Analysis of Stator Internal Phase-to-Phase Short Circuit in the 12-Phase Synchronous Generator With Rectifier-Load System

The 12-phase synchronous generator-rectifier system is widely used in mobile platforms that require high system security. In the system, the stator internal short circuit is a kind of common fault that may compromise the security of the generator. This paper gives detailed analysis on the internal phase-to-phase short-circuit faults, including the faults within the same group of Y-connected phases and those between different groups of Y-connected phases in the 12-phase system. A multiloop mathematical model is built to calculate all the voltages and currents when the faults occur in the system. In the model, the additional short-circuit loop between different phases, as well as the fault effects on both the air-gap magnetic field and the circuit topology of the system, are taken into account. Then a series of fault experiments are carried out on a 12-phase model machine. In view of the good agreement of experiment and simulation results, the effectiveness of the mathematical model and the simulation method is confirmed. Finally, the electric characteristics of the internal phase-to-phase short-circuit faults are summarized, and the fault mechanism is revealed.

I. Introduction

With the development of the power electronic technology, AC generator connected with AC/DC converter supplies DC power in many isolated power systems [1]– [5]. The multiphase generator-rectifier systems have many advantages compared with the traditional three-phase generator-rectifier systems [1]. For example, providing the voltage with 24 pulses on the DC side, the 12-phase synchronous generator with rectifier load system has smaller ripple in the output voltage than the traditional three-phase system. And there is smaller distortion in phase voltages on the AC side as well as smaller EMI. Besides, the 12-phase rectifier system could also increase the power density and efficiency, which makes it an optimal choice to supply high-power and high-quality DC source in ships, aircraft and other mobile platforms.