基于变换法的三角波阻容耦合PWM控制器非线性分析

Nonlinear Analysis of Triangular Wave RC coupled PWM Controller Based on Transformation Method

经阻容耦合的三角波载波信号会影响PWM控制器的传输特性。为研究阻容耦合后耦合信号的变化及其对PWM控制器传输特性的影响,通过对模型电路的分析并运用拉普拉斯(Laplace)变换方法求解出了三角波信号激励下阻容耦合电路的时域响应,再由具体数据仿真得出耦合参数对耦合效果和PWM控制器传输特性的影响并分析了产生这些影响的原因。通过仿真实验发现耦合电容取值偏小时,会导致耦合效果差,耦合波形失真严重,PWM控制器的传输特性变得非线性,从而使得PWM控制器的输出与期望偏差较大,不能满足要求,同时,耦合电路的时间常数偏小,也会使耦合效果差,影响PWM的传输特性。最后,还给出了工程应用中耦合电容和时间常数的参考值选择。

The triangular wave carrier signal via the resistance capacitance coupling will affect the transmission characteristics of the PWM controller. In order to study the change of coupling signal after resistance capacitance coupling and its influence on the transmission characteristics of PWM controller,In this paper,by analyzing the model circuit and using Laplace transform method,the time-domain response of the capacitance-resistance coupling circuit under the excitation of the triangular wave signal is solved,Then the influence of coupling parameters on the coupling effect and the transmission characteristics of the PWM controller is obtained by the simulation of the specific data,and the reasons for these effects are analyzed. Through the simulation experiment,it is found that the coupling capacitance value is too small,will cause the coupling effect is poor,which makes serious waveform distortion coupling,PWM controller output and the expected deviation,cannot meet the requirements,at the same time,the time constant of the coupling circuit is small,also can make the coupling effect is poor,affecting the transmission characteristics of PWM. Finally,the reference values of coupling capacitance and time constant in engineering applications are also given.