Common-Mode Voltage Reduction and Neutral Point Voltage Balance Modulation Technology of Quasi-Z-Source T-Type Three-Level Inverter

Abstract

The quasi-Z-source T-type inverter is a new type of three-level inverter. Compared with other three-level inverters, the quasi-z-source T-type inverter is characterized by its fault tolerance capability and boost capability. In the inverter, the modulation strategy greatly affects the performance. Aiming at the problems in three-level inverters such as excessive common-mode voltage and unbalanced neutral point potential, a space vector pulse width modulation (SVPWM) for a quasi-z-source T-type three-level inverter based via line voltage coordinate is proposed in this paper. The main research work and achievements of this paper include: (1) based on the existing research results, an SVPWM modulation strategy for the quasi-Z-source T-type inverter is proposed. The modulation method proposed by this paper can effectively reduce the common-mode voltage and balance the neutral point voltage. (2) This paper analyzes the principle of the line voltage coordinate system and makes some modifications to the line voltage coordinate system so that the proposed modulation scheme can be applied to the line voltage coordinate system. Compared with the traditional αβ coordinate system, the SVPWM algorithm in the line voltage coordinate system has the characteristic of simple calculation. The simulation and experiment results show that the control method has good performance under the conditions of dynamic response and imbalance.