Jitao Zhang

Magnetoelectric Effect for Rotational Parameters Detection

The magnetoelectric (ME) effect has been successfully demonstrated in the potential device applications of energy harvesters, magnetic sensors, current sensors, microwave and millimeter-wave multiferroic devices, miniature antennas, and even medical applications. To further investigate the role of ME effect in rotational parameters detection, this paper presents an ME rotational parameter sensor consisting of a magnetostrictive/piezoelectric laminated composite (MPLC) and a multi-pole magnetic ring. The relationship between the proposed sensors output signal and the rotational parameters has been analyzed. The output frequency is directly proportional to the rotational speed, and the waveform has a good sin property. In a word, based on the proposed sensor, the rotational speed can be measured by determining the frequency of the output signal, and the rotational position can be detected by the phase discrimination. As the MPLC has the characteristics of high sensitivity and quick response, the starting and stopping times and the eccentricity of rotating pieces can also be measured by the proposed ME rotational parameter sensor.

A Passive Electric Current Sensor Based on Ferromagnetic Invariant Elastic Alloy, Piezoelectric Ceramic, and Permalloy Yoke

This paper presented a passive current sensor in an electric power grid. The sensor consists of an iron-nickel-based ferromagnetic invariant elastic alloy (FIEA) beam with high quality factor (Q-factor), piezoelectric ceramic Pb(Zr,Ti)O3 (PZT8), and a Permalloy yoke. The beam bends in the magnetic field of a current-carrying wire as a result of the magnetostriction of the FIEA, and the PZT8 produces a voltage proportional to the electric current in the wire. The electric current sensitivity is potentially improved due to the high Q-factor of the FIEA/PZT8 beam and the concentration effect of the Permalloy yoke. Experimental data are taken to evaluate the feasibility of the current sensor. At the power frequency of 50 Hz, the sensor shows the linear sensitivities of 300.5, 177.9, 119.2, and 88.8 mV/A from 0.2 to 5 A when the separating distances are 6, 10, 15, and 20 mm, respectively. The performances indicate that the proposed device is promising for power-frequency current sensing applications.

An autonomous current-sensing system for elecric cord monitoring using magnetoelectric sensors

An autonomous current-sensing system consisting of a SmFe2/PZT/SmFe2 self-biased magnetoelectric (ME) composite and a Fe73.5Cu1Nb3Si13.5B9 nanocrystalline flux concentrator for weak current detection at the power-line frequency is presented and characterized. Giant magnetostrictive material of SmFe2 plate with large anisotropic constant provides a huge internal anisotropic field to bias the ME sensors in a closed magnetic loop. Consequently, the additional magnetomotive force induced by the internal field as well as the corresponding increased effective permeability contributes to the sensitivity improvement. Experimental results demonstrate that the presented sensor has a higher sensitivity of 152 mV/A at 50Hz with a slight nonlinearity of ∼0.01%FS and matches well with the predicted value. This presented current-sensing device exhibits approximately 2.3 times higher sensitivity than that of conventional ME composite with PZT and Terfenol-D plates serving as the key sensitive component. These results provide a significant advancement toward promising application of the tri-layer self-biased ME laminate for power-line electric cords monitoring.

Data Processing Method and Experiment of Barometric Altimeter Based on Kalman Filter

It is an effective method to measure the height using a barometric altimeter, but there exists a larger noise defect. The principle of measuring height using the barometric altimeter is elaborated, and the measure noise is analyzed. In order to suppress the height measure noise, the Kalman filtering method is adopted. The state model of Kalman filter is constructed and the state recursive equations are given out. An experiment is done to measure the different floor height in the dynamic and static condition, and the results show that the Kalman filtering evaluation value can track the height change in real time and suppress obviously the height measure noise, and the noise fluctuation reduces to 1/4 of the raw data.

