An Improved Phasor Method for Modelling and Analysis of Modular Multilevel Matrix Converter
Shenquan Liu, Boyang Zhao, Gang Wang, Xifan Wang
Abstract
modular multilevel matrix converter (M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C) has considerable application potential in motor driving and power systems, but its phasor model is rarely studied. This paper proposes a novel method for modelling and analysis of the M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C in the phasor domain. Firstly, an improved phasor method in matrix form is proposed for direct AC/AC MMC family. By including the frequency information into the phasor expression, it is capable of analysis towards interaction between AC variable groups with different frequencies. Secondly, based on the proposed phasor matrix method, the concept of two-dimensional phase-sequence is proposed to facilitate description and calculation of the AC variables in the 3-by-3 matrix-resembled circuit structure of M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C. Network of each phase-sequence is also derived. With the proposed methods, calculation burden for modelling and analysis of the M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C is significantly reduced. Then, the phasor model of M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> C considering the DC, fundamental frequency and 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> -order harmonic components is established. Finally, validation results with time-domain simulation is provided.