Interleaved hybrid control with an upper optimizer of parallel three‐level LLC converters for battery charging applications

Abstract

Abstract This letter proposes an interleaved hybrid control for parallel three‐level (TL) LLC converters in battery charging applications. The duty cycle and the switching frequency are used to adjust the voltage gain; the phase shift control is adopted to realize voltage sharing of the divided capacitors. A virtual equivalent frequency‐gain control is adopted to coordinate multiple control variables. And the current ripples are reduced for the interleaved structure. Based on the performance analysis, an upper optimizer is proposed to update the upper limit frequency and interleaving arrangement in real time. Accordingly, it achieves a wide range of output voltage, and it further improves the system efficiency under light load and low output voltage conditions. A prototype is presented to verify the effectiveness of the proposed method.