Speaker
Description
The magnetoelectric (ME) effect is promising and has been studied for several applications: magnetic sensors [1], current sensors [2], energy harvesting [3] and wireless energy transmission. The extrinsic ME effect is preferred to the intrinsic one for these applications, requiring a magnetostrictive material mechanically coupled to a piezoelectric material. Current sensors based on extrinsic magnetoelectric effect have great potential with strong sensibilities, low cost, and easy fabrication. There are few studies on this kind of sensor, and they are mainly oriented toward the obtention of a great ME effect in ideal conditions [4] (lab environment, 50Hz sinus signal without electrostatic perturbation).
The current sensor presented here is obtained by inserting a trilayer Ni/PZT/Ni ME sample in a toric flux concentrator associated with permanent magnets to apply the required DC bias to obtain the best ME response. Nickel's 150 µm thickness layers are electrodeposited on a PZT square with a 4x5mm² surface and 0.5mm thickness. An amplifier with a bandwidth from 20Hz to 20kHz and a maximum current of 25 A is used for the tests. A winding of 24 turns is made around the toric flux concentrator to obtain a maximum current equivalent to 600 A.turns. The current dynamic is studied, and a 300 A.turns dynamic can be obtained if, for example, a maximum THD of 3$\%$ is required. This sensor aims at power electronics applications. Thus, it requires studying the sensor response to specific current waveforms that could excite mechanical resonances and thus disturb the measure. When a square current of 1 kHz is applied, these resonance frequencies are excited, impacting the sensor bandwidth. A mechanical dampening is proposed to limit this impact, using polyurethane mixed with tungsten powder to coat the ME sample. The results are encouraging because the resonance amplitude is reduced by a factor of 6, improving the sensor's bandwidth. In power electronics applications, the sensor will be subjected to electrostatic disturbances, and it is necessary to study its immunity toward them. Thus, the sensor is tested in an electrical field-controlled environment. An electronic based-on-charge preamplifier connected in differential mode strongly reduces these disturbances.
References
[1] S. Dong, J. Zhai, J. Li, and D. Viehland, “Small dc magnetic field response of magnetoelectric laminate composites,” Applied Physics Letters, vol. 88, no. 8. AIP Publishing, Feb. 20, 2006. doi: 10.1063/1.2178582.
[2] X. Yu, G. Lou, H. Chen, C. Wen, and S. Lu, “A Slice-Type Magnetoelectric Laminated Current Sensor,” IEEE Sensors Journal, vol. 15, no. 10. Institute of Electrical and Electronics Engineers (IEEE), pp. 5839–5850, Oct. 2015. doi: 10.1109/jsen.2015.2451551.
[3] Y. Zhou, D. J. Apo, and S. Priya, “Dual-phase self-biased magnetoelectric energy harvester,” Applied Physics Letters, vol. 103, no. 19. AIP Publishing, Nov. 04, 2013. doi: 10.1063/1.4829151.
[4] J. Zhang, P. Li, Y. Wen, W. He, A. Yang, and C. Lu, “Packaged current-sensing device with self-biased magnetoelectric laminate for low-frequency weak-current detection,” Smart Materials and Structures, vol. 23, no. 9. IOP Publishing, p. 095028, Aug. 14, 2014. doi: 10.1088/0964-1726/23/9/095028.
