A Wide Linearity Range Current Sensor Based on Piezoelectric Effect

Based on piezoelectric effect, this paper presents a wide linearity range current sensor. The sensor contains two parts: an NdFeB/PZT/NdFeB composite (NPNC) and an annular magnetic core (MC) with an airgap to place the NPNC. When an ac current passes through a wire, an ac magnetic field converged by MC is applied along the thickness direction of the composite. The ac magnetic field exerts the attractive or repellent forces on the two magnet layers simultaneously. Thus, these magnetic forces act on the piezoelectric layer, causing it to produce a voltage (V
_out
). Through gathering V
_out
, the current (I
_in
) of power cords can be detected. The volume of the proposed sensor is about 10.52 cm
³
. The output voltage is in direct proportion to Iin. When the I
_in
is up to 500 Arms, V
_out
equals 864 mVpp. With the increasing of I
_in
, the Vout can be further raised linearly. So, the proposed current sensor is pretty suitable for large current detection with the sensitivity of 1.52 mVpp/Arms, which can be enhanced by optimizing the dimensions and specifying more appropriate materials.