An Enhanced Controller for Four Leg Inverter-fed Loads in an Aircraft Power System

This paper proposes a novel controller for improving the output voltage regulation of a three phase four-leg inverter feeding balanced and unbalanced ac loads in an aircraft power system. Conventional autonomous three phase inverter control uses open loop reference phase angle to perform transformation from stationary to synchronously rotating reference frame and vice versa. However, this method can cause inaccuracy in output voltage tracking under heavy loads, due to phase delay caused by significant voltage drop in the output filter and long cable impedances from inverter to load end. To obtain accurate tracking and dynamic response of output voltage with respect to the commanded reference, control improvement based on forward transformation of the sensed feedback output voltage and current using PLL angle is proposed. The proposed strategy is verified through simulation, and also the Controller Hardware-in-Loop(C-HIL) results are provided to show the effectiveness of the proposed control improvement.