Signal Analysis in Back Bias Speed Sensor Systems

Wheel speed sensors determine the angular velocity of rotating axes and are widely used in modern industry with a variety of applications. This paper provides a general introduction to back bias speed sensor systems, presenting and discussing the numerous parameters of a general 3D model. The underlying physical mechanisms of the back bias principle are explained with the help of 2D FEM magneto-static simulations. While 2D simulations do not perfectly reflect the magnetic field dynamics of the real problem, they provide an excellent qualitative understanding of the signal behavior concerning model parameter variations. Based on the previous discussions, a representative cogwheel geometry is proposed and analyzed in detail, featuring a study of the influences of the model parameters on the speed sensor signal. As an outcome of the parameter sensitivity analysis, it was possible to determine the degree of influence of the different model parameters on the quality of the speed sensor signal. In conclusion, this study aims to advance the general understanding of the speed sensor signal in back bias systems for manufacturers and to form a solid basis for future work in this field.