Reduction of harmonic current distortion for single‐phase grid‐tied inverter operated in discontinuous current mode

Abstract

Discontinuous current mode (DCM) with high‐frequency operation can be an effective way to reduce the volume of inductors for low‐power grid‐tied inverter applications. Unlike the controllers designed for continuous current mode operations, current controllers for DCM are required to address their nonlinear characteristics. A feed‐forward controller can be a good choice for the current control of the grid‐tied inverters operated in DCM. However, distortions in the output current cannot be eliminated, and they can be more severe if devices with large output capacitance are applied. Two harmonic current reduction strategies, namely a partial feedback path and an improved modulation, are proposed to reduce the low‐ and high‐order harmonics for single‐phase grid‐tied inverters operated in DCM. The proposed strategies are discussed and verified by a laboratory prototype in some experiments. It is indicated that the proposed modulation can mitigate the influence of device parasitic capacitance on current distortion and expand the device selections. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.