Research And Implementation Of Automotive Wire-controlled Steering System Controller Based On PMSM

As a new steering system,the steering linkage in the traditional steering system has been canceled in the steering-by-wire(SBW)system,and the flexibility of the steering system is greatly increased.Information interaction between the steering wheel and the front wheel is completed by using an electrical signal,and bilateral control of the steering system is completed.The cancellation of the steering linkage makes the force transmission and angular transmission characteristics of the steering system of the vehicle can be set flexibly to meet the driving characteristics of different drivers.As the power part of SBW,the performance of road feeling motor and executive motor directly affects driver’s driving comfort.In this system,the permanent magnet synchronous motor(PMSM)with small torque ripple and high power density was used as the road feeling motor and the executive motor of the SBW system.SBW system based on PMSM was researched,and the main content and innovative work are as follows:Control scheme of the road feeling motor and executive motor was designed.PMSM was used as the road sense motor and the executive motor of the SBW system,the control strategy of id=0 in vector control was used to control the PMSM.The road feeling motor mainly completed the feedback of the torque,and used the single loop(current loop)to control the road feeling motor.The execution motor was mainly controlled by position.According to the idea of servo control,three loops(position,speed and current)control was adopted to control the execution motor.A simulation model was set up for the road feeling motor and the execution motor.The current response and the position response of the motor were observed,and the feasibility of the algorithm was verified.The road feeling needed to be simulated in the SBW system,and simulation of road feeling was based on steering resistance moment in this system.However,the steering resistance moment of the SBW system was difficult to obtain.According to the assist characteristics of the electric power steering(EPS)system,the road feeling torque with EPS characteristics was designed.The possible steering system aligning overshoot was restrained by adding d amping torque to the aligning torque,aligning inadequate at car in low speed was solved by adding active algning torque.The simulation model of SBW system was set up,and the control strategy is verified by simulation.Four-wire resolver was used to detect the rotor position of PMSM.A decoding circuit of four wire resolver based on AD2S 1200 was designed,which solves the disadvantage of high power consumption of unidirectional excitation in four-wire resolver transformer.Because of the disadvantages of high cost and difficulty in installation of angle sensor,the relationship between the electric angle of the road feeling motor and the the steering wheel angle was analyzed,and the steering wheel angle was calculated by using the electric angle of the road feeling motor.The relationship between the electric motor angle and the front wheel angle is analyzed,and the front wheel angle was calculated by using the electric angle of the execution motor.The SBW system controller was designed,the experimental bench of the SBW system was set up,and the proposed control algorithm was tested and analyzed.Experiments showed that the designed circuit can control the PMSM,and the road feeling simulation algorithm could feedback the road information.The design of the executive motor control strategy could complete the control of the front wheel angle and complete the steering.