| Summary: | In the two-stage converter such as PV renewable energy system, the second harmonic fluctuation exists in the DC voltage due to the power coupling between the DC-link and AC system. The second harmonic voltage in the DC link could increase the system loss and decrease the stability of the converter system, and its generation process and transmission mechanism are analyzed in this paper. The mathematical expression of second harmonic voltage in DC-link has been derived. A second band passing filter (BPF) feedback control loop is used to feedback the second harmonic ripple voltage in DC link into the statable modulation index. This strategy can decrease the second harmonic voltage in the DC-link and the third harmonic voltage in the AC sides. Finally, the control parameters are implemented using a simulation platform, and the match suppression strategy is validated by the simulation results.
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