【摘要】 本文提出一种数字化混合控制方案,用于提高同步整流型Buck变换器的轻载效率。该方法重载时工作频率固定,轻载时能平缓地切换为恒定导通时间控制模式,以降低变换器的开关损耗。此外,不同于传统控制方法,所提方法根据驱动信号的导通时间和电感伏秒平衡关系精确预估电感电流过零点,使变换器工作于断续模式从而有效地降低轻载时的导通损耗。这确保同步整流Buck变换器在宽负载变化范围内有较高的转换效率。本文通过理论量化分析和实验对比验证了所提方法的可行性。更多还原

【Abstract】 A digital control scheme is proposed to improve the light-load efficiency for Buck converters with synchronous rectification. The method adopts a fixed switching frequency at heavy load, and smoothly switches to constant on-time control mode at light load for the purpose of reducing the switching losses. In addition, different from traditional control methods, the proposed approach dynamically estimates the inductor current zero crossing point accurately based on on-time of the drive signal and inductor volt-second balance to force converters work in discontinuous conduction mode, which significantly reduces conduction losses at light loads. These features ensure the converters own higher efficiency over a wide load range. Theoretical analysis and experimental results are provided to verify the proposed scheme.更多还原