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=Search terms=
=Search terms=
Ultracapacitors  
*Ultracapacitors  
Ultracapacitors and solar PV
*Ultracapacitors and solar PV
Hybrid battery-ultracapacitor charging
*Hybrid battery-ultracapacitor charging
Constant current charging  
*Constant current charging  
Constant power charging mode
*Constant power charging mode
Hybrid energy storage
*Hybrid energy storage


=Journals=
=Journals=

Revision as of 02:32, 30 May 2013

Photovoltaic charging of ultracapacitors literature review

Search terms

  • Ultracapacitors
  • Ultracapacitors and solar PV
  • Hybrid battery-ultracapacitor charging
  • Constant current charging
  • Constant power charging mode
  • Hybrid energy storage

Journals

literature

Uninterruptible power supply for short-time power back-up using ultracapacitors

Abstract: This paper presents an uninterruptible power supply capable of proving power for several seconds. Ultracapacitors are used as the storage method since they are suitable for pulse power applications and longer life time. Selection of ultracapacitors and controller design for associated power electronic converters are presented in this paper. Further simulation results of the proposed uninterruptible power supply are also included in the paper.

Ultracapacitors: why, how, and where is the technology

Abstract: This paper covers all the basics of Ultra capacitors from why we need them, their advantages, their working and a detailed comparison of various features of Ultra capacitors with that of batteries. Various concerns like the cost issues and the manufacturing problems of the technologies involved are discussed.The present status and the future scope of the technology is also covered.

Effective charging method for ultracapacitors

Abstract:One of the advantages of ultracapacitors is its high power capability, which is applicable for high rate of charging and discharging operation like motor starting and regenerative braking of an electric vehicle. This paper presents a new charging method for ultracapacitors. Comparing with batteries, ultracapacitor can accept a wide range of charging current and can be fully charged within a few minutes. Common chargers for ultracapacitors are usually equipped with current transducers and closed loop circuitry for current control, which are expensive and complicated. The proposed circuit consists of a minimum number of components. It does not require any current transducer or dedicated voltage/current control circuitry. A simple open-loop control system is applicable for the whole charging stage. It is free of stability problem and protects itself from being overloaded by ultracapacitor with zero initial charge. This paper presents the design and operation of the hardware circuit. Both simulation and experimental results are included.

Use of Super-Capacitor to Enhance Charging Performance of Stand-Alone Solar PV System

Abstract:The battery charging performance in a stand-alone solar PV system affects the PV system efficiency and the load operating time. The New Energy Center of National Taiwan University has been devoted to the development of a PWM charging technique to continue charging the lead-acid battery after the overcharge point to increase the battery storage capacity by more than 10%. The present study intends to use the super-capacitor to further increase the charge capacity before the overcharge point of the battery. The super-capacitor is connected in parallel to the lead-acid battery. This will reduce the overall charging impedance during the charge and increase the charging current, especially in sunny weather. A system dynamics model of the lead-acid battery and super-capacitor was derived and the control system simulation was carried out to predict the charging performance for various weathers. It shows that the overall battery impedance decreases and charging power increases with increasing solar radiation. An outdoor comparative test for two identical PV systems with and without supercapacitor was carried out. The use of super-capacitor is shown to be able to increase the lead-acid charging capacity by more than 25% at sunny weather and 10% in cloudy weather.

Maximum power transfer tracking for a photovoltaic-supercapacitor energy system

Abstract:It is important to maintain high efficiency when charging electrical energy storage elements so as to achieve holistic optimization from an energy generation source (e.g., a solar cell array) to an energy storage element (e.g., a supercapacitor bank). Previous maximum power point tracking (MPPT) methods do not consider the fact that efficiency of the charger varies depending on the power output level of the energy generation source and the state of charge of the storage element. This paper is the first paper to optimize the efficiency of a supercapacitor charging process by utilizing the MPPT technique and simultaneously considering the variable charger efficiency. More precisely, previous MPPT methods only maximize the power output of the energy generation source, but they do not guarantee the maximum energy is stored in the energy storage element. Note that the load device takes its energy from the storage element so it is important to maximize energy transfer from the source into the storage element. We present a rigorous framework to determine the optimal capacitance of a supercapacitor and optimal configuration of a solar cell array so as to maximize the efficiency of energy transfer from the solar cells into a bank of supercapacitors. Experimental results show the efficacy of the proposed technique and design optimization framework.

