The Applicability of Electrically Driven Accessories for Turboshaft Engines

Abstract

Improved electrical power generation and actuation systems offer new design approaches for performing the engine control and accessory functions in helicopter propulsion systems. Present helicopter technology utilizes turboshaft engines with mechanically driven accessories. These accessories perform the functions of starting, fuel and lube pumping, variable stator actuation, and inlet particle separation. This paper discusses the applicability of replacing the mechanically driven accessories with their electrically driven counterparts. An electric accessory system is defined, which includes a switched reluctance starter/generator and its associated control unit; an electric pumping and actuation system; and the engine mounting for the starter/generator. A comparison between the mechanically and electrically driven accessory systems is performed on the basis of cost, weight, and reliability. Experience to date with switched reluctance machines and electrically driven turbo shaft accessory systems is summarized. The benefits of electrically driven accessories are shown and recommendations for future activity for his important technology are discussed.