I want to know in which method the switches & DC sources are reduced & what are absolute firing angle for each switches . i have attached my base paper pls suggest any idea reg tis[/size][/font]
The presence of harmonics and the increasing number of switches and DC sources for a higher level is the main problem in the use of the cascade multilevel inverter for the application of medium and high voltage power systems. In this proposed work several new techniques were introduced to reduce the number of DC switches and sources, which overcome the disadvantages of the cascaded multilevel inverter. The THD values for several levels (seven and nine) are compared simulating the proposed module in the MATLAB environment, with and without using soft switching techniques such as PWM, SPWM and the reduction of THDs and the compactness of the proposed module.
A modified multilevel hybrid inverter is introduced employing a bypass diode technique with bridge inverter topology H. Its goal is to reduce the number of controlled switches. The proposed inverter consists of an H-bridge and 3 unit cells. Each unit cell requires a serially connected voltage source and a switch with a parallel diode. In a conventional multi-level converter, the presence of a high number of switches increases harmonics, switching losses, cost and total harmonic distortion. This proposed topology reaches the fifteen level with only seven numbers of switches. It drastically reduces the complexity of the control circuit, cost and low order harmonics and thus effectively reduces total harmonic distortion.