An ANPC based High-Power Medium-Voltage Triple Active Bridge (TAB) DC-DC Converter with Enhanced Modulations

A high-power medium-voltage isolated DC-DC converter is proposed aiming at onboard power distribution for the future electric aircraft. The proposed converter is designed using the triple-active-bridge architecture, which consists of an H-bridge on the low voltage side and two active neutral-point-clamped (ANPC) half-bridge in series on the high voltage side. With this configuration, a high voltage step-up ratio can be achieved while using cost-effective low voltage silicon carbide (SiC) devices. A full power prototype is developed to study the design feasibility, where the H-bridge takes an input voltage up to 1 kV and the converter output can reach up to 4 kV. An improved modulation strategy is presented to control the power flow with reduced voltage overshoot across transformer windings. Also, an algorithm is proposed to address the capacitor voltage imbalance. The feasibility of the proposed converter architecture and its modulation scheme are verified using both simulation and experimental studies.