Single DC Source Fed Cascaded Multilevel Inverter along with AC L-C-L Resonant Converter for High Current and Low Voltage Applications

Abstract

In the beginning, the power supplies employed in very low voltage and high current application such as arc welding, electroplating process. But in this power supplies use in line frequency step-down transformers and rectifier based control circuits, which has the demerits of large size, inefficient, high output ripple and more operational costs. So there is need to improve the power supplies for high current and low voltage applications. Recently, an efficient and switched-mode power supply (SMPS) suited for low voltage and very high current applications. In this uses a multi-level inverter (MLI) to convert line frequency input waveforms to high frequency for reduce the loss and cost. In the present work, we investigate different types of MLI, they are diode clamped MLI, flying capacitor MLI and cascaded H-bridge MLI, and finally proposed a new topology is single DC source fed CML by using single-phase transformers. The output of MLI feeds an AC L-C-L resonant converter and it behave as constant current source and it can reduce the peak-to-peak output ripple, total harmonic distortion (THD). The output stage of AC L-C-L resonant converters consisting of a number of easily constructed planar transformers with center tapped secondary side and rectifier circuit. The planar transformer gives significant advantage leakage inductance, skin effect and winding capacitance can be minimized and also provide isolation at the output side. The proposed structure is modeled and the simulated results are presented to verify its performance.