Comparative Analysis of Modulation Strategies for Indirect Matrix Converter Based on RMS Value of Common-mode Voltage

Abstract

Indirect matrix converters (IMC) feature an AC-AC configuration without an intermediate DC link and wide application prospects in wind power generation, AC transmission, and various other fields, known for their sinusoidal input/output, high power density, and superior operating efficiency. However, these converters inevitably generate common-mode voltages during modulation operations, causing motor damage and affecting the reliable functioning of the systems. This paper aims to enhance the operational reliability of IMCs by suppressing common-mode voltage output, and focuses on five classical modulation methods for suppressing common-mode voltage peaks by 42.3% in IMCs, including the modulation method for synthesizing reference output voltage vectors using adjacent four effective voltage vectors at the inverter stage, that for synthesizing reference output voltage vectors using adjacent three effective voltage vectors at the inverter stage, that for synthesizing reference current vectors using adjacent three effective current vectors at the rectifier stage, that for synthesizing reference current vectors using two adjacent 120° effective current vectors plus a zero-current vector at the rectifier stage, and that for synthesizing reference current vectors using weighted three effective current vectors at the rectifier stage. By modeling the effective value (root mean square, rms) of output common-mode voltages, which incorporates the influence of voltage transfer ratios on these values, a quantitative analysis was conducted to explore the variation patterns of the rms value of common-mode voltages. Following this, an evaluation was performed on the suppression capability of different modulation methods on common-mode voltages. The comparative analysis results indicated that the space vector modulation method of synthesizing reference voltage using adjacent four effective voltage vectors at the inverter stage exhibited the best suppression effect on the rms value of common-mode voltages in IMCs. Additionally, the correctness of the theoretical analysis results was verified through simulations and experiments.

Keywords

• indirect matrix converter(imc)
• space vector modulation
• modeling of root mean square
• common-mode voltage
• voltage transfer ratio