H∞ Robust Control of Ramjet Engine

Abstract

Ramjet engine presents the simplest type of jet engines since it does not possess moving parts, like compressors, shafts and turbines. Besides its simplicity, it provides efficient performances in a wide range of altitudes, supersonic speeds and angles of attack. In order to provide desirable performances during exploitations, a ramjet engine must be operated by means of feedback control. This paper presents the design of robust H∞ controller for thrust controller of the ramjet engine. Linear model of the engine is obtained by numerical solution of nonlinear equations which describe processes in the engine. This model is found for operation points in the operational envelop, defined by a single altitude, a single Mach number and a single angle of attack. The thrust controller is developed by using the H∞ control methodology for single representative operation point. After that, obtained controller is reduced to the PI controller and its performances are compared with performances of the full order controller. Also, these controllers are applied to other operation points which closed-lop performances are then compared. The analysis of necessity for the gain scheduling implementation is performed.