双缘COT调制数字电压型控制Buck变换器分析

为了提高恒定导通时间(constant on-time, COT)调制开关变换器的输出电压稳压精度,基于COT调制和双缘脉冲宽度调制的特点,提出了一种工作于电感电流连续导电模式(continuous conduction mode, CCM)的开关变换器双缘恒定导通时间(dual-edge constant on-time, DCOT)调制方法.介绍了DCOT调制数字电压型控制Buck变换器的工作原理,对比分析了COT调制和DCOT调制数字电压型控制Buck变换器的稳态性能和瞬态性能.结果表明:相比于COT调制,采用DCOT调制的数字电压型控制Buck变换器提高了输出电压的稳压精度,其大小为输出电压纹波峰峰值的50%,且瞬态调节时间减少了1个开关周期.最后,通过仿真和实验结果证明了理论分析的正确性. 

Analysis of Digital Voltage-Mode Controlled Buck Converter with Dual-Edge Constant on-Time Modulation

To improve the accuracy of output regulation in a switching converter with constant on-time (COT) modulation, dual-edge constant-on time (DCOT) modulation scheme for the switching converter in continuous conduction mode was proposed, based on the characteristics of COT modulation and dual-edge pulse-width modulation. The principle of digital voltage-mode controlled Buck converter with DCOT modulation was introduced. Moreover, its steady-state and transient performances were analyzed and compared with those of digital voltage-mode controlled Buck converter with COT modulation. The results show that digital voltage-mode controlled Buck converter with DCOT modulation improves output-regulation accuracy by 50% of peak-to-peak value of output voltage ripple and reduces the transient regulation time by one switching cycle. Finally, the simulation and experimental results validate the correctness of the theoretical analysis.