Multi Level Inverter

Multi Level Inverters are used to produce fine pwm wave forms with muliple voltage steps. It uses one or more power sources and multiple power switches. Main adventage of multilevel inverter is low switching component at output which will reduce the output filter components.
Multilevel inverters have very low switching loss but conduction losses are high. Another adventage is reduced voltage requirment of switching devices. The circuit given below is a three level inverter.The power supply is + - 400V connected as dual polarity bus ie 800V. Four 600V IGBT switches are connected in series and center point is taken as output. The levels are defined by shifting triangle wave above and belo GND (0V). 6V amplitude 50 hz sinewave is the input signal which is reproduced as 385V at output.Out put pwm have three levels 0V +400V and
-400V

Circuit of Multi Level Inverter

Input Sine Wave and level shifted Triangle Wave

PWM gate waveforms

PWM Out Put and Final Out Put

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