دانلود رایگان ترجمه مقاله یکسوساز PFC Sepic و Cuk Rectifiers بدون پل جدید – IEEE 2009

یک یکسوساز PFC Sepic و Cuk Rectifiers بدون پل جدید با تلفات سویچینگ و هدایت پایین

A New Bridgeless PFC Sepic and Cuk Rectifiers with Low Conduction and Switching Losses

Abstract

New bridgeless single phase ac-dc power factor correction (PFC) rectifiers based on Sepic and Cuk topologies are proposed. The absence of an input diode bridge and the presence of only two semiconductor switches in the current flowing path during each switching cycle results in less conduction losses and improved thermal management compared to the conventional Sepic and Cuk PFC converters. The proposed topologies are designed to work in discontinuous conduction mode (DCM) to achieve almost unity power factor in a simple and effective manner. The DCM operation gives additional advantages such as: zerocurrent turn-on in the power switches, zero-current turn-off in the output diode, and reduces the complexity of the control circuitry. The proposed rectifiers are investigated theoretically. Performance comparisons between the proposed and conventional Sepic PFC rectifiers are performed. Simulation and experimental results are provided for a design example of a 65W/48V at 100 Vrms line voltage to evaluate the performance of the proposed PFC rectifier.

1 Introduction

The preferable type of power factor correction (PFC) circuit is the active PFC since it makes the load behave like a pure resistor, leading to near unity load power factor and generating negligible harmonics in the input line current. Most active PFC circuits as well as switched mode power supplies (SMPS) on the market today comprise a front-end bridge rectifier followed by a high frequency dc-dc converter. Fig. 1 shows an example of a conventional PFC Sepic and Cuk rectifiers. Referring to Fig.1, it is clear that the current path flows through two rectifier bridge diodes and the power switch (Q) during the switch on-time, and two rectifier bridge diodes and the output diode (Do) during the switch off state. Thus, during each switching cycle the current flows through three power semiconductor switches. This approach is suitable for a low power range. In the low line input and high power applications, the high conduction loss caused by the high forward voltage drop of the bridge diode begins to degrade the overall system efficiency, and the heat generated within the bridge rectifier may destroy the individual diodes. Hence, it becomes necessary to utilize a bridge rectifier with higher current handling capability or heat dissipating characteristics. This increases the size and cost of the power supply, which is unacceptable for an efficient design. In an effort to maximize the power supply efficiency, considerable research efforts have been directed towards the development of efficient bridgeless PFC circuit topologies [1]-[18]. A bridgeless PFC circuit allows the current to flow through a minimum number of switching devices compared to the conventional PFC circuit. Accordingly, the converter conduction losses can be significantly reduced and high efficiency can be obtained as well as cost savings. Most of the presented bridgeless topologies so far implement a boost-type circuit configuration (also referred to as dual boost PFC rectifiers) because of its low cost and its high performance in terms of efficiency, power factor, and simplicity. These features have led power supply companies to start looking for bridgeless PFC circuit topologies. In [19], a systematic review of the bridgeless PFC boost rectifier implementations that have received the most attention is presented along with their performance comparison with the conventional PFC boost rectifier. On the other hand, the bridgeless boost rectifier has the same major practical drawbacks as the conventional boost converter. In order to overcome the drawbacks of bridgeless PFC boost rectifier, two bridgeless topologies which are suitable for step-up/step-down applications are introduced in [20], [21]. However, the proposed topology in [20] still suffers from having three semiconductors in the current conduction path during each switching stage and it requires an isolated gate-drive. On the other hand, the bridgeless topology presented in [21] has several advantages such as the presence of one or two semiconductors in the current conduction path and reduced voltage stress across the semiconductor devices; however, it also requires an isolated gate-drive.