Disadvantages Of Multilevel Inverter

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CHAPTER - 1 INTRODUTION 1.1 OVERVIEW 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 application [1-3].…show more content…
1.3 Multilevel Converter Classification Advantages of Multilevel Inverter:- A multilevel converter has several advantages over a conventional two-level converter that uses high switching frequency pulse width modulation (PWM). The attractive features of a multilevel converter can be explained as follows.  Staircase waveform quality: Multilevel converters not only can generate the output voltages with very low distortion, but also can reduce the dv/dt stresses; therefore electromagnetic compatibility (EMC) problems can be reduced.  Common-mode (CM) voltage: Multilevel converters produce smaller CM voltage; therefore, the stress in the bearings of a motor connected to a multilevel motor drive can be reduced. Furthermore, CM voltage can be eliminated by using advanced modulation strategies such as that proposed in [19].  Switching frequency: Multilevel converters can operate at both fundamental switching frequency and high switching frequency PWM. It should be focused that lower switching frequency generally means lower switching loss and generate higher efficiency. But every power switch requires a separate gate driver circuit. It results the whole system to be more costly and…show more content…
 Applications in Power Systems: More recent applications have been for power system converters for VAR compensation, stability enhancement and active filtering.  Train Traction, Ship Propulsion, and Automotive Applications: Traction drives are in the medium-voltage high-power range and require very high performance over a wide range of frequencies up to high speed. Usually, to achieve high speed, higher switching frequencies are necessary to be able to control the fundamental frequency. Multilevel converters can produce an apparent higher frequency switched output waveform, without actually increasing the device average switching frequency. Moreover, the additional levels intrinsically improve the voltage THD, thereby enabling further reduction in the switching frequency.  Energy Generation, Conversion, and Transmission: In generation point of view renewable energy like wind, solar etc multilevel converter are play curial role for control and conversion of the system. HVDC transmission system also utilised multilevel inverter

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