Browse Topic: Capacitors
As already well-understood/enormous engineering practices, the inverter AC-side NVH phenomena/mechanisms/measures for motor-equipped vehicle, are already pretty clear. In addition to inverter AC side–induced NVH issues, DC ripple induced by PE switching leads to NVH issues manifesting on the capacitor, inductor, and conductor in terms of reverse piezoelectricity, electrostriction, magnetostriction, Laplace force, and so forth. These DC-side NVH issues are already literally analyzed by a couple of literatures, and mechanisms/measures are explored/applied to electric drive development. And yet, the phenomenon that a pulsating magnetic field inside a battery pack induced by DC current ripple off PE switching brings noise at switching frequency inside the vehicle cabin is newly captured/analyzed by our research, and that has been barely searched during the literature survey. This newly discovered phenomenon is the pivotal point in this paper. Although the noise features like the conventional switching noise that originates at the AC side of the inverter, the mechanism/measures are different; hence, this newly found NVH phenomenon is termed as alternative switching noise by the author, distinguishing itself from the conventional switching noise off AC side of the inverter. The mechanisms and measures associated with this phenomenon are innovatively explored/analyzed, which ultimately offer great aid to BEV/HEV/PHEV NVH interpretation/development. First, in this paper the inverter AC-side NVH issues are overviewed including mechanisms/measures, then DC-side NVH issues from capacitor, inductor, and conductor are reviewed in terms of mechanisms/measures, third the extending exploration/study upon alternative switching noise is described in detail. The relevant analysis for alternative switching noise is barely mentioned/involved during literature survey, and that is newly found/studied within the research delineated in this paper. Fourth, two case studies are exemplified to further validate the mechanisms/measures employed during investigation. In the end, the common strategies addressing the alternative switching noise are summarized, which shall be adopted to keep issues from happening at the very beginning of vehicle development stage.
Researchers at North Carolina State University have now identified a “sweet spot” at which the length of a threadlike energy storage technology called a “yarn-shaped supercapacitor” (YSC) yields the highest and most efficient flow of energy per unit length.
A new bendable supercapacitor made from graphene has been developed that charges quickly and safely stores a record-high level of energy for use over a long period. The technology overcomes the issue faced by high-powered, fast-charging supercapacitors: they usually cannot hold a large amount of energy in a small space.
NASA's Cryogenic Flux Capacitor (CFC) capitalizes on the energy storage capacity of liquefied gases. By exploiting a unique attribute of nano-porous materials, aerogel in this case, fluid commodities such as oxygen, hydrogen, methane, etc. can be stored in a molecular surface-adsorbed state. This cryogenic fluid can be stored at low to moderate pressure densities, on par with liquid, and then quickly converted to a gas, when the need arises. This solution reduces both safety-related logistics issues and the limitations of complex storage systems.
As the U.S. military embraces vehicle electrification, high-reliability components are rising to the occasion to support their advanced electrical power systems. In recent years, electronic device designers have started using wide band-gap (WBG) materials like silicon carbide (SiC) and gallium nitride (GaN) to develop the semiconductors required for military device power supplies. These materials can operate at much higher voltages, perform switching at higher frequencies, and feature better thermal characteristics. Compared to silicon, SiC-based semiconductors provide superior performance. The growing availability of these materials, in terms of access and cost, continues to encourage electrification. With the ever-present pressure of size, weight, and power (SWaP) optimization in military applications, and a desire to keep up with the pace of innovation, there's a need for capacitors that can deliver higher power efficiency, switching frequency, and temperature resistance under harsh conditions. In this article, we explore the rise of electrification in military applications, the enabling role of high-reliability power supplies and converters, and how capacitors are meeting the rigorous requirements of modern electrified land systems.
The portable and electric energy storage market has long been dominated by lithium-ion batteries and supercapacitors, surpassing other energy storage systems in their ability to provide higher energy and power. However, in critical applications such as electric vehicles, there is a growing demand for a device that can efficiently produce both high power and high energy over a significant number of cycles. Meeting these rigorous standards presents new challenges for existing technologies, prompting researchers to explore alternative technologies for energy storage devices.
