A New Three-Phase Hybrid Multilevel Topology with Hybrid Modulation and Control Strategy for Front-End Converter Applications

Abstract

This article presents a novel hybrid three-phase multilevel topology with a hybrid modulation and a control strategy for lower-medium voltage front-end converters. The proposed topology consists of a series arrangement of a three-phase full bridge and a packed U-cell. Each phase leg of the circuit comprises eight active switches and two DC link sources, which are connected to a shared DC bus voltage source, thus generating seven levels of output voltage. The active switches of the proposed topology are categorized based on voltage stresses and controlled using a low-frequency space vector PWM and high-frequency alternative phase opposition disposition PWM techniques. To validate the proposed topology and demonstrate the performance and effectiveness of the hybrid modulation and control schemes, simulations in MATLAB/Simulink and experiments on a custom-designed laboratory prototype have been carried out, and the results are discussed in detail. Moreover, a comprehensive comparison has been conducted among the relevant topologies, which reveals several advantages that include a reduced voltage and a current total harmonic distortion (THD) of 11.28% and 1.76%, respectively, minimized switch loss by 10.3 kW, improved efficiency by 0.26%, and decreased the component count with two levels increased in the output voltage.

Keywords

• hybrid medium voltage multilevel converter
• hybrid modulation and control
• space vector pulse width modulation (SV-PWM)
• alternative phase opposition disposition pulse width modulation (APOD-PWM)