Compact Design of a Wide Bandwidth High Current Sensor Using Tilted Magnetic Field Sensors

Abstract

Magnetic field-based current sensors are widely used due to their galvanically isolated measurement principle. A well-proved concept is based on the discrete realization of the Ampère´s law using a circular array of magnetic field sensors. Depending on the linear operating range of the magnetic field sensors the radius of the circular array has to be chosen, leading to large dimensions for high current values. This paper presents a novel approach to build a compact wide bandwidth current sensor based on the combination of tilted tunnel-magnetoresistance sensors and a Rogowski coil. The used tunnel-magnetoresistance sensors are characterized and show an increased linear range in the a current sensor application if they are tilted. In addition, the sensor sensitivity is varied with the tilt angel. A novel current sensor concept based on tilting in combination with repositioning the magnetic field sensors is presented. This concept offers the opportunity to reduce the size of state-of-the-art current sensors based on magnetic field sensors significantly. The proposed concept is verified in a current sensor prototype and the DC current linearity, the dynamic behavior as well as the signal-to-noise ratio is characterized.