PCMC Boost变换器与EMI滤波器的级联设计

Cascaded Design of EMI Filters with PCMC Boost Converters

为避免电磁干扰(EMI)滤波器与峰值电流模式控制下Boost变换器级联时的性能下降,同时保持级联后的稳定性和动态性,提出利用状态空间平均法来构造Boost变换器的小信号模型,以获得阻抗等传递函数集;设计了使变换器环路增益具有4 kHz的控制带宽和67°的相位裕度的比例积分(PI)控制器;在Matlab上设计的EMI滤波器达到相关标准规定的噪声抑制,通过图形化阻抗比判据结合奈奎斯特稳定判据来评估级联系统的稳定性,并对构成闭环的级联系统进行了仿真和建模.仿真和实验结果证明,文中设计的级联型EMI滤波器不仅能抑制噪声电流,达到欧盟EMC标准,而且保持了级联系统的稳定,动态性能良好,从而提供了一个在PCMC Boost变换器应用的解决方案.

In order to avoid the performance degradation of EMI filters with PCMC Boost converters under peak current-mode control and to guarantee the stability and robustness of the cascaded system, the state-space averaging method is used to construct a small-signal model of the converter for obtaining the transfer function set of such parameters as impedance. Then, a PI controller, whose loop gain is of a control bandwidth of 4 kHz and a phase margin of 67°, is designed. Moreover, an EMI filter corresponding to the noise suppression stipulated by relevant standards is designed with Matlab, with its stability being evaluated by the graphical impedance ratio and the Nyquist stability validation. Finally, a closed-loop cascaded system for simulation and modeling is constructed. Simulated and experimental results indicate that the designed EMI filter can not only suppress the noise current to the acceptable level stipulated by EMC standard but also guarantee the stability and dynamic performance of the cascaded system. It is thus concluded that the cascaded approach is effective in the application of PCMC Boost converters.