Research on the Topology and Control Scheme of an Innovative Modular Multilevel Converter

Daixiang Zhu, Ming Ding

Department of Electrical Engineering, Hefei University of Technology, Hefei 230009, China.

DOI: 10.4236/epe.2013.54B286                

Abstract

This paper presents a new modular multilevel converter (MMC) topology. Compared to conventional multilevel converters, MMC has much lower switching frequency (50 Hz) resulting in lower switching losses, and consequently, lower total losses of the transmission system. The fundamental concept and the applied control scheme are introduced in detail. A modified multilevel fundamental switching modulation scheme adopting the multicarrier pulse width modulation concept is presented. A capacitor voltage balancing technique is proposed. With the established simulation model of the 11-level MMC, the modulation and balancing strategy presented are confirmed by MATLAB/SIMULINK simulations. The multicarrier pulse width modulation converter strategy enhances the fundamental output voltage and reduces total harmonic distortion. This new type of converter is suitable for high-voltage drive systems and power system applications such as high voltage dc (HVDC) transmission, reactive power compensation equipment and so on.

Keywords

Sub-Modular; Modular Multilevel Converter; Fundamental Switching Modulation; Topology; CAPACITOR Voltage Balancing

Conflicts of Interest

The authors declare no conflicts of interest.

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