Browse Topic: Capacitors

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Traction Voltage Level in Two-Wheelers: Considerations on Safety and Performance2024-32-006204/18/2025
Most electric 2-wheelers on the market today seek to replace combustion engine vehicles from 50cc to 150cc which equates to an electric motor power between 2 and 12 kW. The traction voltage level of these vehicles is mostly between 44V and 96V. However, the actual choice of voltage on a specific vehicle seems to be arbitrary and higher voltage does not necessarily correlate with higher motor power. This paper seeks to highlight considerations and tradeoffs which feed the choice of traction voltage levels. Important criteria are electrical safety standards and their impact on vehicle electrical architecture, the performance and availability of key electronics parts such as capacitors, MOSFETs, and gate drivers, while also highlighting functional safety aspects. This paper shows by a comprehensive analysis of the motor drive that for the vehicle class mentioned above the traction voltage level can be kept below 60V without any performance impact, while also ensuring electrical and
Schmitt, Stefan
Effect of Mesopore Structure of Carbon Gel on Improving the Capacity of Electric Double-Layer Capacitors2024-32-002604/18/2025
Electric double-layer capacitors (EDLCs) store charge by adsorbing ions at the electrode-electrolyte interface, offering fast charge/discharge rates, high power density, minimal heat generation, and long cycle life. These characteristics make EDLCs ideal for memory backup in electronic devices and power assistance in electric and hybrid vehicles. However, their energy density is lower than that of batteries, necessitating improvements in electrical capacity and potential. Traditionally, activated carbon with a high specific surface area has been used, but recent research focuses on mesoporous carbon materials for better ion diffusion. This study uses resorcinol-formaldehyde-carbon cryogel (RFCC) with mesopores and organic electrolytes with a wider electrochemical window. Various RFCCs with different pore sizes were synthesized and evaluated. Comprehensive investigations into the pore structures and surface properties of both synthesized carbon gels and commercial mesoporous materials
Cheng, Zairan, Okamura, Tsubasa, Ohnishi, Yuto, Nakagawa, Kiyoharu
Ultrahigh-Energy-Density CapacitorTBMG-3961308/01/2021
Capacitors that rapidly store and release electric energy are key components in modern electronics and power systems; however, the most commonly used ones have low energy densities compared to other storage systems like batteries or fuel cells, which in turn cannot discharge and recharge rapidly without sustaining damage. By introducing isolated defects to a type of commercially available thin film in a straightforward post-processing step, a team has demonstrated that a common material can be processed into a top-performing energy storage material.
A Multi-Objective Power Component Optimal Sizing Model for Battery Electric Vehicles2021-01-072404/06/2021
With recent advances in electric vehicles, there is a plethora of powertrain topologies and components available in the market. Thus, the performance of electric vehicles is highly sensitive to the choice of various powertrain components. This paper presents a multi-objective optimization model that can optimally select component sizes for batteries, supercapacitors, and motors in regular passenger battery-electric vehicles (BEVs). The BEV topology presented here is a hybrid BEV which consists of both a battery pack and a supercapacitor bank. Focus is placed on optimal selection of the battery pack, motor, and supercapacitor combination, from a set of commercially available options, that minimizes the capital cost of the selected power components, the fuel cost over the vehicle lifespan, and the 0-60 mph acceleration time. Available batteries, supercapacitors, and motors are from a market survey. The considered lifespan is taken as 10 years, and the traveling distance is estimated at
Shinde, Akash, Kshirsagar, Kunal, Arshad, Saad Bin, Patil, Unmesh, Zhang, Jiangfeng
Development of High Frequency Response Battery and Enhancement of Power Density for Inverter2021-01-075304/06/2021
We propose low inductance batteries and enhance power density for a inverter. Conventionally, the capacitors are used for smoothing ripple of the inverter. The low inductance battery which responds at carrier frequency of inverter can reduce the capacity of the smoothing capacitors and enable to enhance power density for the inverter. For reducing the inductance, it is necessary to separately understand the impact of electrochemical reaction under wide range of assumed conditions and structural reaction on frequency characteristics. Furthermore, it is also necessary to design the low inductance batteries based on combining the both of characteristics. However, there are no study focusing on modeling by combining such different domains. Therefore, we made original inductance model inside battery considering frequency characteristics among all materials and structural influence with electromagnetic field analysis simulator. Then, we compared obtained simulated values with actual battery
Komatsu, Daiki, Inoue, Takeshi, Yamauchi, Shin
Stretchable Micro-Supercapacitors to Self-Power Wearable DevicesTBMG-3854802/01/2021
A stretchable system that can harvest energy from human breathing and motion for use in wearable health-monitoring devices may be possible, according to an international team of researchers, led by Huanyu “Larry” Cheng, the Dorothy Quiggle Career Development Professor in Penn State’s department of engineering science and mechanics. The research team, with members from Penn State and Minjiang University and Nanjing University, both in China, recently published its results in Nano Energy.
