Current Sensing Technologies in Power Systems

Current sensing in modern power systems encompasses a range of technologies designed to measure alternating and direct currents with high precision, wide bandwidth and robust performance under varying environmental and load conditions. Traditional instrument current transformers remain widespread for high-power AC metering and protection, relying on magnetic induction but suffering from saturation and limited DC response. Semiconductor‐based sensors, including Hall-effect, anisotropic (AMR) and giant (GMR) magnetoresistive devices, offer compact, non-intrusive measurement with broad frequency response but often require compensation for nonlinearity, thermal drift and conductor position. Tunnel magnetoresistance (TMR) elements have emerged for medium-voltage applications, combining high sensitivity and linearity in closed-loop configurations. Fluxgate sensors provide exceptional accuracy for DC and low-frequency AC by maintaining zero flux in the core through feedback, making them ideal for calibration and hybrid AC+DC transducers. Advances in sensor arrays, compensation algorithms and integrated digital control now enable miniature, low-cost modules for grid monitoring, power-electronics diagnostics and renewable integration, meeting the demands of smart grids and electric-vehicle infrastructure.

Research from Nature Portfolio

Recent studies have introduced a dual air-gap closed-loop TMR current sensor optimised for medium-voltage DC distribution. By applying a minimum magnetic field uniformity coefficient to select core inner radius, air-gap spacing and section dimensions, the design mitigates conductor eccentricity errors. A prototype rated for ±50 A demonstrated relative errors below 0.2 % under nominal conditions. This work highlights how careful modelling of the magnetic circuit and closed-loop TMR elements can yield compact sensors with enhanced linearity and stability for emerging DC power networks.

Research from all publishers

One innovation employs a zero-flux self-oscillating fluxgate transducer to achieve simultaneous AC and DC measurement up to 500 A AC and 300 A DC. The addition of a secondary iron core and tailored windings suppresses ripple effects and maintains zero-flux control, resulting in a calibration-grade device with class 0.05 accuracy and a simplified circuit topology compared to multi-core designs.

A rectangular yokeless current transducer utilising an array of 16 microfluxgate sensors around a busbar has been demonstrated for 400 A range applications. This architecture delivers 15-fold noise reduction and seven-fold improvement in temperature stability over yoke-based counterparts, with excellent crosstalk rejection. Long-term field trials confirm its reliability and suitability for smart-grid monitoring.

Current Sensing Technologies in Power Systems publication trend

The graph below shows the total number of articles in current sensing technologies in power systems across all publications each year (not limited to Nature Index journals).

Technical terms

Current transformer (CT): A device using magnetic induction to produce a scaled secondary current proportional to a primary AC current, widely used for metering and protection.

Tunnel magnetoresistance (TMR): A quantum‐mechanical effect in layered thin films where electrical resistance varies with applied magnetic field, offering high sensitivity and linearity in current sensors.

Fluxgate sensor: A magnetic field sensor that drives a core into saturation and measures the feedback required to maintain zero net flux, enabling precise DC and low-frequency AC detection.

Zero-flux principle: A closed-loop control technique that continuously nulls magnetic flux in a sensor core via feedback windings, ensuring linear response and wide dynamic range.

Hall-effect sensor: A semiconductor device that generates a voltage proportional to the perpendicular magnetic field produced by a current-carrying conductor, enabling non-contact measurement.

References

1. Optimal design of dual air-gap closed-loop TMR current sensor based on minimum magnetic field uniformity coefficient. Scientific Reports (2023).
2. A High Accuracy AC+DC Current Transducer for Calibration. Sensors (2022).
3. Rectangular Array Electric Current Transducer with Integrated Fluxgate Sensors. Sensors (2019).