A seven level switched capacitor multilevel inverter with asymmetric input sources for microgrids

This paper presents a seven level inverter utilizing switched-capacitor technique. Proposed topology employs two asymmetric DC voltage sources as input and generates a multilevel staircase output. The structure includes a front-end switched-capacitor based DC-DC converter cascaded by a back-end H-bridge inverter. The frontend SC DC-DC converter feeds three DC voltage levels to the H-bridge inverter which produces the corresponding bipolar levels. Such inverters have the potential to be employed in AC microgrids where there are several asymmetric DC sources available. The inverter naturally solves the problem of capacitor voltage balancing as the capacitor is charged to a constant value twice every cycle. This topology also eliminates the need for series connection of individual voltage sources which require voltage balancing algorithms. Simulation and experiment results for the proposed inverter are presented.