*Article* **Three-Phase Five-Level Cascade Quasi-Switched Boost Inverter**

#### **Van-Thuan Tran 1, Minh-Khai Nguyen 2,\*, Cao-Cuong Ngo 3 and Youn-Ok Choi 4,\***



Received: 30 January 2019; Accepted: 1 March 2019; Published: 6 March 2019

**Abstract:** This paper presents a three-phase cascaded five-level H-bridge quasi-switched boost inverter (CHB-qSBI). The merits of the CHB-qSBI are as follows: single-stage conversion, shoot-through immunity, buck-boost voltage, and reduced passive components. Furthermore, a PWM control method is applied to the CHB-qSBI topology to improve the modulation index. The voltage stress across power semiconductor devices and the capacitor are significantly lower using improved pulse-width modulation (PWM) control. Additionally, by controlling individual shoot-through duty cycle, the DC-link voltage of each module can achieve the same values. As a result, the imbalance problem of the DC-link voltage can be solved. A detailed analysis and operating principle with the modulation scheme and comprehensive comparison for the CHB-qSBI are illustrated. The experimental and simulation results are presented to validate the operating principle of the three-phase CHB-qSBI.

**Keywords:** cascaded H-bridge inverter; three-phase inverter; Z-source network; quasi-switched-boost network; shoot-through
