Harmonic Optimization of Cascade Multilevel Inverter with Unequal DC Sources

Multilevel inverter have been attracting increasing interest recently due to the increased power rating, improving harmonic performance, and reduced electromagnetic inference (EMI) emission. A voltage source inverter is commonly used to supply a variable frequency variable voltage to a three phase induction motor in a variable speed application. The output voltage contains harmonics the different type of harmonics elimination methods are available. But all the methods have some limitations. This project deals with how to reduce the particular harmonics in the output voltage of inverter. The concept of the harmonic stepped waveform technique for the multilevel inverter is to be presented. By applying this concept, selected harmonic can be eliminated, and the output voltage THD can be improved. A procedure to achieve the appropriate switching angle is to be proposed. The proposed project is to be simulated by using MATLAB and the results are to be compared with experimental setup. The AT mega Microcontroller is to be used for generating required pulses to the cascaded multilevel inverter.