Abstract
A novel gradient-type magnetoelectric (ME) current sensor operating in magnetic field gradient (MFG) detection and conversion mode is developed based on a pair of ME composites that have a back-to-back capacitor configuration under a baseline separation and a magnetic biasing in an electrically-shielded and mechanically-enclosed housing. The physics behind the current sensing process is the product effect of the current-induced MFG effect associated with vortex magnetic fields of current-carrying cables (i.e., MFG detection) and the MFG-induced ME effect in the ME composite pair (i.e., MFG conversion). The sensor output voltage is directly obtained from the gradient ME voltage of the ME composite pair and is calibrated against cable current to give the current sensitivity. The current sensing performance of the sensor is evaluated, both theoretically and experimentally, under multisource noises of electric fields, magnetic fields, vibrations, and thermals. The sensor combines the merits of small nonlinearity in the current-induced MFG effect with those of high sensitivity and high common-mode noise rejection rate in the MFG-induced ME effect to achieve a high current sensitivity of 0.65–12.55 mV/A in the frequency range of 10 Hz–170 kHz, a small input-output nonlinearity of <500 ppm, a small thermal drift of <0.2%/ in the current range of 0–20 A, and a high common-mode noise rejection rate of 17–28 dB from multisource noises.
Highlights
Current sensors are of great importance in electrical condition monitoring for the purposes of planning for effective energy usage and fault prediction in modern electrical systems [1,2,3,4,5,6,7]
A modern railway electrification system may require thousands and even millions of current sensors to form a sensor network in various operating environments involving high electric field noise induced by high-voltage (>1 kV) apparatuses, high magnetic field noise caused by heavy-current (>100 A) cables, high vibration noise raise from high running speeds
We may find that the high frequency component voltage noise (v T) is doubled because of random phase lag between
Summary
Current sensors are of great importance in electrical condition monitoring for the purposes of planning for effective energy usage and fault prediction in modern electrical systems [1,2,3,4,5,6,7]. ME current sensors have received considerable research and application attention for AC current sensing by detecting the magnetic field strength in the vicinity of current-carrying cables in accordance with Ampere’s law and by converting the detected magnetic field strength into voltage on the basis of the ME effect in a single ME composite [20,21,25] This is because of their distinct features of compacted size (~10 mm) and easy installation in comparison to current transformers and Rogowski coils; their large sensitivity (up to 0.5 V/A) in excess of 100 times over the Hall sensors; the fact they are free of external power supplies, signal conditioners, and/or other auxiliary means as normally required in the fluxgate sensors; and the added merits of small input-output nonlinearity (
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