中文摘要：

为了解决断续电流模式下的Buck直流变换器建模困难的问题,针对这个离散的、时变的、非线性系统,提出引入虚拟开关数将一个开关周期中的三种电路拓扑统一到一组状态空间方程中。在应用动态相量法时,为保证模型的合理性,动态相量模型中保留傅里叶级数中的直流量、基频分量和二次分量,讨论虚拟开关占空比的取值,建立其非线性、大信号、时不变模型。仿真结果表明,动态相量模型接近于时域模型,验证了动态相量模型的合理性。

英文摘要：

In order to solve the problem of modeling on the Buck DC-DC converter working in discontinuous conduction mode（DCM）,which is a discrete,time-varying,nonlinear system,three circuit topologies in a switching cycle are unified to a set of state space equations by a virtual function.When using the dynamic phasor,the DC component,fundament frequency component and second harmonic components of Fourier series are retained in order to ensure the rationality of the model.The value of the virtual switch duty cycle is discussed and a non-linear,large signal,time-invariant model is built.Simulation results show that the dynamic phasor model is similar to the time-domain model.Its validation is also proved.