Control Techniques for TCM-Based Buck Active Power Decoupler Without DC-Link Current Sampling

Active power decoupling (APD) circuits are frequently employed to suppress dc-side second harmonic of single-phase inverters. Triangular current mode (TCM) control enables the realization of zero-voltage switching. However, due to the considerable current ripple and variable switching frequency under TCM modulation, it is quite difficult to accurately detect, sample and control the inductor current. In this article, based on a buck APD circuit under TCM modulation, a voltage closed-loop control strategy combined with time prediction method is proposed, which eliminates the need to sample the dc bus current and the decoupling inductor current. The approach achieves effective harmonic suppression and full-range soft switching with easy control. In addition, the effect of turning off the APD circuit for a short period of time on switching frequency and harmonic suppression is explored. The proposed strategy is validated on a 600 W experimental prototype.