A modified five-level hybrid converter with large output voltage range and high efficiency

Abstract

This paper presents a modified five-level hybrid converter which based on a T-type converter (T2C) with H-bridge (HB) cell. The considered converter, which is referred to as T2C-HB, utilizes merits of T2C converter and cascade H-bridge converter while avoids their disadvantages. It has high efficiency advantage over NPC in low voltage applications and doesn't need extra isolated power to supply HB part. A larger range of output voltage can be achieved based on sinusoidal pulse width modulation (SPWM). The conduction paths and H-bridge dc-link capacitors balance conditions are well analyzed in this paper. A proposed switching sequence is designed based on three principles of balancing capacitors voltage, no unwanted voltage jump appearing in the dead-time period and minimum switching losses. The validity of the modified converter, modulation strategy and switching sequence is verified by simulation and experiment results.