A Virtual RLC Damper to Stabilize DC/DC Converters Having an LC Input Filter while Improving the Filter Performance

The$LC$filter at the input of a dc/dc converter may cause instability when the converter is controlled as a constant power load (CPL) and one of the effective solutions is to reduce the output impedance of the$LC$input filter with different stabilization dampers. In this letter, the impact of these dampers on the$LC$filter is analyzed with two-port network analysis and it is found that the existing dampers all degrade the performance of the original$LC$input filter to some extent. In order to overcome this drawback, an$RLC$damper is proposed to stabilize the whole system while improving the performance of the$LC$input filter. In addition, this$RLC$damper is also designed to achieve high robustness against the parameter variations of the$LC$input filter. Furthermore, in order to avoid the power loss when implementing the damper physically, a control strategy for the CPL is proposed to implement the$RLC$damper as a virtual$RLC$($VRLC$) damper. The actual effectiveness of the$VRLC$damper and its impact on the CPL are fully evaluated via two-port network analysis as well. Finally, experimental results from a 100-W 48–24-V buck converter with an$LC$input filter are presented to demonstrate the proposed$VRLC$damper.