Modular Power Electronics System of DC Microgrids and transportation (EV/rail/ships/aircraft) Systems

DC microgrids and electrified transportation systems (EVs, rail, ships, and more-electric aircraft) increasingly require high step-up/step-down conversion, bidirectional power flow, and compact hardware under wide voltage and load variations. This ODLP lecture focuses on switched-inductor (SL), switched-capacitor (SC), and hybrid SL–SC modular converter systems as a topology-driven solution set for these demands. The primary emphasis is on a system topology taxonomy covering classical SC charge-pump families, multilevel SC ladder structures, SL cell-based boost converters, quadratic and cascaded SL stages, and hybrid SL–SC systems suitable for the targeted applications.

Key circuit-level mechanisms are highlighted—voltage-lift action, capacitor stacking, inductor reconfiguration, and modular cell addition—to show how conversion gain, semiconductor stress, ripple, and component count scale with the number of cells. The lecture then maps topology choices to system application constraints, including regulated DC bus formation for DC microgrids, traction DC-link interfacing, onboard auxiliary power supplies, and fast transient response during regenerative operation and load steps. Practical design tradeoffs for SL/SC systems are addressed, including input-current ripple shaping via interleaving, capacitor charge balancing, startup and inrush mitigation, efficiency versus conduction loss in high-gain operating modes, and EMI/thermal implications associated with high di/dt and dv/dt loops. Finally, the session outlines modular integration strategies—cell redundancy, rapid replacement, and fault-tolerant operation—enabling scalable and upgradeable power electronic systems for next-generation DC microgrids and transportation electrification.