On Nonlinear Control of Single-Phase Converters With Active Power Decoupling Function

Abstract

In this paper, a nonlinear controller is presented for regulating an emerging class of high power density, high power-conversion efficiency, and high reliability (H3) single-phase power converters featuring small buffering capacitors. The proposed controller combines the best features of input–output feedback linearization and an automatic-power-decoupling (APD) control strategy, and achieves enhanced dynamic performances as compared to existing solutions based on linear control techniques. By feedback linearization, the plant models of H3 single-phase converters are fully linearized and decoupled, and thus fast dynamics, large-signal asymptotic tracking, and global stability can be achieved with simple linear controllers. Additionally, the APD strategy further strengthens the robustness of the closed-loop system as active pulsating power buffering (of the instantaneous power difference between the ac-port and the dc-port of the converter) of basically any form can be achieved. With the proposed nonlinear controller, we are able to further exploit the potential and unlock several new features intrinsic in H3 single-phase converters, e.g., active voltage holdup function, allowing extended holdup time (comparable to existing products with large dc-link capacitors) with only a small energy storage. The general theory, design procedures, and practical considerations of the nonlinear controller are detailed. A 100-W hardware prototype is also built to demonstrate the advantages of the proposed solution. New opportunities of H3 single-phase power converters with the aid of the proposed nonlinear control are also suggested for future research.