基于简化状态轨迹的半桥LCC谐振变换器无噪声Burst模式控制策略

A Novel Noiseless Burst Mode Control of Half-Bridge LCC Resonant Converter Based on Simplified State Trajectory

半桥LCC谐振变换器在轻载工作模式下,其高开关频率和谐振腔中较大的无功电流会显著降低变换器的工作效率。Burst模式是一种可有效提高变换器轻载效率的方法。但传统Burst模式会造成谐振腔电压电流剧烈振荡进而增加损耗,甚至引发变压器饱和。该文推导半桥LCC变换器不同模态的简化状态子轨迹。在此基础上,提出半桥LCC变换器的Burst模式简化状态轨迹控制策略。该策略通过控制半桥开关管的开关时间,保证半桥LCC变换器谐振腔无振荡,使变换器稳定可靠地工作在高效率状态。此外,针对极轻载条件下Burst模式的噪声污染问题,该文基于半桥LCC变换器Burst模式的简化状态轨迹,进行能量求解和改进控制,保证半桥LCC变换器Burst模式工作频率在人耳敏感的频带以外,抑制噪声的产生。最后,搭建实验装置对所提出的半桥LCC变换器Burst模式进行实验验证。实验结果证明,上述方法显著提高了半桥LCC变换器的轻载工作效率,消除了谐振腔的剧烈振荡和噪声污染。

When the half-bridge LCC resonant converter works in light load mode,its high switching frequency and large reactive power in the resonant circuit reduce the efficiency of the converter significantly.Burst mode is an effective method to improve the light load efficiency of the converter.However,the conventional burst mode will cause the voltage and current to oscillate and further increase the loss,and even cause the transformer to saturate.In this paper,the simplified state sub-trajectories of different modes of half-bridge LCC converter were derived,and the state trajectory control strategy of the burst mode for half-bridge LCC converter was derived.By controlling the switching time of the half-bridge,there is no oscillation during burst off time,which makes the half-bridge LCC converter work in high efficiency stably.Besides,considering the noise pollution problem of burst mode under extremely light load conditions,the improved control is proposed based on the simplified state trajectory to ensure that the LCC converter works outside the audible band to avoid noise.Finally,an experimental prototype was built.The experimental results show that the proposed method can significantly improve the light load efficiency of the half-bridge LCC converter,and eliminate the oscillation and noise pollution of the resonant circuit.