AC power source based on series-connection between modular multilevel converter and linear power amplifier

This paper proposes a hybrid topology for ac power source (ACPS) application composed of a modular multilevel converter (MMC), operating as main amplifier, and a linear power amplifier (LPA), operating as correction amplifier. The MMC and LPA are associated in series. This way, it is possible to gather the modularity, reliability and higher efficiency provided by the MMC and the high waveform fidelity provided by the LPA. Additionally, it is possible to reproduce a voltage waveform with a high bandwidth and, differently from previous works, with a topology that requires a unique dc source for the main amplifier. The control of the MMC is implemented by controlling the inner current and the submodule capacitor voltages; meanwhile, the control of the LPA is responsible for defining the output voltage. Experimental results are presented to demonstrate the suitable performance of the proposed topology in terms of dynamic response, output waveform fidelity and efficiency.