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Nowadays, the three-level T-type inverters (3LT2Is) are widely employed in applications with high-performance requirements. The 3LT2Is commonly suffer from neutral point voltage (NPV) unbalance and common-mode voltage (CMV) variation. The medium vector pulse width modulation (MVPWM), which generates the reference voltage using medium and V0[OOO] zero voltage vectors, eliminates the CMV variation in 3LT2Is. However, it cannot keep the NPV balance, negatively affecting power quality. This article proposes a hybrid method to simultaneously eliminate CMV variation and guarantee the NPV balance without topological change or extra hardware. The proposed method uses MVPWM when NPV is balanced, eliminating CMV variation. If NPV goes unbalanced, it utilizes novel high/low triangle PWM (H/LPWM) and MVPWM in a hybrid manner to balance the NPV. The H/LPWM, similar to MVPWM, synthesizes voltage using medium and V0[OOO] voltage vectors to maintain the CMV elimination advantage during the NPV balancing process. However, the difference between H/LPWMs and MVPWM switching patterns adjusts the average neutral point current to balance the NPV. Noteworthy that the proposed method provides NPV balancing ability for the entire power factor range. As a result, it is usable for various applications of 3LT2I, such as photovoltaic inverters and motor drives. The proposed method is carrier-based, which reduces the execution time and simplifies the practical implementation. The simulation study and experimental evaluation have been accomplished, and their results demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Nowadays, neutral point voltage (NPV) balancing control and leakage current (LC) reduction methods are considered to improve the reliability of transformerless three-level T-type (3LT2) inverter. Medium vector pulse width modulation (MVPWM) method can control the inverter operation to eliminate the LC; however, is powerless to balance the NPV. Alternatively, discontinuous PWM (DPWM) methods can be implemented to balance the NPV. In this article, a hybrid method for transformerless 3LT2 inverter is proposed to simultaneously minimize the LC and accomplish balancing control in case of NPV unbalancing. The proposed method applies MVPWM switching patterns to eliminate LC while the NPV is balanced. If the NPV becomes unbalanced, it applies specific switching patterns of the DPWM methods as alternative patterns to balance the NPV with minimal LC. Accordingly, the proposed method not only maintains the LC elimination advantage of the MVPWM method but also realizes the NPV balancing capability without any topology modification or adding electrical components. Noteworthy, even the NPV balancing is accomplished with minimal flow of the LC. The proposed method is carrier-based PWM, which shortens execution time and simplifies practical implementation. Experimental tests have been accomplished and results demonstrate the effectiveness of the proposed method on adding the NPV balancing capability with minimal LC to the MVPWM method. [ABSTRACT FROM AUTHOR]