23-04-2015, 11:10 PM
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seven level inverter ppt
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24-03-2017, 02:23 PM
The new topology has the advantage of its reduced number of devices compared to the conventional H-cascade multi-level inverter, and can be extended to any number of levels. Modes of operation are described for 5-level inverters, as similar modes will be obtained for higher levels. Simulations of seven levels of the proposed inverter topology along with experimental corroborative results are presented. This article deals with the analysis and simulation of the inverter of seven levels. This article presents the seven-level inverter with harmonic reduction along with the reduction. Harmonic reduction is achieved by selecting appropriate switching angles. The verification of functionality of the inverter of seven levels is done with MATLAB.
The multi-level inverter was first introduced in 1975. The three-level inverters were the first multi level inverter introduced. A multilevel converter is an electronic power system that synthesizes a desired output voltage from various levels of direct current voltages as inputs. With an increasing number of DC voltage sources, the output voltage waveform of the converter approaches an almost sinusoidal waveform while a fundamental frequency switching scheme is used. The main advantage of the multi-level inverter is its small output voltage, which results in a higher output quality, a lower harmonic component, better electromagnetic compatibility and lower switching losses. While many topologies of different multilevel inverters have been proposed, the two most common topologies are the cascaded Hbridge inverter and its derivatives, and the inverter with diodes. The main advantage of both topologies is that the classification of the switching devices is greatly reduced to the classification of each cell. However, they have the drawback of the large number of switching devices required which is equal to 2 (k-1) where k is the number of levels. This number is quite high and can increase the complexity of the circuit, and reduce its reliability and efficiency. The cascade bridge inverter H has a modular design and the problem of unbalance of the DC link voltage does not occur, so it is easily extended to several levels. Due to these advantages, the cascaded H-bridge inverter has been widely applied to applications such as HVDC, SVC, stabilizers and high power motor drives. The blocked diode inverter needs only a cc bus and voltage levels are produced by several series capacitors that divide the dc bus voltage into a set of capacitor voltages. The balance of the capacitors is very complicated especially on a large number of levels.
In addition, the three-phase version of this topology is difficult to implement because of the problems of neutral point balancing. The output waveforms of multilevel inverters are in a staggered form; Therefore, they have reduced harmonics compared to a square wave inverter. To further reduce harmonics, carrier-based PWM methods are suggested in the literature. This article presents how a reduced harmonic distortion is achieved for a new topology of multilevel inverters using the programmed PWM technique. This new topology has the advantage of its reduced number of switching devices compared to conventional cascaded H-bridge and diode-locked converters for the same number of levels. It can also be extended to any number of levels. The operating modes of a 5-level inverter are shown, where similar modes can be performed for higher levels. The operation of the inverter is controlled by switching angles based on PWM with the aid of the pulse generator. These angles are obtained from the resolution of the equations of the waveform using the theory of the resultant. Simulation of higher levels of the proposed inverter topology is performed with MATLAB The validity of the proposed topology and the harmonic elimination method are verified experimentally for 7 level inverters.
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