Research On Electromagnetic Inductive Torque Sensor For Electric Power Steering System

With the development of society, people have increasingly high demand on vehicle safety, environmental protection and energy saving. Vehicle electric power steering system (EPS) begins to replace the traditional hydraulic power steering system gradually, because of its energy-saving, environmental protection, good dynamical characteristics, simple structure, easy installation and maintenance, etc. Torque sensor’s performance affects the dynamical characteristics of EPS directly as one of the most critical components in the EPS. The development of torque sensor begins from contact to contactless. Contactless electromagnetic induction torque sensor is one of the developing directions of EPS torque sensor because of its advantages of simple structure, ease of integration, high measurement precision and good applicability and effectiveness. This thesis studies and designs a kind of contactless electromagnetic inductive torque sensor.This thesis introduces the principle of EPS, and analyzes the main EPS torque sensors from variety, principle and advantages and disadvantages in domestic and overseas. The basic principle of torque measurement method is introduced in EPS. The fundamental theory of eddy current effect is analyzed and the contactless inductive coupling method is introduced based on this. The basic structure of the contactless inductive angle sensor and torque sensor is introduced. Second, the contactless inductive angle sensor is analyzed through3d electromagnetic field analysis software Ansoft Maxwell. Researching related parameters to the influence of the Angle sensor for the design of the sensor rotor and receiving coil. The relationship between the receiving coil induction voltage amplitude with the rotor position is analyzed through Ansoft software Maxwell3D transient.The sensor driver circuit is designed and which is verified correctly by Multisim. The corresponding driver circuit and receiving coil PCB board is established by Altium Designer. The induction voltage amplitude of receiver coils is analyzed. Experimental results show that Induction voltage amplitude is sine curve corresponding to rotor position changes and receiving coil model is correct. The contactless inductive angle algorithm and torque algorithm is introduced. Finally the corresponding angle algorithm and torque sensor algorithm model is established through Matlab/Simulink software, and the simulation results validate the correctness of algorithm of torque. It would be references and theoretical bases to the development of sensor technology of steering system.