【摘要】 分析了具有PI控制的Buck变换器中的低频振荡现象。利用离散模型研究了Buck变换器中的低频振荡现象,结果表明系统产生低频振荡的原因是状态变量发生了Hopf分岔。采用状态空间平均的小信号模型分析了变换器的稳定性,它所确定的稳定运行临界点恰好与从离散模型得到的Hopf分岔点的位置相吻合,这表明线性的小信号平均模型可以准确的预测低频振荡的参数稳定域。通过分析发生低频振荡后的频率和幅值,结果表明Buck变换器中的低频振荡现象实际上是一种自激振荡。最后通过数值仿真和电路实验验证了理论分析的合理性。更多还原

【Abstract】 Low frequency oscillation in a closed loop Buck converter implementing proportional-integral(PI) controller was investigated.Firstly,the stability of closed loop Buck converter was studied by discrete models.The results show that low frequency oscillation implies the Hopf bifurcation occurrence.Then,the stability of the closed loop buck converter was analyzed by small signal averaged models.It is presented that the critical point of stability obtained by averaged models is consistent well with the Hopf bifurcation point,which shows that parameter stability domain of the low frequency oscillation can be estimated by linear small signal averaged models.Furthermore,the amplitude and frequency of the low frequency oscillation were investigated and the results indicate that the low frequency oscillation can be regard as one kinds of self-excited oscillation.Finally,the proposed approach is verified by numerical simulation.更多还原