THD analysis of cascaded H-bridge multilevel inverters in fuel cell applications

Multilevel inverters have been drawing growing attention in the recent years especially in the distributed energy resources area due to the fact that several batteries, fuel cells, solar cell, wind and micro turbines can be connected through multilevel inverter to feed a load or the ac grid. Multilevel inverter becomes an alternative in the area of high power medium-voltage energy control. Recently multilevel power conversion technology has been a very rapidly growing area of power electronics with good potential for further developments. For a multilevel inverter, switching angles at fundamental frequency are obtained by solving the selective harmonic elimination equations in such a way that the fundamental voltage is obtained as desired and certain lower order harmonics are eliminated. In this Paper we analyze the performance of various kinds of single phase inverters i.e. two level and multilevel inverters with and without Multiple Pulse Width Modulation Techniques (MPWM) for fuel cell applications and suggest best topology depending on harmonics available in the output.