AMR Yokeless Current Sensor with Improved Accuracy

Mlejnek, Pavel; Ripka, Pavel

doi:10.1016/j.proeng.2016.11.301

Cited by 16 publications

(9 citation statements)

References 2 publications

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“…As it was presented in our previous paper [16] the measurement error of AMR current transducer is lower than 0.01% in the range ±11 A when the current carrying conductor is placed exactly in the center of the transducer. However, this cannot be guaranteed in the real application such as measuring the current in cables.…”

Section: Theoretical Backgroundsupporting

confidence: 59%

“…After that, the compensation current was adjusted to compensate the magnetic field generated by Helmholtz coil. The sensitivity and compensation coil factor (related to the bridge voltage as in [16]) were computed from the measured values (Table 1), where we also indicate their deviations from the average value.…”

Section: Variation Of Amr Sensor Parametersmentioning

confidence: 99%

“…The AMR current sensor zero output (sensor output for the zero measured current) is affected by the offset of the individual AMR sensors and by the external fields (which come from the Earth magnetic field and human-made field sources such as near electric currents) as was presented in [16]. In this paper, we assume that the offset (zero-current) correction is possible.…”

Section: Reading Of the Individual Amr Residualmentioning

confidence: 99%

“…In our previous paper [16] we introduced the methods how to improve the accuracy of the yokeless current transducer ( Figure 1) with a circular array of anisotropic magnetoresistors (AMR). Eight KMZ51 [17] magnetic field sensors are arranged around the measurement hole.…”

Section: Introductionmentioning

confidence: 99%

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Off-Center Error Correction of AMR Yokeless Current Transducer

Mlejnek

Ripka

2017

Journal of Sensors

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We present a method of calibration and error correction of the AMR yokeless current transducer consisting of a circular array of eight anisotropic magnetoresistors (AMR) with one feedback compensation loop. The main sources of errors are the nonidentical parameters of AMR sensors and off-center position of the measured current. It is well known that AMR sensors from the same batch have 2% spread of the sensitivity; we found that the variation of the factor of the internal compensation coil is the same. We developed a novel calibration process using the readings of individual residual uncompensated voltages of the AMRs. The position of the current inside the measurement hole is estimated from the individual voltages considering the influence of external DC magnetic field such as the Earth's field. During the calibration phase, the sensor outputs are measured for several positions of the current conductor inside the measuring hole. As a result of calibration the lookup table of error corrections is calculated and stored in the memory, and then these values are used for the correction during the measurement of the unknown current. This procedure reduces the off-center error from 0.4% to 0.06%.

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Section: Theoretical Backgroundsupporting

confidence: 59%

Section: Variation Of Amr Sensor Parametersmentioning

confidence: 99%

Section: Reading Of the Individual Amr Residualmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Off-Center Error Correction of AMR Yokeless Current Transducer

Mlejnek

Ripka

2017

Journal of Sensors

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“…A weak point of this design is the poor stability of the bias field with temperature and in time [20]. An application of an AMR sensor array in a circular transducer is reported in [21].…”

Section: Magnetoresistorsmentioning

confidence: 99%

Contactless measurement of electric current using magnetic sensors

Ripka

2019

Tm - Technisches Messen

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We review recent advances in magnetic sensors for DC/AC current transducers, especially novel AMR sensors and integrated fluxgates, and we make critical comparison of their properties. Most contactless electric current transducers use magnetic cores to concentrate the flux generated by the measured current and to shield the sensor against external magnetic fields. In order to achieve this, the magnetic core should be massive. We present coreless current transducers which are lightweight, linear and free of hysteresis and remanence. We also show how to suppress their weak point: crosstalk from external currents and magnetic fields.

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