Active Reduction of Pressure Ripple in Power Steering Systems

The fluid borne noise in the power steering system of an automobile can couple with the chassis vibrational modes to produce audible noise in the passenger compartment. If the pressure ripple produced by the power steering pump, which is the main source of fluid borne noise, is reduced, the automobiles can be made quieter. In this paper, an active, broadband (bandwidth ∼1 kHz) noise cancellation technique based on piezoelectric actuators is presented. A reduction in pressure ripple by a factor of up to five is observed in a EHPS system. The design of control electronics also presents some challenges. The restrictions and advantages of feedback electronics used are also discussed.