc converter supplied from the common dc link. The PWM rectifier, a traction inverter, and a bidirectional dc–dc converter are all SiC power MOSFET-based converters for high efficiency and high power density. A physical simulator is a valuable tool in the design and testing of all SiC converters. It is equipped with software programs for a catenary model, rail track model, and vehicle model, and permits the performance verification of various control, modulation, and energy-saving strategies. The physical simulator system developed in this article also allows the performance verification of a vehicle formation on a prespecified real track and evaluation of benefits of the onboard supercapacitor ESS in real time.

Modeling and continuous co-simulation of URT traction electric network-Trains with OESS

The paper presents the traditional urban rail transit (URT) vehicles model that do not carry onboard energy storage systems (OESS) and are not eligible for continuous traction electric network-Trains co-simulation. This paper analyzes the challenges and key issues of the simulation modeling of trains with OESS. Moreover, it summarizes the simulation parameter categories and establishes a state description function and a power source modular Train model. Based on the state parameter transfer method, a continuous simulation strategy for Train with OESS relay crossing traction stations virtually is proposed. Its implementation method using the PSCAD/EMTDC software is also elaborated on. The verification of the model precision, modular multi-parameters input and the continuous dynamic multi-Trains cross-substation simulation are conducted through measured data and simulation results.

A dsPIC based optimal sizing of solar PV plant using ultra capacitors for transient power delivery

Solar PV sources are being increasingly implemented in many applications due to the growing concern of environmental pollution. The capacity of solar PV depends both on the transient power and nominal power required by any type of motor loads. The present investigation reports on a method to optimize the required capacity of Solar Panel by augmenting an Ultra capacitor bank for powering the transient needs of BLDC Motor. A PID based high quality dynamic response characteristics controller was designed to improve the speed transient response of the BLDC motor thereby reducing the transient energy requirement of the BLDC Motor. Tuning of PID parameters is critical to optimise the transient behaviour of the motor. The under damped step response tuning method has achieved an optimal PID parameters without any loss in speed transients when compared with other major tuning methods. PID controller is programmed in dsPIC controller that has high-resolution control and minimal control loop delays, thereby reduces torque ripples, harmonics and improves the dynamic behaviour in all speed ranges. The proposed optimal design of PV system augmented with Ultra capacitor for transient power delivery has been modelled and simulated in MATLAB/Simulink, which resulted in a reduction of plant size by 50 percent. The results obtained in simulation are verified experimentally.

Modeling of the Thermal Behaviors of an Ultracapacitor and Comparison with Measurement Data

Ultracapacitors (UCs), known by different names such as supercapacitors, electrochemical double-layer capacitors, double-layer capacitors or electrochemical capacitors, have the potential to meet the high pulse power capability of the energy-storage systems for automotive applications. The primary advantages of UCs are higher power density and longer shelf and cycle life as compared to those of batteries. In the high pulse power operations for automotive applications, a large amount of heat is produced inside a UC cell. Because the lifetime and performance of a UC depend strongly on temperature, it is important to predict accurately the thermal behaviors of a UC for the efficient and reliable systems integration from an application perspective. In this work, a three-dimensional thermal model is presented to predict the thermal behaviors of the UC. Both of the irreversible and reversible heat generations inside the UC cell are considered. The effective density and specific heat capacity of the various compartments of the cell are estimated based on the mass fractions of the components of each cell compartment. The effective thermal conductivities of the various compartments of the cell are estimated based on the equivalent networks of parallel and series thermal resistances of the cell components. The validation of the three-dimensional thermal model is provided through the comparison of the modeling results with the experimental IR image at various charge/discharge currents.

