International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
Soft-Switching Two-Switch Resonant Ac-Dc Converter Aqulin Ouseph1, Prof. Kiran Boby2, , Prof. Dinto Mathew3 1PG
Scholar,Department of Electrical and Electronics Engineering, Mar Athanasius College of Engineering,
Kothamangalam, Kerala, India
2,3Assistant
Professor, Department of Electrical and Electronics Engineering, Mar Athanasius College of Engineering, Kothamangalam, Kerala, India
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Abstract - In AC to DC converters, power factor has significant importance. Most power converters and equipments are developed to have power factor correction technology to improve their performance. A soft-switching two-switch resonant ACDC converter with high power factor is presented. In this converter, a boost PFC circuit is integrated with a soft-switching resonant converter in order to achieve high power factor. This topology provide low component stress, high frequency operation, zero voltage switching, and applicability under a wide range of input and output conditions. The voltage across the main switches is confined to the dc-link voltage and the energy of the transformer leakage inductance is also recycled. Softswitching operation of main switches and output diodes is achieved in a resonant manner and the switching losses are significantly reduced. Thus, the overall efficiency is improved.
Key Words: Power factor correction(PFC), Soft switching, Resonant converter, Boost converter 1. INTRODUCTION The power supply unit is an essential circuit block in all electronic equipment. It is the interface between the AC mains and the rest of the functional circuits of the equipment. These functional circuits usually need power at one or more fixed dc voltage levels. Switched mode power supplies (SMPS) are most commonly used for powering electronic equipment since they provide an economical, efficient and high power density solution compared to linear regulators. In order to conserve energy, high overall power conversion efficiency is required. However, conventional AC/DC switched mode power supplies introduce some adverse effects on the AC side [1]. Examples of such effects are, distortion of input current/voltage, input voltage dip due to the presence of bulk capacitors and electromagnetic interference (EMI) due to high frequency switching.
2. SOFT-SWITCHING TWO-SWITCH RESONANT AC-DC CONVERTER Soft-switching two-switch resonant AC-DC converter with high power factor merges a boost converter and a two switch resonant converter. The circuit diagram of the converter is shown in figure 1. The boost PFC circuit is designed to operate in discontinuous conduction mode (DCM) to achieve a high power factor. The maximum voltages across main switches and clamping diodes are confined to the dc-link voltage Vdc. The secondary side consists of an output capacitor and a voltage doubler with a resonant tank. The voltage of output diodes are clamped to Vo and so it has no high spike voltage due to voltage doubler topology. Soft-switching operation of main switches and output diodes is achieved due to resonance between transformer leakage inductance and a resonant capacitor and critical conduction mode (CRM) operation of a two switch resonant converter. CRM operation reduces switching losses of main switches at their turn-on and zero-current switching (ZCS) of the output diodes reduces the switching losses and alleviates reverse recovery problem of output diodes. In addition, the energy stored in leakage inductance and magnetizing inductance of the transformer is recycled. The boost PFC cell is composed of a boost inductor L b, reverse-blocking diode Db, and a main switch S1. In the two-switch resonant DC-DC module, the transformer T1 is modeled as the magnetizing inductance Lm, the leakage inductance L k, and an ideal transformer with a turns ratio of n:1. To simplify the total transformer leakage inductance, L k is referred to the secondary side. The capacitor Cdc is a DC bus capacitor. The snubber diodes D1 and D2 are cross-connected across the main switches S1, S2, and the primary winding. The operation of the converter in one switching period T S can be divided into six modes.
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