Flow meter

A flow meter, comprising:

• a rotating structure, having a shaft, a rotating element, and a magnetic element;
• wherein the rotating element can be driven by a fluid in a pipeline to rotate around the shaft, the magnetic element is arranged on the rotating element with two magnetic poles parallel to a tangent line of rotating circle of the rotating element;
• a sensing element, separated from the rotating structure by a distance, and comprising a first sensing unit and a second sensing unit, which respectively senses a magnetic field of the magnetic element in a first direction and a second direction to generate a first magnetic field component signal and a second magnetic field component signal;
• and
• a processing circuit, connected to the sensing element, and generating an angle of the rotating structure according to the first magnetic field component signal and the second magnetic field component signal,
• wherein the processing circuit calculates magnetic field intensity according to the first magnetic field component signal and the second magnetic field component signal, and stored an upper bound of the magnetic field intensity and a lower bound of the magnetic field intensity in advance;
• when the magnetic field intensity is higher than the upper bound, the processing circuit produces an information of abnormal external magnetic field interference;
• when the magnetic field intensity is lower than the lower bound, the processing circuit produces an information that the rotating structure is damaged.