Active Power Decoupling for Current Source Converters: An Overview Scenario

For single-phase current source converters, there is an inherent limitation in DC-side low-frequency power oscillation, which is twice the grid fundamental frequency. In practice, it transfers to the DC side and results in the low-frequency DC-link ripple. One possible solution is to install excessively large DC-link inductance for attenuating the ripple. However, it is of bulky size and not cost-effective. Another method is to use the passive LC branch for bypassing the power decoupling, but this is still not cost-effective due to the low-frequency LC circuit. Recently, active power decoupling techniques for the current source converters have been sparsely reported in literature. However, there has been no attempt to classify and understand them in a systematic way so far. In order to fill this gap, an overview of the active power decoupling for single-phase current source converters is presented in this paper. Systematic classification and comparison are provided for researchers and engineers to select the appropriate solutions for their specific applications.