Proposal of a series configuration hybrid ac power source

With the aim of synthesizing high quality voltage waveforms without penalizing the system efficiency, this paper proposes to implement a hybrid ac power source (ACPS) associating in series a cascaded multilevel inverter topology, operating as main amplifier, with a low-voltage/low-power linear power amplifier (LPA), operating as correction amplifier. Considerations about the modulation strategy, control approach and design methodology are presented and investigated through the paper. The theoretical analysis is confirmed by means of experimental results from a 500 W IGBT based laboratory prototype composed of an asymmetrical cascaded multilevel inverter associated with a commercial low-power LPA. The ACPS performance was evaluated under linear and nonlinear loads, along with under a load step.