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This paper introduces a capacitive differential wireless power transfer (DWPT) architecture to efficiently charge an array of unmanned aerial vehicles (UAVs) on a telecom tower as a UAV airport. A switched capacitor (SC) based ladder differential power processing (DPP) converter is utilized to regulate the voltages of multiple series-stacked wireless charging modules from a high-voltage DC bus. The half-bridge switches in the DPP circuit are reused as an inverter in a capacitive power transfer (CPT) system with a double-sided LC-compensation network, featuring reduced semiconductor component count and device stress. The capacitive coupling plates are integrated into landing platforms and UAV landing gears for high coupling capacitance and minimum influence on aerodynamics. An experimental prototype and related design considerations are presented to achieve high efficiency and ensure robust performance against misalignments. The DWPT architecture is verified through an 8-port DPP converter supporting up to 8 CPT charging modules. 

High performance computing needs high performance power electronics. This paper presents the design of an ultra-efficient series-stacked hard-disk-drive (HDD) data storage server with a multiport ac-coupled differential power processing (MAC-DPP) architecture. A large number of HDDs are connected in series and ac-coupled through a multi-winding transformer with a single flux linkage. The MAC-DPP architecture offers very low power conversion stress, can achieve extremely high efficiency, and can reduce the magnetic size and the component count. A hybrid time-sharing and distributed phase-shift control strategy is developed to modulate the ac-coupled multi-input-multi-output (MIMO) power flow. A 10-port MAC-DPP prototype was designed to support a 300 W data storage system with 10 series-stacked voltage domains. The MAC-DPP converter was tested with a 50-HDD 12TB testbench, which can maintain normal operation of the server against the worst hot-swapping scenario. The 300 W MAC-DPP prototype can achieve 99.7% peak system efficiency and over 100 W/in 3 power density.