Improved direct torque control load torque estimator with the influence of steering angle for dual induction motors electric vehicle traction drive system

Front-wheel direct-driven dual motors of an electric vehicle (EV) with a single controller configuration offer great potential and flexibility for improving system performance, efficiency and safety. The objective of the paper is to design a new load torque estimator of Direct Torque Control (DTC) by merging the electrical model with the mechanical model of an EV traction system to improve the dual motors single controller configuration. The electrical model utilise Space Vector PWM (SVPWM) DTC control of dual induction motors fed Five-leg Inverter (FLI) while the mechanical model takes the 14DOF vehicle dynamic model as its main structure. The new technique used is by integrating lateral force with longitudinal force produced at the touch point of a tyre with road surface as the input to the new load torque estimator of DTC. The new load torque estimator technique results were, then, compared with the standard load torque estimator that used the voltage and current feedback only. The findings showed that while torque estimator of conventional DTC had no effect of steering angle on the speed, torque and current performance of the motors, the new load torque estimator showed a significant impact. The speed, torque and current responds of the motors now have precisely been estimated; following the trajectory of the steering angle. Hence, for future research the new load torque estimator with the accurate and precise speed and torque response can further be utilized in stability, slip and skid and traction control or even for electronic braking system

Geological, geoarchaeological, biological, and historical heritage of Lenggong geopark development

The Lenggong Valley is uniquely significant in national and international geological heritage and was declared a UNESCO Archaeological Heritage Site in 2012. The Lenggong Valley was formed 550 million years ago. It is one of the oldest in Peninsular Malaysia, equivalent to the rock formations in Langkawi and Jerai. The geological evolution in the Lenggong Valley also produced biodiversity and the history of early human prehistoric to the present time. Due to this privilege, the Lenggong Geopark nomination development effort started in 2020 by forming the Geopark Promotion and Development Committee. Lenggong Geopark covers an area of 2,068 km2 (enclosed by the boundaries of the Lenggong Parliament). A total of 27 geosites have been identified, depicting four important geological and historical tectonic evolutions and special geomorphic features in the Lenggong Valley. Eight biosites are still preserved, involving granite mountain, limestone, and lowland ecosystems covered by different forest types. It is the limestone hills that contain a large number of rare and endemic flora species. In addition, eight geoarchaeological sites were also identified that depicts the interaction between early humans and the geological landscape. The unique and preserved traditions of life, art and culture have added value to the geopark. Therefore, active efforts continue to be carried out in the development of geosites and programs with the local community to foster a high sense of pride and belonging to a place, in addition to an understanding of the preservation and conservation of natural and cultural heritage in Lenggong Geopark. Various activities based on tourism activities are also planned to stimulate the economy and introduce Lenggong as the second national geopark area in the State of Perak

Synthesis and characterization of sodium bismuth titanate (Na0.5Bi0.5TiO3) ceramic by sol-gel method at different sintering temperature

Sodium Bismuth Titanate is a prominent candidate for a lead-free piezoelectric material. In this research, Na0.5Bi0.5TiO3 was synthesized at different sintering temperature by sol-gel method in which the solutions were prepared by using sodium acetate CH3COONa, bismuth (III) acetate Bi(CH3COO)3, tetra-n-butyl titanate Ti(OC4H9)4, as starting materials. Acetic acid glacial and 2-methoxyethanol as solvents and acetylacetone as a reagent to stabilize tetra-n-butyl titanate. The obtained BNT powder was analyzed using XRD, FESEM, FTIR. The mechanical properties of BNT was determined by hardness testing to investigate the strength of the samples. Pellets have been formed and sintered at 940 oC, 960 oC, 980 oC, 1000 oC for 5 hours. The XRD analysis confirmed that the perovskite structure was obtained at each temperature.The effect of slightly different sintering temperature on the structural was studied in detail. FESEM analysis of pellets showed the well-developed grains having larger size at higher sintering temperature. Hardness analysis that was examined by using Rockwell hardness testing shows that hardness measurement increased as the sintering temperature increased due to the amount of strain or defect content in the compact powders

Wpływ wstępnej obróbki na strukturę celulozy bakteryjnej z Nata de Coco (Acetobacter xylinum)

