Investigation Of Vehicle Active Suspension Based Upon Electromagnetic Acutator

The suspension system is an important component of the vehicle chassis system, and there is extremely vital significance to improve the performance of the vehicle suspension system for the vehicle's riding and handling performance. The effect of the traditional passive suspension system is limited due to the contradictions between the riding and handling performance. For semi-active suspension system, it cannot provide active force and just consume energy, thus its performance is far less than that of the active suspension system. In the research of the vehicle active suspension system, there is a great achievement about the control algorithm, but relatively lack in the key part of the active suspension system namely actuator. Based on this, this thesis is studied emphatically on the vehicle active suspension actuator. Under a comprehensive review and analysis on the current research at home and abroad, it puts forward a kind of tubular electromagnetic actuator as active suspension actuator solution and probes into various influential factors about the electromagnetic force. Meanwhile, combining with actuator simulation and experimental data, making the vehicle suspension system for this particular carrier, it does a comprehensive and in-depth research.A kind of relatively reasonable cylinder type electromagnetic linear actuator structure is designed, and the finite element model (FEM) is built up. Through the electromagnetic finite element simulation software of Ansoft and Flux, the consistency of the FEM is checked. Based on this result, it systematically explores the influence of the structure parameters to the electromagnetic force, such as air-gap thickness, copper thickness and the mode of winding connection. In addition to this, the influence of power supply voltage and frequency to the electromagnetic force is also analyzed. Finally, the temperature field of the electromagnetic actuator stalled is simulated to provide the basic theoretical basis for the electromagnetic actuator design.The mathematical model of this electromagnetic actuator (EMA) is constructed, and electromagnetic force experiments are carried out to study the characteristics of EMA, using the three-phase self coupling contact pressure regulator and the three-phase controlled regulator to study the steady and transient response of EMA. Meanwhile, combined with the finite element simulation analysis, the consistency of the FEM and the dynamic mathematical model is checked.The drive circuit of the tubular electromagnetic linear actuator is designed, and the dead zone unit is produced. By AutoBox DSPACE control system and intelligent power module IPM, the main power circuit is built up, and the simple test platform is also built up. Through the test platform, the constant force, square wave force and triangle wave force experiments are tested. Through the test, it shows the drive circuit design is feasible.The dynamic mathematical model of the quarter car active suspension system is constructed. Then the outer-loop optimal control and inner-loop EMA vector control are analyzed. During the study of outer-loop optimal control, three different weight coefficients are chosen, for example, comfortable mode, typical mode and hard mode. By the simulation analysis of frequency domain, it also shows the compromise. At the same time, the effect of time delay on the performance of active suspension system is further explored. It can be found that when the time delay is in 20ms or less, the optimal control algorithm can maintain the suspension system stability. After that the typical mode weight coefficient is chosen to simulate the suspension response during the three different kinds of the sinusoidal road in the time domain. In the situation of an uneven road disturb at 2Hz and amplitude is 0.05m, the body vertical vibration accelerationcan improve about 66.7%, suspension travel 25.4%, and the tire dynamic load 62%. In the situation of an uneven road disturb at 5Hz and amplitude is 0.03m, the body vertical vibration accelerationcan improve about 62.7%, suspension travel worse 6.4%, the tire dynamic load can improve about 19.5%. In the situation of an uneven road disturb at 10Hz and amplitude is 0.01m, the body vertical vibration acceleration can improve about 8.3%, suspension travel worse 180%, the tire dynamic load worse 170.3%.