Design of a High Frequency 3-Phase 3-Level Hybrid Active-NPC Inverter

This paper presents design and implementation of a three-level hybrid active neutral point clamped (3L-ANPC) inverter using Gallium-Nitride (GaN) switches. This paper shows a modest usage of wide band gap (WBG) devices for achieving a high frequency converter. The ANPC benefits from hybrid modulation in which only two switches out of 6 active switches are modulating with high frequency (HF, carrier frequency) and the rest are switching with the reference frequency or low frequency (LF). Therefore, WBG switches can be utilized for these two HF switches. In this paper, gallium-nitride (GaN) FETs have been used for the HF switches. Two different switch technologies plus two different modulation schemes have introduced a hybrid 3L-ANPC. The semiconductor losses are calculated and modified with respect to the switch technologies. A three-phase 10 kW hybrid 3L-ANPC is designed using two 650 V GaN-FETs and four 650 V Si-MOSFETs for each phase. The switching frequency of the GaN-FETs is optimized to be at 100kHz. Different modulation schemes are implemented in the FPGA of a dSPACE device and the converter is tested at various conditions.