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.