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Abstract-Existing methods of incorporating an active filter into an AC/DC converter for eliminating electrolytic capacitors usually require extra power switches. This inevitably leads to an increased system cost and degraded energy efficiency. In this paper, a concept of active-filter integration for singlephase AC/DC converters is reported. The resultant converters can provide simultaneous functions of power factor correction (PFC), DC voltage regulation and active power decoupling for mitigating the low-frequency DC voltage ripple, without an electrolytic capacitor and extra power switch. To complement the operation, two closed-loop voltage-ripple-based reference generation methods are developed for controlling the energy storage components to achieve active power decoupling. Both simulation and experiment have confirmed the eligibility of the proposed concept and control methods in a 210 W rectification system comprising an H-bridge converter with a half-bridge active filter. Interestingly, the end converters (Type I and Type II) can be readily available using a conventional H-bridge converter with minor hardware modification. A stable DC output with merely 1.1% ripple is realized with two 50 μF film capacitors. For the same ripple performance, a 900 μF capacitor is required in conventional converters without an active filter. Moreover, it is found out that the active-filter integration concept might even improve the efficiency performance of the end converters as compared with the original AC/DC converter without integration.

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A component-minimized and low-voltage-stress single-phase PFC rectifier without electrolytic capacitor is proposed in this paper. Component minimization is achieved by embedding an active pulsating-power-buffering (PPB) function within each switching period, such that typical add-on power electronic circuits for PPB is no longer needed. Additionally, with a three-level flying-capacitor configuration, the voltage stresses of switching devices can be reduced more than 50% as compared to existing solutions that are based on embedded PPB. The relationship between the inductance requirement and the patterns of the modulation carriers, and how it can be utilized to minimize the magnetics of the rectifier, is also discussed. A 110 W hardware prototype is designed and tested to demonstrate the feasibilities of the proposed rectifier. An input power factor of over 0.97, peak efficiency of 95.1%, and output voltage ripple of less than 4.3%, across a wide load range have been experimentally obtained.

Abstract-Existing control schemes for a single-phase ac-to-dc converter with active powerdecoupling function typically involve a dedicated power-decoupling controller. However, due to the highly coupled and nonlinear nature of the single-phase system, the design of the power-decoupling controller based on the conventional linear control techniques is cumbersome, and the control structure is complicated. Additionally, with the power-decoupling control, it is generally difficult to achieve satisfied dynamic responses and robust circuit operation. Following a recently proposed automatic-power-decoupling control scheme, this paper proposes a nonlinear control method that can achieve enhanced dynamic responses and strong disturbance rejection performance without the need for a dedicated power-decoupling controller. The proposed controller has a simple structure, of which the design is straightforward. In addition, the control method is generally applicable to single-phase ac-to-dc systems with active power-decoupling function. Simulation and experimental results validate the feasibility of the proposed control method on a two-switch buck-boost PFC rectifier prototype.Index Terms-Automatic power decoupling control, single-phase ac-to-dc converters, power decoupling.

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