Innovative design of multilevel dc ac converters with symmetrical and asymmetrical structure for medium voltage applications

Abstract

The power converters are the promising sort of device for maintaining power quality in highly sensitive loads such as commercial and industrial equipment, home appliances and measuring instruments. The design of novel power electronic converters is essential to improve the feasibility of power generation via existing energy resources. Nonlinearity of power converters causes harmonics; especially, in the two-level converters which produce higher harmonic content in the output waveform due to higher dv/dt stress, high thermal stress, high mechanical stress and ultrasonic vibration created in nonlinear inductive elements. Moreover, it requires additional cooling arrangements as it is operating at high switching frequency. In order to suppress the harmonics and enhance the power quality in the output waveform, the highly designed LC filters are employed. Therefore, the efficiency and reliability of the system get degraded. The multilevel DC-AC converters are involving under research and development for nearly more than three decades and it stands to flourish for medium-voltage industrial applications. There are so many novel contributions and new multilevel DC-AC converters have been proposed by the researchers in the recent years. The multilevel DC-AC converters are attracting the researchers due to their increased power ratings, enhanced harmonic profile and minimized electromagnetic interference (EMI) which can be achieved by the DC step output voltage waveform. Furthermore, the multilevel DC-AC converters have high demand in the field of grid connected photo-voltaic (PV) systems, electric vehicles, and medium-voltage automotive industrial drives. newline newline newline