Hardware Design Considerations for a 100 W USB Type-C Power Delivery in Aircraft Application

The in-seat charging has evolved to USB Type-C Power Delivery (PD) standard under the increasing power demand from various consumer electronics devices. The PD charger developed in this paper utilizes a totem-pole power-factor-correction (PFC) circuit as the front-end converter and the LLC resonant converter as the second stage. Three-level flying capacitor-based switching legs are applied in both stages to achieve a high density and efficiency in the aircraft application. The common-mode (CM) current induced by LLC due to the high switching frequency affects the sensing circuit of the PFC stage as they share one control unit. This further impacts the PFC input current quality through the control loop. More isolation stages and CM mitigation methods are needed for the PWM signal transfer of LLC so that the characteristics of the PFC stage will not be affected by LLC which is verified experimentally.