Model-Based Control for Grid-Tied Inverters Operated in Discontinuous Current Mode with Low Harmonic Current Distortion

Low-power grid-tied inverters can be designed to operate in a discontinuous current mode (DCM) with a model-based feedforward control, which can be advantageous for further increasing the switching frequency to achieve high power density. However, current distortions can be generated due to the parasitic capacitance of the devices. To address the issue, an improved modulation for the DCM is proposed in this article. We describe the proposed modulation and, then, demonstrate its improved performance by a time-domain simulation. We also discuss the proposed modulation in comparison with another method that has been proposed previously. The proposed method is also verified by experiments using a 400-W laboratory prototype. A significant improvement in the current harmonics by the improved modulation has been confirmed.