552 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 52, NO. 2, APRIL 2005 A Quasi-Resonant Quadratic Boost Converter Using a Single Resonant Network Luiz Henrique Silva Colado Barreto, Ernane Antônio Alvez Coelho, Member, IEEE, Valdeir José Farias, João Carlos de Oliveira, Luis Carlos de Freitas, and João Batista Vieira, Jr. Abstract—This paper presents a quadratic boost converter using a single quasi-resonant network to reach soft commutation. A res- onant inductor, a resonant capacitor, and an auxiliary switch form the resonant network and the main switch operates in a zero-cur- rent-switching way. A complete analysis of this converter is pre- sented. According to the simulation and experimental results, this quadratic boost converter provides a larger conversion ratio than that provided by the conventional boost converter (for a given duty ratio ), and presents optimum performance, which operates with soft-switch commutation using a single resonant network. Index Terms—DC–DC power conversion, lossless circuits, reso- nant power conversion. I. INTRODUCTION N OWADAYS, the utilities and power quality committees demand that the electronic equipment with one or more active switches present low electromagnetic interference (EMI) in the power system. A simple way of solving this problem is the use of switching techniques that employ null current and/or null voltage. These techniques increase the converter efficiency and switch lifetime. Quadratic converters [1] operate basically as two conven- tional converters in cascade; for example, the quadratic boost converter operates as two conventional boost converters in cas- cade. Therefore, to reach a soft commutation such converters usually use two commutation cells [2], [3]. The main goal of this work is to find a single cell to replace these two cells. As an extensive research was carried out on the literature, it could be seen that conventional resonant and quasi-resonant converters [4]–[6] provide zero-current switching (ZCS) and/or zero-voltage switching (ZVS) [7], [8] and, therefore, they can operate at high frequencies. The converter shown in Fig. 1 uses a quasi-resonant network to reach soft commutation (ZCS). Although these techniques have a load limitation, because there are current and/or voltage peaks over the switches, this cell is very suitable in this case, because this converter operates with soft commutation using a single cell. Manuscript received May 9, 2003; revised June 3, 2004. Abstract published on the Internet January 13, 2005. This work was supported by CAPES, CNPq, and FAPEMIG. L. H. S. C. Barreto is with the Centro de Tecnologia, Departamento de En- genharia Elétrica, Universidade Federal do Ceará, 60455-760 Fortaleza, Brazil. E. A. A. Coelho, V. J. Farias, J. C. de Oliveira, L. C. de Freitas, and J. B. Vieira, Jr. are with the Núcleo de Eletronica de Potencia, Faculdade de Engenharia Elétrica, Universidade Federal de Uberlândia, 38400-902 Uberlândia, Brazil (e-mail: batista@ufu.br). Digital Object Identifier 10.1109/TIE.2005.844255 Fig. 1. Quadratic boost converter associated to a quasi-resonant network. Fig. 2. First stage. II. PROPOSED QUADRATIC BOOST CONVERTER The developed converter (Fig. 1) is called a quasi-resonant quadratic boost converter (QR-QBOOST). It employs the reso- nance principle to achieve the lossless commutation, although it presents inherent pulsewidth-modulation (PWM) characteris- tics. One resonant network is added to a quadratic boost converter (corresponding to two boost converters in cascade, where a single active switch is present). A resonant inductor, a resonant capacitor, and an auxiliary switch form the resonant network. The auxiliary switch operates under ZCS condition because it is placed in series with the resonant inductors. This resonant inductor allows the main switch to operate under ZCS. III. PRINCIPLE OF OPERATION To simplify the analysis, the boost inductances and are assumed to be large enough so that they can be considered as ideal current sources and , respectively, the voltages across and present no ripple, all components are treated as being ideal, and the currents and flow through diodes and , respectively, until the main switch is turned on at instant “ .” According to Fig. 1, six operating stages are described as follows. First Stage ( – )—(Fig. 2). This is the first linear stage. This stage begins when the main switch is turned 0278-0046/$20.00 © 2005 IEEE