Grid-tied inverter with current-mode asynchronous sigma-delta modulation

The objective of this paper is to propose a current-mode asynchronous sigma-delta modulation (CASDM) control strategy for grid-tied inverters. The proposed CASDM has the merits of circuit simplicity and low harmonic components which is especially good for grid-tied inverter applications. The major contribution of this paper includes that developing the CASDM control scheme thoroughly and applying it to the grid-tied inverter successfully. It is also true that the developed CASDM can be used for other power electronics applications such as the current-controlled motor driver, active power line conditioner, and so on. In this paper, the operation principle of the CASDM will be introduced and mathematical expression of the controller will be derived. Finally, computer simulations and hardware experimental results are shown to verify the performance of the grid-tied inverter with the proposed CASDM.