Supercapacitor Based on Manganese OxideTBMG-3833801/01/2021
A new supercapacitor based on manganese oxide could combine the storage capacity of batteries with the high power and fast charging of other supercapacitors. By combining manganese oxide with cobalt manganese oxide, a heterostructure is formed in which interfacial properties can be tuned.
Spin Capacitor for Energy-Efficient ElectronicsTBMG-3682505/01/2020
Researchers have created a spin capacitor that can generate and hold the spin state of electrons for a number of hours. Previous attempts have only held the spin state for a fraction of a second. In electronics, a capacitor holds energy in the form of electric charge. A spin capacitor is a variation on that idea. Instead of holding just charge, it also stores the spin state of a group of electrons; in effect, it freezes the spin position of each of the electrons.
Design of a Flexible Hybrid Powertrain Using a 48 V-Battery and a Supercapacitor for Ultra-Light Urban Vehicles2020-01-044504/14/2020
Global warming has put the transport sector, a major contributor of CO2 emissions, under high pressure to improve efficiency. In this context, ultra-light vehicles weighting less than 500 kg, as well as hybrid powertrains, are nowadays seen as promising development trends. The design process of the powertrain of a vehicle combining the advantages of the two concepts is presented in this paper. Through a performance study based on a simple MATLAB model, and mathematical simulation, a proposal is made. A powertrain using a battery and supercapacitor 48V dual power source network, two electric motors and clutches to switch between conventional, parallel, series and full electric modes proves to be an interesting system in terms of performance and costs. A simulation study conducted on a scenario with different outcome possibilities showed that high modularity of the system allows to achieve fuel efficiencies equivalent to approximately 3 l/100 km on the Artemis cycle. Finally, integration
El Ganaoui-Mourlan, Ouafae, Miliani, El Hadj, Carlos Da Silva, Daniel, Couillandeau, Matthieu, Gonod, Charlie, Miller, Guillaume
Novel electrochemical capacitors with high-energy density using intercalated metal-organic framework electrodes2019-01-226012/19/2019
The energy-density improvement of capacitors while maintaining high power, long-term-cycle stability and safety is challenging. Asymmetric capacitors using non-faradaic and intercalation electrodes are proposed in order to achieve this. However the reported asymmetric capacitors with graphite-based negative electrode have a safety risk, which is an internal short circuit due to Li deposition when further high-energy density is performed. Here asymmetric capacitors consisting of intercalated metal-organic frameworks (iMOFs) negative operating potential range of 0.5-1.0 V vs. Li/Li+ that enable Li deposition reduction and activated carbon positive electrodes is proposed to construct a high volumetric energy (ca. 60 Wh L-1) and power densities with safety.
Ogihara, Nobuhiro
Downhill Safety Assistant Driving System for Battery Electric Vehicles on Mountain Roads2019-01-212909/15/2019
When driving in mountainous areas, vehicles often encounter downhill conditions. To ensure safe driving, it is necessary to control the speed of vehicles. For internal combustion engine vehicles, auxiliary brake such as engine brake can be used to alleviate the thermal load caused by the continuous braking of the friction brake. For battery electric vehicles (BEVs), regenerative braking can be used as auxiliary braking to improve brake safety. And through regenerative braking, energy can be partly converted into electrical energy and stored in accumulators (such as power batteries and supercapacitors), thus extending the mileage. However, the driver's line of sight in the mountains is limited, resulting in a certain degree of blindness in driving, so it is impossible to fully guarantee the safety and energy saving of downhill driving. Therefore, taking a pure electric light truck as an example, the system proposed in this paper first analyzes the driver's driving intention, proposes
Feng, Jia'ao, Tian, Zhongpeng, Cui, Jian, Zhou, Fangyu, Tan, Gangfeng
Stretchable Power Source for WearablesTBMG-3473707/01/2019
Researchers have created highly stretchable supercapacitors for powering wearable electronics that consist of crumpled carbon nanotube (CNT) forests. The supercapacitors demonstrated solid performance and stability, even when stretched to 800% of their original size for thousands of stretching/relaxing cycles.
