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A Nine-Level T-Type Converter for Grid-Connected Distributed Generation

Research Authors
Ibrahim Harbi, Mostafa Ahmed, Jose Rodriguez, Ralph Kennel, Mohamed Abdelrahem
Research Department
Research Date
Research Year
2022
Research Journal
IEEE Journal of Emerging and Selected Topics in Power Electronics
Research Publisher
IEEE
Research Vol
10
Research Rank
Q1
Research_Pages
5904-5920
Research Website
https://ieeexplore.ieee.org/document/9763544
Research Abstract

This article presents a new high-efficiency nine-level T-type converter (9L-T2C) for grid-connected applications based on the three-level T-type converter (3L-T2C). The proposed 9L-T2C outperforms other common dc-link nine-level converters in terms of the required number of active switches and capacitors, flying capacitors (FCs) voltage ratings, and efficiency. Only ten power switches, eight gate drivers, and two FCs are required for each phase. Exploiting the available pole-redundant states, an FCs balancing algorithm is developed to stabilize the two FCs with one voltage sensor in steady-state and dynamic operation. Moreover, an effective balancing method is proposed for dc-link capacitors without the need for further redundant states and integrated into FCs balancing. The FCs and dc-link balance are integrated into the phase-disposition pulsewidth modulation (PD-PWM) method, eliminating the need for an additional controller. Considering the designed PD-PWM method, a mathematical analysis is performed to establish the relationship between the FCs size and the desired ripple. A comprehensive comparison with other converters is provided to demonstrate the merits and application areas of 9L-T2C. The operation of the proposed 9L-T2C with the capacitors’ balancing scheme is validated for stand-alone and grid-connected operation via simulation investigations and experimental setup.

Research Rank
International Journal