The integration of Constant Power Loads (CPLs) in Medium Voltage Direct Current (MVDC) electrical systems poses significant challenges for system stability due to the presence of tightly controlled converters. This paper addresses the modeling and analysis of such instabilities through modal decomposition and small-signal stability techniques. Mitigation strategies are proposed based on the design of SISO and MIMO decoupling controllers. The research starts from the formulation and linearization of the nonlinear dynamic equations of a DC-link supplying a CPL, followed by a decomposition into symmetric and antisymmetric modes to highlight the system's dynamic behavior. The approach is then generalized to systems with n converters using a transformation matrix that enables scalable modal separation. A dedicated procedure is proposed for constructing a dynamic decoupling matrix to minimize cross-couplings in MIMO systems. Regulator dynamics and asymmetry effects are included. The Frobenius norm quantifies interconnection strength, guiding control strategy selection. This work supports robust MVDC system design, with applications in naval, aerospace, and terrestrial microgrids.
