A Two-Stage Isolated AC-DC Converter for More Electric Aircraft

Nowadays, increasing use of power electronics at industrial applications, using active power electronic converters has become increasingly popular in more electric aircraft (MEA) application. In airplanes due to presence of sensitive loads and low space, the use of active three-phase rectifiers instead of conventional transformer rectifier units (TRUs) becomes more interesting. In this paper, a two-stage converter topology with a VIENNA rectifier in the first stage following a DC-DC converter and a high-frequency transformer in the second stage is proposed to obtain a regulated 28 V
DC
output voltage. In the proposed topology the stepped-up DC voltage of VIENNA stage becomes pulsating voltage by a DC-DC converter and will be stepped-down by a high frequency transformer. The resulting topology has a more compact design and higher efficiency and lower total harmonic distortion (THD) with output isolation compared to conventional TRUs. The control scheme for VIENNA rectifier is a double-loop current-voltage controller based on hysteresis current control that is a simple scheme and more advantageous compared to other control methods for rectifier units. In order to verify the effectiveness of the converter simulation results will be presented which show a power factor of 0.996 and input current total harmonic distortion (THD) about 4% and conversion efficiency more than 95 percent.