Enhancement of Sensorless Control for Non-Sinusoidal Multiphase Drives-Part I: Operation in Medium and High-Speed Range

This two-part study proposes a new sensorless control strategy for non-sinusoidal multiphase permanent magnet synchronous machines (PMSMs), especially integrated motor drives (IMDs). Based on the Sliding Mode Observer (SMO), the proposed sensorless control strategy uses the signals (currents and voltages) of all fictitious machines of the multiphase PMSMs. It can estimate the high-accuracy rotor positions that are required in vector control. This proposed strategy is compared to the conventional sensorless control strategy that applies only current and voltage signals of the main fictitious machine, including the fundamental component of back electromotive force (back EMF) of non-sinusoidal multiphase PMSMs. Therefore, in order to choose an appropriate sensorless control strategy for the non-sinusoidal multiphase PMSMs, these two sensorless control strategies will be highlighted in terms of precision with respect to rotor position and speed estimation. Simulations and the experimental results obtained with a non-sinusoidal seven-phase PMSM will be shown to verify and compare the two sensorless control strategies. In this part of the study (part I), only sensorless control in the medium and high-speed range is considered. Sensorless control at the zero and low-speed range will be treated in the second part of this study (part II).

Effect of laser-textured micro dimples on inhibition of stick-slip phenomenon of sliding guideway

Purpose This study aims to investigate the efficacy of micro dimple in inhibiting stick-slip phenomenon on the sliding guideway. Design/methodology/approach In this study, micro-dimples were fabricated by laser on surfaces of steel disk and guideway. The disks and guideways were respectively performed pin-on-disk tribological tests and working condition experiments to study differences in lubrication condition and friction stability between textured and untextured surfaces. Findings Micro-dimples help reduce critical sliding speed that allows contact surfaces to enter in hydrodynamic lubrication regime. This increases hydrodynamic lubrication range and narrows speed range where stick-slip phenomenon can occur, enhancing sliding guideway’s adaptability for broader working conditions. Furthermore, friction stability on the textured surface improved, lowering the occurrence possibility of stick-slip phenomenon. Finally, difference between static and kinetic frictions on the textured surface is lower relative to the untextured surface, which decreases the critical velocity when the stick-slip phenomenon occurs. Originality/value The results indicate that laser-textured micro-dimples are significantly conducive to inhibit stick-slip phenomenon, thus providing smoother movement for the guideway and eventually increasing precision of the machine.

Aerodynamic Analysis of an Arrow with Different Fletch Configurations: A Computational Approach

Archery is being contemplated from hundreds of years; however there have been not many investigations expressing and clarifying the optimal design and aerodynamic effectiveness of an Arrow. Presently Archery has turned into a significant game in Olympics. Every nation is showing colossal interest in delivering champions. So, it is important to work on the solidness of the Arrow to such an extent that its precision and aerodynamic characteristics improve. Broad examination is proceeding to work on the streamlined exhibition of the Arrow. So, this study intends to explore the aerodynamic characteristics of an Arrow for various fletches and diverse Arrow points. To accomplish this, the initial trends of aerodynamics characterization were obtained by XFLR5 v6.51 and then deep flow analysis was performed by Computational Fluid Dynamics using ANSYS Fluent. The outcomes are upon to show that the Arrow performs better at a speed range of 40-60 m/s and angles of attack from - 5 to +5 degrees. MATLAB is employed in plotting all of the non-dimensional data fluctuations, since it is the most trusted plotting software. The outcomes are validated with existing research work and significant conclusions are obtained.

A Study the Effect of Biodiesel Blends and the Injection Timing on Performance and Emissions of Common Rail Diesel Engines

This paper presents a study on the effect of the ratio of biodiesel and injection timing on the performance of diesel engines and their emissions. The research engine is a cylinder engine AVL-5402, simulated by software AVL-Boost. The simulated fuel includes fossil diesel and biodiesel blended with a replacement rate from 0% to 50%, with a simulation mode of 2200 (rev/min), at a rate of a 25%, 50% and 75% load. In this speed range, the engine has the lowest fuel consumption. The parameters to be evaluated are power, fuel consumption and emissions, based on the proportions of blended biodiesel. The results show that there is a relationship between the proportion of blended biodiesel, injection timing and the parameters of the engine. Specifically, the ratio of the biodiesel blend increases, injection timing tends to move closer to the top dead center (TDC), the tendency reduce engine power, fuel consumption increases, the emissions of CO and soot reduces, while NOx increases.

EXHAUST NOISE ANALYSIS RESEARCH FOR A SINGLE-CYLINDER DIESEL ENGINE AND EVALUATION OF NOISE FILTRATION BY SIMULATION

The paper develops an ana lysis of exhaust noise for a single-cylinder diesel engine tested in laboratory conditions. The acoustic signal at the engine exhaust system, for the speed range 1,300 – 2,700 rpm was measured and recorded. The results of the noise recordings were subjected to a processing from which the variation of the noise level depending on the engine speed was obtained. Next, the physiological effect of acoustic filtrations for noise recordings was analyzed by simulation. This allowed the optimization of the exhaust noise, having identified the areas and the optimal attenuation effect. In the performed simulations, it was found that the low frequencies require the highest attenuation background.

CFD Analysis of Flow Over Pickup Truck with And Without Covering Cargo Area Using OpenFOAM

Pickup truck serves purpose as car as well as small truck. Pickup truck is popularly used in USA and Saudi Arabia. Pickup truck consists of enclosed cab and an open cargo space. Here CFD analysis of full scale pickup truck is performed using free CFD software OpenFOAM for speed range from 40km/hr to 140km/hr. For turbulence modelling k-ω model is used. This work investigates effect of covering cargo area on aerodynamics drag. Covering cargo area decreases drag coefficient by 5.2% by horizontally covering cargo area whereas decreases by 13% by inclined surface covering cargo area. Thus, covering cargo area reduces drag coefficient as recirculation zone is reduced. Inclined cover case shows drastic rise in lift force, requiring attention for safety as traction will be affected.

Development of HTU-model variable chipping clearance cassava chipper

The objective of this research was to design, construct and evaluate a variable chipping clearance cassava chipper for processors which will produce uniform and varying cassava chip geometry for multipurpose usage. It consists of a drive shaft with varying chipping clearances (6, 18, and 28 mm) to produce varied chip geometry. The average throughput capacity of the chipper was found to be 475.5 kg·h^–1 at a speed range of 460–800 rpm with a chipping clearance of 6–28 mm. The average chipping efficiency ranges from a minimum–maximum of 76.6–99.4% for the selected operational speeds and chipping clearances. The chipping capacity and the output to input ratio is dependent on the operational speeds and chipping clearances of the machine.