basic two level inverter

The concept of multilevel Inverter (MLI) is kind of modification of two-level inverter.

A two-level Inverter creates two different voltages for the load i.e. suppose we are providing Vdc as an input to a two level inverter then it will provide + Vdc/2 and – Vdc/2 on output. In order to build an AC voltage, these two newly generated voltages are usually switched. For switching mostly PWM is used reference wave is shown in dashed blue line. Although this method of creating AC is effective but it has few drawbacks as it creates harmonic distortions in the output voltage and also has a high dv/dt as compared to that of a multilevel inverter. Normally this method works but in few applications it creates problems particularly those where low distortion in the output voltage is required.