Three-Phase Split-Source Inverter-Fed PV Systems: Analysis and Mitigation of Common-Mode Voltage

Abstract

Common-mode voltage (CMV), caused by standard high-frequency pulsewidth modulated (PWM) voltage source inverters (VSIs), is a major area of interest in various applications, such as electric motor drives, transformerless photovoltaic systems, and grid-tied inverters. Since VSIs have only the buck capability during the inversion mode, an additional boosting stage either in the dc side or in the ac side has to be utilized for low-voltage-fed applications. On the other hand, single-stage solutions, with buck and boost capabilities, represent an interesting alternative with reduced cost, complexity, and converter volume. Among the possible single-stage solutions, split-source inverter (SSI), which has been recently proposed, has several merits over its counterparts. One of the questionable aspects concerning this topology is the CMV, which has not been investigated yet. This article examines the induced CMV with the SSI. This is done by examining the CMV waveforms for VSI and SSI topologies, and then, comparing each other under different PWM schemes. Furthermore, this article proposes the use of the discontinuous space vector PWM scheme with the SSI to mitigate the CMV, where the analysis shows a significant reduction in the CMV compared to the other schemes. In order to validate the introduced analysis, simulation model has been designed using MATLAB/Simulink environment, and simulation results are presented. Moreover, a prototype has been built-up for testing the proposed concepts and the obtained experimental results are provided.