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Nigsch S.,University of Applied Sciences and Arts Western Switzerland | Cuk S.,TESLAco | Schenk K.,University of Applied Sciences and Arts Western Switzerland
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Power Factor Correction (PFC) has been established for a long time to fulfill the harmonic standards. To meet the demand for a compact, efficient solution, a so-called True Bridgeless Single Stage PFC was recently introduced. By eliminating the input rectifier the efficiency is significantly improved. In addition, this topology provides galvanic isolation while employing only one single active switch. In this paper a True Bridgeless Single Stage PFC is analyzed, designed and characterized through measurements on a hardware realization. To optimize the converter with respect to efficiency, power density or cost, analytical expressions for all occurring voltages and currents in each component are derived. With the derived small signal model, the current and voltage compensator can be designed optimally, to ensure a stable and fast control behavior. In addition, a non-dissipative clamp circuit is introduced to limit the switch voltage without causing significant losses. The results of the theoretical analysis are verified by simulation and experimental measurements. © 2015 IEEE. Source

A new class of bridgeless PFC converters has been developed based on novel hybrid-switching method, eliminating the need for full-bridge rectifier. The true single-stage power processing results in several advantages in comparison with conventional two-stage, bridge-type PFC converters,. These converters provide efficiency of more than 98% achieved with appropriate switching devices, 0.999 Power Factor Correction (PFC), reduced cost, size and weight, and single low-cost magnetics. The new bridgeless PFC converter operates directly from the ac line and is the first true single-stage bridgeless ac-dc PFC converter. This method also leads to a specific converter topology consisting of three switches, including one controllable switch S and two passive current rectifier switches CR1 and CR2. One active switch S alone controls the other two diode switches whose roles are changed automatically according to the polarity of the ac input voltage. Source

A bridgeless power factor converter (PFC) based on a novel switching method eliminates full-bridge rectifiers and helps to reduce the size and cost of switching power supplies. The Three-Phase Bridgeless PFC converter extension provides unity power factor operation, low total harmonic distortion, and eliminates the large output DC storage capacitor, yet results in small output ripple voltage. The Power Factor Correction is based on forcing the input line current iAC of the converter to become proportional and in phase to the input ac line voltage by use of the appropriate control circuit. One circuit, which can be utilized, comprises the conventional PFC IC controller to which current folding and voltage folding signal processing circuits are added externally. Three-Phase Bridgeless PFC converter eliminates large output storage capacitor and yet results in low output ripple voltages. It provides the most efficient connection between three-phase ac transmission line and the local DC transmission system. Source

A new Single-stage AC-DC Converter achieves Power Factor Correction (PFC) and isolation. This converter operates directly from the ac line, eliminating a full-bridge Rectifier needed in conventional PFC converters, which require at least two or three processing stages to achieve isolation. The Bridgeless PFC converter and its duty ratio modulation control have been shown to operate directly from the ac line and without the need for the Full-Bridge rectifier in front. This converter has only three switches and operates on the basis of the new hybrid- switching method. This hybrid switching method results in the DC voltage gain being dependent on the duty ratio only and having the same DC voltage gain as the ordinary boost converter for either positive input voltage or negative input voltage, providing an automatic ac line rectification without the need for a front-end bridge rectifier. Source

The single-stage isolated bridgeless PFC Converter with pulsating input current attains improved efficiency of over 98% compared to 89% of the Three-stage approach, offering simultaneously significant size and cost reductions, while maintaining the near unity power factor of 0.999 and 1.7% total harmonic distortion. A very clear objective to increase the efficiency is to devise a converter, which can eliminate a front-end full-bridge rectifier. Past attempts failed to eliminate diode-bridge rectifiers, leading to the belief that the solution to such a goal may be impossible and that such converter topology could not exist. The current rectifier CR2 also responds automatically to the state of the switch S and polarity of the input ac voltage. For the positive polarity it conducts during the OFF-time interval of switch S and for negative polarity, it conducts during the ON-time interval of switch S. Source

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