A Novel Virtual Space Vector Modulation With Optimized Neutral-Point Voltage Control Capability for Ten-Switch Three-Phase Three-Level Inverter
Xiaojun Deng, Xiaonan Zhu, Hongliang Wang, Di Kang, Yang Jiang, Xiumei Yue, Shixiong Zuo, Tianfu Sun
Abstract
Ten-switch three-phase three-level inverter (TP-TLI) is receiving more attention owing to the reduced system cost compared to traditional TP-TLIs. However, it still faces serious neutral-point voltage (NPV) balance problems. This article proposes a novel virtual space vector modulation (NVSVM) with optimized neutral-point voltage control (NPVC) capability. A set of virtual vectors are selected to generate zero NP current. By analyzing the vector synthesis principle over the full modulation areas, a new control degree, which is utilized to optimize the NPVC capability and reduce line voltage total harmonic distortion (THD), is introduced. Besides, a dead time compensation method based on volt–second balance is also given to reduce the switching loss. The NVSVM not only improves the NPVC capability without dc offset and obvious ac oscillations in NPV under the full range of modulation index and power factor conditions but also reduces line voltage THD and the switching loss. Theoretical analysis shows that the available NP current for the proposed NVSVM is about 2.75 times greater at most than that for traditional VSVM. Simulation and experimental results are given to validate the effectiveness of the NVSVM and control strategies.