Improved output voltage quality using space vector modulation for multilevel inverters

Space vector modulation (SVM) has received wide acceptance due to many benefits over other techniques such as higher output voltages, lower total harmonic distortion (THD), high-efficiency and flexible to be implemented in vector control systems. In digital implementation, the SVM equations can be optimally computed by eliminate the use of complex forms. In this paper, the simple SVM based on twolevel inverter is employed for higher levels of inverters. This is to retain the simplicity of SVM computation for three-level and five-level cascaded H-bridge multilevel inverter (CHMI). Moreover, the proposed method utilizes two controller boards to perform high computational workloads and to eliminate glitch and error problems. Experiment results show that the THD of output voltage in five-level CHMI gives the smallest value among the results obtained from other levels

An improved FPGA implementation of direct torque control for induction machines

This paper presents a novel direct torque control (DTC) approach for induction machines, based on an improved torque and stator flux estimator and its implementation using Field Programmable Gate Arrays (FPGA). The DTC performance is significantly improved by the use of FPGA, which can execute the DTC algorithm at higher sampling frequency. This leads to the reduction of the torque ripple and improved flux and torque estimations. The main achievements are: i) calculating a discrete integration operation of stator flux using backward Euler approach, ii) modifying a so called non-restoring method in calculating the complicated square root operation in stator flux estimator, iii) introducing a new flux sector determination method, iv) increasing the sampling frequency to 200kHz such that the digital computation will perform similar to that of the analog operation, and v) using two’s complement fixed-point format approach to minimize calculation errors and the hardware resource usage in all operations. The design was achieved in VHDL, based on a Matlab/Simulink simulation model. The Hardware-In-the-Loop (HIL) method is used to verify the functionality of the FPGA estimator. The simulation results are validated experimentally. Thus, it is demonstrated that FPGA implementation of DTC drives can achieve excellent performance at high sampling frequency

High performance speed control of single-phase induction motors using switching forward and backward EKF strategy

The aim of this research is to provide a high performance vector control of single-phase Induction Motor (IM) drives. It is shown that in the rotating reference frame, the single-phase IM equations can be separated into forward and backward equations with the balanced structure. Based on this, a method for vector control of the single-phase IM, using two modified Rotor Field- Oriented Control (RFOC) algorithms is presented. In order to accommodate forward and backward rotor fluxes in the presented controller, an Extended Kalman Filter (EKF) with two different forward and backward currents that are switched interchangeably (switching forward and backward EKF), is proposed. Simulation results illustrate the effectiveness of the proposed algorithm

A Novel Method for Rotor Field-Oriented Control of Single-Phase Induction Motor

This paper presents a novel rotor field-oriented control (RFOC) method for asymmetrical single-phase induction motor (SPIM). It is shown in this paper that by using a suitable transformation matrix (TM) for stator current variables, the asymmetrical equations of SPIM are transformed into symmetrical equations. Based on this similarity, a novel vector conrol technique for SPIM is presented. Performance of the proposed method is assessed using MATLAB/SIMULINK software. Simulation results showed the excellence speed and torque responses obtained using the proposed technique

Peralihan Sistem Mata Pencaharian Hidup Orang Rimba (Studi Kasus di Desa Bukit Suban Kecamatan Air Hitam Kabupaten Sarolangun)

Orang Rimba merupakan masyarakat adat dengan salah satu karakteristiknya yang menonjol yaitu bahwa mereka masih menjaga tradisi peninggalan nenek moyangnya. Berdasarkan tradisi dan kebudayaan Orang Rimba, nenek moyang mereka melakukan kegiatan berburu dan meramu bahan makanan hasil hutan guna memenuhi kebutuhan hidup. Realita di lapangan ada kelompok Orang Rimba yang melakukan USAha dalam memenuhi kebutuhan hidupnya yaitu dengan bercocok tanam. Penelitian ini dilakukan untuk mengetahui peralihan dan faktor-faktor yang mempengaruhi peralihan sistem mata pencaharian hidup Orang Rimba. Penelitian ini dilakukan di Desa Bukit Suban Kecamatan Air Hitam Kabupaten Sarolangun. Lokasi penelitian dipilih secara sengaja dengan pertimbangan bahwa di Desa ini terdapat Orang Rimba yang telah tinggal menetap dan melakukan cocok tanam menetap. Informan pada penelitian ini adalah Orang Rimba dan pemerintah desa. Data penelitian ini dianalisis dengan menggunakan model interaktif yang terdiri dari tiga alur kegiatan yang terjadi secara bersamaan yaitu: reduksi data, penyajian data dan penarikan kesimpulan/verifikasi. Hasil penelitian menunjukkan bahwa terjadi peralihan sistem mata pencaharian hidup dimana Orang Rimba melakukan mata pencaharian baru yang ditandai dengan dilakukannya cocok tanam menetap dengan tetap melakukan mata pencaharian hidup yang sebelumnya yaitu berburu dan mengumpulkan makanan. Peralihan sistem mata pencaharian hidup tersebut dipengarui tiga fakor, yaitu: kebijakan pemerintah, interaksi dengan warga desa, dan norma atau aturan yang mempengaruhi Orang Rimba dalam pemanfaatan lahan dan pengambilan sumberdaya alam

