Research Papers

Self-Powered Eddy Current Damper for Rotordynamic Applications

[+] Author and Article Information
Mario Silvagni

Department of Mechanical and
Aerospace Engineering–Mechatronics Laboratory,
Politecnico di Torino,
C.so Duca degli Abruzzi, 24,
Torino 10129, Italy
e-mail: mario.silvagni@polito.it

Andrea Tonoli

Department of Mechanical and
Aerospace Engineering–Mechatronics Laboratory,
Politecnico di Torino,
C.so Duca degli Abruzzi, 24,
Torino 10129, Italy
e-mail: andrea.tonoli@polito.it

Angelo Bonfitto

Department of Mechanical and
Aerospace Engineering–Mechatronics Laboratory,
Politecnico di Torino,
C.so Duca degli Abruzzi, 24,
Torino 10129, Italy
e-mail: angelo.bonfitto@polito.it

Contributed by the Technical Committee on Vibration and Sound of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received March 31, 2014; final manuscript received July 21, 2014; published online November 12, 2014. Assoc. Editor: Ryan L. Harne.

J. Vib. Acoust 137(1), 011015 (Feb 01, 2015) (8 pages) Paper No: VIB-14-1112; doi: 10.1115/1.4028228 History: Received March 31, 2014; Revised July 21, 2014; Online November 12, 2014

The vibration control of rotors is often performed using elastomeric or fluid dampers together with rolling element or hydrodynamic type bearings. Electromagnetic dampers seem a valid alternative to conventional solutions and also to active magnetic bearings (AMBs) because their simpler architecture, size and, if of transformer type, also for the absence of power electronics, position sensors, and any fast feedback loop. However, transformer eddy current dampers require a constant voltage power supply than can be provided by an embedded generator to reduce cost and improve the reliability. The present paper proposes a self-powered damper to fulfill these requirements. A three-phase permanent magnet electric generator (connected to the rotating shaft) generates the required power for the damping device. The generator is connected to the damping circuit by means of tuned impedance and a three-phase rectifier.

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Fig. 1

RTR: (a) picture with supporting structure and rotor: damper are not installed and (b) section view of the rotor of the machine and of the elastic supports. (1) LPT disk, (2) LPT roller bearing, (3) LPT beam support, (4) LPC beam support, (5) LPC ball bearing, (6) LPC disk, and (7) hollow shaft.

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Fig. 2

Sketch of the self-powered magnetic damper (power supply on the upper coil is not reported)

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Fig. 3

Qualitative characteristic of generated voltage (dashed), of electromagnetic damper (dotted), and of the resulting damping effect (continuous)

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Fig. 4

Block diagram of the self-powered magnetic damper system

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Fig. 5

Equivalent circuit of the permanent magnet generator

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Fig. 6

Sketch of a two electromagnet semi-active magnetic damper (the elastic support is omitted)

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Fig. 7

(a) Mechanical impedance of a transformer eddy current damper in parallel to a spring of stiffness Km. (b) Mechanical equivalent.

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Fig. 8

Required torque to drive the generator with different tuning circuit inductances

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Fig. 9

Required power to drive the generator with different tuning circuit inductances

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Fig. 10

Electromagnetic damper coil voltage with different tuning circuit inductances

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Fig. 11

BEM voltage evaluation during no load operation of the generator

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Fig. 12

Torque characteristic of the short-circuited generator

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Fig. 13

Fitting of the electromagnetic damper coil inductance

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Fig. 14

FRF of the rotor (standstill) at various supply voltages

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Fig. 15

Measured and estimated coil current during the run-down test

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Fig. 16

Unbalance response with the electromagnetic damping device disabled

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Fig. 17

Unbalance response with the self-powered electromagnetic damper enabled

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Fig. 18

Effect of constant voltage supply compared to the self-powered solution



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