A novel charging control scheme for super capacitor energy storage in photovoltaic generation system

Abstract:A control scheme is described to charge series-connected super capacitors for photovoltaic generation systems. Based on the features of the super capacitors charge, the control scheme consists of three modes, i.e., the constant current charge mode, the constant power charge mode, and the constant voltage charge mode. The shift of three modes can be realized by controlling the duty of IGBT in the Boost-Buck converter system. Meanwhile, the high voltage, which is more suitable for application, can be obtained. Compared with the normal charge method with series-connected current-limiting resistance and the charge method with the constant current charge mode and the constant voltage charge mode, the proposed charging control scheme can shorten the charging time and improve the usage of the electric power generated from the PV arrays. The advantage described above is verified by simulations.

Research on Supercapacitor Charging Efficiency of Photovoltaic System

Abstract:the model of supercapacitor and its charging performance with constant voltage charging mode, constant current charging mode and constant power charging mode were studied. A numerical method to calculate the efficiency of these charging modes was inducted. To analyze the storage performance of supercapacitor in PV system, using this method, the maximum charging efficiencies of supercapacitor when its terminal voltage raise from zero to the rated voltage with different charging modes were presented. The multi-stage charging efficiency curves were retrieved, which indicated that the constant power charging mode is more suitable when supercapacitor are charged in PV system. A MPPT plus constant power control charging strategy using two-stage Buck-Boost converter to charge supercapacitor in PV system was proposed. The simulation results showed that this strategy effectively ensure the charging efficiency of the system.

Technology Research Of Novel Energy Storage Control For The PV Generation System

Abstract:Recent years, technologies for new energy have developed rapidly since the energy crisis and the environmental pollution got worse. And the solar energy generation technology tends towards the stage of a large number of applications in engineering from the research stage. This paper designed a grid-connected PV system firstly, then introduced the operation principle of the various parts as well with the control strategy of the power flow. The design of energy storage is of great significance as the output power of PV cells array is greatly affected by the light intensity and the temperature change. Battery is used as the energy storage device normally in the traditional energy storage system. In this paper, it used the Ultracapacitor as the energy storage device after comparing with the battery, and designed the charge-discharge control strategy according to the characteristics of the ultracapacitor. Finally it verified the feasibility of the energy storage control strategy through the simulation models which was built based on the PSCAD/EMTDC platform.

Using Ultracapacitors in Photovoltaic Systems. A technical proposal

Control of Bidirectional DC-DC Converter for Supercapacitor Automotive Application

Abstract: The purpose of this paper is to study a sliding- mode controller to regulate the voltage and current a bidirectional DC-DC converter . The converter is placed between a supercapacitor array (SA) and a DC-link �xed at 42V. Supercapacitor array is re- garded as powered system with high current and low voltage source. The DC-DC converter is bidi- rectional: it is a Boost converter when the SA pro- vides the power requirement of the DC link and a Buck converter when SA is charged from the DC link. The output voltage ( Boost case) and the inductor current (Buck case) are regulated at con- stant values using a sliding mode approach.

MCU Controlled DC-DC Buck/Boost Converter for Supercapacitors

Abstract: This work is focused on DC to DC conversion, what is a crucial function to enable the use of supercapacitors for energy storage. A theoretical study and comparison of methods, algorithms and techniques for software controlled DC-DC converters have been used to develop a system what can step up or down a DC variable voltage and transform it into a steady state voltage. As a result a new control theory based on Bang-Bang control has been developed with an ARM LPC1768 processor. It was implemented to solve the commercial converters problems because they cannot work with supercapacitors due to their low internal resistance. The outcome is a device what can provide a programmable voltage between 4.5 V and 25 V, hardware can support up to 6 A and it is able to control the operating current owing through the converter. It can be used with the supercapacitors as shown in this work but it can also be used as a general platform for voltage and energy conversion. Furthermore, the designed hardware has the potential to work with smart grids via Ethernet connector, solar panels with MPPT algorithms and, at last, manage energy between di�erent kinds of DC voltage sources and devices.

Isolated Bidirectional DC–DC Converter for SuperCapacitor Applications

Abstract: This paper proposes a new bidirectional DC/DC converter for supercapacitor applications. The proposed converter has a parallel structure in supercapacitor side (where voltage is low and current is high) and a series structure in the other side. This structure increases efficiency of the converter. For current sharing in the parallel side of the proposed converter, two different methods are recommended and compared in this paper: Current balancing transformer (CBT) and two separate inductors (TSI). Simulation and experimental results show performance of the proposed converter.

