Isolation Based Reduced Switch Nine-Level High-Gain Multilevel Inverter

In this article, a reduced switch transformer based nine-level multilevel inverter (MLI) has been developed to overcome the use of a number of multiple dc sources and to reduce the number of low-frequency transformers with high-gain and galvanic isolation feature. The envisaged topology uses six number of switches, six number of gate driver circuits, a single dc source and a single multiwinding transformer (MWT). To generate the nine-levels, the proposed topology is controlled by phase deposition pulse width modulation (PDPWM) with a carrier frequency of 3 kHz. The design and efficiency analysis of the MWT have also been discussed and compared in detail with several other invented topologies in terms of the number of device counts, gate drive circuit, transformer required, voltage boosting features and power handling capacity. An extensive loss and thermal management analysis of the envisaged MLI is also presented. A brief simulation of the topology is done in the MATLAB/Simulink environment and the test is also performed in the laboratory for a maximum load of 0.92 kW.