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A review on influence of different flushing methods on Material Removal Rate using EDM.

Manav Rachna International University-Gurpreet Singh Matharou
  • Technical Paper
  • 2019-28-2543
Published 2019-11-21 by SAE International in United States
Electrical release machining (EDM), is a material removal procedure whereby a coveted shape is acquired by utilizing electrical releases (sparks). Material is expelled from the work piece by a progression of quickly repeating current releases between cathode and anode, isolated by a dielectric fluid and subject to an electric voltage. At the point when the voltage between the two terminals is expanded, the power of the electric field in the volume between the anodes winds up more prominent than the quality of the dielectric (in any event in a few spots), which separates, enabling current to stream between the two cathodes. This wonder is the equivalent as the breakdown of a capacitor (condenser). Accordingly, material is expelled from the cathodes. Once the present stops (or is quit, contingent upon the sort of generator), new fluid dielectric is generally passed on into the between cathode volume, empowering the strong particles (flotsam and jetsam) to be diverted and the protecting properties of the dielectric to be reestablished. Including new fluid dielectric in the between anode volume is…

Graphene Lid Extends Photoemission Electron Microscopy to Liquids

  • Magazine Article
  • TBMG-34753
Published 2019-07-01 by Tech Briefs Media Group in United States

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.

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Power Electronic Noise-Simulation Measurement Comparison

AVL LIST GmbH-Markus Resch, Thomas Resch, Stephan Brandl
AVL Software and Functions Gmbh-Peter Olbrich, Hartwig Reindl
Published 2019-06-05 by SAE International in United States
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 simulated using the wave-based approach (WBT). Simulation and experimental results are compared in a frequency range up to 10 kHz.The developed simulation methodology can successfully identify the main noise sources from the equipped PCB. Critical peak noise responses…
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The ‘Relativity’ of High Q Capacitors

  • Magazine Article
  • TBMG-34557
Published 2019-06-01 by Tech Briefs Media Group in United States

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.

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Features of Modeling Thermal Development Processes of the Vehicle Engine Based on Phase-Transitional Thermal Accumulators

Belarusian National Technical University-Heorgi Kukharonak
Donbas National Academy of Civil Engineering & Architecture-Valery Aleksandrov
Published 2019-04-02 by SAE International in United States
The utilization of different types of energy in phase-transitional thermal accumulators and its further use for thermal development of different subsystems of hybrid vehicles enables to significantly increase their operational efficiency. The system of the combined utilization of thermal and electrical energy in phase-transitional thermal accumulators (TA) is offered. To charge TA, it uses thermal energy of exhaust gas, a coolant and motor oil of the internal combustion engine and electrical energy which is utilized by energy recovery system when braking the vehicle. It consists of consecutive stages of heat accumulation when charging TA from different energy sources of the hybrid vehicle, its storage and use for rapid heating of vehicle separate subsystems. The main heat and power characteristics of system components and heat accumulating materials used in phase-transitional TA have been justified. Schemes and designs of a physical model to utilize electrical energy using high-capacity condensers for charging phase-transitional TA have been offered. The results of experimental and computational studies show theoretical comparison of the main indicators of the developed system in charging phase…
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Detection of Presence and Posture of Vehicle Occupants Using a Capacitance Sensing Mat

Clemson University-Rahul Prasanna Kumar, Yunyi Jia
Ford Motor Company-David Melcher, Pietro Buttolo
Published 2019-04-02 by SAE International in United States
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 product to generate grayscale capacitance-sensing images. The images are real-time pictorial representation of the capacitance of each touch-node. When the mat…
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DC Link Capacitor Active Discharge by IGBT Weak Short Circuit

SAE International Journal of Advances and Current Practices in Mobility

Tongji University-Zhihong Wu, Xiezu Su, Yuan Zhu, Mingkang Xiao
  • Journal Article
  • 2019-01-0606
Published 2019-04-02 by SAE International in United States
DC link active discharge is mandatory in new energy vehicles. This paper first analyzes the necessity of active discharge in automotive inverters and then introduces the commonly used discharge methods. After reviewing the pros and cons of the current methods, a new discharge solution using IGBT (Insulated Gate Bipolar Transistor) modules WSC (Weak Short Circuit) is proposed. The essence of WSC is to make one of the shooting through IGBTs (two IGBTS forms a half bridge topology) entering into active work area by controlling its gate voltage VGE, where the short current is controlled in safe range and IGBT VCE voltage is relative large. Hence, large transient power is produced inside IGBT in this condition. By this method, the DC link capacitor energy will be consumed by the weak turned on IGBT gradually. Since the IGBT module has a dedicated cooling loop, the heat generated during discharging process can be transferred into coolant. In order to discharge the DC link capacitor safely, an optimized discharge topology is suggested in which PWM method is applied. This…
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Design of a SiC Based Variable Voltage Converter for Hybrid Electric Vehicle

Ford Motor Company-Fan Xu, Baoming Ge, Lihua Chen, Boris Curuvua
Published 2019-04-02 by SAE International in United States
Variable Voltage Converter (VVC) is adopted in Power-Split structure of hybrid electric vehicles (HEVs) to optimize the Electric-Drive (e-Drive) system performance. With the wider availability of Silicon Carbide (SiC) power semiconductor for automotive applications, there are new opportunities to further optimize and improve performance of VVC, e.g. lower power loss, smaller size, and lighter weight, comparing to use traditional Silicon (Si) IGBT and diode. In this paper, a SiC based VVC is designed, prototyped, and evaluated. In order to maximize the benefits of SiC power devices in VVC application, each key component is carefully designed and selected, including SiC power module, power capacitor, and power inductor. The characterization and evaluation results demonstrate the benefits of advanced SiC devices in VVC design optimization, and such benefits quantified in this paper.
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Electric double layer capacitors prepared with polyvinyl alcohol and multi-walled carbon nanotubes

Carbon Sci-Tech Labs, School of Electrical and Computer Engi-Carla Giselle Martins Real, Rafael Vicentini, Willian Gonçalves Nunes, Otávio Vilas Boas, Lenon Henrique Costa, Davi Marcelo Soares, Hudson Zanin
Published 2018-09-03 by SAE International in United States
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 showed that EDLCs devices present specific capacitance of ∼4.8 Fg-1, energy density of ∼0.1 Wh kg-1, power density of ∼600W kg-, fast charge transfer at electrode/electrolyte interface and high lifetime All these results encourage further development on PVA/MWCNT materials as electrode for EDLCs and Li-Air…
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Polyacrylonitrile and activated carbon composite for electric double layer capacitors

Carbon Sci-Tech Labs, School of Electrical and Computer Engi-Carla Giselle Martins Real, Rafael Vicentini, Willian Gonçalves Nunes, Otávio Vilas Boas, Thayane Almeida Alves, Davi Marcelo Soares, Hudson Zanin
Published 2018-09-03 by SAE International in United States
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. The authors solely responsible for the content of the paper.
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