Hybrid Electric Propulsion Using Doubly Fed Induction Machines

Abstract

This paper considers a hybrid electric propulsion architecture where most of the electric power is transmitted from the generator to the motors without conversion. Doubly fed induction machines are chosen for generation and propulsion, due to their ability to operate over a range of speeds using reduced-size power converters. The focus of this paper is on the presentation and demonstration of a strategy that allows for the stable and independent operation of multiple motors using the power produced by a single generator. The control methodology includes synchronization, soft-start, and closed-loop speed control of each motor as a means of controlling output thrust. The validation is carried out on a low-power test bed using fractional horsepower machines. The success obtained at a small-scale suggests that the proposed strategy would be worth evaluating at higher power levels, with a potential application to commercial transport aircraft.