Performance Evaluation of Battery and Super-Capacitor for Electric Vehicle with Hybrid Techniques

In recent trends, Plug-in Hybrid Electric Vehicles (PHEVs) have an excessive opportunity due to its charging facilities and charge storage system. Through appropriate design and development, Electric Vehicles (EVs) not only eliminate the pollution but also make the system more efficient over traditional vehicles. However, still it is in the progress of the investigation and has several unanswered issues. The performance of PHEV depends upon proper utilization of electric power which is solely affected by the battery State-Of-Charge (SOC). SOC determination becomes a vital problem in whole area where it comprises a battery storage; because it has several drawbacks such as weak power density, longevity, etc. one probable and favourable resolution for this issue is multi-source EV. Both the batteries and Ultra-Capacitors (UC) can reduce the aforementioned disadvantages in existing systems. This proposed work has more efficiency because of the combined design model of both battery and super-capacitor. Hence, in this work, the Particle Swarm Optimization (PSO) technique with Fuzzy Logic Controller (FLC) is implemented for optimal sharing of power between the battery and the super-capacitor.A

Impact of ultra‐capacitor on automatic generation control of electric energy systems using an optimal FFOID controller

Automatic generation control (AGC) acts as a significant part in alleviating dynamic oscillations and sustaining constancy in frequency and scheduled tie-line power to establish the reliable, secure, and stable operation of electric energy systems under dynamic conditions. AGC needs energy storage system (ESS) and elevated expert, intelligent, and flexible control strategies to ensure generation-demand balance in modern complex structured energy systems following inconsistent load demands. Hence, this paper utilizes a new fuzzy fractional order integral derivative (FFOID) controller along with ultra-capacitor (UC) ESS to solve AGC issue in energy systems effectively. The imperialist competitive algorithm is employed to tune the output scaling factors like integral, derivative, and noninteger order of integrator/derivative of FFOID controller using ISE performance index. Initially, the technique is applied on a one-area nonreheat thermal system. Then, to demonstrate its competency and scalability, the study is boosted to prevalent two-area nonreheat thermal, two-area multisource multi-unit hydrothermal, and three-area reheat thermal energy system models. The advantage of the proposed controller is demonstrated by juxtaposing the outcomes with those offered by various best claimed intelligent control approaches expressed in the contemporary literature and fuzzy proportional integral (FPI)/fuzzy FO PI (FFOPI) controller. The UC with the FFOID controller outperforms other methods. The robustness analysis proves that parameters of the utilized controller acquired at nominal situation are healthy enough and necessarily not needed to retune under broad alterations in the system loading/parameters, size/position of load perturbation, and under the appearance of system constraints and random load pattern with/without noise.

Load frequency control of multi‐area hybrid power system integrated with renewable energy sources utilizing FACTS & energy storage system

AbstractThis article proposes the minimization of the frequency deviations in the three‐area hybrid power system. The application of thyristor controlled phase shifter (TCPS) and ultracapacitor (UC) is utilized on load frequency control (LFC). The quality of power supply is affected due to continuous and random changes in load during the operation of the power system. Hence, a power system control is required to maintain a continuous balance between power generation and load demand. LFC plays an important role in maintaining constant frequency and voltage in order to ensure the reliability of electric power. The proportional integral derivative (PID) is adopted for the LFC scheme. The three‐area system considered in this article is integrated with conventional and renewable energy sources such as solar, biomass, and fuel cell. TCPS connected in series with the tie‐line ensures the stabilization of the system and provides additional service like dynamic power flow control in the tie‐line and the power quality is sustained by the subordinate control of supercapacitor energy storage. The system variability is basically due to the frequency fluctuations when it is subject to the load deviations. Thus, the suppression of peak value of frequency deviation through power modulation control is the only way to reduce this problem. By using this method, the efficiency of proposed technique becomes better in deregulated environment which is accepted for the load frequency control scheme. By utilizing these technologies, the better results are obtainable than without the usage of TCPS and a supercapacitor.

Comprehensive Study on Dynamic Parameters of Symmetric and Asymmetric Ultracapacitors

Electrical storage components such as ultracapacitors (UC) have received significant attention from various industrial sectors, from electric vehicles to renewable power plants. This article presents the investigations on dynamic properties of asymmetric Li-ion hybrid (CPQ2300S: 2300 F, 2.2–3.8 V, JSR Co., Tokyo, Japan) and symmetric double-layer (BCAP3400: 3400 F, 2.85 V, Maxwell Technologies Co., San Diego, CA, USA) ultracapacitors. The internal resistance and capacitance of both UCs were slightly changed with respect to current and voltage alterations, but these changes were more prominent for the Li-ion UC. The internal resistance of the Li-ion UC became five times larger and its capacitance decreased significantly when the temperature decreased from +25 °C to −20 °C. More importantly, the double-layer UC exhibited nearly constant capacitance for a wide range of temperature changes (0 °C to −40 °C), although internal resistance increased somewhat. Electrochemical impedance spectroscopy analysis of both UCs was performed for the frequency range of 1 Hz–1 kHz and in the temperature range from −15 °C to +30 °C. It was observed that the temperature effects were much more pronounced for the asymmetric Li-ion UC than that of the symmetric double-layer UC. This work also proposes an improved equivalent circuit model based on an infinite number of resistance-capacitance (r–C) chains. The characteristic behavior of symmetric UCs can be explained precisely by the proposed model. This model is also applicable to asymmetric UCs, but with less precision.

