Design And Control Research Of Electromagnetic Active Suspension Actuator

With the improvement of the economic level and the development of science and technology,people’s requirements for the riding comfort,driving safety and operational stability of vehicles have also been continuously improved.Traditional passive suspensions are becoming more and more difficult to meet the corresponding requirements.Active suspension systems can adjust the body attitude in real time based on vehicle attitude information and road surface information,combined with certain control strategies.In this way,the dynamic performance of the vehicle is optimized under various working conditions.As the core component of active suspension,the actuator has always been one of the focuses of research.Therefore,based on the active suspension system integrated in the wheel hub,this paper designs a permanent magnet linear motor as the actuator of the active suspension,and analyzes and optimizes the characteristics of the actuator.Through the joint simulation of actuator inner loop current hysteresis comparison control and active suspension outer loop robust control,the rationality of the designed linear motor actuator structure and the effectiveness of the combined control strategy of the inner and outer loops of the electromagnetic active suspension are verified.The specific work content includes the following aspects:Firstly,the cylindrical permanent magnet synchronous linear motor was selected as the actuator of the active suspension system.The working principle of the actuator was introduced,and the design goal and structure scheme of the linear motor actuator were determined.The material selection,permanent magnet design,slot pole number matching design,coil winding design and rotor core design of permanent magnet linear motor were completed.Finally,a 12 slot 14 pole permanent magnet linear motor actuator was designed.Then,according to the designed motor parameters,a nonlinear analytical model of the magnetic field of the actuator,the induced electromotive force of the winding and the electromagnetic force output by the actuator was established.A two-dimensional finite element simulation model of the permanent magnet linear motor with rotational symmetry about the central axis was established in the Maxwell electromagnetic simulation software.The finite element simulation results showed the existence of saturation and end effects.Based on the analytical model and the finite model,the winding flux and induced electromotive force of the motor were compared and analyzed,and the correctness of the established model was verified.The static and dynamic output characteristics of the designed actuator were analyzed,which showed that the electromagnetic force output by the designed actuator gradually tends to nonlinear saturation after the control current reaches 4.3A,and its dynamic output has obvious volatility.It provided a theoretical model foundation for the subsequent joint control of electromagnetic active suspension considering the influence of nonlinear factors.In addition,the incremental length of the end of the secondary mover core was optimized,so that the thrust fluctuation caused by the end effect was reduced to 26%of the initial value when the incremental length takes the optimal value of 3.5mm.Finally,based on the nonlinear model of electromagnetic force,the current hysteresis comparison controller of the actuator was designed.Taking into account the nonlinear saturation characteristics of the electromagnetic force of the actuator,in order to make the actuator work in the linear stage as much as possible,the output of the actuator was limited to the electromagnetic force range corresponding to 4.3A.Then based on the 7DOF suspension model,the H2/H∞ robust controller of the active suspension was designed,and the multi-objective genetic optimization algorithm was performed on the controller parameters.In Matlab/Simulink,a simulation model of electromagnetic linear motor actuator inner loop current control and active suspension outer loop robust control was established.The joint control system was simulated on the C-level road.The simulation results showed that the designed permanent magnet linear motor actuator has a good tracking effect on the target active force required by the active suspension,and it can still meet the performance requirements of the active suspension after limiting the actuator output to the linear working stage.The sprung mass acceleration,pitch angular acceleration and roll angular acceleration are improved by 24.43%,28.94%and 28.85%respectively.It verified the rationality of the actuator structure design and the effectiveness of the combined control strategy of the inner and outer loops of the electromagnetic active suspension.