Mark Alan Preston

Flux-current methods for SRM rotor position estimation

A family of nonintrusive methods is presented for estimating the shaft angle of a switched reluctance machine. Such methods can be utilized for commutation control of the SRM (switched reluctance machine) thereby eliminating the requirement for a shaft position sensor. These methods rely on the machines inherent flux/current magnetic characteristics to infer rotor position from measurements of stator flux-linkage and current during normal phase excitation. Position estimation schemes are presented for SRMs in which both single and multiple simultaneous phases are excited. Also presented is a simulated sensing performance using measured SRM data processed according to the proposed position lumped-parameter estimation scheme.<<ETX>>

Integration of Magnetic Bearings in the Design of Advanced Gas Turbine Engines

Active magnetic bearings provide revolutionary advantages for gas turbine engine rotor support. These advantages include tremendously improved vibration and stability characteristics, reduced power loss, improved reliability, fault-tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural network design and advanced materials utilization will permit major increases in thrust to weight performance and structural efficiency for future gas turbine engines.However, obtaining the maximum payoff requires two key ingredients. The first key ingredient is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-density power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies and the test hardware currently in place for verifying the performance of advanced magnetic actuators, power electronics and digital controls. The second key ingredient is to go beyond the simple replacement of rolling element bearings with magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper approach to designing with composites, whereby the designer tailors the geometry and load carrying function of the structural system or component for the composite instead of simply substituting composites in a design originally intended for metal material. This paper describes methodologies for the design integration of magnetic bearings in gas turbine engines.Copyright