New symmetrical hybrid multilevel DC-AC converters

This paper presents the analysis of new symmetrical hybrid multilevel inverters for high-voltage and high power applications. A three-level cell (denominated in the text by TC) and its respective commutation pattern are proposed. The purpose of the circuits presented here is to minimize the reverse voltage stress that affects the power switches and decrease the harmonic distortion of the voltage applied to the load. As a characteristic of the proposed cells, some of the switches operate at low frequency while others are switched at high frequency. To validate the operating principle a single-phase low power prototype has been built, operating at 1.6 kHz for the fast switches and 50 Hz for the slow switches.