Precise modelling of switching and conduction losses in cascaded h-bridge multilevel inverters

Nowadays, voltage source multilevel inverters are being used extensively in industry due to its many advantages, compared to conventional two level inverters, such as higher output voltage at low switching frequency, low voltage stress(dv/dt), lower total harmonic distortion (THD), less electro-magnetic interference (EMI), smaller output filter and higher fundamental output. However, the evaluation of multilevel inverter losses is much more complicated compared to two level inverters. This paper proposes an on-line model for precise calculation of conduction and switching losses for cascaded h-bridge multilevel inverter. The model is simple and efficient and gives clear process of loss calculation. A singlephase 7-level cascaded h-bridge with IGBT's as switching devices has been used as a case study of the proposed model. The inverter has been controlled using selective harmonic elimination in which the switching angles were determined using the Genetic Algorithm (GA). MATLAB-SIMULINK is used for the modelling and simulation

Power loss investigation in HVDC for cascaded H-bridge multilevel inverters (CHB-MLI)

In the last decade, the use of voltage-source multilevel inverters in industrial and utility power applications has been increased significantly mainly due to the many advantages of multilevel inverters, compared to conventional two level inverters. These advantages include: 1) higher output voltage at low switching frequency, 2) low voltage stress (dv/dt), 3) lower total harmonic distortion (THD), 4) less electro-magnetic interference (EMI), 5) smaller output filter, and 6) higher fundamental output. However, the computation of multilevel inverter power losses is much more complicated compared to conventional two level inverters. This paper presents a detailed investigation of CHB-MLI losses for HVDC. Different levels, and IGBT switching devices have been considered in the study. The inverter has been controlled using selective harmonic elimination in which the switching angles were determined using the Genetic Algorithm (GA). MATLAB-SIMULINK is used for the modelling and simulation. This investigation should result in a deeper knowledge and understanding of the performance of CHB-MLI using different IGBT switching devices

Reliability And Validity Of An Arabic Version Of The Self-Determination Assessment – Internet (sda-I)

Self-determination is related to the desirable transition outcomes of an individual. It has gained an increasing amount of attention in numerous fields, including education, sociology, psychology, and other fields related to human behavior. However, there are no measures originally written in Arabic that accurately measure an individual’s self-determination. Thus, during this study, an Arabic version of the Self-Determination Assessment – Internet (SDAi) was developed from the regular English version of the assessment. The SDAi measures the cognitive, emotional, and behavioral factors related to self-determination. The purpose of this study was to develop and then test the reliability and validity of an Arabic version of the SDAi. In addition, the use of the Arabic SDAi as an effective tool to assess self-determination among Arabic-speaking students’ parents and teachers was examined. The participants were 336 Saudi students studying at universities in the United States and 53 parents and 60 teachers who resided in the state of Michigan, were Arab American, and could read Arabic. An Arabic version of the SDAi was translated and back-translated by the investigator and associated research team members for the study. The investigation of the SDAi’s internal consistency and reliability, and exploratory factor analysis (EFA) were the focus of this study. The SDAi had high levels of internal consistency and reliability; and the Cronbach’s alpha was 0.85 for the entire scale of SDSS-SF, and 0.95 for both the SDPPS and SDAPS scales. Principal Component Analysis resulted in the SDSS-SF, a five-factor model explaining 43.632% of the variance, a five-factor model where 67.30% of the variance was explained for the SDPPS scale, and a five-factor model also explained 66.72% of the variance for the SDAP scale. These findings confirm that the SDAi assessment is a valid measure for estimating the degree of self-determination in Saudi students studying in American universities and the degree of self-determination and perceptions of Arab American parents and teachers who live in the state of Michigan

Optimum SHE for cascaded H-bridge multilevel inverters using: NR-GA-PSO, comparative study

Selective Harmonic Elimination (SHE) is very widely applied technique in the control of multilevel inverters that can be used to eliminate the low order dominant harmonics. This is considered a low frequency technique, in which the switching angles are predetermined based on solving a system of transcendental equations. Iterative techniques such as NR and Heuristic techniques such as GA and PSO have been used widely in literatures for the problem of SHE. This paper presents a detailed comparative study of these three techniques when applied for a 7-level CHB-MLI

A Differential Turbo Detection Aided Sphere Packing Modulated Space-Time Coding Scheme

A signal construction method that combines orthogonal design with sphere packing has recently shown useful performance improvements over the conventional orthogonal design. In this contribution, we extend this concept and propose a novel Sphere Packing (SP) modulated differential Space-Time Block Coded (DSTBC) scheme, referred to here as (DSTBC-SP), which shows performance advantages over conventional DSTBC schemes. We also demonstrate that the performance of DSTBC-SP systems can be further improved by concatenating sphere packing aided modulation with channel coding and performing SP-symbol-to bit demapping as well as channel decoding iteratively. We also investigate the convergence behaviour of this concatenated scheme with the aid of Extrinsic Information Transfer (EXIT) Charts. The proposed turbo-detected DSTBC-SP scheme exhibits a ’turbo-cliff’ at Eb/N0 = 6dB and provides Eb/N0 gains of 23.7dB and 1.7dB at a BER of 10?5 over an equivalent-throughput uncoded DSTBC-SP scheme and a turbo-detected QPSK modulated DSTBC scheme, respectively

A Turbo Detection and Sphere-Packing-Modulation-Aided Space-Time Coding Scheme

Arecently proposed space-time block-coding (STBC) signal-construction method that combines orthogonal design with sphere packing (SP), referred to here as STBC-SP, has shown useful performance improvements over Alamouti’s conventional orthogonal design. In this contribution, we demonstrate that the performance of STBC-SP systems can be further improved by concatenating SP-aided modulation with channel coding and performing demapping as well as channel decoding iteratively. We also investigate the convergence behavior of this concatenated scheme with the aid of extrinsic-information-transfer charts. The proposed turbo-detected STBC-SP scheme exhibits a “turbo-cliff” at Eb/N0 = 2.5 dB and provides Eb/N0 gains of approximately 20.2 and 2.0 dB at a bit error rate of 10?5 over an equivalent throughput uncoded STBC-SP scheme and a turbo-detected quadrature phase shift keying (QPSK) modulated STBC scheme, respectively, when communicating over a correlated Rayleigh fading channel. Index Terms—EXIT charts, iterative demapping, multidimensional mapping, space-time coding, sphere packing, turbo detection