High Transformer Utilization Ratio and High Voltage Conversion Gain Flyback Converter for Photovoltaic Application
Binxin Zhu, Yujin Yang, Kaihong Wang, Jiaxin Liu, D. Mahinda Vilathgamuwa
Abstract
A flyback converter with a high transformer utilization ratio and high voltage conversion gain for photovoltaic application is proposed in this article. By adding the “coat circuit” to the topology of the basic flyback converter, the energy can be transferred from the primary winding of the transformer (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) to the secondary winding of the transformer (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) when the switch is working not only in off-state but also in on-state, which effectively improves the utilization, reduces the maximum electromagnetic flux density of the transformer during charging, and avoids the saturation of the transformer. Additionally, the “coat circuit” can also increase the voltage conversion gain of the flyback converter and reduce the voltage stress of devices, making the proposed converter attractive for photovoltaic power systems. This article analyzes in detail the working principles and performances of the proposed converter. The theoretical analysis is further corroborated through simulation and experimentation using a prototype with a power rating of 200 W.