Abstract:

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 averagingmethod is used to construct a small-signal model of the converter for obtaining the transfer function set of such parametersas impedance.Then,a PI controller,whose loop gain is of a control bandwidth of 4 kHz and a phase marginof 67°,is designed.Moreover,an EMI filter corresponding to the noise suppression stipulated by relevantstandards is designed with Matlab,with its stability being evaluated by the graphical impedance ratio and theNyquist 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 tothe acceptable level stipulated by EMC standard but also guarantee the stability and dynamic performance of thecascaded system. It is thus concluded that the cascaded approach is effective in the application of PCMC Boost converters.

Key words: cascaded system, EMI filter, Boost converter, peak current-mode control, PI control