This is a Hyperbolic Tangent model for 200 KN large-scale magneto-rheological fluid damper (a model of the PWM Servo-Amplifier used to drive the damper is also included) developed at the University of Connecticut.
The physical counterpart of this model is the 200 kN large-scale MR dampers that are manufactured by the Lord Corporation. The damper is 1.47 m (58 inches) in length, weighs approximately 2.734 kN (615 lbs), and has an available stroke of 584 mm (23 inches). The damper's accumulator can accommodate a temperature change in the fluid of 80oF (27oC). The damper can provide control forces of over 200 kN (45 kip). The MR damper is controlled with a low voltage, current driven command signal. The coil resistance is approximately 4.8 ohms, with an associated inductance measured to be approximately 5 henrys (H) at 1 ampere (A) and 3 H at 2 A.
An Advanced Motion Controls PWM Servo-Amplifier (30A8) powered by an 80 volts (V) DC, 5 A unregulated linear power supply is used to provide the command signal that controls the electromagnetic field for each damper. The PWM Servo-Amplifier is controlled by a 0 - 5 V DC signal and utilizes pulse-width modulation for current control. The input control signal can be switched at a rate up to 1 kHz, although the rise time of the current signal is limited by the inductance of the MR damper. Each damper has been fitted with a 1.5KE75A transient voltage suppressor to protect the MR damper electromagnetic coils from unintended and damaging voltage peaks, limiting the peak voltage to 75 V. A PWM amplifier model which is described as a second order transfer function with a constant delay is also included.
This model is specially tuned for the MR dampers that Prof. Richard Christenson at the University of Connecticut owned but are currently hosted at two real-time hybrid simulation test facilities at the Smart Structures Technology Laboratory at the University of Illinois at Urbana Champaign and the Lehigh University Network for Earthquake Engineering Simulation facility. This model may be needed to tweak for specific damper since it has been noticed that even damper with the same model may have slightly different behaviors.
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