Modularized bi-directional grid-tied inverter with asynchronous sigma-delta modulation

The objective of this paper is to propose a modularized bi-directional grid-tied inverter (BGI) with asynchronous sigma-delta modulation (ASDM) control for the renewable energy (RE)-supplied DC power system. The proposed BGI can be operated either in the grid-tied mode (GTM) or the power factor correction mode (PFCM) which is necessary features for the RE-supplied DC power system. The proposed BGI with ASDM control scheme has the merits of circuit simplicity, quick response, and low electromagnetic interference. Moreover, the proposed BGI has redundant central controller which can increase the system reliability. The major contribution of this paper includes that developing the modularized BGI with ASDM control scheme for GTM and PFCM operations thoroughly and applying it to the RE-supplied DC power system successfully. In this paper, the mathematical equations of the proposed BGI with ASDM will be derived. Computer simulations and hardware experiments are shown to verify the performance of the proposed modularized BGI with ASDM control.