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Preliminary testing of a 125kW power inverter for a switched reluctance aircraft engine starter/generator system has been completed and system testing of the complete starter/generator system has been initiated. The starter/generator employs a single switched reluctance machine (SRM) and a generating system architecture that produces two separate 270Vdc buses from that single SRM The machine has six phases with three of the phases connected to one inverter supplying 125kW to one 270Vdc bus while the other three phases are connected to a second inverter supplying 125kW to the other 270Vdc bus. Each bus has its own EMI filter and controller in addition to its own inverter. Two types of inverters have been developed, one type employs MOS Controlled Thyristors for the controlled switches and the other type employs Insulated Gate Bipolar Transistors. The link capacitor bank for each inverter employs multilayer ceramic capacitors to meet the starter/generator's temperature requirements.

The design results for a 250 kW switched reluctance aircraft engine starter/generator system power inverter are presented. The starter/generator employs a single switched reluctance machine and a generating system architecture that produces two separate 270 Vdc buses from that single switched reluctance machine. The machine has six phases with three of the phases connected to one inverter supplying 125 kW to one 270 Vdc bus while the other three phases are connected to a second inverter supplying 125kW to the other 270 Vdc bus. Each bus has its own EM1 filter and control in addition to its own inverter. Two types of inverters have been developed, one type employs MOS Controlled Thyristors (MCTs) for the controlled switches and the other type employs Insulated Gate Bipolar Transistors (IGBTs). High-current 500 A peak turn-off MCT modules were specifically developed for the MCT inverters. Two of these modules are placed in parallel to form the required 1000 A switches.

The work reported in this paper has been conducted by General Electric Company and Sundstrand Corporation as part of a contract sponsored by the USAF, Wright Laboratories, and WPAFB under contract no. F33615-90-C-2052. The objective of this contract is to prove the feasibility of an integral starter/generator (IS/G) through the preliminary design stage and demonstrate the starter/generator technology in the externally-mounted version (EIS/G) using switched reluctance (SR) machine technology. This paper reports on the detailed design and analysis of the EIS/G. The analysis and design encompassed definition of requirements and constraints, electromagnetic design, thermal analysis, mechanical stress and fit analysis, bearing and critical speed analysis, and mechanical layout and packaging.

The work reported in this paper has been conducted by GE-Aircraft Engines as part of a contract sponsored by the USAF, Wright Laboratories, WPAFB, under Contract No. F33615-90-C-2052. The objective of this contract is to prove the feasibility of an Integral Starter/Generator (IS/G) through the preliminary design stage and demonstrate the starter/generator technology in the externally mounted version utilizing switched reluctance machine technology. This paper will report on the progress for the IS/G through the preliminary design stage. The key points of the electrical machine design, integration design, and impact on the engine dynamics will be discussed. The key message of the results obtained is, that the integration of such a machine into an existing engine is practical and that no new center-line engine design is necessary to bring this technology to flight demonstration.

The idea of an all electric aircraft (secondary power) has been around for many years. Its benefits in terms of weight and operational cost savings have been in-creasingly better defined over time. Little has hap-pened, however, toward realizing this system, pro-bably, because one of the key components of such a system, the electrical generator has not achieved the acceptance in the engine world to warrant any more definite steps toward the all electric system. Support and size considerations dictate that this generator be integrated into the gas turbine (Integral Starter/Generator - IS/G). The last IS/G studies in the middle and late 70's found that even the best technology of the day, the PMG technology, did not solve all the concerns about its application to the IS/G task. Developments in the power electronics area since then have made an old electrical machine concept, the switched reluctance machine, a viable alternative for the integral starter/generator function.