Verification of a Low Component Nine-Level Cascaded-Transformer Multilevel Inverter in Grid-Tied Mode

The main problem related to cascaded H-bridge (CHB) cell multilevel inverters is their using of a large number of components, such as switches and dc-sources. Therefore, minimization of components in these kinds of devices is of great importance. Cascaded-transformer multilevel inverters (CTMIs) have completely eliminated the need for several dc-sources in CHBs. Thus, minimization of the other components in CTMIs can lead to obtain an optimized structure for multilevel inverters. This paper introduces a simple and compact structure for transformer-based multilevel inverters. Since the number of utilized components in the proposed structure is remarkably reduced, the cost, volume, and complexity are minimized. The performance of the suggested inverter has been scrutinized through two different strategies. First, it is tested under condition of supplying a local load, and second, employing sample-based current control strategy; its performance is inspected when being connected to the grid. In the latter test, the leakage inductances of the transformers are utilized to execute the sample-based current control strategy, thus, the need for extra filter is eradicated. The feasibility of the suggested topology has been validated by using the laboratory-built prototype along with a computer-aided simulated model.