Research On Electromagnetic Differential Active Guidance Control Of Independently Rotating Wheels

The application of a U-shaped axle bridge in Independently Rotating Wheels（IRWs）releases the space under the vehicle floor and has the advantage of high critical lateral instability velocity,which promotes its application in urban light rail low-floor vehicles and the next generation of high-speed trains.But the IRWs has the problem of insufficient steering ability in the application.At present,the measures to improve the steering performance of IRWs can be divided into optimizing the wheel tread profile,designing a special bogie structure,coupling independent wheelset bogie,and active steering control,and active steering control is the development tendency of independent wheelset steering.Referenced on the principle of the electromagnetic coupler in the wind-generation synchronous generator,the Electromagnetic Differential Rotational Active Guidance Control（EDRAGC）was proposed.An electromagnetic coupler is added as an actuator between the left and right wheels of IRWs,and the Electromagnetic Coupler Vector Control System（ECVCS）is used to control the left and right wheels to rotate at a certain differential rotating speed to compensate for the distance difference between the inner and outer rails,to realize the wheelset guidance.In this thesis,the following research was carried out for the EDRAGC with the IRWs system:（1）The principle of differential active guidance control was expounded based on the motion characteristics of the IRWs as reflected by the distribution of poles of the IRWs.Combining the mathematical model of electromagnetic torque of electromagnetic coupler and the mechanical model of IRWs under steady-state conditions,the guiding mechanism of IRWs with EDRAGC through straight and curved lines were illustrated,respectively.（2）Based on high-order sliding mode control and nonsingular terminal sliding mode control,Super-Twisting Second-order Nonsingular Terminal Sliding Mode（STSNTSM）control was proposed.The terminal sliding mode surface is designed by inverse hyperbolic sine function to avoid singularity problem.The Super-Twisting second-order sliding mode with proportional sliding mode term is introduced to suppress chattering and accelerate convergence rate.The simulation results show that STSNTSM can well weaken the sliding mode control system chattering and has high control accuracy and convergence speed.（3）The ECVCS with the load observation is designed,based on the dynamic model of the electromagnetic coupler and the STSNTSM control.The simulation results show that the ECVCS has high control accuracy,anti-disturbance capability in tracking the fixed and variable differential rotational speed,while the outer rotor winding current has a weak high-frequency chattering.（4）The control objective,layout scheme,and adaptability to primary suspension stiffness parameters of the vehicle are studied by using SIMPACK and MATLAB/Simulink co-simulation method.The research shows that the steering performance of IRWs vehicles can be improved with zero yaw angle and zero lateral displacements as the control objectives,but the former has a more obvious improvement effect on the steering performance of IRWs vehicles.The optimal layout scheme is to configure the EDRAGC only in the guide wheelset;the optimal range of lateral and longitudinal stiffness for each node of primary suspension is 4～5 MN?m^-1 for lateral stiffness and 10～20 MN?m^-1 for longitudinal stiffness.