谷值电流型脉冲序列控制反激变换器分析

Valley Current Mode Pulse Train Control for Flyback Converters

工作于电感电流连续导电模式(CCM)的脉冲序列控制反激变换器存在的低频振荡现象,严重影响了脉冲序列控制开关变换器的稳态及瞬态性能。为消除该低频振荡现象,提出了开关变换器的谷值电流型脉冲序列控制技术。在一个开关周期内,谷值电流型脉冲序列控制开关变换器的励磁电感储能变化量为零,有效解决了脉冲序列控制CCM反激变换器的低频振荡问题。论文对谷值电流型脉冲序列控制CCM反激变换器的工作原理及控制策略进行了系统、深入的分析。研究了不同负载时控制脉冲循环周期内的脉冲组合方式和输出电压纹波。设计实现了谷值电流型脉冲序列控制器,仿真与实验结果验证了理论分析的正确性及控制器设计的可行性。

For pulse train(PT) controlled switching converter, when it operates in continuous conduction mode(CCM), the low-frequency oscillation will occur. The low-frequency oscillation makes the state and the transient performance of the converter worse. In order to eliminate the low-frequency oscillation phenomenon existed in traditional PT controlled switching converter operating in CCM, a valley current mode pulse train(VCM-PT) control technique of switching converters is proposed. When VCM-PT controlled flyback converter operates in CCM, the variation of the energy stored in the transformer is zero in a switching cycle. Thus the VCM-PT controlled CCM flyback converter can effectively inhibit the low-frequency oscillation. In this paper, the principle and control strategy of VCM-PT control are studied with flyback converter operating in CCM as an example. The output voltage ripple and the combination of control pulses in a pulse train repetition cycle are analyzed. The pulse train controller is designed. Simulation and experimental results verify the theoretical analysis and the feasibility of our controller design.