Novel passive controller design for enhancing boost converter stability in DC microgrid applications

Boost converters have Non-Minimum Phase (NMP) characteristics, which makes the stable closed loop control design difficult. Based on the passive theory, this paper proposes to add a feed-forward loop in the conventional double loop closed loop to compensate the NMP effect. Therefore, the potential instability caused by NMP can be avoided. Such compensation is especially useful for DC microgrids applications where boost converters are widely used as interface converters. Two types of feed-forward gain are discussed and compared. The gain of K with high-pass filter is used eventually for integrating with conventional droop control because it does not change low frequency quiescent operation point. The stability of the proposed controller is analysed through loop gain on s-plane. Besides, how the output impedance of converter is shaped by the passive controller is analysed. The experimental results validate the effectiveness of the proposed passive controller.