Model-based characterization of permanent magnets with a 3D Hall-Sensor array

Demagnetization and defects of permanent magnets used in electric drives can occur during their production or due to operating stresses and lead to reduced reliability and performance. In this paper a novel technique for magnet quality monitoring is proposed. It uses an array of 3D Hall-Sensors to measure the magnetic flux density in the proximity of the magnet. The measurement system and the expected defects are modeled analytically. Based on this model an optimal estimation method for nonlinear systems is used to determine the critical parameters of the magnet. For these parameters pass/fail limits can be applied for production tests and quality monitoring. During our research simulations and measurements were carried out to validate the proposed method.