LCL Filter Design with the Inductor Nonlinear Behavior Consideration in the Three Phase Grid-Connected Inverter

摘要

Power inverter is an important part of a grid-connected system. Compared with the traditional L or LC filter, LCL filter is widely used in the grid-connected inverter due to its harmonic attenuation performance and system stability. The resonance frequency of LCL filter is determined by the parameters ofits components. However, the inductance of inductor may change in accordance with the current flowing through it that would have an impact on the harmonic attenuation. This paper presents a nonlinear inductor model to determine the components of LCL filter on a three-phase grid-connected inverter system. The control method of the proposed system is a double current closed-loop control method. The current harmonic distortion and total harmonic distortion are analyzed and compared with the traditional linear inductor model. The experimental results show that the LCL filter can be designed more efficiently when the nonlinear characteristics of the inductor is considered.