Circular Array Of Magnetic Sensors Research Articles

Crosstalk analysis and Current Measurement Correction in Circular 3D Magnetic Sensors Arrays

The circular array of magnetic sensors is a research hotspot in the field of power electronics, especially for the measurement of direct current(DC). The high linearity, large dynamic range, small size and low power consumption of circular magnetic sensors arrays for current measurement are an improvement over the current sensors utilizing a ferromagnetic core. However, due to the absence of core magnetization, the external magnetic field can easily enter the magnetic sensors, which will affect the measurement accuracy. Therefore, this paper focuses on the influence of the interference field from the conductor positioned outside the circular array and proposes a model of the target conductor penetrating the circular array with the interference conductor outside the circular array. This model is used to analyze the influence of relevant parameters of the interference conductor and the target conductor on the crosstalk error. An interference-rejecting method of circular 3D magnetic sensor arrays is proposed, which establishes the model of magnetic flux density measurement to calculate the target conductor current. The simulation results show theoretically that the method can greatly reduce the crosstalk error and correct current measurement. 3-D tunnel magnetoresistance (TMR) chip is selected as the magnetic sensors of the circular array in the laboratory experiment, and the experiment errors can be reduced to around 1%. The simulation and experiment results verify that the interference-rejecting method can correct measurement results and improve the accuracy of the target current.

Impact of Coreless Current Transformer Position on Current Measurement

Magnetic sensors have been widely used for current measurements in diverse industries. In order to achieve a large current measurement without an iron core structure, magnetic sensors are often arranged to be a circular array for designing a new electronic current transformer (ECT). However, this ECT with a circular array of magnetic sensors usually suffers from tradeoffs between the number of sensors and the measurement accuracy. This paper visualizes this tradeoff and proposes a 3-D magnetic-field model to analyze the impact of the magnetic sensor circular array position on current measurements. We develop an analytical expression of the current measurement errors to estimate the minimum number of required magnetic sensors and point out the acceptable deviations of the ECT position under various accuracy classes. Based on the estimation results, we design a new circular array with eight magnetic sensors and build a three-phase current measurement system. The test results demonstrate the efficiency and the robustness of the designed class-1.0 ECT, which successfully maintains accuracy class 1.0 under various position deviations in balanced or unbalanced three-phase power delivery systems.

Influence of the Conductor Position on a Circular Array of Hall Sensors for Current Measurement

Contactless galvanically isolated magnetic field-based current sensors utilizing a ferromagnetic core have been widely used for decades in many applications such as power distribution, power electronics, and drive technologies to mention just a few fields of interest. Measurement techniques like circular arrays of magnetic-field sensors are of high interest in the field of power electronics, especially for dc current sensing. The low power consumption, high sensitivity, and mechanical flexibility of modern circular arrays of magnetic sensors for current measurement are an improvement over older closed-loop high power consumption systems. In this paper, we will theoretically and experimentally show the influence of the inner displacement of the conductor on the accuracy of the circular array of magnetic-field sensors. The calculation of the current is based on the Kelvin–Stokes theorem. The experimental results were taken with six Hall-effect sensors which are uniformly placed as a circular array. The measurements have been taken at different distances and angles to the conductor. To prove the theoretical background the currents were calculated in all cases for a number of six and three sensors.

Circular Array of Magnetic Sensors for Current Measurement: Analysis for Error Caused by Position of Conductor.

This paper analyzes the measurement error, caused by the position of the current-carrying conductor, of a circular array of magnetic sensors for current measurement. The circular array of magnetic sensors is an effective approach for AC or DC non-contact measurement, as it is low-cost, light-weight, has a large linear range, wide bandwidth, and low noise. Especially, it has been claimed that such structure has excellent reduction ability for errors caused by the position of the current-carrying conductor, crosstalk current interference, shape of the conduction cross-section, and the Earth’s magnetic field. However, the positions of the current-carrying conductor—including un-centeredness and un-perpendicularity—have not been analyzed in detail until now. In this paper, for the purpose of having minimum measurement error, a theoretical analysis has been proposed based on vector inner and exterior product. In the presented mathematical model of relative error, the un-center offset distance, the un-perpendicular angle, the radius of the circle, and the number of magnetic sensors are expressed in one equation. The comparison of the relative error caused by the position of the current-carrying conductor between four and eight sensors is conducted. Tunnel magnetoresistance (TMR) sensors are used in the experimental prototype to verify the mathematical model. The analysis results can be the reference to design the details of the circular array of magnetic sensors for current measurement in practical situations.

Crosstalk in Circular Arrays of Magnetic Sensors for Current Measurement

Circular arrays of magnetic-field sensors are of high interest in the field of power electronics for use in galvanically isolated dc current sensing. The low power consumption, high sensitivity, and mechanical flexibility of modern circular arrays of magnetic sensors for current measurement are an improvement over older closed-loop high power consumption systems. Due to their high sensitivity, such magnetic sensor arrangements are strongly influenced by magnetic fields originating not only from a targeted conductor but also from sources of interference. In this paper, we present a theoretical and experimental evaluation of the crosstalk interference in a circular array of fluxgate sensors for current measurement. We attempt to improve the modeling and the experimental setup of the state of the art method by applying a displacement in the angular position of the sensing array. Utilizing our techniques in the experimental evaluation of the rejection method, we have seen an improvement in error rejection and in turn an increased measurement accuracy of our target current source. In the best case, we have seen accuracy to within 0.02% of the current measured.

Circular arrays of magnetic sensors for current measurement

A single solid-state magnetic sensor can measure a current flowing in a conductor in a noncontact way. In order to improve the accuracy of the measuring system and to reduce the crosstalk effects of other magnetic fields, circular arrays of magnetic sensors can be fabricated, still preserving low costs. In those kind of arrays, the sensing elements are assembled on a circle around the conductor. The sum of the sensor output signals is an approximation of Ampere's circulation. A quite satisfactory crosstalk effects reduction can be thus achieved. More sophisticated algorithms that combine sensor output signals are necessary in order to further reduce crosstalk effects. This paper presents an algorithm that is able to calculate the intensity of a dc current flowing in a rectangular bus-bar, in the presence of crosstalk fields.