Research On Switched Reluctance Motor And Control System On EPS

Electric power steering system (EPS) possesses the advantages of energy-saving,benefit toenvironmental protection,high level of active safety, has been widely used inthe field of cars.In order to improve the performance of EPS, the motor has become aresearch hotspot as a key part. Switched reluctance motor (SRM) which is a newmechatronics drive system with simple structure, small size and powerful output hasbroad application prospects.In this study, SRM for EPS is researched. The major contents include: the structuredesign of motor, optimization analysis and performance computation, design andsimulation of control system.Firstly, based on the matching demand of EPS assisted motor in fixed model,500W SRM is designed. The structure size is initially determined according toexperiential formulae of motor design. Stator and rotator material are cold-rolled siliconsteel sheet DW360-50which has good magnetic property.Secondly, parameters of the motor are optimized analysis and performanceevaluated using Ansoft software on the basis of initial design.(1) Motor parameterssuch as outer diameter, pole arc combination, yoke and turn number of windings areanalyzed using Ansoft/RMxprt software. A structure size plan with best rated power,rated speed and efficiency is chosen.(2) Motor static and transient analysis is doneusing Ansoft/Maxwell2D software. Static characteristics which can be used asfollow-up simulation data reference are studied by static transient analysis. Motorperformance parameters on the rated condition is obtained，which has little differencecompared with RMxprt calculated results. It verifies the verify of motor structuredesign.The control system of EPS includes the content of two following:(1) Referring tothe relevant test data curve assisted characteristic is designed which can get requiredtorque at different vehicle speed and steering wheel moment.(2) The torque controlsystem of EPS is designed based on expected torque. In torque regulator, desired currentis obtained relying on torque-angle characteristic of motor by the look-up table method;Hysteresis control strategy is employed in current inside loop. Finally, the whole control system simulation model is built using Simplorer andMatlab/Simulink. Simulation results show that the design of switched reluctance motorcan achieve the assisted effect, and verify the rationality of designed motor structure andcontrol system.