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Modulation Strategy for Minimisation of Leakage Current in Grid-Connected PV Panels

SRM Institute Of Science And Technology-Anitha Daniel, Uthra Rangarajan, Kalaiarasi Nallathambi
  • Technical Paper
  • 2019-28-0114
To be published on 2019-10-11 by SAE International in United States
This paper presents a switching strategy for the cascaded multilevel H bridge inverter of five levels to reduce the leakage current in the grid connected transformerless PV system. Minimization of the leakage current in solar panels is vital in a transformerless grid connected PV panels. But due to the absence of transformers which provide galvanic isolation, CMV techniques are applied which results in leakage currents from PV panel to ground. This current causes hazards to humans and large currents may lead to fire hazards. The proposed switching strategy reduces the continuous transients at switches, hence avoiding high frequency switching. This switching technique requires only a single modified carrier wave for all 2m+1 levels of operation. The sinusoidal carrier waveform is modified as humped sinusoidal waveform to reduce switching losses. In this paper, the progressed switching strategy has been incorporated to PV fed five level multilevel inverter connected to grid and its effectiveness has been validated.
 

Low Cost, Fireproof, and Light Aircraft Interior

Sardou Societe Anonyme-Max Sardou
  • Technical Paper
  • 2019-01-1857
To be published on 2019-09-16 by SAE International in United States
Low cost, fireproof, and light aircraft interior Fire is a dramatic issue in aircraft nowadays, especially with composite air crafts. An additional issue is the dangerous use of flammable Li-Ion batteries in a lot of appliances. we propose in order to avoid dramas to produce aircraft interiors, fire doors, cargo bay walls, as well than cargo container able to contain a fire inside them, with our ceramic composite called TOUGHCERAM ®. We have developed a low-cost, ceramic, damage tolerant, this ceramic is flexible between minus 100°C and plus 350°C. TOUGHCERAM ® poly-crystalize between 60°C and 110°C and can be reinforced with fibbers like carbon or basalt one. TOUGHCERAM ® survive 90 minutes to a propane 1900°C torches. TOUGHCERAM ® does not burn, nor smoke. In this paper we will explain how it is possible to develop a fully mineral ceramic offering such unique mechanical and fire properties.
 

Smart Cylinder Deactivation Strategies to Improve Fuel Economy and Pollutant Emissions for Diesel-Powered Applications

FEV Group GmbH-Thomas Körfer
FEV Italia SRL-Mauro Scassa, Marco Nencioni, Shino George
  • Technical Paper
  • 2019-24-0055
To be published on 2019-09-09 by SAE International in United States
Further improvement of the trade-off between CO2- and pollutant emissions is the main motivating factor for the development of new diesel engine concepts, from light-duty car applications via medium-duty commercial vehicles up to large long-haul trucks. The deactivation of one or more cylinders of a light-duty diesel engine during low load operation can be a sophisticated method to improve fuel economy and reduce especially NOx emissions at the same time. Dynamic Skip Fire (DSF) is and advanced cylinder deactivation technology, where the decision to fire or skip singular units of a multi-cylinder engine architecture is taken just prior to each firing opportunity, based on a balanced rankling of multiple input parameters. A DSF-equipped engine incorporates the ability to selectively deactivate cylinders on a cylinder event-by-event basis for best matching of the requested driver’s torque demand at optimum fuel efficiency, while ensuring no drawback in terms of drivability with respect to fully firing engine. Dynamic Skip Fire has already demonstrated significant fuel economy improvements for throttled spark-ignition engines on a number of different applications. The publication…
 

Numerical Modeling of Internal Helmholtz Resonators Created by Punching Small Holes on a Thin-Walled Tube

University of Kentucky-Hao Zhou, T. W. Wu
Published 2019-06-05 by SAE International in United States
Helmholtz resonators are normally an afterthought in the design of mufflers to target a very specific low frequency, usually the fundamental firing frequency of the engine. Due to space limitations in a complex muffler design, a resonator may have to be built by punching a few small holes on a thin-walled tube to create a neck passage into a small, enclosed volume outside the tube. The short neck passage created by punching a few small holes on a thin-walled tube can pose a great challenge in numerical modeling, especially when the boundary element method (BEM) is used. In this paper, a few different BEM modeling approaches are compared to one another and to the finite element method (FEM). These include the multi-domain BEM implemented in a substructure BEM framework, modeling both sides of the thin-walled tube and the details of each small hole using the Helmholtz integral equation and the hypersingular integral equation, and modeling just the mid surface of the thin-walled tube. The FEM and BEM solutions are used to estimate the effective neck…
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Impact-Resistant Battery Electrolyte Solidifies When Hit

  • Magazine Article
  • TBMG-34633
Published 2019-06-01 by Tech Briefs Media Group in United States

Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. Inspired by the unusual behavior of some liquids that solidify on impact, researchers have developed a practical and inexpensive way to help prevent these fires.

