Research On Steering Motor Control Algorithm And Software Modeling Of Steer-by-wire System

The steer-by-wire system eliminates the mechanical connection between the steering system and the steering actuator.The steer-by-wire system mainly completes the following of the steering wheel to the steering wheel angle.The main content of this paper is to study the steering motor control algorithm applicable to the steer-by-wire system,and realize the steer-by-wire system to complete the driver’s steering requirements quickly.Firstly,the mathematical model of the permanent magnet synchronous motor in the stationary coordinate system is studied.Using the coordinate transformation,the mathematical model of the PMSM in the rotating coordinate system is obtained.The SVPWM model based on rotor field oriented vector control algorithm is built to lay the foundation for the motor control algorithm development.Based on the requirements of the steer-by-wire system,this article designs a three-closed-loop vector control system for the steer-by-wire motor.Based on the control principle,The PI regulator of the position loop,speed loop and current loop are designed.and the current loop add a feed forward link to improve the dynamic response.Finally,the simulation verifies the three closed-loop vector control system designed in this paper.Then,the stator current decision-making control strategy in the base-speed of the steer-by-wire motor is studied.By analyzing the maximum torque-current ratio control strategy,the output stator torque needs the smallest stator current vector at the same time.the calculation formula of the traditional control strategy is complicated.In this paper,the solution of the direct-axis current and the quadrature-axis current is transformed into the solution of the stator current vector angle,which reduces the difficulty of the solution.The influence of the PMSM electromagnetic parameters on the control strategy of the MTPA is analyzed.The model reference adaptive parameter identification method is used to identify the on-line parameters the motor,but the voltage equation rank of the PMSM in the rotating coordinate system is 2,can only recognize two electromagnetic parameters.The analysis shows that the greatest influence on MTPA control strategy is the quadrature-axis inductance and rotor permanent magnet flux linkage.The MTPA control strategy based on MRAS parameter identification is used in the base speed and simulation analysis is performed.Next,we study flux-weakening control algorithm.We first analyze the field-weakening control theory,that is,the limits of the current limit circle and the voltage limit ellipse.the requirement of good dynamic response and robustness for field-weakening control,advanced-angle field-weakening control base on a fuzzy PI strategy is proposed.research on the principle and implementation method of the advanced-angle field-weakening control.The design process of the fuzzy controller for the field-weakening control voltage loop PI controller is introduced.Finally,the simulation and analysis of control strategy.Finally,The process of automatic code generation based on MATLAB/simulink is studied.The encapsulation process of BLOCK and the modification method of TLC file are introduced.The simulink full model including the upper layer control and the bottom layer driver module was built,and a key to generate a motor control algorithm program.The hardware architecture of the PMSM controller and the composition of the steer-by-wire test stand are developed.Verifying the effectiveness of the control strategy of the steer-by-wire steering motor designed in this paper through a steer-by-wire test stand.