Improved Energy Management Algorithm With Time-Share-Based Ultracapacitor Charging/Discharging for Hybrid Energy Storage System

The efficiency, durability, and health of the energy storage system components depend on controlling the power flow subjected to proper operational constraints. It is achieved by energy management algorithm (EMA). Conventional EMAs restrict the ultracapacitor (UC) operation to a reference voltage to prevent it from overcharging/undercharging. This leads to very narrow utilization of the UC voltage range. However, UC voltage can safely be varied from zero to maximum-rated voltage. Rather than employing a UC voltage control loop that operates concurrently to transient load demand, a time-share-based approach has been used for UC charging/discharging. Hence, EMA has been modified in the present work by utilizing the UC voltage band instead of a UC reference voltage, which increases its power delivery capacity by approximately two to four times. In this paper, the proposed EMA improves the transient performance of the system and reduces the UC size. An experimental prototype of the system is designed, and the proposed EMA is tested in the different operating regions for validation.

Wavelet-transform Algorithm Application in Hybrid Power System Optimization of Electric Vehicles

In order to reduce the changing times of battery’s output power loads and currents, a novel energy management strategy was developed for hybrid power system including a battery pack and an ultracapacitor (UC) pack. The strategy is utilizing wavelet-transform algorithm to allocate power components with different frequency contents among the on-board energy sources. The models of hybrid power system were developed and simulated in MATLAB/Simulink. Simulation results show that: Compared with the logic threshold strategy, the wavelet control method can avoid battery to receive chaotic high-frequency components more effectively. Meantime, the utilization of ultra-capacitor can be improved. Thus battery can be protected and the efficiency of electric vehicles can be increased.

Highly confined radial contour modes in phononic crystal plate based on pillars with cap layers

We investigate highly confined and isolated surface modes in a phononic crystal plate based on pillars with cap layers. The structure is made of a thin membrane supporting periodic pillars each composed of one cylinder surmounted by a disk shaped cap layer. An optimal choice of the geometrical parameters and material composition allows the structure to support isolated radial contour modes confined in the cap layer. In this study, we consider diamond and gold (Au) as the pillar and cap layers, respectively, and aluminum nitride as a thin membrane owing to the strong contrast in their elastic and density properties and to their compatibility with the integrated circuit technology and microwave electroacoustic devices. The phononic crystal based on diamond pillars allows us to induce a wide stop band frequency, and the addition of the Au disk shaped layer on diamond pillars enables us to introduce flat modes within the bandgap. We demonstrate that one can optimize the flat mode frequencies by varying the geometrical parameters of the Au cap layer. The quality factor (Q) of a cavity resonator composed of one line gold/diamond pillar surrounded by an array of diamond pillars on both sides has been investigated. These results clearly show that, using this design approach, one can (i) reduce the acoustic energy leakage out of the resonator and (ii) optimize the cavity resonator’s Q factor by varying only the geometrical parameters of the gold cap layer. The proposed design provides a promising solution for advanced signal processing and sensing applications.

Minimizing Data Center Uninterruptable Power Supply Overload by Server Power Capping

Recent analyses show an increase in data center (DC) service downtime due to the increase in power supply outages caused by overloaded uninterruptable power supplies (UPSs). As a solution to the UPS overload problem, this letter presents a developed power distributor manager (PDM) that caps the power consumption of the dc by enforcing a power restriction on the running servers based on a UPS power minimization cost function. The PDM proposed controls the power consumption per UPS in a dc by means of processor time-sharing and dynamic frequency scaling, which eliminates UPS overloading problems, and thus reduces server outages.