A Switched-Capacitor Based Multilevel Inverter with Extendable Levels having Enhanced Voltage Gain for Renewable Energy Applications

Abstract

Various Switched-Capacitor based Multilevel Inverters (SCMLI) are suggested in literature. These converters can, however, provide fixed levels of ac output voltage. A higher number of renewable energy units must be linked in line for the converter to be able to create an extendable ac output voltage. This is because the converter needs switches with high voltage stress and low voltage gains. To fill this gap, an SC-MLI is proposed in this paper to produce 5, 7, 9 and 11-levels in ac output voltage waveform with a voltage gain of 1, 1.5, 2 and 2.5, respectively. Instead of altering the converter design, these levels of ac output voltage can only be obtained by changing the switching scheme. The proposed converter includes 12 switches, 2 dc-link capacitors and 2 switched-capacitors units along with one dc voltage source. The proposed configuration also has the advantage of having fewer devices with the capacitor voltage self-balancing and higher efficiency due to greater power loss sharing amongst the switches. Furthermore, auxiliary diodes are not needed for the proposed converter. This feature makes the proposed converter to be used in high efficiency applications. The proposed topology can further be extended for a higher number of levels and higher voltage gain by including cascaded connections of the proposed converter. A one-kW power-rated prototype that was developed in the lab is used to validate the proposed converter's performance.