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Abstract

Piezohydraulic and piezopneumatic frequency rectification is analyzed with a steady-state model of work and energy transfer. In this paper, piezohydraulic actuation is defined as the use of incompressible fluid to rectify the oscillatory motion of a piezoelectric device into unidirectional motion; piezopneumatic actuation is the use of a compressible gas such as air. The steady-state analysis is based on the definition of two efficiency metrics. The mechanical efficiency is defined as the ratio of mechanical work transferred to the load to the total mechanical work performed by the actuator, and the electrical efficiency is defined as the ratio of electrical energy expended to the peak energy required. The analysis demonstrates that piezohydraulic rectification is inherently more efficient than piezopneumatic rectification due to the assumption of fluid incompressibility. The mechanical efficiency is 100% when using incompressible fluid (ideal) but drops to below 40% when using compressible gas. The maximum electrical efficiency of piezohydraulic rectification is also four times higher than that of piezopneumatic actuation (29% to 7%). The overall efficiency of the rectification process (defined as the product of the mechanical and electrical efficiencies) is an order of magnitude greater when using incompressible fluid than when using compressible gas (29% to 2.8%). Thus, frequency rectification using compressible gas will require peak energy inputs that are ten times greater than that of incompressible fluid for an equivalent amount of mechanical work output. The significant difference in peak energy requirements is attributed to the reduced coupling between the actuator and the load that occurs due to compressibility of the gas. These results represent an upper bound on the efficiency because they neglect other sources of system losses, such as material hysteresis and frictional losses within the piston and seals of the actuator.

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References

Berner, N. T. and D. E. Brei . 1999. “Modeling and Study of the Quasi-Static Behavior of Piezoceramic Telescopy Actuation Architectures.” in ASME Adaptive Structures and Material Systems, volume AD-59, pp. 189-197.

Dorf, R. C. and J. A. Svoboda . 1996. Introduction to Electric Circuits. Wiley, New York.

Giurgiutiu, V. , C. A. Rogers and Z. Chaudhry . 1996. “Energy-Based Comparison of Solid-State Induced-Strain Actuators.” Journal of Intelligent Material Systems and Structures, 7(1): 4-14.

Hagood, N. W. et al. 2000. “Microhydraulic Transducer Technology for Actuation and Power Generation,” in Proceedings of the SPIE, Paper Number 3985-81.

Leo, D. J. 2000. “Energy Analysis of Piezoelectric-Actuated Structures,” Journal of Intelligent Material Systems and Structures, 10(1): 36-45.

Leo, D. J. and K. Nasser . 2000. “Air Flow Control Systems for Miniature Fuel Cells,” in Proceedings of the SPIE, Paper Number 3985-83.

Main, J. , D. Newton , L. Massengil and E. Garcia . 1996. “Efficient Power Amplifiers for Piezoelectric Applications,” Smart Materials and Structures, 5(6): 766-775.

Mauck, L. and C. S. Lynch . 1999. “Piezoelectric Hydraulic Pump,” in Proceedings of the SPIE, volume 3668, pp. 844-852.

Mauck, L. and C. S. Lynch . 2000. “Piezoelectric Hydraulic Pump Development,” in Proceedings of the SPIE, Paper Number 3985-85.

10.

Nasser, K. , D. J. Leo and H. H. Cudney . 2000. “Compact Piezohydraulic Actuation System,” in Proceedings of the SPIE, Paper Number 3991-41.

11.

Near, C. D. 1996. “Piezoelectric Actuator Technology,” in Proceedings of the Smart Structures and Materials Conference, volume 2717, pp. 246-258.

12.

Nowicki, J. 1973. Power Supplies for Electronic Equipment: Volume 1 Rectifiers, Inverters, and Converters. Leonard Hill Books, London.

13.

Paine, J. S. and Z. Chaudhry . 1996. “The Impact of Amplification on Efficiency and Energy Density of Induced Strain Actuators,” in Proceedings of the ASME Aerospace Division, volume AD-52, pp. 511-516.

14.

Roberts, D. , N. Hagood , J. Carretero , H. Li , R. Mlcak and Y. Su . 2000. “Piezoelectrically Driven Hydraulic Amplification Microvalve for High Pressure High Frequency Applications,” in Proceedings of the SPIE, Paper Number 3985-59.

15.

Wallaschek, J. 1995. “Piezoelectric Ultrasonic Motors,” Journal of Intelligent Material Systems and Structures, 6(1): 71-83.

Efficiency of Frequency-Rectified Piezohydraulic and Piezopneumatic Actuation

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