Fixed-Frequency Phase-Shift Modulated Capacitor-Clamped <i>LLC</i> Resonant Converter for EV Charging
Jiayang Wu, Sinan Li, Tang Xiao, S.Y.R. Hui
Abstract
<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter has been widely employed in electric vehicle (EV) charging applications. However, conventional frequency-modulated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters generally demand a wide frequency variation range and are difficult to scale up, while the traditional phase-shifted (PS) <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters have the issues of ease of losing soft-switching condition and high turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current. In response to these challenges, this article proposes a new method for EV charging applications based on the capacitor-clamped <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter topology and fixed-frequency PS modulation. Compared with traditional PS <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters, the proposed method can achieve 1) smaller phase shift variation range, 2) lower turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current, and 3) wider soft switching range, resulting in higher efficiency. An 825-W prototype with 200 V input and 125–210 V output range verified the features of the proposed idea, and the efficiency reaches 97.82% at the maximum output power.