Extended T-Type Topology of Single-Phase Multi-Level Inverter

In recent years, the multilevel DC/AC static converters are increasingly used for their benefits especially in terms of reduction of total harmonic distortion (THD) of the output current and reduced voltage stress on semiconductors at switching moments. In this article, an Extended T-Type structure of multilevel inverter is proposed for photovoltaic systems. This structure has the advantage of being simple; on the one hand, it contains only switches (no switching capacitors and clamping diodes, etc.) and the number of these switches corresponds exactly to the required number of voltage levels, and on the other hand, the control scheme is much simpler to implement and suitable for variable RMS value operations. The modulation used is based on the technique of sinusoidal fundamental frequency pulse width modulation (PWM) with a single carrier. The performances (THD, voltage stress on the semiconductors) of the inverter are analyzed by simulations in the Matlab-Simulink environment on an example of a nine-level inverter.