Starter/generator employing resonant-converter-fed induction machine. I. Analysis

A new procedure to start a jet engine (JE) and to generate power by means of a single induction machine (IM) directly coupled to the turbine is presented. The JE is brought to an initial speed by the motoring operation of the IM. Later, the IM is taken into generating mode and the turbine is applied to its excitation. The turbine catches up and starts to drive the induction generator (IG). The generated power is converted to a three-phase, 400 Hz voltage-regulated bus via a double stage power conversion utilizing a 20 kHz parallel resonant high frequency AC link and pulse density modulated converter technology. Independent of the engine speed, a constant amplitude and constant frequency three-phase voltage-regulated AC bus is formed and maintained by the proper control of the power converters. The feasibility of operation of such a system has been demonstrated in software where the JE turbine is modeled and replaced by a DC machine. An introduction, background, operation principles of the overall system, and the related software simulations are presented and discussed.