Approximate Discrete-Time Small-Signal Models of DC–DC Converters With Consideration of Practical Pulsewidth Modulation and Stability Improvement Methods
Approximate Discrete-Time Small-Signal Models of DC–DC Converters With Consideration of Practical Pulsewidth Modulation and Stability Improvement Methods
复制标题
DOI：
10.1109/tpel.2018.2864924
复制
发表时间：
2019-05
影响因子：
6.7
通讯作者：
Xin Li;X. Ruan;Xiaoling Xiong;Mengke Sha;C. Tse
中科院分区：
文献类型：
--
作者：
Xin Li;X. Ruan;Xiaoling Xiong;Mengke Sha;C. Tse
众所周知，平均模型不足以描述前沿和后沿脉宽调制 (PWM) 对 DC-DC 转换器稳定性的影响。本文利用降压、升压和升降压转换器的离散时间模型，并考虑前沿和后沿 PWM 的影响，推导了离散时间域中占空比到输出电压传递函数 Gvd(z) 的一般表达式。基于dc-dc变换器的低通特性和矩阵函数的相关性质，推导了频域Gvd的近似表达式，该表达式简单且精确，可达开关频率的一半。使用近似 Gvd，分析了三种基本 DC-DC 转换器在前沿和后沿 PWM 下的稳定性。结果表明，降压转换器的稳定性不受 PWM 类型的影响，而前沿调制升压和升降压转换器比后沿调制转换器具有更好的稳定性。由于后沿调制在 PWM 控制器集成电路中普遍采用，因此提出将调制信号零阶保持 (ZOH) 方法和电感电流反馈控制方法用于后沿调制升压和升降压转换器，以达到与前沿调制转换器相同的效果。构建了实验降压和升压转换器，以验证所提出模型的准确性和所提出控制方案的有效性。
It is generally known that averaged models are inadequate in describing the effects of leading-edge and trailing-edge pulsewidth modulation (PWM) on the stability of dc–dc converters. In this paper, using discrete-time models of the buck, boost, and buck–boost converters and considering the effects of leading-edge and trailing-edge PWM, the general expressions of the duty-cycle-to-output-voltage transfer function, Gvd(z), in the discrete-time domain are derived. Based on the low-pass characteristics of the dc-dc converters and related properties of the matrix functions, approximate expressions of Gvd in the frequency domain are derived, which are simple and accurate up to half the switching frequency. Using the approximate Gvd, the stability of the three basic dc–dc converters under leading-edge and trailing-edge PWM is analyzed. It is shown that the stability of the buck converter is unaffected by the type of PWM, while the leading-edge modulated boost and buck–boost converters have better stability than the trailing-edge modulated ones. Since the trailing-edge modulation is commonly available in PWM controller integrated circuits, the modulation signal zero-order holding (ZOH) method and the inductor current feedback control method are proposed for use in the trailing-edge modulated boost and buck–boost converters to achieve the same effect of leading-edge modulated converters. Experimental buck and boost converters were constructed for verification of the accuracy of the proposed model and the validity of the proposed control schemes.