 

Graphene Coating Takes Oxygen Out of Lithium Battery Fires

  • Magazine Article
  • TBMG-34601
Published 2019-06-01 by Tech Briefs Media Group in United States

Lithium batteries allow electric vehicles to travel several hundred miles on one charge. Their capacity for energy storage is well known — so is their tendency to occasionally catch on fire. This “thermal runaway” occurs most frequently when the batteries overheat or cycle rapidly.

 

Generation and Oxidation of Soot due to Fuel Films Utilizing High Speed Visualization Techniques

Continental Automotive France-Jerome Helie
Continental Automotive Systems-William Imoehl
Published 2019-04-02 by SAE International in United States
For a better understanding of how soot is generated due to fuel films, a constant volume vessel was used together with four visualization techniques due to their high spatial (2D) and time resolution: Schlieren, natural luminosity, diffused back illumination and OH* chemiluminescence. The analysis was performed keeping the injection pressure at 30 bar and changing the plate temperature on which the spray impacts: 80, 120, 160 and 200 °C. The fuel is a mixture of iso-octane, hexane, toluene and 1-methylnaphthalene, which presents similar properties to commercial gasoline. Valuable insights were gained from the results that infer the real nature of the radiation observed during combustion events in gasoline direct injection (GDI) engines due to the presence of a fuel films which are conventionally described as “pool fires”. The results show that the highest quantity of soot is generated between plate temperatures of 80 and 120 °C. The composition of the fuel film and the flow field generated after the passage of the flame front are of paramount importance in the description of the soot generated…
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Vibration Rating Prediction Using Machine Learning in a Dynamic Skip Fire Engine

Tula Technology Inc-Aditya Mandal, Anastasios Arvanitis, S Kevin Chen, Li-Chun Chien, Vijay Srinivasan, Matthew Younkins
Published 2019-04-02 by SAE International in United States
Engines equipped with Dynamic Skip Fire (DSF) technology generate low frequency and high amplitude excitations that could reduce vehicles drive quality if not properly calibrated. The excitation frequency of each firing pattern depends on its length and on the rotational speed of the engine. Excitation amplitude mainly depends on the requested engine torque by the driver. During the calibration process, the torque characteristics that results in production level of noise, vibration, and harshness (NVH), must be identified, for each firing pattern and engine speed. This process is quite time consuming but necessary.To improve our process, a novel machine learning technique is utilized to accelerate the calibration effort. The idea is to automate the vibration rating procedure such that given the relevant power-train parameters, a vibration rating associated with that driving condition can be predicted. This process is divided into two (2) prediction models. The first model is a multiple additive regression trees that predicts the seat accelerometer data based on the various engine and vehicle parameters. The predicted seat accelerometer data is used as an…
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mDSF: Improved Fuel Efficiency, Drivability and Vibrations via Dynamic Skip Fire and Miller Cycle Synergies

Tula Technology, Inc.-Elliott Ortiz-Soto, Benjamin Wolk, Hao Chen, Matthew Younkins
Published 2019-04-02 by SAE International in United States
mDSF is a novel cylinder deactivation technology developed at Tula Technology, which combines the torque control of Dynamic Skip Fire (DSF) with Miller cycle engines to optimize fuel efficiency at minimal cost. mDSF employs a valvetrain with variable valve lift plus deactivation and novel control algorithms founded on Tula’s proven DSF technology. This allows cylinders to dynamically alternate among 3 potential states: high-charge fire, low-charge fire, and skip (deactivation). The low-charge fire state is achieved through an aggressive Miller cycle with Early Intake Valve Closing (EIVC). The three operating states in mDSF can be used to simultaneously optimize engine efficiency and driveline vibrations. Acceleration performance is retained using the all-cylinder, high-charge firing mode.Although mDSF can be implemented with a variety of valvetrains, the most cost-efficient solution for mDSF is comprised of asymmetric intake valve lifts and/or ports, with one high-flow power charging port and one high-efficiency Miller port. The power charging port is deactivated independently, whereas the Miller port deactivation is coupled to the exhaust valves. High-charge firing is realized with all four valves active,…
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Instrumentation and Processor in Loop Verification for Dynamic Skip Fire Technology

Tula Technology Inc.-Arnav Mohan, Karthik Deepak Natraj, Joe Serrano
Published 2019-04-02 by SAE International in United States
Amid various cylinder deactivation technologies in automobile engines which provide better fuel efficiency, Dynamic Skip Fire (DSF) has proved to be promising. In DSF, a firing decision is made before every cylinder firing opportunity based on the engine torque requested. Providing this technology to automakers in form of a software object integratable with the customer’s engine controller is done by careful specification of interfaces and execution context definitions. The timing and performance of the software objects integrated with controller firmware can be dependent on the platform and compiler development environment used by the customer. This paper discusses the development of a code test environment for producing high-confidence verification. To do so an industry-accepted verification tool suite is used. Execution timing data of various functions of the source code is analyzed in detail, as well as input-output correctness. Critical software issues are readily identified before delivery to the customer. A method for determining the computational time required for the software modules is shown, and advantages of this method are discussed. Further advantages of this procedure for…
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