Phase-Shift Modulated Hybrid LLC and Half-Bridge Converter With Fixed Frequency for Wide Voltage Gain Range Application
Haiming Yu, Xiaogao Xie, Hanjing Dong
Abstract
In this article, a novel hybrid <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> and half-bridge (HB) converter is proposed for wide voltage gain applications. The proposed converter is composed of a conventional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter and a HB converter. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter and the HB converter are connected in parallel on the primary side with an auxiliary winding of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> transformer inserted in the primary power loop of the HB converter, while the secondary windings of two converters transformers are inversely connected and share a voltage-doubler rectifier. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> and HB operate with the same fixed frequency, and the phase-shift modulation control between two converters is utilized to regulate the output voltage. Zero-voltage switching of all the primary switches and zero-current switching of all second side diodes can be achieved over a wide range of output voltage and load conditions. Detailed principle and voltage gain analysis based on time-domain method has been presented. After that, a simple approximate analysis method is proposed so that the voltage gain can be obtained more easily and main parameters of the converter can be fast optimally designed. Finally, a 1 KW laboratory prototype with 400 V input/50 V–450 V output has been built up to verify the theoretical analysis of the proposed converter. The peak efficiency achieves 97.9%, and features good voltage regulation capability. Thus, the proposed converter is suitable for wide voltage gain range applications.