A Novel Multilevel DC/AC Inverter Based on Three-Level Half Bridge With Voltage Vector Selecting Algorithm

Abstract

A novel multilevel inverter based on a three-level half bridge is proposed for the DC/AC applications. For each power cell, only one DC power source is needed and five-level output AC voltage is realized. The inverter consists of two parts, the three-level half bridge, and the voltage vector selector, and each part consists of the four MOSFETs. Both positive and negative voltage levels are generated at the output, thus, no extra H bridges are needed. The switches of the three-level half bridge are connected in series, and the output voltages are (<inline-formula> <tex-math notation= LaTeX >$V_{o}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation= LaTeX >$V_{o}$ </tex-math></inline-formula>/2, and 0). The voltage vector selector is used to output minus voltages (<inline-formula> <tex-math notation= LaTeX >$-V_{o}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation= LaTeX >$-V_{o}$ </tex-math></inline-formula>/2) by different conducting states. With complementary working models, the voltages of the two input capacitors are balanced. Besides, the power cell is able to be cascaded for more voltage levels and for higher power purpose. The control algorithm and two output strategies adopted in the proposed inverter are introduced, and the effectiveness is verified by simulation and experimental results.