本文在高阶谱域研究故障诊断中非线性耦合特征提取,为了简化计算并得到有效的二次相位耦合特征,将双相干特征的计算转化到极坐标下进行.在分析故障机理的基础上,仅通过计算几个角切片来提取特征,该思想很易于推广到其它高阶方法中.最后,通过对轴承进行实验证明了该方法的有效性. In order to simplify the calculation and obtain effective secondary phase coupling characteristics, the calculation of bi-coherence features is transformed into polar coordinates.On the basis of analyzing the fault mechanism, Only by calculating several angular slices to extract features, the idea is easy to generalize to other higher-order methods.Finally, the experimental results show that the method is effective.