Study of Current Measurement Method Based on Circular Magnetic Field Sensing Array

Abstract

Classic core-based instrument transformers are more prone to magnetic saturation. This affects the measurement accuracy of such transformers and limits their applications in measuring large direct current (DC). Moreover, protection and control systems may exhibit malfunctions due to such measurement errors. This paper presents a more accurate method for current measurement based on a circular magnetic field sensing array. The proposed measurement approach utilizes multiple hall sensors that are evenly distributed on a circle. The average value of all hall sensors is regarded as the final measurement. The calculation model is established in the case of magnetic field interference of the parallel wire, and the simulation results show that the error decreases significantly when the number of hall sensors n is greater than 8. The measurement error is less than 0.06% when the wire spacing is greater than 2.5 times the radius of the sensor array. A simulation study on the off-center primary conductor is conducted, and a kind of hall sensor compensation method is adopted to improve the accuracy. The simulation and test results indicate that the measurement error of the system is less than 0.1%.

Measurement of the DC current based on magnetic fluids with an orthogonal magnetic field

“…Substituting equation (16) into equation 11, we obtain the induced voltage of measuring coil, which is shown as equation (17).…”

“…At the same time, DC current measurement is becoming more important. [6][7][8][9][10] Usually, DC current measurement methods generally include shunt resistance method, 10 DC transformer method, 11 DC comparator method, 12,13 Hall element method, 14 DC fluxgate sensor method, 15 circular magnetic field sensing method, 16 and optical fiber sensor method. [17][18][19][20] Magnetic fluid is a solid-liquid mixture system, in which the strong magnetic particles are mixed into the base carrier liquid, and then surfactant is added to disperse the magnetic particles in the base carrier liquid uniformly.…”

Practical Adaptation of a Low-Cost Voltage Transducer with an Open Feedback Loop for Precise Measurement of Distorted Voltages

“…In Figure 11 , waveforms of the line-to-line voltages for the output voltage inverter registered by the voltage probe U ab , the transducer (see Figure 1 ) with 22 kΩ, and the transducer made by LEM [ 24 ] with 22 kΩ with and without correction are presented. For better visibility in Figure 11 a,b, the waveforms with and without correction are presented for a 8-ms time span.…”

“…The application of integrated-circuit sensors placed in the air gap of a magnetic core for the measurement of AC and DC voltages, currents, and magnetic flux density in electrical machines is constantly being developed [ 1 , 2 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. For AC and DC currents with a magnetic flux density, contact and contactless measurement, Hall-effect sensors, magnetoresistive current sensors, and coils (e.g., the Rogowski coils are only suitable for AC currents) [ 16 , 17 , 22 , 23 , 24 ] are commonly used. In cases of voltages up to 1 kV, with output separation, both magnetoresistive current sensors and Hall-effect sensors can be used after placing them in the air gap of a ferromagnetic core, and voltage measurement is carried out by using the current to measure magnetic flux in the measuring winding that is wound around the core [ 25 , 26 , 27 ].…”

“…Voltage transducers with both closed and open feedback loops are available on the market [ 4 ]. In order to amplify the measured voltage, current, or magnetic field, the Hall-effect sensor is placed in the core air gap [ 2 , 7 , 8 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. The magnetic flux density shape in the core and in the air gap depends on the electric and magnetic properties of the core and on the range of measured frequencies.…”