*Article* **A Shear-Mode Piezoelectric Heterostructure for Electric Current Sensing in Electric Power Grids**

**Wei He 1,\* and Aichao Yang 2**


Received: 1 June 2019; Accepted: 21 June 2019; Published: 23 June 2019

**Abstract:** This paper presents a shear-mode piezoelectric current sensing device for two-wire power cords in electric power grids. The piezoelectric heterostructure consists of a cymbal structure and a permalloy plate. The cymbal structure is constructed from a permanent magnet, a brass cap, and shear-mode piezoelectric materials. The permalloy plate concentrates the magnetic field generated by the two-wire power cord on the magnet. Under the force amplification effect of the cymbal structure, the response of the device is improved. A prototype has been fabricated to conduct the experiments. The experimental average sensitivity of the device is 12.74 mV/A in the current range of 1–10 A with a separating distance of d = 0 mm, and the resolution reaches 0.04 A. The accuracy is calculated to be ±0.0177 mV at 1.5 A according to the experimental voltage distribution. The current-to-voltage results demonstrate that the proposed heterostructure can also be used as a magnetoelectric device without bias.

**Keywords:** piezoelectric current sensing device; two-wire power cord; cymbal structure; force amplification effect; sensitivity