Graphene Lid Extends Photoemission Electron Microscopy to LiquidsTBMG-3475307/01/2019
By capping liquids with graphene (an ultrathin sheet of pure carbon), researchers can easily image and analyze liquid interfaces and the surface of nanometer-scale objects immersed in liquids. In the imaging technique known as photoemission electron microscopy (PEEM), ultraviolet light or X-rays bombard a sample, stimulating the material to release electrons from a region at or just beneath its surface. Electric fields act as lenses, focusing the emitted electrons to create an image.
Power Electronic Noise-Simulation Measurement Comparison2019-01-145106/05/2019
A growing development of hybrid or fully electrical drives increases the demand for an accurate prediction of noise and vibration characteristics of electric and electronic components. This paper describes the numerical and experimental investigation of noise emissions from power electronics, as one of the new important noise sources in electric vehicles. The noise emitted from the printed circuit board (PCB) equipped with multi-layer ceramic capacitors (MLCC) is measured and used for the calibration and validation of numerical model. Material properties are tuned using results from experimental modal analysis, with special attention to the orthotropic characteristic of the PCB glass-reinforced epoxy laminate sheet (FR-4). Electroacoustic excitation is pre-calculated using an extension of schematic-based EMC simulation and applied to the structural model. Structural vibrations are calculated with a commercial FEM solver with the modal frequency response analysis. Sound radiation is
Klarin, Borislav, Olbrich, Peter, Resch, Markus, Resch, Thomas, Brandl, Stephan, Reindl, Hartwig
The ‘Relativity’ of High Q CapacitorsTBMG-3455706/01/2019
For many high-power RF applications, the “Q factor” of embedded capacitors is one of the most important characteristics in the design of circuits. This includes products such as cellular/telecom equipment, MRI coils, plasma generators, lasers, and other medical, military, and industrial electronics.
Detection of Presence and Posture of Vehicle Occupants Using a Capacitance Sensing Mat2019-01-123204/02/2019
Capacitance sensing is the technology that detects the presence of nearby objects by measuring the change in capacitance. A change in capacitance is triggered either by a change in dielectric constant, area of overlap or distance of separation between the electrodes of the capacitor. It is a technology that finds wide use in applications such as touch screens, proximity sensing etc. Drawing motivation from such applications, this paper investigates how capacitive sensing can be employed to detect the presence and posture of occupants inside vehicles. Compared to existing solutions, the proposed approach is low-cost, easy to deploy and highly efficient. The sensing system consists of a capacitance-sensing mat that is embedded with copper foils and an associated sensing circuitry. Inside the mat the foils are arranged in rows and columns to form several touch-nodes across the surface of the mat. The system segregates row and column capacitances from each other and computes their tensor
Prasanna Kumar, Rahul, Melcher, David, Buttolo, Pietro, Jia, Yunyi
Impedance Modeling and Aging Research of the Lithium-Ion Batteries Using the EIS Technique2019-01-059604/02/2019
As the core component of electric vehicles (EVs), batteries attach increasingly general attention along with the rapid expansion of electric vehicle market. Battery performance effect directly the safety and reliability of the EVs, so its managing technologies are more and more crucial. Among them, the methods of estimating the state of health (SoH) and predicting remaining useful life become the focuses, which are essential to ensure their dependability and optimum performance over time. This paper mainly focuses on impedance modeling and aging research (aging diagnosis and life prediction) of lithium-ion batteries. Electrochemical impedance spectroscopy (EIS) technique is used to obtain impedance characteristic of batteries. On the one hand, equivalent circuit modeling (ECM) can be motivated by EIS, with the goal to fit measured impedance data using circuit elements. On the other hand, the aging research of batteries can be analyzed using the resistance information provided by EIS
Gao, Qian, Dai, Haifeng, Wei, Xuezhe, Jiang, Bo
Fabric Alternative to Batteries for Wearable DevicesTBMG-3414804/01/2019
Wearable biosensors for health monitoring lack a lightweight, long-lasting power supply. A new method was developed for making a charge-storing system that is easily integrated into clothing for embroidering a charge-storing pattern onto any garment.