A Non-Resonant Magnetoelectric Energy Converter for Scavenging Magnetic Field Energy From Two-Wire Power Cords

A non-resonant magnetoelectric (ME) energy converter is presented for scavenging power-frequency magnetic field energy from two-wire power cords. The device is composed of a Terfenol-D/Pb(Mg1/3Nb2/3)O3-PbTiO3(PMNT)/Terfenol-D ME transducer, a NdFeB manget, and E-shaped magnetic yokes. The ME transducer, the magnet, and the magnetic yokes constitute a magnetic circuit, and the bias magnetic field of the ME transducer can be tuned by adjusting the contact area between the magnet and the magnetic yokes to obtain optimal power output. Meanwhile, the power-frequency magnetic field of the power cord is concentrated to the ME transducer by the magnetic yokes, which can potentially improve the power output of the device. Experiments were undertaken to evaluate the potential of energy scavenging from nearby power cords. When coupled to an appliance power cord carrying a current of 16 A, the device generated a rms voltage of 2.46 V and a maximum power of 6.05 × 10-6 W with a matching load resistance of ~1 MQ. At a duration of 205 ms, the device can supply power for a temperature-humidity wireless sensor through an up-conversion management circuit with the power consumption of 90 mW at transmitting and 18 mW at receiving.

Dual-peak self-biased magnetoelectric couplings in symmetrical multiferroic heterostructures

In this study, the results of an investigation of dual-peak resonance ME couplings at zero magnetic bias in a symmetric ME heterostructure consisting of two distinct ferromagnetic layers Terfenol-D and SmFe2 plates placed between piezoelectric plate PZT-5H is presented, and the magnetostrictive layers with positive and negative magnetostrictions. A negative shear force as well as large internal anisotropic field is provided by SmFe2 plate due to its ferromagnetic and magnetostrictive properties, and the Terfenol-D plate provides a positive shear force to provoke a higher shear-stress transfer. In this architecture the SmFe2 plate plays two key roles: (i) it serves as piezomagnetic phase providing a negative shear force; (ii) it can provide an internal field to bias the ME composite due to its ferromagnetism with obvious hysteresis and large remnant magnetostriction oriented the direction [111] of easy-magnetization axis.

Broadband high-sensitivity current-sensing device utilizing nonlinear magnetoelectric medium and nanocrystalline flux concentrator

A broadband current-sensing device with frequency-conversion mechanism consisting of Terfenol-D/Pb(Zr.Ti)O3 (PZT)/Terfenol-D magnetoelectric laminate and Fe73.5Cu1Nb3Si13.5B9 nanocrystalline flux concentrator is fabricated and characterized. For the purpose of acquiring resonance-enhanced sensitivity within broad bandwidth, a frequency-modulation mechanism is introduced into the presented device through the nonlinearity of field-dependence giant magnetostrictive materials. The presented configuration provides a solution to monitor the weak currents and achieves resonance-enhanced sensitivity of 178.4 mV/A at power-line frequency, which exhibits ∼3.86 times higher than that of direct output at power-line frequency of 50 Hz. Experimental results demonstrate that a weak step-change input current of 1 mA can be clearly distinguished by the output amplitude or phase. This miniature current-sensing device provides a promising application in power-line weak current measurement.

Dual-Peak Self-Biased Magnetoelectric Couplings in Tb 0.3 Dy 0.7 Fe 1.92 /Pb(Zr,Ti)O 3 /SmFe 2 Symmetrical Multiferroic Heterostructures

A trilayer magnetoelectric (ME) composite consisting of a soft piezoelectric PZT-5H plate, a magnetostrictive Terfenol-D plate, and a rare-earth ferromagnetic Samfenol plate is fabricated and characterized for studies on the multipeak self-biased ME effects. In this symmetrical magnetostrictive/piezoelectric heterostructure, high shear-stress transfer to excite the bending resonance mode is induced by the magnetostrictive materials with opposite signs of magnetostriction, and a large internal anisotropic field is provided by a Samfenol plate due to its distinct ferromagnetism and magnetostriction. Consequently, hysteretic behavior can be simultaneously observed at both bending vibration resonance and transverse vibration resonance. Results demonstrate that the nonzero remnant ME coefficients of 0.7 and 2.23 V/Oe occur at bending frequency of 42.2 kHz and transverse frequency of 108.3 kHz, respectively, and the estimates of resonance frequencies are in agreement with the data. These characteristics provide the promise of this dual-peak self-biased symmetrical multiferroic heterostructure for low frequency magnetic field detection without the benefit of additional permanent magnets.