Pola Makan dengan Kadar Gula Darah Pasien Dm Tipe 2

Pola makan yang salah dapat menyebabkan kenaikan kadar gula darah pada pasien diabetes mellitus tipe 2. Penelitian ini bertujuan mengetahui hubungan pola makan dengan kadar gula darah pasien diabetes mellitus tipe 2 di wilayah kerja puskesmas Kota Makassar. Desain penelitian yang digunakan adalah survei analitik dengan pendekatan studi cross-sectional, dilaksanakan pada bulan April-Mei 2014 di wilayah kerja Puskesmas Batua Raya dan Bara-barayya. Populasi penelitian, yaitu rata-rata jumlah pasien yang berkunjung perbulan di Puskesmas Batua Raya dan Bara-barayya, yaitu 67 orang. Pengambilan sampel dilakukan dengan menggunakan purposive sampling dengan jumlah sampel 46 orang. Instrumen penelitian adalah kuesioner identitas diri, food recall 24 jam, food picture, alat pemeriksaan gula darah, nutrisurvey, dan SPSS. Hasil yang diperoleh, pada asupan energi, karbohidrat, dan lemak bermakna dengan nilai p0,05 yaitu 0,162. Variabel Jenis, gula dan hasil olahannya (p>0,05) yaitu 0,133. Sedangkan variabel sayur dan buah bermakna dengan nilai p 0,000. Variabel jadwal makan nilai p=0,460. Beban glikemik sendiri memiliki hubungan dengan kadar gula darah dibuktikan nilai p<0,05 yaitu, 0,004. Kesimpulan dari penelitian bahwa ada hubungan pola makan dengan kadar gula darah pasien DM tipe 2 wilayah kerja puskesmas Kota Makassar Tahun 2014

Semi-analytical approach to criteria for ignition of excitation waves

We consider the problem of ignition of propagating waves in one-dimensional bistable or excitable systems by an instantaneous spatially extended stimulus. Earlier we proposed a method (Idris and Biktashev, PRL, vol 101, 2008, 244101) for analytical description of the threshold conditions based on an approximation of the (center-)stable manifold of a certain critical solution. Here we generalize this method to address a wider class of excitable systems, such as multicomponent reaction-diffusion systems and systems with non-self-adjoint linearized operators, including systems with moving critical fronts and pulses. We also explore an extension of this method from a linear to a quadratic approximation of the (center-)stable manifold, resulting in some cases in a significant increase in accuracy. The applicability of the approach is demonstrated on five test problems ranging from archetypal examples such as the Zeldovich--Frank-Kamenetsky equation to near realistic examples such as the Beeler-Reuter model of cardiac excitation. While the method is analytical in nature, it is recognised that essential ingredients of the theory can be calculated explicitly only in exceptional cases, so we also describe methods suitable for calculating these ingredients numerically.Comment: 31 page, 20 figures, as resubmitted to Phys Rev E on 2015/09/20 and accepted on 2015/09/2

Impact of Arrivals on Departure Taxi Operations at Airports

Aircraft taxi operations are a major source of fuel burn and emissions on the ground. Given rising fuel prices and growing concerns about the contributions of aviation to air pollution and greenhouse gas emissions, recent research aims to develop strategies to reduce fuel burn at airports. In order to develop such strategies, an understanding of taxi operations and the factors that affect taxi-out times is required. This paper describes an analysis of taxi-out times at two major U.S. airports in order to identify the primary causal factors affecting the duration of taxi-out operations. Through an analysis of departures out of John F. Kennedy International Airport and Boston Logan International Airport, several variables affecting taxi-out times were identified, including primarily the number of arrivals and number of departures during the taxi-out operation of an aircraft. Previous literature suggests that the number of arrivals on the surface has limited influence on taxi-out times; however, this analysis demonstrates that the number of arrivals is in fact significantly correlated with taxi-out times. Furthermore, we find that arrivals have a greater impact on taxi-out times under runway configurations where there is increased interaction between arrivals and departures

DEVELOPMENT OF A RECHARGEABLE ELECTRONICALLY CONTROLLED MOTORISED WHEELCHAIR FOR DISABLED AND ELDERLY PEOPLE

The physically challenged, old-age people, and most paralysed patients need means of transportation from place to place to ease their movement. The earlier available wheelchairs are manually driven that need extra effort of either the physically challenged or an assisting person to move. Nowadays, the level of communication and socialization strongly depends on easy access to mobile transportation. &nbsp;This paper presents a developed motorized wheelchair that facilitates movement of physically challenged people both in the hospital and in their home by taking into account aesthetics, low cost, ease on maintenance with market competitive advantage using locally sourced materials. The developed wheelchair is designed to work for 3 hours under a maximum load of 90 kg with navigation buttons. A working efficiency of 65 % was obtained under full operation. This design brings a new competition into the wheelchair market and gives more comfort to the physically challenged peoples’ mobility than the existing manually driven one