New Cascaded-Transformers Multilevel Inverter for Renewable Distribution Systems

this paper presents a novel reduced switches-number cascaded-transformer multilevel inverter (CTMLI). The proposed MLI circuit consists of four high-frequency (HF) and eight line-frequency power switches forming three H-bridge inverters. One H-bridge forms the PWM inverter whereas other bridges form the Level inverters, which generate the multilevel output voltage in staircase waveform. Also, three cascaded transformers are utilized, which operates at high, medium and line frequency, respectively. The operating principles of proposed inverter will be deeply illustrated for optimized transformers turn ratios (1 :2 :6). The proposed CTMLI operation is verified using computer-aided simulation results for 19-level output voltage synthesis. DSPACE DS1103 digital controller is used to control the experimental prototype for stand-alone load voltage regulation.