Search

A component-minimized and low-voltage-stress single-phase power factor correction 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 are 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 more than 0.97, peak efficiency of 95.1%, and an output voltage ripple of less than 4.3% across a wide load range have been experimentally obtained. [ABSTRACT FROM AUTHOR]

Active pulsating power buffering (PPB) function can effectively reduce the twice-line frequency energy storage requirement in a single-phase rectifier. Existing single-phase solutions with active PPB must utilize more than two active switches in their circuits. Compared with conventional single-active-switch solutions without active PPB (e.g., a boost power-factor-correction (PFC) rectifier), the cost of additional semiconductor switches and gate drive circuitry in an active PPB-based rectifier may not be justified for low-power applications. This paper presents a family of single-switch single-phase rectifier with active PPB. Taking advantage of the on-time and off-time of a single switch, the proposed rectifiers are formulated by merging two converters that are duty and frequency controlled. The steady-state characteristics of these converters are analyzed. A step-by-step design procedure is provided, and an active control method for limiting the maximum switching frequency for wide-load-range operation is presented. A 100-W prototype is built for the demonstration of the proposed single-switch rectifier concept. It is envisaged that this concept, when combined with other circuit formulation techniques, e.g., partial power processing, dc-voltage feedback, may lead to new derivatives of single-switch rectifiers with more advanced features. [ABSTRACT FROM AUTHOR]

Conventional hysteresis-modulation-based sliding-mode (SM) controller exhibits a varying switching frequency. Existing SM controllers for achieving constant-switching-frequency operation often have complicated structures and/or are less straightforward to design to meet different steady state, transient, and loading requirements. In this paper, a new direct SM voltage controller based on parabolic modulation (PM) is proposed and applied to a buck converter. The objective is to achieve constant-switching-frequency operation of a switching converter with simple control structure and good operating performance. Both theoretical study and experimental work on a buck converter show that the proposed PM-based SM control can achieve 1) constant switching frequency in the continuous-conduction mode (CCM) and quasi-constant switching frequency in the discontinuous-conduction mode (DCM) of operation, 2) inherent input-disturbances rejection and superior reference tracking performance, and 3) seamless mode transition between CCM and DCM. [ABSTRACT FROM PUBLISHER]