PDM变换器的等效电路模型与小信号分析

Equivalent circuit modeling and small-signal analysis for pulse-density-modulated inverter

针对基于脉冲密度调制(PDM)控制方式的DC/AC变换器,并根据电路等效原理,建立了PDM变换器的等效电路模型。根据该等效电路模型,采用状态空间平均法,分别建立了连续导电模式(CCM)和间断导电模式(DCM)下PDM变换器的状态空间平均方程,分析了基于输出电流幅值的动态小信号特性,最后建立了PDM变换器的小信号模型。该模型确切反映了变换器的动态特征,为PDM电源的小信号分析及其控制系统设计提供了理论支持。该模型还为正弦波电流幅值调制(SCAM)提供了理论依据。

The control strategy of the DC/AC inverter based on Pulse-Density-Modulation （PDM） is briefly introduced, and the equivalent circuit of the proposed inverter is modeled in this paper. According to the equivalent circuit modeling as well as applying the average-state-space method, the average-state-space equations for PDM inverter are respectively built up both in Continuous Conducting Mode （CCM） and in Discontinuous Conducting Mode （DCM）. Using the small-signal analysis method based on the average-state-space equations, small-signal models of the PDM inverter are established on the conditions both DCM and CCM. The small-sig- nal models represent factually the dynamic characteristics of the PDM inverter and also provide a valid researching method for PDM inverter by means of its output current amplitude. In addition, it is helpful to analyze and/or design the kindred control systems based on Sinusoidal Current-Amplitude- Modulation （SCAM）.