International Journal of Power Electronics and Drive System (IJPEDS) Vol. 8, No. 2, June 2017, pp. 812~825 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v8i2.pp812-825  812 Journal homepage: http://iaesjournal.com/online/index.php/IJPEDS ZVS Full Bridge Series Resonant Boost Converter with Series- Connected Transformer Mohamed Salem 1 , Awang Jusoh 2 , N. Rumzi N. Idris 3 , Tole Sutikno 4 , Iftikhar Abid 5 1, 2, 3 Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81300 Skudai, Malaysia. 4 Department of Electrical Engineering, Universitas Ahmad Dahlan, Indonesia. 5 Advanced Photon Source, Argonne National Laboratory, Cass Avenue, Argonne, USA Article Info ABSTRACT Article history: Received Feb 3, 2017 Revised Apr 3, 2017 Accepted Apr 17, 2017 This paper presents a study on a new full bridge series resonant converter (SRC) with wide zero voltage switching (ZVS) range, and higher output voltage. The high frequency transformer is connected in series with the LC series resonant tank. The tank inductance is therefore increased; all switches having the ability to turn on at ZVS, with lower switching frequency than the LC tank resonant frequency. Moreover, the step-up high frequency (HF) transformer design steps are introduced in order to increase the output voltage to overcome the gain limitation of the conventional SRC. Compared to the conventional SRC, the proposed converter has higher energy conversion, able to increase the ZVS range by 36%, and provide much higher output power. Finally, the a laboratory prototypes of the both converters with the same resonant tank parameters and input voltage are examined based on 1 and 2.2 kW power resprctively, for veryfing the reliability of the performance and the operation principles of both converters. Keyword: Full bridge converter High frequency transformer Series resonant converter Soft switching Zero voltage switching Copyright © 2017 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Mohamed Salem, Energy Conversion Engineering Department, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81300 Skudai, Malaysia. Email: moha_so_2009@yahoo.com / smohamed3@live.utm.my 1. INTRODUCTION Resonant converters have been extensively studied since the 80s [1]. They provide the possibility to achieve low switching losses and allow switches to control resonance at high switching frequency. However, increasing the operating frequency will increase the switching losses and decrease the system efficiency. An answer to this problem is to replace the "Chopper" switch of a standard topology by a "resonant" switch, which uses the resonances of circuit capacitances and inductances to shape the waveform, which then shapes the current or voltage through the switching element. Therefore, when switching takes place, there is no current or the voltage flowing through it. A zero current switching (ZCS) characterizes the current waveform, while a zero voltage switching circuit (ZVS) characterizes the voltage waveform. The resonant converter not only achieves soft switching at turn on and off, but also has less switching losses compared to PWM hard switching converter. For resonant converter, the soft switching method depends on the ratio of the normalized frequency. If the normalized frequency F is higher than unity (1), the performance of the converter will be under ZVS condition. Meanwhile, if it is less than unity, the performance of the converter will be under ZCS condition [2]. Furthermore, a high switching frequency is required in such converters to cut down the size and weight of the converter. At high frequencies, the converter has the ability to achieve soft-switching which is used to reduce the switching losses. However, this will cause high electromagnetic interference di/dt and dv/dt, which still can affect the system efficiency [3]-[7]. Series resonant converter