基于输出电流轨迹的机车逆变器开路故障在线诊断方法

为了适应车载逆变器负载变化范围大的特点,兼容现有变流器的应用场合,保障行车安全,同时提高逆变器开路故障的检修效率,提出一种基于两相输出电流轨迹的功率管开路故障在线诊断方法。在三相基本平衡的情况下,用解析的方法推导得到两相电流合成的轨迹为笛卡尔坐标系下的一个椭圆,椭圆的倾角和离心率与电流幅值无关,其大小与电流幅值成正比。通过理论分析证明,对于单管开路故障和两管开路故障共21种故障类型,电流轨迹有21种不同的特征,对这些轨迹进行观测或辨识可以达到隔离故障的目的。同时,提出不受负载变化影响的故障定位方法。最后,利用d SPACE实验平台验证了该数学模型的准确性以及在线诊断方法的有效性。

An Online Diagnostic Method Based on Output Current Locus for Open-Circuit Faults of Inverters

Considering the special situation of locomotive inverters, an online diagnostic method for open-circuit faults of inverters is proposed to ensure the traffic safety, and improve the maintenance efficiency. Assuming that two output currents have equivalent magnitudes, the locus of these two currents is proved to be an ellipse by restrict mathematic inference. The obliquity and the centrifugal rate of the ellipse are independent of the current amplitude, while the size of the ellipse is proportional to the current amplitude. Through the theoretical analysis, it is found that any single switch open-circuit fault or double switches open-circuit fault corresponds to a unique locus characteristic. By observing or identifying the locus, fault can be isolated accurately. It is certified that load variation will not affect the method. Finally, the accuracy of the mathematical model and the validity of the online diagnosis method are verified by the dSPACE platform.