Electric double layer capacitors prepared with polyvinyl alcohol and multi-walled carbon nanotubes2018-36-031309/03/2018
Portable electronics, wearables, electric vehicles and solar cells are sectors in increasingly development which include innovation and miniaturization of the devices. In this scenario, the development of smaller and lightweight energy storage devices, which store more energy, is required. Besides, it is desirable for these devices to be environmentally friendly to minimize pollution. In an attempt to meet these requirements, this work purposes the development and the characterization of nanofibers-based electrode composed of Polyvinyl alcohol (PVA) and multi-walled carbon nanotubes (MWCNT) for electric double layer capacitors (ELCDs) devices with aqueous electrolyte. This composite has been prepared by electrospinning technique and consolidate an electrical conductive and high-surface material electrode. After that, the PVA/MWCNT electrode was assembled in coin cell device with Sodium Sulfate (Na2SO4) electrolyte for electrochemical characterization. The characterization results
Real, Carla Giselle Martins, Vicentini, Rafael, Nunes, Willian Gonçalves, Boas, Otávio Vilas, Costa, Lenon Henrique, Soares, Davi Marcelo, Zanin, Hudson
Polyacrylonitrile and activated carbon composite for electric double layer capacitors2018-36-031009/03/2018
Electrospinning of polymers blends solutions offers the potential to produce nanofibers for using in a variety of applications. Here, we report the synthesis of nanofibers with polyacrylonitrile (PAN) and activated carbon (AC) composite by employing this technique. As-produced material is an electrical conductive and high-surface material electrode with outstanding electrochemical properties, which we explore electric double layer capacitors (EDLCs) coin cell devices. Our results show that EDLCs manufactured with PAN/AC composite have fairly high specific capacitance, low internal impedance and high lifetime. All these results encourage further development of PAN/AC materials as electrode for EDLCs and Li- Air batteries devices. This new generation of devices are opening niches of applications on multi-millionaire markets such as electric vehicles & solar and wind power systems. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE
Real, Carla Giselle Martins, Vicentini, Rafael, Nunes, Willian Gonçalves, Boas, Otávio Vilas, Alves, Thayane Almeida, Soares, Davi Marcelo, Zanin, Hudson
Cryo-Fluid Capacitor (CFC)TBMG-2903406/01/2018
NASA’s Kennedy Space Center (KSC) has created the Cryo-Fluid Capacitor (CFC) that capitalizes on the energy storage capacity of liquefied gases, and the relative simplicity of high-pressure gas bottles while limiting the downfalls associated with both methods. By exploiting a unique attribute of nanoporous materials — aerogel, in this case — fluid commodities such as oxygen, hydrogen, methane, etc. can be stored in a molecular surface adsorbed state at densities on par with liquid, at low to moderate pressure, and then supplied as a gas, on-demand, to a point of interest.
System-Level Investigation of Traction Inverter High-Temperature Operation2018-01-046404/03/2018
In this paper, the high-temperature capability of the traction inverter was investigated by applying coolant with temperature much higher than the typical allowed value until the system fails. The purpose of this study is to identify the weakest link of the traction inverter system in terms of temperature. This study was divided into two stages. In the first stage, a series of nondestructive tests were carried out to investigate temperature rise (ΔT) of the key component above coolant temperature as a function of the outside controllable parameters-i.e., dc link voltage, phase current, and switching frequency. The key components include power modules, gate driver board, gate driver power supply, current sensors and dc link capacitor. Their temperatures were monitored by thermocouples or on-die temperature sensors. The result showed that temperature rises of most key components were strongly affected by phase current, moderately affected by switching frequency, and slightly affected by
Lu, Xi, Xiao, Kewei, Lei, Guangyin, Chen, Chingchi
Transmission-Mounted Power Control Unit Including 12-Volt DC-DC Converter for Two-Motor Hybrid System2018-01-045704/03/2018
This research proposes a third-generation power control unit (PCU) for a two-motor hybrid system. To make a more compact intelligent power unit (IPU) to be located under the second seat, a PCU with a 12-volt DC-DC converter (DCDC) that mounts directly on the transmission was developed, whereas the DCDC was previously mounted within the IPU. Since this has a considerable impact on the engine room layout, the technology described below was used to make the PCU even more compact than the second-generation unit. The power module, a key component of the PCU, now uses Ag nanoparticles sintering bonding rather than conventional solder bonding. This helps lower thermal resistance and enables smaller power semiconductors. The voltage control unit (VCU) has a new circuit that uses a multi-stage switching circuit and electric power transfer capacitor instead of the conventional chopper circuit. This makes it possible to shrink the reactor to less than 65% of its usual volume without raising the
Ozuchi, Yasuhiro, Tomokage, Ryoji
A Technical, Environmental and Financial Analysis of Hybrid Buses Used for Public Transport2018-01-042404/03/2018