This paper presents a structural analysis of various methods to produce bacterial cellulose (BC) from Nata de Coco (Acetobacter xylinum). BC sheet, BC chem and BC mech powders were successfully prepared using oven drying, chemical and mechanical treatment. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM) were used to analyze the structure of prepared BC. The structure of bacterial cellulose was compared with the structure of commercial microcrystalline cellulose (MCC) and cotton fabric. The XRD results showed that the BC sheet sample had the highest degree of crystallinity (81.76%) compared to cotton cellulose (75.73%). The crystallite size of cotton was larger than the BC sheet, with the value of 6.83 ηm and 4.55 ηm, respectively. The peaks in the FTIR spectra of all BC were comparable to the commercial MCC and cotton fabrics. FESEM images showed that the prepared BC sheet, BC mech, and BC chem had an almost similar structure like commercial MCC and cotton fabric. It was concluded that simple preparation of BC could be implemented and used for further BC preparation as reinforcement in polymer composites, especially in food packaging.Niniejszy artykuł zawiera analizę struktury celulozy bakteryjnej (BC) wytworzonej z Nata de Coco (Acetobacter xylinum) różnymi metodami. Folia BC i proszki BC chem oraz BC mech zo -stały wytworzone poprzez suszenie w piecu, obróbkę chemiczną i mechaniczną. Do oceny struktury celulozy bakteryjnej stosowano dyfrakcję rentgenowską (XRD), spektroskopię Fouriera w podczerwieni (FTIR) i skaningową mikroskopię elektronową z emisją polową (FESEM). Strukturę celulozy bakteryjnej porównano ze strukturą handlowej celulozy mikrokrystalicznej (MCC) i tkaniny bawełnianej. Wyniki XRD wykazały, że najwyższy stopień krystaliczności miała próbka arkusza BC (81,76%) w porównaniu z celulozą bawełnianą (75,73%). Wielkość krystalitów bawełny była większa niż folii BC i wynosiła, odpowiednio, 6,83 ηm oraz 4,55 ηm. Piki widm FTIR wszystkich otrzymanych form celulozy bakteryjnej były porównywalne z komercyjnymi tkaninami bawełnianymi i z celulozy mikrokrystalicznej. Zdjęcia FESEM folii BC oraz proszków BC mech i BC chem również były podobne do komercyjnej MCC i tkaniny bawełnianej. Stwierdzono, że z wykorzystaniem prostych technik można otrzymać BC, która może być stosowana jako wzmocnienie w kompozytach polimerowych, w szczególności w opakowaniach do żywności

Hardware development for zero crossing of a multilevel single phase rectifier chopper for plug-in electric car battery charger using a PIC microcontroller

This paper focuses on developing the hardware for a controller and of a zero crossing circuit for an electric car battery charger. A novel topology of a battery charger is studied and tested. A conventional rectifier has drawbacks in terms of harmonic currents. This paper describes a five-level single-phase rectifier associated with buck chopper with a control signal which draws a clean sinusoidal line current for the application in a plug-in battery charger. The MATLAB/Simulink results reveal that the proposed battery charger performance is better compared to the conventional method

Sensorless Speed Control of Independent Dual-PMSM Drives Fed by a Five-Leg Inverter

Various control algorithms have been investigated for speed sensorless of an AC motors using three-leg inverter by other researchers. Unfortunately, these sensorless techniques are mainly focus on single motor controlled drive with a single three-le inverter. Resent research has shown that the dual-motor drives can be independently controlled by using a Five-Leg Inverter (FLI). This paper introduces the new control strategy based on speed sensorless technique of independent dual- Permanent Magnet Synchronous Motor (PMSM) drives using FLI. The simulation is implemented in MATLAB/Simulink to evaluate the overall motor drive performance. The transient behavior is examined for various speed commands, load disturbance, inertia and during zero speed operation, so that a thorough comparison is enable. The simulation results also proved that the performance characteristics of sensorless dual-PMSM are almost similar to the sensory system except for the startup condition. For future research, there is a need to emphasize on the start-up method for sensorless dual-PMSM drives