Neel Effect Toroidal Current Sensor

In this paper, a configuration for a Neel effect ac-dc current sensor designed with second harmonic sensing in view is proposed. This configuration relies on the use of two toroidal superparamagnetic cores wound in opposite direction with respect to each other and connected in series. An analytical model is developed, which shows that the component of the output signal at the excitation frequency, which is useless, should be removed provided that the windings are symmetrical. The latter principle is validated experimentally and a prototype device is characterized for different excitation conditions. Open loop dc and ac current measurements are carried out over the [-110 A, 110 A] range.