Researchers at Drexel University are one step closer to making wearable textile technology a reality. Recently published in the Royal Society of Chemistry’s Journal of Material’s Chemistry A, materials scientists from Drexel’s College of Engineering, in partnership with a team at Accenture Labs, have reported a new design of a flexible wearable supercapacitor patch. It uses MXene, a material discovered at Drexel University in 2011, to create a textile-based supercapacitor that can charge in minutes and power an Arduino microcontroller temperature sensor and radio communication of data for almost two hours.
Researchers have developed a low-cost device that can selectively capture carbon dioxide gas while it charges. Then, when it discharges, the carbon dioxide (CO2) can be released in a controlled way and collected to be reused or disposed of responsibly.
As the electrification of automobiles continues to accelerate, the need for a safe, reliable, high-power energy-storage technology is greater than ever. Ultracapacitors already have an established place in Voltage Stabilization Systems (VSS) for internal-combustion engine (ICE) stop-start applications. By providing additional voltage support during a high-current cranking event, voltage levels are maintained to allow proper operation of accessories without interruption and enable proper operation as battery state-of-health declines.
Micro-supercapacitors could revolutionize the way we use batteries by increasing their lifespan and enabling extremely fast charging. Now, researchers at Chalmers University of Technology have developed a method that represents a breakthrough for how such supercapacitors can be produced.
A new bendable supercapacitor made from graphene has been developed that charges quickly and safely stores a record-high level of energy for use over a long period. The technology overcomes the issue faced by high-powered, fast-charging supercapacitors: they usually cannot hold a large amount of energy in a small space.
This research aims at developing the suboptimal energy management strategy by using artificial neural network (ANN) for a triple-electrical-energy electric vehicle (EV). The controller hardware designs will be implemented in the future. Firstly, we constructed a low-order dynamic equations that abstracted the characteristics of the vehicle, including energy sources (the fuel cell, lithium battery, and supercapacitor), driver’s model, traction motor, transmission, and longitudinal vehicle dynamics, etc.. The key parameters were mostly retrieved from the commercialization software-Advanced Vehicle Simulator (ADVISOR). Base on the vehicle structure of the Toyota Mirai, we built the range-extended EV. The powertrain system included an 110kW fuel cell set, a 40Ah lithium-ion battery set, and a 165F/48V supercapacitor and a 150kW AC motor. The ECMS control strategy included a six-layer for-loop: the battery state-of-health (SOH), power demand, the battery state-of-charge (SOC??), the supercapacitor state-of-charge (SOC????), the power ratio of battery to power demand(α) and the power ratio of the supercapacitor to power demand(β). The ECMS data for ANN training was divided to two parts, the input part is four for-loop and the output part is α and β. To evaluated the benefit of the ANN, a rule-based (RB) control was designed as well. A standard driving cycle, New European Drive Cycle (NEDC), was chosen for the energy improvement evaluation. The energy consumption for RB and ECMS is [17.6258, 8.9141kWh], respectively, in two-time NEDC cycles. The energy improvement for ECMS is approximately 50% and the ANN accuracy is higher than 90%. The hybrid system can be scaled down to a small mobility in the near future.
This document contains definitions currently used in the automotive industry as they relate to energy storage and batteries for starting, lighting, and ignition applications, as well as for hybrid electric vehicles (HEV) and electric vehicles (EVs). It is intended that this document be a resource for those writing other battery, HEV, and EV documents, specifications, standards, or recommended practices. The use of the term “battery” in this document can be assumed to be a rechargeable battery (secondary battery). The terminology may be applied to other industries if desired.
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.
This article presents a two-stage Dynamic Programming (DP)-based approach to solving the problem of Hybrid Energy Storage System (HESS) component sizing, specifically, the lithium-ion (Li-ion) battery and ultracapacitor (UC) for a mild hybrid electric powertrain. In the first stage, optimal sizing of the battery for the powertrain without a UC is solved for a specified drive cycle, which is used in the reported literature. In the second stage, the battery is complemented with a UC cascaded through a direct current-to-direct current (DC/DC) converter in a semi-active configuration. A DP-based formulation is then constructed and solved for the hybrid energy storage subsystem. While the first-stage DP problem has an objective function to minimize the fuel consumption while sustaining the battery charge at the end of the drive cycle, the second-stage DP problem is solved for minimization of the battery capacity loss (i.e., maximization of battery life and better utilization of the battery in terms of its throughput and stress by the virtue of limiting the power transients/C-Rates). A heuristic layer at the top level of the two-stage DP framework ensures economic sizing of the battery and UC that effectively meets the objectives of arriving at a battery and capacitor size for an economic HESS. This novel approach could be easily extended to multiple standard drive cycles and real-life drive cycles.
