Topology and Voltage Balance of Series-Connected T-type Inverter for Medium-Voltage Drive Applications

The three-level T-type multilevel inverter has proven itself as a promising, highly-efficient, and low-switch-count topology. This paper presents a new topology configuration using series connected T-type multilevel inverters for medium-voltage applications. The proposed topology utilizes the series connection of low power T-type modules to enable medium-voltage operation. The proposed topology is modular, highly efficient, less complex, and with lower component count, compared to other topologies with the same number of levels and voltage operating range. In addition, a simple level-shifted pulse width modulation (LS-PWM) method is proposed for achieving voltage balance between the dc-link capacitors. The results show the effectiveness of the proposed topology and the proposed LS-PWM method for medium-voltage applications. Moreover, the proposed topology has been compared with the existing medium-voltage converter topologies in the literature.