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Vibration Control

Vibration Control. Presentation in Control engineering research seminar 21.2.2011. Why vibration control. Linear motion. Rotation. Vibrations occur almost everywhere few examples :. Why vibrations control. Vibrations are damped to get Less noise to surroundings -> comfort for users

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Vibration Control

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  1. Vibration Control Presentation in Control engineering research seminar 21.2.2011

  2. Why vibration control Linear motion Rotation Vibrations occur almost everywhere few examples:

  3. Why vibrations control Vibrations are damped to get • Less noise to surroundings-> comfort for users • Decrease conduction of vibration into the structures-> comfort for users/operators • Less wear of parts and need for maintenance-> less costs

  4. Passive and active vibration control Materials and structures are chosen/designed such that the vibrations are minimized Passively + cheap to design and maintain - works well only on small frequency band Actively An actuator is added to the system to exert opposite force to damp vibrations + more effective on all frequencies and for all kinds of disturbances - expensive to design and maintain Vibrations can be controlled

  5. Active vibration control • How the system is modeled? • How accurate model should be chosen? System modeling Measurement and estimation • What can be measured directly? • What needs to be estimated? • Depends on the model structure • What can be controlled? • Depends on the model structure and the measurements Control Vibration control consists of (as almost every control problem)

  6. System modeling Lumped parameter system Active Distributed parameter system Passive Finite element modeling How accurate the system modeling should be?

  7. Example d(t) Choose signal F(t) such that disturbance d(t)is eliminated d + x Only signal x(t) can be measured F System + Compensator Simple model

  8. Vibrations in electrical machines Structure of an AC induction motor

  9. Rotor vibrations y x ω ω z Radial vibrations Torsional vibrations

  10. Actuator rotor stator stator windings How can we apply force to the stator? A common approach is to use a magnetic bearing In our approach an additional winding mounted to the stator is used Department of Automation and Systems Technology http://autsys.tkk.fi/en/

  11. Laval-Jeffcott rotor model y x ω z Simply a disk attached to a shaft supported at both ends Disk is rotating at constant speed ω

  12. Example Complex electro-magnetic equations inside Laval-Jeffcott rotor model d Plant: v ym + Plant Act yem + yin Actuator: where A more complex model

  13. Example continues Choose signal F(t) such that disturbance d(t)iseliminated Process d Dist v ym + Plant Act + yem yin Only signal ym(t) can be measured Controller But the task is again the same

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