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One of the major problems in electric power quality is the harmonic contents. This paper focuses on elimination (reduction) of harmonics in a H-bridge multi-level voltage-source inverter. Here the basic concept is to eliminate specific harmonics with a proper choice of switching angles. This technique is very efficient for improving the multi-level inverter output voltage quality. In This paper, Generalized...
This work approximates the selective harmonic elimination problem using Artificial Neural Networks (ANN) to generate the switching angles in an 11-level full bridge cascade inverter powered by five varying DC input sources. Five 195 W solar panels were used as the DC source for each full bridge. The angles were chosen such that the fundamental was kept constant and the low order harmonics were minimized...
This paper studied the real solution number of the switch angles for the inverters which are based on the Selective Harmonic Eliminated PWM (SHEPWM) technology. By the method of variable substitution, the nonlinear transcendental equations can be transformed to a Semi-Algebraic system. Then, with the help of the latest progress in the mechanical proving software for the Semi-Algebraic systems, an...
Nowadays high quality power is essential for medical, research and industrial applications to produce good quality results and analysis. In this paper, an attempt has been made to improve the quality of power. A single phase seven level cascaded multi level inverter with identical dc supply is designed to reduce the harmonic components of the output voltage. Genetic algorithm optimization technique...
This paper applies the selective harmonic elimination technique to 5-phase, 2-level inverters to assess the ability of the technique to eliminate specific harmonics. Whilst the technique is well-known, there is little information on its application to five-phase drives, where there are specific and important differences to three-phase counterparts. This includes the need to eliminate different harmonics,...
Linear programming models are formulated and solved to determine the switching angles that optimally minimize the values of the undesired harmonics in cascaded multilevel inverters with staircase output voltage waveform. Three cases are discussed. Case 1 assumes fixed equal values of the input dc voltages. A mixed integer linear programming (MILP) model is applied. In case 2 this model is modified...
The basic concept of a multilevel converter is to synthesize a staircase voltage wave-form by the use of several lower voltage DC sources. Capacitors, batteries, fuel cells and photovoltaic modules can be used as DC sources. A multilevel converter has several advantages, like a high voltage quality and low electromagnetic compatibility problems. Two different modulation schemes for multilevel inverters...
Inverters are power devices used for many industrial applications such as power conversion, the speed control of induction motors etc. When a magnetic device is energized by an inverter power supply, its magnetic core is subjected to additional core losses due to harmonic contents. One solution to this problem may be the selective harmonic elimination based on the simultaneous solution of non-linear...
An improved pulse width modulation (PWM) method for three-phase inverters using the Walsh function harmonic elimination method with harmonic injection technique is presented, together with a noniterative algorithm that produces a set of linear equations that relates switching angles with the output phase voltage fundamental. The approach used gives a set of solutions with a near-linear trajectory...
This paper presents a stochastic Newton method to compute the switching angles in multilevel converters so as to produce the required fundamental voltage while at the same time not generate higher order harmonics. For Newton method, a good initial guess which should be very close to exact solution patterns is necessary, so using stochastic techniques gives a new way to find possible initial values,...
Selected harmonic eliminated pulse width modulation technique applicable to the five-level voltage-source inverter is studied in details in this paper, which includes the foundation of selected harmonic elimination nonlinear equations and the chosen for initial switching angles. A method for producing initial angles of the nonlinear equations by using SPWM control is adopted, which may get a high...
In this paper, the elimination of harmonics in a cascade multilevel inverter by considering the nonequality of separated dc sources by using particle swarm optimization is presented. Solving a nonlinear transcendental equation set describing the harmonic-elimination problem with nonequal dc sources reaches the limitation of contemporary computer algebra software tools using the resultant method. The...
A novel formulation of quarter-symmetry SHE-PWM problems for five-level voltage inverters is proposed. The SHE modulation scheme features a broad solution space and can eliminate a large number of low-order harmonics. An effective method for obtaining initial values of switching angles is proposed. To illustrate the effectiveness of the proposed SHE method, a five-level voltage source inverter with...
Because of the difficulty of calculating switching angles, the values of the angles were achieved by using the CFT and Matlab . Cascaded multilevel inverter was adopted in the structure of the main circuit in order to implement the multiple-phase shifting and meet the need of using the high voltage and large power equipments. In this paper a method to selected harmonic elimination(SHE) choosing initial...
Multilevel inverters have been widely used in medium and high voltage applications. Selective harmonics elimination for the staircase voltage waveform generated by multilevel inverters has been studied extensively in the last decade. Most published methods on this topic aimed at solving high-order multi-variable polynomial equation groups derived from Fourier series expansion. A totally different...
This paper describes a grid-connected photovoltaic (PV) system with the function of active power filter (APF), in which a Z-source network is employed to boost the DC bus voltage during periods when the PV array output is low. After modeling the Z-source network and H-bridge converter, a state space model of Z-source inverter is derived. The model reflects the fact that the Z-source inverter has two...
Multilevel inverters supplied from equal and constant dc sources almost donpsilat exist in practical applications. The variation of the dc sources affects the values of the switching angles required for each specific harmonic profile, as well as increases the difficulty of the harmonic eliminationpsilas equations. This paper presents an extremely fast optimal solution of harmonic elimination of multilevel...
Harmonics and switching frequency cause a major problem in power system. A novel harmonic elimination technique and low switching frequency in a three-phase pulse width modulation (PWM) inverter are proposed in this paper. This inverter is associated with a LC filter. The technique determines the commutation angles based by solving a set of nonlinear system equations. This commutation angles are determined...
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