This paper presents a technical, financial and environmental analysis of four different hybrid buses operated under Buenos Aires driving conditions. A conventional diesel bus is used as reference and three electric hybrids equipped with different energy storage technologies, Li-Ion, NiMH batteries and double layer capacitors (ultracapacitors), are evaluated, along with a hydraulic hybrid platform which uses high-pressure accumulators as its energy buffer. The operating conditions of the buses are set using real driving GPS data collected from various bus routes within the city. The different vehicle platforms are modeled on AUTONOMIE SA and validated by comparing the obtained fuel consumption results to those reported by local transport authorities and values found in the literature. The embedded energy and CO2 emissions of each platform are estimated using GREET and the total cost of ownership of each vehicle is calculated and compared to that of the conventional bus. Furthermore
Orbaiz, Pedro, van Dijk, Nicolás, Cosentino, Santiago, Oxenford, Nicolas, Carignano, Mauro, Nigro, Norberto Marcelo
Modularized Simulation Tool to Evaluate Battery Solutions for 12 V Advanced Start Stop Vehicles2018-01-044604/03/2018
The 12 V advanced start stop systems can offer 5-8% fuel economy improvement over a conventional vehicle. Although the fuel economy is not as high as those of mild to full hybrids, its low implementation cost makes it an attractive electrification solutions for vehicles. As a result, the 12 V advanced start stop technology has been evolving fast in recent years. On one hand, battery suppliers are offering a variety of energy storage solutions such as stand-alone lead acid, stand-alone LFP/Graphite, dual batteries of lead acid parallel with NMC/LTO, LMO/LTO, NMC/Graphite, and capacitors, etc. For dual battery solutions, the architecture also varies from passive parallel connection to active switching. On the other hand, OEM are considering to leverage a lot more use out of traditional 12 V SLI (start, light, and ignition) for functions such as power steering, air conditioning, heater, etc. Depending on battery architecture and vehicle functioning design, the energy management strategy
Zhang, Zhenli, Jin, Zhihong, Watson, Thomas
Demolition Probe Gives Construction Workers a BreakTBMG-2870304/01/2018
Initially designed for use on the Moon, the Electro-Hydraulic Fracturing system — developed at Auburn University with NASA funding — relies upon short, high-pulse power created by ultra-high capacitors. Two electrodes featuring a high voltage difference are placed in a small amount of non-toxic liquid — an ounce of water, for example. After the proprietary probe is placed in a drilled hole within concrete or rock, a very rapid release of high-voltage electrical energy, stored in the capacitors, is discharged. The liquid provides the spark between electrodes, resulting in a high-temperature containable “plasma ball.” The ping-pong-ball-sized bead creates a shock wave with pressures that exceed the material’s compressive strength, causing a fracture.
Inexpensive Method for Manufacturing Supercapacitor ElectrodesTBMG-2830902/01/2018
Supercapacitors can store and deliver energy faster than conventional batteries. But to realize advanced applications, supercapacitors need better electrodes, which connect the supercapacitor to the devices that depend on their energy. These electrodes need to be both quicker and cheaper to make on a large scale, and also able to charge and discharge their electrical load faster.
Process Turns Carbon Dioxide into 3D Graphene with Microporous SurfaceTBMG-2815601/01/2018
The conversion of carbon dioxide to useful materials usually requires high energy input due to its ultrahigh stability. A heat-releasing reaction between carbon dioxide and sodium was developed to take carbon dioxide and turn it into 3D graphene with micropores across its surface.
Creating an Impedance Matching Method for Wireless Battery ChargingTBMG-2818901/01/2018
Keysight Technologies Santa Rosa, CA
High-Energy-Storage CapacitorTBMG-2781911/01/2017
A method was created for electroless deposition of conformal ultrathin (<20 nm) metal oxides on the high-surface-area walls of commercial carbon nanofoam papers, typically 0.1–0.3 mm thick. The resulting ultrathin metal oxides rapidly take up and release electrons and ions, thereby storing energy at 300–600 Farads per gram of oxide, while the carbon nanofoam paper serves as a three-dimensional current collector and defines a pre-selected porous electrode architecture.
Power Systems Infrastructure of Hybrid Electric Fuel Cell Competition Go Kart2017-01-245210/08/2017
This paper documents the electrical infrastructure design of a Hybrid Go Kart competition vehicle which includes a dual Fuel Cell power system, Ultra Capacitors for energy storage, and a dual AC induction motor capable of independent drive. The Kart was built primarily to compete in the 2009 Formula Zero international event. This paper emphasized the vehicle model and control strategy as a result of three (3) graduate student research projects. The vehicle was fabricated and tested but did not participate in the race competition since the race organization folded. The vehicle model was developed in Simulink to determine whether the fuel cell and ultra-capacitor combination will be sufficient for peak transient power requirement of 14 kW. The vehicle’s functional description and performance specifications are documented including the integration of the fuel cell power modules, energy storage system, power converters, and AC motor and motor controllers.
