Mechanically Flexible Sensor Array for Current Measurement

Contactless galvanically isolated magnetic field-based current sensors utilizing hard ferromagnetic cores are widely used in many applications, for example, power converters for drives or wind turbines. New measurement methods, e.g., circular arrays of magnetic field sensors, offer some advantages, such as low weight, mechanical flexibility, and independence of the nonlinear and hysteretic behavior of the core. Those sensor arrays can be operated in an open-loop manner or in a closed-loop manner with an additional compensation coil. The advantages of the open-loop design, which we use in this article, are lower cost, lower weight, and the opportunity to realize a mechanically flexible sensor array. In this article, we show the theoretical and experimental influence of the mechanical bending on the accuracy of circular arrays of magnetic field sensors used for current measurement. Furthermore, the inner displacement of the conductor in combination with different bendings is considered. The experimental results were taken with 12, 6, 4, and 3 Hall effect sensors that were uniformly placed on the circular array.