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Abstract

A novel single-phase digital control circuit-based five level inverter (FLI) is presented in this paper. Based on the determined switching angle, one switching cycle of the inverter is divided into segments from which the switching sequence of the inverter switches is digitized. A programmed counter built around JK flip flops with logic gates provided the needed switching signals for the H-bridge inverter. Proposed inverter is verified through simulation in a MATLAB/SIMULINK environment and simulation results are given. Simulation results show notable reduction in total harmonic distortion (THD) in the inverter output voltage and load current. With an RL load (of 200 Ω and 0.250H), a single digit THD of 8.5 1% for the inverter load current is realized. Comparison of the novel control circuit-dependent FLI with the conventional and contemporary power-circuit-dependent cascaded H-bridge inverter (CHBI) show that the novel FLI is synthesized with lesser number of power circuit and control circuit components.

Abstract

This paper presents a novel converter which can reduce the harmonics like the conventional multipulse converters with input three phase transformer. To reduce total harmonic distortion of input current and improve the weight and size of converters, it is suggested to use multi-pulse rectifiers with an electronic phase shift. The basic module is a 6-pulse rectifier on fully controlled switches with the reverse blocking ability. Switching frequency either coincides or is twice the power frequency. The proposed solutions allow refusing from the electromagnetic phase-shifting devices (power transformers or auto-transformers) and thereby significantly reduce the weight of the device. Unlike power factor correction systems with high-frequency modulation, the proposed converters are significantly different, as they have better electromagnetic compatibility and the virtual absence of dynamic switching losses of power switches.

Abstract

In electrical distribution systems, a great amount of power are wasting across the lines, also nowadays power factors, voltage profiles and total harmonic distortions (THDs) of most loads are not as would be desired. So these important parameters of a system play highly important role in wasting money and energy, and besides both consumers and sources are suffering from a high rate of distortions and even instabilities. Active power filters (APFs) are innovative ideas for solving of this adversity which have recently used instantaneous reactive power theory. In this paper, a novel method is proposed to optimize the allocation of APFs. The introduced method is based on the instantaneous reactive power theory in vectorial representation. By use of this representation, it is possible to asses different compensation strategies. Also, APFs proper placement in the system plays a crucial role in either reducing the losses costs and power quality improvement. To optimize the APFs placement, a new objective function has been defined on the basis of five terms: total losses, power factor, voltage profile, THD and cost. Genetic algorithm has been used to solve the optimization problem. The results of applying this method to a distribution network illustrate the method advantages.

Abstract

The requirements relating to the emission of auxiliary AC supply sockets in traction vehicles have been extended in standard PN-EN 50121-3-2:2015 by voltage harmonics measurement. This applies to the public on-board AC supply grid which is accessible to all passengers. It is concerned with providing the quality of power supply which is required by computer devices and mobile phone rechargers. This article presents the requirements and test methods resulting from extended standard scope. Normative factors, for which levels of permissible voltage harmonics in the public supply grid of traction vehicle have been defined are discussed. Examples of comparative results obtained from measurements and analyses of voltage harmonics within on-board supply grids are also presented. The presented results include extended calculations of distortion factors for groups and subgroups of supply voltage harmonics. In order to improve the quality of voltage within the on-board grid, which did not meet the requirements, simulation calculations were performed and an additional output sinusoidal filter was proposed.

Performance Enhancement of Embedded System Based Multilevel Inverter Using Genetic Algorithm

This paper presents an optimal solution for eliminating pre specified order of harmonics from a stepped waveform of a multilevel inverter topology with equal dc sources. The main challenge of solving the associated non linear equation which are transcendental in nature and therefore have multiple solutions is the convergence of the relevant algorithms and therefore an initial point selected considerably close to the exact solution is required. The paper describes an efficient genetic algorithm that reduces significantly the computational burden resulting in fast convergence. An objective function describing a measure of effectiveness of eliminating selected order of harmonics while controlling the fundamental component is derived. The performance of cascaded multilevel inverter is compared based on computation of switching angle using Genetic Algorithm as well as conventional Newton Raphson approach. A significant improvement in harmonic profile is achieved in the GA based approach. A nine level cascaded multi level inverter is simulated in MATLAB Simulink and a proto type model has been fabricated to validate the simulation results.

Comparison of Multiple Carrier Disposition PWM Techniques Applied for Multi-Level Shunt Active Filter

This work presents the simulation of a shunt active filter using seven-level cascaded inverter. The ultimate objective is to bring out the influence of multiple carrier level shifted PWM techniques on the performance of a shunt active filter. Classical disposition PWM techniques such as PD, POD and APOD have been used to generate the gating signals for the inverter active switches. A comparison is presented to substantiate the effect of these techniques in filtering. The comparison is made from the perspective of reduction in THD of source currents after filtering. For compensation current extraction synchronous detection method has been used. The harmonic reduction is achieved in source currents as well as source voltages.

X., ZHAO B., An improved active frequency drift islanding detection method with lower total harmonic distortion, Proc. IEEE Energy Conversion Congress and Exposition, Denver 2013, 5248-5252. [11] YAFAOUI A., WU B., KOURO S., Improved active frequency drift anti-islanding detection method for grid connected photovoltaic systems, IEEE Trans. Power Electr., 2012, 27(5), 2367-2375. [12] FALKOWSKI P., SIKORSKI A., Predictive control of active power of AC/DC converter with constant average switching frequency, Przegl. Elektr., 2013, 89(12), 53-56.

(MMHCS) circuit. The OTA-based circuits were designed in a 0.35 μm CMOS technology and simulation results are presented. Materials and methods Three types of OTA-based CMOS circuits were made: class-A, class-AB and current conveyor. The performances of these circuits were compared with the MMHCS circuit in order to obtain linearity, total harmonic distortion, output current, and impedance response in the frequency range from 10 Hz to 1 GHz. Comparisons were done by using PSPICE simulator from Orcad (2009 version). The basic OTA-based circuits were modified using

Abstract

A review of the literature gives several guidelines for the design of a Permanent Magnet Synchronous Generator (PMSG) for Small Wind Turbines (SWT) applications. This paper presents Finite Element Analysis (FEA) of a Surface Mounted PMSG. Several optimization tests are run in order to yield the lowest Total Harmonic Distortion (THD) and cogging torque with the highest induced voltage. The results of the optimization tests are then utilized to design an initial “optimized” circumferential Internal PMSG. This optimized design is then compared to a non-optimized design, as well as the results of the Surface Mounted PMSG.

Abstract

An analysis, design and simulation of digital controlled symmetrical seven levels inverter is presented in this paper. Against the contemporary use of two asymmetrical DC sources with two H-bridge cells to generate seven levels inverter two DC sources of equal voltage ratings are used through digital control strategy to realize seven levels output voltage. By utilizing limited number of active switching components and avoiding the usual complex PWM control techniques for multilevel inverters by way of digital control strategy, high efficiency multilevel inverter systems due to reduction in total harmonic distortion and switching losses is guaranteed. Owing to symmetry of the H-bridge cells, a simple and single programmed counter built around J-K flip is required irrespective of number of cascades. The analyzed and designed system has been simulated in MATLAB/SIMULINK environment. With an R-L load of 200 Ω and 200 mH, improved total harmonic distortions (THDs) for the inverter current and voltage are 7.59% and 16.89% respectively. The obtained results show that the control-circuit-based multilevel inverter topology is most suited for applications in solar powered inverter systems.