Influence of PM wedges in Wound-Rotor Synchronous Starter/Generator

In the starting mode, the exciter hardly provides enough field current for Main Generator to start the aircraft engine, owing to the low speed. In this paper PM wedges are used in the Wound-Rotor Synchronous Starter/Generator to improve the excitation field. By magnetized at tangential direction, installed adjacent salient wound-rotor poles, these PM-wedges combine parallel flux path with rotor fielding windings. It can increase the electromagnetic torque in starter mode and improve the out-put voltage in the generator mode. What's more, this method can de-excite entirely in the short-circuit fault and keep the higher safety than other structures.

I. INTRODUCTION

With the development of More Electric Aircraft (MEA), the Integrated Starter/Generator (ISG) system based on a multi-stage brushless Wound-Rotor Synchronous Machine becomes more and more popular, owing to its high safety (when facing short circuit problem, the fielding current can be cut off) [1]. This ISG system is consist of a Pre-Exciter (PE), a Main Exciter (ME), a Rotating Rectifier and a Main Machine (MM) [2]-[4]. The ME provides the field current for MM through the rotating rectifier.