Today, magnetic resonance imaging (MRI) technology is widely used by healthcare professionals to examine soft tissues and organs in the body. MRI is an excellent diagnostic tool because it can be used to detect a variety of potentially life-threatening issues ranging from degenerative diseases to tumors in a noninvasive manner. To understand the design challenges involved in developing MRI equipment, specifically when it comes to the selection of radio-frequency (RF) and electrical components such as capacitors, it’s first important to understand the basic physics behind the way MRI machines operate.
Supercapacitors are devices that store a dense electrical charge in an electrical field that provides electronics or a power grid with a quick jolt of power on demand. They have a capacitance value far higher than typical capacitors but at the cost of lower voltage limits. Unlike typical capacitors, supercapacitors don’t use conventional solid dielectric (insulator) — they utilize electrostatic double-layer capacitance (typically made of carbon) and electromechanical pseudo-capacitance (metal oxide or conducting polymer). Both contribute to the capacitor’s total capacitance and are designed for many rapid charge/discharge cycles over long-term energy storage. Hybrid supercapacitors boost that capacitance, energy density, and operating voltage (3.8 V maximum) up to 10X over symmetric supercapacitors.
Circuit designs exploiting the increased energy storage provided by supercapacitors require more careful consideration of the increased power handling than that of batteries when charging these devices. The unique composition of electrochemical double-layer capacitors (EDLC) inherently allows them to withstand large currents. Table 1 is a brief list of AVX cylindrical (SCC) and series-connected module (SCM) SuperCapacitors, displaying peak current supply and sink current capability. These maximum specifications will typically exceed current capability of charge sources and lead to failures within the power supply system.
This paper presents a compact thermal management solution for a high-power traction inverter. The proposed design utilizes a stacked cooling system that enables heat extraction from two of the largest heat sources in a power inverter: the power module and the DC-link capacitor. The base plate of the power module has circular pin fins while the capacitor comes with a flat surface which must be placed on a cold plate to provide the adequate heat dissipation. Incorporating individual cooling mechanisms for the DC-link capacitor and the power module would increase the weight, complexity and overall volume of the inverter housing. The proposed cooling system mitigates these problems by integrating the cooling mechanisms of the power module and the DC-link capacitor within a single cooling system. The cooling mechanism is designed to provide a uniform coolant flow with minimal pressure drop across the heat sink of the power module and DC-link capacitor. The uniform coolant flow also ensures minimal coolant temperature gradient across the switching devices in the power module and the capacitors cells. This maintains a uniform junction temperature in the capacitor cells and the switching devices. The proposed design is validated using Computational Fluid Dynamics.
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. As a results, we found that both values were corresponding each other and it is possible to design the low inductance battery with this approach. Finally, we verified smoothing effect for inverter output using our low inductance battery module. We conducted smoothing test by high frequency current as input into the battery module. We confirmed that battery voltage fluctuation was reduced less than 5% at an current condition which voltage fluctuation was more than 5% for normal batteries. As a results we have shown it is possible to reduce smoothing capacitors by using low inductance batteries.
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 50.9 miles per day using a combination of standard driving cycles. The resulting optimization problem is solved with the help of a quasi-static powertrain model which is developed using MATLAB/Simulink. A Genetic Algorithm is used to find the optimal solution in the case study. Normalized weighting factors are given to help users meeting their preferred performance during the power component design. Battery packs in the case study are chosen from LiFePO4 18650 cells with total capacity up to 100 kWh. Seven available types of supercapacitors along with 6 popular motors are also included in the design options. Two samples of the design results are compared to analyze the relevant tradeoff between performance indicators and cost.
Researchers have engineered a novel type of supercapacitor that remains fully functional even when stretched to eight times its original size. It does not exhibit any wear and tear from being stretched repeatedly and loses only a few percentage points of energy performance after 10,000 cycles of charging and discharging. The supercapacitor could be part of a power-independent, stretchable, flexible electronic system for applications such as wearable electronics or biomedical devices.
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