An Optimal Burst Mode Control Method for CLLC Converter Based on Time Domain Model

The CLLC resonant converters are drawing more and more attention due to their superiority in high efficiency, high power density, and low electromagnetic interference (EMI). However, CLLC converter still suffers the problems of unsatisfactory voltage regulation and low efficiency under light-load conditions. To address this issue, a burst mode control method with dual active modulation for CLLC converter is proposed in this paper. With the aid of time-domain model and offline particle swarm optimization (PSO) algorithm, the proposed method optimizes the switching sequences of the pulse packets to achieve the minimum current RMS with the same transmitted energy and requires only sampling of the input and output voltages. Comparative experiments were conducted on a 1-kW prototype and the results show that the light load efficiency can be improved by applying the proposed burst mode control. Peak efficiency of 97.4% is achieved at 10% rated load, which is an improvement of more than 2% compared to the previous burst mode approaches.