International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
DESIGN OF BRIDGELESS HIGH-POWER-FACTOR BUCK-CONVERTER OPERATING IN DISCONTINUOUS CAPACITOR VOLTAGE MODE. D.Navin Sam1 , R.Joe Chandran2 1..Assistant professor, Department of Electrical and Electronics Engineering. Bethlahem Institute of Engineering,Karungal-629157. 2. .Assistant professor, Department of Electrical and Electronics Engineering. Bethlahem Institute of Engineering,Karungal-629157. ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - In this paper, a new bridgeless single phase ac–
supply efficiency, considerable research efforts have been directed toward designing bridgeless PFC circuits where the current flows through a minimum number of switching devices compared with the conventional PFC rectifier. Accordingly, the converter conduction losses can be significantly reduced, and higher efficiency can be obtained and cost savings. Recently, several bridgeless PFC rectifiers have been introduced to improve the rectifier power density and/or reduce noise emissions via soft switching techniques or coupled magnetic topologies [4]–[10].
dc power factor correction (PFC) rectifier based on buck topology operating in discontinuous capacitor voltage mode (DCVM) is proposed. The bridgeless topology and the presence of only one or two semiconductor switches in the current flowing path during each interval of the switching cycle result in lower conduction losses compared with the conventional DCVM buck PFC rectifier. The DCVM operation offers additional advantages such as zero-voltage turn-off in the power switches, zero-voltage turn-on in the output diode, and continuous input current. Hence, the electromagnetic interference noise emission is minimized. The converter achieves high power factor naturally with low total harmonic distortion in the input current. All the simulation works is carried out in MATLAB/SIMULINK and the results are presented.
However, all of these rectifiers operate in DICM and suffers from high switch current stress causing higher conduction losses. In addition, a more robust input filter must be employed to suppress the high-frequency components of the pulsating input current, which increases the overall weight and cost of the rectifier. Interleaving two bridgeless boost converters can significantly minimize the input current ripple and doubles the transferable power [11]. However, besides the complex control, interleaving PFC boost converters have low efficiency at low power levels due to high component count. Thus, for universal input line and for low-power applications (<300 W), all of the reported topologies in [4]–[11] suffer from having low efficiency at low input line (Vac = 90 Vrms) due to the high input current, which produces higher conduction losses in the circuit components. Operating the converter at the boundary of DICM/CCM with variable switching frequency [12] can improve the efficiency at low line at the expense of complex control. On the other hand, the buck PFC is an attractive solution for universal input voltages at power levels (< 300 W). The buck PFC can achieve high efficiency over the entire universal input line voltage range with distorted input current that comfortably passes the limits imposed by IEC 61000-3-2 requirements [1]. In addition, the ability of the buck PFC converter to generate output voltages less than the line peak voltage has beneficial effect on the performance of the downstream dc/dc output stage because it allows a more efficient design for the dc/dc stage by using lower voltagerated semiconductor devices. In [13], a bridgeless buck PFC
Key Words: Discontinuous capacitor voltage mode
(DCVM), electromagnetic interference (EMI), power factor correction (PFC), total harmonic distortion (THD).
1.INTRODUCTION Power supplies with active power factor correction (PFC) techniques are becoming necessary for many types of electronic equipment to meet harmonic regulations and standards, such as the IEC 61000-3-2 [1]. Discontinuous inductor current mode (DICM) and discontinuous capacitor voltage mode (DCVM) are typically suitable for low-power applications; however, both topologies have, in general, inherent PFC properties unlike continuous current mode (CCM) topologies. Active PFC techniques based on basic dc– dc converter topologies have been developed for high power factor (PF) and low input current harmonic ac/dc rectification [2], [3]. However, conventional PFC rectifiers allow the current to flow through two bridge diodes in addition to the switching component of the converter. This results in higher conduction losses increasing the thermal stresses of the converter. In an effort to maximize the power
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