Bidirectional Isolated Asymmetrical Multilevel Inverter

This brief presents a bidirectional asymmetrical multilevel inverter (MLI) that requires a single dc voltage source and low component count. Considering the weights assigned to the turns ratio involving the primary and multiple secondary windings of the transformer, as well as a proper switching logic, one can obtain an ac output voltage with up to 15 levels. The topology consists of a transformer, an H bridge on the primary side, and asymmetrical cells associated with bidirectional switches on the secondary side. Staircase modulation is employed to reduce the harmonic content of the output voltage, whereas a comprehensive analysis is derived. An experimental prototype rated at 1 kW is designed and implemented in the laboratory to validate the theoretical claims.