通过试验发现，磁记忆检测信号与构件的损伤状态之间具有明显的相关性，通过检测法向磁场的过零点可以实现对构件早期损伤的检测。

It is found that the MMM signal has apparent relationship with the damage, and that by the zero value of the MMM signal, the hidden damage in the ferromagnetic component can be detected.

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因此提出了一种改进的过零检测算法：零点斜率测频法。

An improved method which measures frequency through the slope of zero based on the cross-zero detecting is presented.

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本文采用反电动法控制永磁直流无刷电机，是通过检测反电动势过零点获得转子位置实现无传感器控制。

Using Back-EMF method to control BLDCM, it can realize sensor-free control method by detecting the zero point of EMF in this paper.

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