Open-Circuit Fault Diagnosis of Rotating Rectifier by Analyzing the Exciter Armature Current

Based on the differences between waveforms of asynchronous exciter three-phase armature currents with the rotating rectifier under various working conditions (healthy and open-circuit conditions), a fault diagnosis method of rotating rectifier is proposed in this article. To describe these differences, the conceptions of ratio, residual, and sum are defined, and corresponding calculation functions are created. Through the analysis of the asynchronous exciter armature current with the rotating rectifier under five categories of working conditions, three-phase ratios and residuals are calculated by observing which the fault type can be confirmed. Then the faulty diode(s) location is achieved by the sum value. The experimental results show good agreement with theoretical analysis and simulation results, which verifies the feasibility and effectiveness of the proposed method.

I. Introduction

The BRUSHLESS wound-rotor synchronous starter/generator (BWSSG) is widely used in many applications, such as aircrafts, submarines, and power plants [1]–[4]. The BWSSG is made up of three parts: an asynchronous exciter (AE), a rotating rectifier, and a main generator (MG), as shown in Fig. 1. Generally, the rotating rectifier mounted on the rotor shaft is a three-phase full-bridge diode rectifier, and fed directly into the filed winding of the MG. Through the rotating rectifier, the AE provides the excitation current for the MG both in the starting and generating modes, which shows that the rectifier plays a significant role in the system [5], [6]. In other words, the diode(s) getting faulty will decrease the output current capability, which may lead to the startup failure and degrade the electricity generation performance. Fig. 1.

Structure of the BWSSG.