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TECHNICAL PAPERS

# Disturbance Attenuation Using a dc Motor for Radial Force Actuation in a Rotordynamic System

[+] Author and Article Information
Rainer Leuschke, Brian C. Fabien

Department of Mechanical Engineering,  University of Washington, Seattle, WA 98195

J. Dyn. Sys., Meas., Control 129(6), 804-812 (Jan 18, 2007) (9 pages) doi:10.1115/1.2789471 History: Received February 01, 2006; Revised January 18, 2007

## Abstract

This paper presents a technique for attenuating the external disturbances acting on the rotor of a prototype flywheel energy storage device. The approach uses a three-phase axial flux brushless dc motor to simultaneously produce a torque and a radial force. This is accomplished by using two phases of the motor for torque generation, and one phase to produce the radial force. The paper develops a set of equations that can be used to predict the forces generated by the motor coils. These equations are used to implement a feedback control system to suppress the effects of external excitations. The nonlinear controller requires the velocity measurements and the angular displacement of the flywheel. The controller essentially adds damping to the system, and the constant feedback gains solve an optimization problem that involves a $H∞$ bound on the disturbance attenuation. The experimental results clearly demonstrate that the dc motor can be used to suppress unwanted radial vibrations due to external disturbances.

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## Figures

Figure 1

Axial flux FES device

Figure 2

Experimental setup of the prototype

Figure 3

Motor configuration

Figure 4

FES geometry and mechanical model

Figure 5

Coil 1 model

Figure 6

Displacements due to coil 1∕3 actuation

Figure 7

Displacements due to Coil 2∕4 actuation

Figure 8

Zero speed (θ̇z=0) frequency response

Figure 9

Open-loop frequency response

Figure 10

Closed-loop frequency response

Figure 11

Open-loop response, θ̇z=0rpm

Figure 12

Closed-loop system, θ̇z=0rpm

Figure 13

Open-loop system, θ̇z=500rpm

Figure 14

Closed-loop system, θ̇z=500rpm

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