Berry, Kingsley Joel, Traore, Abdrahamane, Krishna, Aravind, Gangadhar, Pavankumar, Taylor, Allan
Tantalum Capacitors for Medical ApplicationsTBMG-2747209/01/2017
Modeling and Experiment Validation of the DC/DC Converter for Online AC Impedance Identification of the Lithium-Ion Battery2017-01-119803/28/2017
The lithium-ion battery plays an important role in saving energy and lowering emissions. Many parameters like temperature have an influence on the characteristic of the battery and this phenomenon becomes more serious in an electric vehicle. In this paper, the application of a boost DC/DC converter to the battery system of high power for online AC impedance identification is proposed. The function of the converter is to inject a current excitation signal into the battery at work and the normal output current is drawn by a load. Through analyzing the average state space equations and deriving the small signal model of the converter, the gain function is deduced of the fluctuated current signal against the fluctuated duty cycle which controls the converter. The control algorithm is designed and the system model is verified using Matlab/Simulink with respect to the disturbance current signal generation, the gain function and its variation with frequency range. Then the converter is
Hong, Po, Jiang, Hongliang, Li, Jian qiu, Xu, Liangfei, Ouyang, Minggao
Traction Inverter Design with a Direct Bypass to Boost Converter2017-01-124703/28/2017
Direct bypass to DC-DC boost converter in traction inverter increases converter's capability and efficiency significantly by providing a lower loss path for power flow between the battery and DC-link terminal. A bypass using diode is an excellent solution to achieve this capability at low cost and system complexity. Bypass diode operates in the linear operating region (DC Q-point) when the battery discharges through the bypass diode to drive the electric motors. Therefore, thermal stress on the DC-link capacitor is shared between the input and DC-link capacitors through the bypass diode. On the other hand, inverters introduce voltage oscillation in the DC-link terminal which results in unwanted energy oscillation through the bypass diode during battery charging. Both of these phenomena have been explained in details. It is possible to eliminate this power oscillation during battery charging using minimum voltage level boosting at a reduced frequency or using a bi-directional switch
Alam, Mohammed Khorshed, Chen, Lihua, Zhou, Yan, Xu, Fan, Yang, Shuitao
DC-Link Capacitor Sizing Considerations for HEV/EV e-Drive Systems2017-01-123403/28/2017
Dc-link capacitor sizing considerations are discussed for HEV/EV e-Drive systems. The capacitance value of the dc-link in HEV/EV e-Drive systems affects numerous factors. Some of the most significant are the system stability and the maximum tolerable dc-bus transient voltage with operating point change or with worst-case energy dump into the capacitor. Also requiring attention is the equivalent series resistance and inductance of the capacitor module. The former affects thermal behavior of the capacitor module and the latter affects voltage spikes occurring at every turn-off of a power semiconductor switch. In addition, these factors are dependent on other power-stage component parameters, control structures and controller gains. Also such effects and cross-couplings are operating-point dependent. This makes the dc-link capacitor sizing for HEV/EV e-Drive systems a complex task and it looks as if the task is done primarily by empirical manner with possibly more than enough safety
Sridharan, Srikanthan, Kimmel, Joseph, Kikuchi, Jun
Energy Harvesting in Automotive Key fob Application2017-26-035101/10/2017
Evolution in Radio Frequency (RF) semiconductor technology has led to highly power efficient devices. A typical automobile key fob for remote lock-unlock operations operates on 3V lithium coin cell battery having 200 mAh capacity and can last up to 75,000 key press events or two to three years. The typical transmission currents are less than 10 mA while sleep currents are less than 0.1 uA. As the lithium coin cell batteries are not rechargeable, they need to be replaced and safely disposed. Improper disposal of lithium batteries impose risk to the environment as lithium is highly poisonous and reactive. This paper proposes to replace the coin cell battery with a RF energy harvesting circuit involving voltage multiplier circuit consisting of zero bias schottky detector diodes and a hybrid energy storage capacitor. Authors have conducted experiments as well as simulation to evaluate the feasibility of the RF energy harvester replacing conventional coin cell battery. RF energy harvesting
Gambhir, Ameya, Yadav, Dhananjay, Pawar, Ganesh
High Energy Ignition Strategies for Diluted Mixtures via a Three-Pole Igniter2016-01-217510/17/2016
A three-pole spark igniter, with the concept to broaden the ignition area, is employed in this paper to investigate the effect of spark discharge strategies on the early ignition burning process. The prototyped three-pole igniter has three independent spark gaps arranged in a triangular pattern with a circumradius of 2.3 mm. Direct-capacitor discharge techniques, utilizing close-coupled capacitors parallel to the spark gap, are applied on the three-pole igniter to enhance either the transient spark power or the overall energy. In particular, the simultaneous discharge of high energy plasma on three spark gaps can produce a surface-like ignition process which intensifies the plasma-flame interaction, thereby producing a rapid flame kernel development. The ignition strategies are evaluated in both constant volume combustion vessels and a modified single-cylinder metal engine. In the results, for both the lambda sweep and the CO2 dilution tests performed in the constant volume combustion
Yu, Shui, Xie, Kelvin, Yu, Xiao, Wang, Meiping, Zheng, Ming, Han, Xiaoye, Tjong, Jimi
Finding Flaws in Medical ImplantsTBMG-2465505/01/2016
Cracks in ceramic capacitors, devices that store electric charge in electronic circuits, can cause damage to such disparate objects as medical implants and spacecraft. The cracks, which are often hidden initially, can start conducting electricity, depleting batteries, or shorting out electronics. Detecting these cracks in capacitors before they evolve into electrically conducting pathways and cause failures is something that researchers at the National Institute of Standards and Technology (NIST), along with collaborators from the University of Maryland, NASA Goddard Space Flight Center, and Colorado State University have spent years investigating.
