Delta-Sigma Modulation Based Common-Mode Voltage Elimination in Direct Matrix Converter
Tabish Nazir Mir, Bhim Singh, Abdul Hamid Bhat
Abstract
The direct matrix converter (DMC) offers a compact and robust solution over typical ac–dc–ac converter, by enabling direct ac–ac power conversion without any energy storage requirements. Moreover, it offers enhanced source current quality, innate bidirectionality and power factor correction capabilities. Its industrial suitability is further advocated by the elimination of common-mode voltage through the DMC topology. Space vector modulation and model predictive control based approach to common-mode voltage elimination in matrix converter, are previously proposed. This article proposes the delta-sigma modulation for common-mode voltage elimination in matrix converter, which is computationally less cumbersome and performs better as compared to previously documented methods. This method utilizes only six most optimum states of DMC that yield zero common-mode voltage, and performs load voltage and source current control by computing each error variable (delta), integrating it (sigma) and further minimizing it within a hysteresis band. Source current control necessitates load current estimation, which is done through predictive model of the load, hence eliminating load current sensors.