Study on Modulation Strategy with Neutral-Point Balancing Control for Three-Level Two Stage Matrix Converter

Abstract

Aim to the three-level neutral-point potential balancing problem of three-level two stage matrix converter(TLTSMC),which is a new topology from matrix converter family that can synthesis three-level voltage in order to improve output performance in terms of reduced harmonic contents, this paper discussed the operating principles and a space vector modulation strategy with neutral-point potential balancing control for this topology. The method is divided into two control stages. Space vector PWM without zero vectors is used for rectifier stage. The modulation method of inverter stage based on the virtual space vector concept only requires the condition that the flow of neutral-point current equals zero, so the neutral-point balancing problem of this topology is effectively settled. The commutation principle of TLTSMC is analyzed. Finally, the validity and feasibility of this modulation method is tested by simulation and experiment, the result indicates that TLTSMC with the modulation strategy produces better output performance in terms of reduced harmonic contents and is also able to maintain sinusoidal input currents, furthermore, guarantees the balancing of neutral-point potential over the full range of output voltage.