Disadvantages And Disadvantages Of Multilevel Inverters Used In Conventional Inverter

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Abstract— Multilevel inverter used in variable speed drive system is attracting more attention, due to various advantages that they offer when compared to standard 3-phase two level drives. For proper functioning of such systems pulse width modulation (PWM) strategy is of crucial importance. Control complexity of multilevel inverters increases rapidly with an increase in number of phases and the number of levels. The inherent low switching frequency in medium voltage industrial drive presents various challenges. Multilevel inverter topologies are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference…show more content…
So that the voltage and current is of poor qualities and the switching frequency causes more amount of switching losses. Those drawbacks are rectified using three phase neutral point clamped multilevel inverter. The voltage and current quality are better and the switching losses are reduced when compared to the conventional technique. Also the THD is found to be better.

Advantages of Multilevel Inverter over Conventional Inverters: Two level inverters can create two different output voltages for the load, whereas in multilevel inverters several voltage levels are added to create a smoother stepped waveform. Generate output voltages with lower harmonic distortions and lower dv/dt. Generate lower common mode voltage. Operate with lower switching frequency. With lower switching frequency switching losses can be
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The complete system will consist of two sections; a power circuit and a control circuit. The power section consists of a power rectifier, filter capacitor, and three phase diode clamped multilevel inverter. The motor is connected to the multilevel inverter. An ac input voltage is fed to a three phase diode bridge rectifier, in order to produce dc output voltage across a capacitor filter. A capacitor filter, removes the ripple contents present in the dc output voltage. The pure dc voltage is applied to the three phase multilevel inverter through capacitor filter. The multilevel inverter has 24 MOSFET switches that are controlled in order to generate an ac output voltage from the dc input voltage. The controlled ac output voltage is fed to the induction motor drive. The motor windings are highly inductive in nature; they hold electric energy in the form of current. This current needs to be dissipated while switches are off. Diodes are connected across the switches give a path for the current to dissipate when the switches are off. These diodes are also called freewheeling
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