Fully Integrated TL-C-L Filter for Grid-Connected Converters to Reduce Current Harmonics

This paper proposes a trapped-LCL filter, which has an LC resonator trap at the inverter side. The proposed filter design is based on the magnetic integration of multiple coils on a single core. The mutual inductances between these coils are utilized to improve the output current quality. The model and analyses presented in this paper demonstrate that the proposed filter has many promising advantages. Such advantages are: reduced cost and volume, durability against the grid impedance parameter differences, switching frequency and its multiple harmonics attenuation, which is easily designed according to the values of filter parameters, thereby reducing the current total harmonic distortion (THD) of the converter, and there are no resonance peaks. Based on these advantages, the fully integrated T-LCL filter can become a promising trap filter. A simulation model of AC / DC single-phase grid-connected converter with the proposed filter were created and tested in Matlab/Simulink, which provide simulation results verifying the superiority of the proposed filter. Finally, the proposed filter is validated by performing hardware-in-the-loop (HIL) experiments.