Stability Enhancement of DC Cascaded System Including CPLs by Using Nonlinear Inductor in Source-Interface DC-DC Converter

This paper proposes an enhanced stability scheme for source-interface DC-DC converter in the cascaded systems with constant power loads (CPLs) by using magnetic powder core fabricated nonlinear inductor (NI). CPLs are known for their negative incremental impedance (NII) characteristics, which creates a mismatch between the source-interface DC-DC converter and load converter impedances, leading to system destabilization. To address this issue, this paper introduces the use of the NI in the source-interface DC-DC converter to enhance system stability. Initially, a canonical form of the system is established to access the control-to-output transfer function. Subsequently, stability criteria for the control-to-output characteristics of the system are established to derive the stable power range plane in which the crucial role of the NI is highlighted in enhancing stability. Eventually, the effectiveness of the proposed scheme is verified by the experimental results.