Non-Cascading Structure based Bi-Quadratic Step- Down Converter: Analysis and Design Sunil Kumar 1 , K. P. S. Rana 2 and Vineet Kumar 3 1 Department of Electronics and Communication Engineering, J. B. Institute of Technology, Dehradun, Uttarakhand, India-248197 Email: sunilkumar5593@gmail.com 2-3 Division of Instrumentation and Control Engineering, Netaji Subhas University of Technology, Sector-3, Dwarka, New Delhi, India-110078 Abstract—In the present paper, a step down converter employing combination of Flyback and Forward converters, using a non-cascading scheme, is presented. The voltage conversion ratio in a bi-quadratic converter depends on bi-quadratic power of the duty cycle. Due to this effect, the range of obtainable output voltages has become wider. This means the difference of any two consecutive output realizable voltages becomes narrower than that achieved by using relatively lower power of the duty cycle. Here, for stepping up the output voltage, the outputs of the flyback and forward sub-converters are combined in series with each other. Due to such configuration, a larger output voltage is obtained. A comparison is given to indicate the extension in voltage conversion ratio as the duty cycle is raised to higher power. For validation, a converter of 24 V, 24 W rating is presented. Index Terms— non-cascading structure, bi-quadratic, voltage conversion ratio, discontinuous conduction mode, intermediate capacitor, switching cycle. I. INTRODUCTION A class of converters known as non-cascading structure is divided into three main categories. It is an alternative arrangement for cascading combination of the converters as the later has poor efficiency. The efficiency improves through the use of cascading structures at the cost of the input power factor. Initially, the class was used for three main purposes but now it is useful for other applications as well. An important application of it is to keep the output of converters dependent of higher power of duty cycle. Many configurations are available in literature where the voltage conversion ratio depends upon quadratic power of the duty cycle. Such converters are known as quadratic converters. A quadratic converter is reported in [1] where it is found that the power factor remains intact and at the same time, the voltage conversion ratio also widens. The voltage stress on the main power switch varies with the capacitor voltage which, in turn, decreases with the increasing load in continuous conduction mode (CCM). In CCM, the capacitor voltage varies with the load and at lower load it increases. Due to this, stress on the power switch increases. How different combinations of converters can be employed to get non-cascading structures is suggested in [2]. A large number of new structures are derived by combining converters, in non-cascading structures. A so called flyboost cell, has been reported in [3] which, by its structure, can be considered a member of non-cascading structure that is suitable for improvement of both of the efficiency and power factor. The non-cascading structures find applications mainly for the input power factor Grenze ID: 01.GIJET.9.1.321_1 © Grenze Scientific Society, 2023 Grenze International Journal of Engineering and Technology, Jan Issue