Power Transistors’ Fault Diagnosis Method of SR S/G for More Electric Aircraft With Cross-Leg Current Analysis

Abstract

More electric aircraft (MEA) is expected to optimize aircraft performance, and the switched reluctance starter/generator (SR S/G) system is recommended as a key technique for MEA implementation. In order to improve safety and reduce aircraft maintenance time, it is necessary to quickly identify and locate electrical faults in the electrical system. This article proposes a fault diagnosis method for the power converter of SR S/G for MEA. Through the distortion analysis of cross-leg current, the proposed methods are capable of detecting both open circuit (OC) and short circuit (SC) of power transistors in the asymmetric half-bridge converter (AHBC). Each phase current can be calculated by taking the absolute value of the cross-leg current. Different faults are preliminarily detected through the sudden change of current. After monitoring the fault occurrence, different switching states and digital cross-leg current will be recorded, which determines the fault type and the fault power transistor. The proposed method does not require additional hardware and complex calculations so that the methods have good robustness and reliability. In addition, the proposed methods are suitable for SR S/G operating at various control modes. A three-phase 12/8 structure SR S/G is adopted in this article, and the method is applicable for the SR S/G. Moreover, experiments carried out in different working modes validate the feasibility and effectiveness of the proposed fault diagnosis method.