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Comparative Analysis Of Multilevel Inverter

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Abstract—This paper presents comparative study of 3,5and 7 level of multilevel inverter. This comparison is done on the basis of power loss, cost weight and total harmonic distortion. For each inverter IGBT’S and MOSFET’S are used as switching devices to make the comparison more accurate. Multilevel Inverters are used for power electronics application such as facts, ups etc. The function of an inverter is to change a dc input voltage to a symmetrical ac output voltage of desired magnitude and frequency and the output can be fixed and variable at a fixed and variable frequency. A variable output voltage can be obtained by varying the gain of inverter which is normally found by Pulse width modulation control. In this paper we proposed the phase…show more content…
A diode-clamped inverter having 2(n-1) switching devices and (n-1)(n-2) clamping diodes [1]. In spite of the fact that each switching device is only required to block a voltage level. The clamping diode need to have different reverse voltage blocking rating. If the blocking voltage rating of each diode is same as that of switching device, the number of diode required for each phase is (n-1) (n-2). So the feature of the diode- clamped multilevel inverter is high voltage rating for blocking diodes. When number of level is high enough, the harmonic content is low to avoid the need of filters and inverter efficiency is high. Numerous industrial applications have begun to require higher power apparatus in recent years. Some medium voltage motor drives and utility applications require medium voltage and megawatt power level. For a medium voltage grid, it is troublesome to connect only one power semiconductor switch directly. As a result, a multilevel power converter structure has been introduced as an alternative in high power and medium voltage situations. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic, wind, and fuel cells can be easily interfaced to a multilevel converter system for a high power…show more content…
For the 3-level multilevel inverter with low distortion, we use phase Disposition PWM technique. For simulating diagram of 3-level multilevel inverter, we use two capacitors on the dc bus. The RLC branch is in series. In the RLC branch we eliminate either the resistance, inductance or capacitance of the branch, the R, L,C values are automatically set respectively to 0,0 and infinity. In the RLC branch, R is 1 ohm, L is 1-3 H and C is 1-6 F. The one dc voltage source block implements the ideal dc voltage source. There are 4 diodes we use in the simulation diagram of 3- level inverter. A diode is the semiconductor device that is controlled by its own voltage and current. When the diode is forward biased, diode voltage is greater than zero and it start to conduct with a small forward voltage across it.it turns off when the current flow into the device becomes zero. When the diode is reverse biased the diode voltage is less than zero and it stays in the off state. In the simulation of 3-level multilevel inverter, we use eight MOSFETs as a switching device for better output and low distortion. The metal oxide semiconductor field effect transistor is a semiconductor device controllable by the gate signal (g>0), the MOSFET is connected in parallel with an internal diode that turns on when the MOSFET device is reverse
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