Study on the Effect of Eddy Current for Inductive Angle Sensor with Resonant Structure

Planar inductive position sensor based on PCB has the advantage of low cost and reducing the error caused by winding manufacturing. For inductive sensor with resonant structure, the undesired eddy current caused by conductive shell influences the amplitude and carrier phase of output signals when the sensor is integrated in the motor. This change affects signal demodulation feasibility of the sensor and reduces the signal-to-noise ratio. For this problem, the influence of ferromagnetic materials and eddy current is here discussed. A modified coupling model of multiple coils considering eddy current is proposed to describe a system with modulation characteristics, and the corresponding equivalent circuit equations are established. A prototype is manufactured to verify the performance of the proposed design, and the ferrite is used to suppresses the coupling between the sensor and metallic environment. According to the experimental results, the sensor signal demodulation is achieved properly, and the linear angle estimation realized at a uniform speed.