Switched Capacitor Integrated (2n + 1)-Level Step-Up Single-Phase Inverter

摘要

This article presents a novel switched capacitor (SC) based (2n + 1)-level single-phase inverter with a reduced number of components and input dc voltage supply. This inverter is designed in a way that just one dc source is required to generate different voltage levels. The circuit consists of three major parts, i.e., front-end boost stage, active SC cell(s) in the middle, and H-bridge inverter at the end. The total number of output voltage levels is up to (2n + 1) levels, where n >= 2 is the number of switching cells, which consists of three active switches and two capacitors. Compared with conventional SC-based multilevel inverter topologies, the proposed topology features many advantages, such as low number of semiconductor devices, quasi-resonant charging of capacitors that reduce the inrush current and current stress on the devices, self-balancing of capacitor, and reduced voltage stress on the switches. Moreover, a simple sinusoidal pulsewidth modulation technique is employed here to generate the modulation signals for the proposed inverter. The operating principle is presented in detail followed by comparative analysis, thermal modeling, and design guidelines. Finally, computer simulation and laboratory test results are carried out for a five-level inverter with one SC cells as well as a seven-level inverter with two SC cells as two examples to verify the performance of the proposed (2n + 1)-level inverter. Measurement results show that the proposed inverter has the 96.5 +/- 1% efficiency over a wide range of load with a peak efficiency of 98.56%.