Design of magnetorheological damper with short time response

For efficient fast control of suspension systems with magnetorheological dampers controlled by semi-active algorithms, the time response of the magnetorheological damper is one of the most important parameters which influences the performance of the suspension system. The time response of commercial magnetorheological dampers with common controllers is in the range of tens of milliseconds, which is too long for efficient real-time control of car suspension. This article describes the ways how to design magnetorheological damper with short response time. First part describes the elimination of long time response caused by high inductance of electrical circuit of magnetorheological damper using current controller. The second part describes elimination of long time response caused by eddy currents which are induced in the magnetic circuit of magnetorheological damper. The new piston of the magnetorheological damper is designed from material with high relative permeability but low electrical conductivity (ferrite). The time responses of magnetic induction and damper forces were measured and compared to original commercial Delphi damper. Results showed rapid improvement in time response when the current controller is used and when the piston is constructed from ferrite materials.