A Novel Equivalent Circuit Model for Lithium-ion Battery with Complex Electrical Element Parameters2016-01-119704/05/2016
An equivalent circuit model for lithium-ion battery including capacitor and inductor with complex parameters is proposed. The imaginary part of the complex-valued capacitor expresses diffusion processes instead of constant phase element, which leads to a higher computational efficiency by removing the exponential variant calculation. The inductor with the complex parameter, the imaginary part accounting for the frequency-dependent magnetic hysteresis loss of battery current collectors and cables, can accurately regenerate the impedance characteristics at high frequencies with various linear slope angles to the real axis in a Nyquist plot. The fitted electrochemical impedance spectrum of a lithium iron phosphate/graphite battery with this proposed model is compared to the measured data. The maximum relative error of the impedance magnitude is 4.94% at the frequencies between 0.01 Hz and 10 kHz. The electrical component parameters of the proposed equivalent circuit model are calculated
Wu, Zhengbin, Weng, Rongcheng, Zhang, Zhiqun, Li, Juan
Model-Based Evaluation of Chemistry Selection for Dual Energy Storages for 12V Advanced Start-Stop Vehicles2016-01-120904/05/2016
Passively parallelizing two energy storage systems, one is energy type and the other is power type, requires minimal modifications of auto makers and thus a cost-effective method to enable advanced start stop technology. Traditional lead acid battery, lithium-ion battery, capacitor, are all candidate chemistries for dual energy storage solutions. However due to the dual nature of the technology the open circuit potential, resistance, and some other control variables should match in order to achieve optimal performance. In this work we use coupled equivalent circuit model and electrochemical model to study a few options of dual systems, namely the lead acid with NMC/LTO, lead acid with LFP-Graphite, and lead acid with capacitor. A few charging and discharging pulses are designed and simulated to evaluate the regen receiving capability and cranking capability of different chemistries. Also a driving cycle is simulated for different battery combinations to characterize their fuel economy
Zhang, Zhenli, Jin, Zhihong, Wyatt, Perry
Integrated Solar Array Power Management SystemTBMG-2426304/01/2016
When solar cells are electrically connected to form solar arrays, they are organized into strings. Each string represents a specific number of cells connected in series to produce a specific voltage. The strings are then connected in parallel to add their currents to meet the array power requirement. This requires that the strings have the same voltage. Blocking diodes are used to take out strings with voltage that is too low, resulting in loss of power. When the arrays are mounted to a non-coplanar surface such as a spacecraft body or inflatable structure, many strings will have voltages lower than the rated voltage. This regulator manages the voltage of each string individually so that its power may be used, regardless of its voltage. It does this by converting each string’s energy into a series of high-voltage pulses that charges a reservoir capacitor to one of a set of common voltages used by the spacecraft bus. This allows for use of all of the illuminated strings in producing
Calibration Requirements for Testing Coupling-Decoupling NetworksTBMG-2443104/01/2016
Coupling-Decoupling Networks (CDNs) are the unglamorous workhorses that get “hitched up” to an impulse generator in order to perform impulse testing on powered equipment. As such, performance and calibration requirements for CDNs have not been specified to the same level of detail as the impulse generator. This is no longer the case with the Third Edition of IEC 61000-4-5, the international standard for surge immunity testing.
Two-Stage Power System Boosts Energy-Harvesting EfficiencyTBMG-2383301/21/2016
A two-stage power management and storage system from Georgia Institute of Technology improves the efficiency of triboelectric generators to harvest energy from irregular human motion, such as walking, running or finger tapping. The storage device supplies DC current at voltages appropriate for powering wearable and mobile devices such as watches, heart monitors, and thermometers.
