High Frequency Voltage Injection based Fault Detection of Rotating Rectifier for Three-stage Synchronous Starter/Generator in the Stationary State

Based on the rotating high frequency voltage injection, a novel fault detection method for rotating rectifier of the three-stage synchronous starter/generator in the stationary state has been proposed. The high frequency voltage is imposed on the stator windings of the main generator and the high frequency current feature signal extracted on the stator windings of the main exciter is used for fault detection. To obtain the feature signal, the high frequency current signal in the main exciter with the rotating rectifier under different working conditions has been analyzed. Compared with existing fault detection techniques, the proposed method shows little dependency on the rotor position information and the parameters of machines. Experimental results verify the feasibility and effectiveness of this method.

I. Introduction

With the development of more/all electric aircrafts, the three-stage synchronous generator, widely used in current aircraft power system, has been fully considered as candidate to be integrated starter/generator due to its high safety and low cost in maintenance [1]–[3]. Fig. 1 shows the typical structure of three-stage synchronous starter/generator (TSSG) with three-phase exciter, which consists of the pre-exciter (PE), the main exciter (ME), the rotating rectifier and the main generator (MG). The PE is a permanent magnet generator which does not connect to the system in the startup process and a wound-rotor synchronous machine serves a MG. The ME is a rotating-armature electrically excited synchronous generator with three-phase field windings. Since the rotating rectifier constructs the bridge between the ME and the MG, the safety of the rotating diodes strongly affects the function of TSSG and the safety of the aircraft [4]. In addition, the failure rate of rectifier diodes is higher than other components for the influence of centrifugal force and thermal stress. Therefore, it draws high demand on the failure detection of rectifier diodes especially before the TSSG starts. Fig. 1.

Structure of the wound-rotor synchronous starter/generator with a three-phase brushless exciter.