Vibration Control of a Flywheel Energy Storage Device Using a DC Motor as a Radial Force Actuator

This paper presents a technique for vibration suppression in a rotordynamic system. The approach implemented involves using a DC motor for simultaneous torque and radial force actuation. Here, the rotor is supported via passive permanent magnetic bearings. The permanent magnets are arranged so that, for small motions, the rotor can be treated as a spinning top that is supported radially by linear springs. The device includes an axial flux, three phase, brushless DC motor that is used to produce a torque. The same motor is also used to develop radial forces to control the vibration of the rotor. This is accomplished by using two phases of the motor for torque generation, and one phase to produce radial forces. The paper develops a set of equations that can be used to predict the radial force generated by the motor coils. These equations are used to implement a feedback control system to regulate the radial position of the rotor. Experiments are conducted to verify the coil force equations and demonstrate the effectiveness of the feedback control scheme.