AC/DC Converter with DC Fault Suppression for Aircraft +/− 270 VDC Distribution Systems2015-01-241109/15/2015
The increasing electrical demand in commercial and military aircraft justifies a growing need for higher voltage DC primary distribution systems. A DC system offers reduced power losses and space savings, which is of major importance for aircraft manufacturers. At present, challenges associated with DC systems include reliable fast acting short circuit protection. Solid State Contactors (SSC) have gained wide acceptance in traditional 28 VDC secondary systems for DC fault interruption. However, the reliable operation at higher operating voltages and currents requires further technology maturation. This paper examines a supporting method to SSC for more reliable fault mitigation by investigating bidirectional AC/DC converter topology with DC fault current blocking capability. Replacement of semiconductor switches with full bridge cells allows instant reversal of voltage polarities to limit rapid capacitor discharge and machine inductive currents. Demonstration of this capability is
Sztykiel, Michal, Fletcher, Steven, Norman, Patrick, Galloway, Stuart, Burt, Graeme
Nanowire Yarn Boosts Supercapacitor EfficiencyTBMG-2250107/09/2015
Researchers at the Massachusetts Institute of Technology discovered that yarn made of niobium nanowires enables more efficient supercapacitors. The new approach uses the yarns as the electrodes in tiny supercapacitors. Adding a coating of a conductive polymer to the yarn further increases the capacitor’s charge capacity.
Stacked Capacitor Special Lead AdapterTBMG-2218606/01/2015
The current installation method for tall, stacked capacitors is very cumbersome because the lead form is very sharp and prone to solder cracking due to thermal cycling. An astringent installation process was developed to obtain the best chance of a successful solder joint with a proper heel fillet so the chance of cracking is minimized.
Carbon Nanotube Tower-Based SupercapacitorTBMG-2163303/01/2015
A new technology to create electrochemical double-layer supercapacitors is provided using carbon nanotubes as electrodes of the storage medium. This invention allows efficient transport between the capacitor electrodes through the porous nature of the nanotubes, and has a low interface resistance between the electrode material and the collector. Carbon nanotubes directly grown on a metal surface are used to improve the supercapacitor performance. The nanotubes offer a high surface area and usable porosity for a given volume and mass, both of which are highly desirable for supercapacitor operation.
Negative Dielectric Constant Material Based on Ion-Conducting MaterialsTBMG-2140802/01/2015
Metamaterials, or artificial negative index materials (NIMs), have generated great attention due to their unique and exotic electromagnetic properties. A negative dielectric constant material, which is an essential key for creating the NIMs, was developed by doping ions into a polymer, a protonated poly(benzimidazole) (PBI).
Digital DC CDI for Small Engines: Low Cost Solution and Challenges with 8 Bit Microcontroller2014-01-286010/13/2014
Emerging markets like India is very cost sensitive for small engines like motorcycle. Capacitive discharge Ignition (CDI) with carburetor is popular low cost solution with good engine performance. CDI system accumulates charge inside the ignition capacitor, until a point at which a signal allows to release discharge of the stored charge to the spark plug through high tension coil. This paper will focus on single spark digital two teeth DC CDI solution and below design challenges with two sparks. 1 Higher power dissipation in step up fly back converter 2 Need higher CPU speed, flash size and restrictions on engine map profile for advance angles This paper will elaborate above problems and their solutions with test results for optimizing solution cost and achieve performance. Solutions include, exploring 8 bit microcontroller peripherals usage and smart software to boost MCU performance for engine dynamic conditions and to achieve lower losses in flyback converter.
Ugale, Ramdas
Study of Two-Motor Hybrid Bulldozer2014-01-237609/30/2014
Hybrid bulldozers use less fuel by providing better efficiency and fewer emissions, which was confirmed by one Caterpillar application of D7E in the market in 2010. To take advantages of the series hybrid bulldozer system, Chinese government launched similar hybrid bulldozer with independent double motor design. The Hybrid Bulldozer Power-Train system includes 14 components including motor, motor control system, engine, super capacitor to BMS and etc. This specific hybrid architecture, compared with D7E, removes the complicated hydraulic steering system. Instead, the steering function was developed by running both traction motors, further simplifying the power-train system. A Diesel engine is used to propel the attached generator to produce AC power which is then converted to DC power and connected with the main power link (super capacitor). DC power is finally converted back to AC to propel those two independent traction motors. CAN network is applied for communication. Information
Wang, Hongyu, Liu, Lin, Zheng, Guanyu, Liu, Xiaohui, Zhao, Xiumin
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