An Improved Feedforward Controller for Minimizing the DC-link Capacitance in a Brushless Synchronous Generator based Aircraft DC Power System

This paper proposes feedforward control improvements for minimizing the DC-link capacitance in a brushless Synchronous Generator (SG) based aircraft DC power system. The proposed techniques involve an output power based feedforward compensation for the DC-link voltage regulation control and a feedforward steady-state duty cycle compensation for the exciter SG field current control. This control scheme helps to meet the tight MIL-STD-704F transient voltage requirements for 270V aircraft DC power system with minimum DC-link capacitance. The proposed controller is validated through simulation and Controller Hardware-in-Loop (C-HIL) experiments for a 50KVA three-stage brushless SG system model with 600 ¼F DC-link capacitance and results are provided at different speeds of the machine.