MODELING BATTERY-ULTRACAPACITOR HYBRID SYSTEMS FOR SOLAR AND WIND APPLICATIONS

Abstract: The purpose of this study was to quantify the improvement in the performance of a battery with the addition of an ultracapacitor as an auxillary energy storage device for solar and wind applica- tions. The improvement in performance was demonstrated through simulation and modeling. A ceraolo battery model and a third order ultracapacitor ladder model were implemented in Mat- lab/Simulink. Sample battery load cycles for solar and wind applications have been obtained from literature and the corresponding C-rates were quanti�ed. The C-rate for the solar load cycle was found to be 0.3C and 0.2C for the wind load cycle. The performance of the battery- ultracapacitor system was checked for the sample solar and wind load cycles and compared with the performance of the battery system without an ultracapacitor. A reduction of 50.5% in bat- tery RMS currents was found for the solar load cycle and 60.9% for the wind load cycle. This reduction in battery RMS currents was found to be directly proportional to the ultracapacitor contribution. Given the low C-rates for the sample load cycles it was deduced that the addition of an ultracapacitor will not signi�cantly improve the battery life to justify the high initial costs.

Sizing Ultracapacitors For Hybrid Electric Vehicles

Abstract: An efficient energy storage medium is essential in all hybrid electric vehicles. The advances in double layer electrolytic capacitor technology have opened new areas to complement batteries as a storage medium. In this paper we will review some of the present applications of ultracapacitors as well as to provide guidelines for sizing ultracapacitors for minimal mass in hybrid electric vehicles. Equations for both constant current as well as constant power discharge are discussed. An iterative method for determining the minimum number of ultracapacitor cells is introduced. The effects of ultracapacitor sizing on the rating of interface power electronics are examined.

ULTRACAPACITOR/ BATTERY HYBRID FOR SOLAR ENERGY STORAGE

Abstract: All stand alone photovoltaic systems require an energy buffer to bridge the mismatch between available and required energy. Battery technology, chiefly the lead acid battery, is the most popular form of energy storage utilized. Nevertheless in a photovoltaic application, the storage battery generally has the highest life time cost in the system, it has a profound effect on the systems reliability and global performance. Photovoltaic panels are not an ideal source for charging batteries as the output is unreliable and heavily dependent on weather conditions an optimum charge/ discharge cycle cannot be guaranteed. Using an ultracapacitor and battery hybrid system it is aimed to prolong the lifetime of the battery, making the overall system more efficient and reliable. The ultracapacitor/ battery hybrid system will be controlled by an energy management system (EMS) implemented in labview. The EMS will implement maximum power point tracking (MPPT) and the chosen battery charging algorithm.

Ultracapacitor Energy Storage for MicroGrid Micro-generation

Abstract:A microsource interface with energy storage would help to realise the plug and play functionality of a MicroGrid. This paper discusses the energy storage interface. Selection and sizing of the energy storage unit is explained. A bi-directional converter is used to interface the storage, and a controller is implemented to keep the output voltage of the converter approximately constant. The energy storage unit was connected to a PV system in simulation. The system response to the irradiance, temperature and load variations were analysed in this paper.

TurboCap: A Batteryless, Supercapacitor-based Power Supply for Mini-FDPM

Abstract: This paper describes TurboCap, a batteryless, supercapacitor-based power supply subsystem for a handheld, laser-based breast cancer detector named the Mini-FDPM. Supercapacitors have high power density and are a better match with the power usage pattern than batteries. However, the multivoltage requirement poses a new problem on the selection of supercapacitor topology for conversion efficiency and for formfactor minimization. Experimental results show that our design can efficiently power the Mini-FDPM system for energy-efficient, untethered operation in a compact size while supporting fast recharge.

Energy Harvesting by Sweeping Voltage-Escalated Charging of a Reconfigurable Supercapacitor Array

Abstract: EscaCap is an energy harvester that uses a boostup charge pump to perform maximum power-transfer tracking (MPTT) while charging a reservoir supercapacitor array (RSA) with a reconfigurable topology. Unlike buck-down type harvesters, the voltage-doubling charge pump of EscaCap enables the sensor nodes to operate under low ambient power conditions. The supercapacitors in the RSA can be dynamically configured for series or parallel topologies by means of a switch array for not only minimizing leakage of the supercapacitors but also improving the charging speed. Furthermore, the RSA of EscaCap is modular and can be easily expanded. Experimental results show that EscaCap can harvest energy efficiently under low and high solar irradiation conditions, achieve shorter charging time, and demonstrate flexibility and robustness.

See also

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