Magnetic Torque Sensing Module Design for EPS

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Magnetic Torque Sensing Module Design for EPS

Zhong, Hong Sheng / Guan, Lifeng / You, Wei

The torque sensing module is an important part of EPS (Electronic Power Steering) system. There are various solutions in the market based on different technologies i.e. Potential meter, Inductive and Hall sensing. As a trend, more and more EPS system integrators adopt Hall-based torque sensing solution, most of which consist of a magnetic ring, a magnetic flux detector to read the magnetic flux from the magnetic ring and a flux conductor/concentrator to lead the magnetic signal to a Hall device to convert magnetic flux level to electronic signal. However, available solutions require high mechanical precision from the magnetic flux detector and conductor/concentrator. Also, the magnetic ring in the existing solution is magnetized after its preformation which causes a lower signal-to-noise ratio at the input of the entire system due to the process and brings about less accuracy of the torque sensing module. In order to overcome these obstacles, a new torque sensing module design based on Hall sensing principles is proposed in this paper. This article provides a brief background of the current market and technical situation will be introduced, followed by explanations on Hall-based magnetic torque sensing module in terms of operation principles. Then new design of the torque module will be proposed. Next, a detailed magnetic analysis will be shown. Based on this analysis, this paper will present the simulation results.