Zero magnetic field type magnetic field sensor

This paper presents a new magnetic field sensor named the zero magnetic field type, on the basis of its principle of operation, which is as follows: when the magnetic field level in the core used as a sensor is shifted by an unknown field to be detected, a controlled field is so superimposed in the opposite direction to the unknown field that the original zero magnetic field state is resotred. Then the unknown field can easily be detected from the controlled field. Consequently, detection performance is expected to be unaffected by geometrical configurations, magnetization properties, and demagnetization effects of the core used as a sensor. Moreover, temperature variations of the core and the existence of resistance and leakage inductance in the windings arranged on the core also do not directly degrade performance. This paper certifies that the proposed sensor certainly has the forementioned properties. In addition, the following are clarified: (1) the upper limit of the detectable range does not exist in principle; (ii) the accuracy is 0.02 percent for the full scale 20 kA/m and realizes the order of 4 × 10−4 percent/oC for temperature variations of −76o C to 300oC; (iii) the magnetization property required of the core used as a sensor is that it has as sharply a rectangular B-H loop as possible; (iv) as a result, sensor design is greatly simplified.