Electric power conversion systems – Current conversion – With voltage multiplication means
Reexamination Certificate
1999-09-23
2001-11-13
Berhane, Adolf Deneke (Department: 2838)
Electric power conversion systems
Current conversion
With voltage multiplication means
Reexamination Certificate
active
06317342
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to power conversion and to micro-electromechanical (MEM) devices.
2. State of the Art
A large proportion of present power electronics research focuses on miniaturization of power converters. The goal is to maximize efficiency and power density. Power densities of approximately 50 W/cm
3
have been reported in the literature for discrete switch-mode supplies. Efforts at miniaturizing power converters often are hampered by the difficulty of integrating magnetic components with other circuit elements using existing processing technology. In the area of micromachined electrostatic sensor and actuators, for example, such sensors and actuators often require high voltages for proper operation. Currently, these voltages must be generated off-chip, because magnetic components are generally unavailable in ICs.
One interesting approach integrates an inductor with a capacitor using microstrip theory. This method permits the manufacture of integrated LC structures suitable for power conversion applications. Apparently, these devices are not compatible with existing planar integrated circuit technology. Yachi et al. (“A new planar microtransformer for use in micro-switching converters,”
PESC,
pp. 20-26, June 1991) outlines a planar microtransformer manufactured by dry process techniques using Cu, Ta, and CoZrRe as the magnetic material. This process apparently permits integration of a microtransformer with power semiconductor devices. A problem with this device is the large series resistance of the device, apparently caused by the contact resistance between the two separate metallization steps needed to define the coil. Another approach for constructing integrated power supplies has been based on the methodology of switched capacitor circuits. Drawbacks of this approach include lack of isolation and inherent switching losses.
An electrostatic microresonant power conversion devices is described in a paper of the same name,
IEEE PESC,
Vol. II. pp. 997-1002, 1992, by the present inventors. As described therein, the approach followed is to replace the LC tank in a resonant converter with a micromechanical device, thereby avoiding the fabrication of magnetic components. Two micromechanical devices are coupled in tandem. Isolation and energy transfer between primary and secondary ports is achieved with an insulating mechanical coupling. The device is manufactured by planar techniques using readily available silicon processing equipment. This compatibility permits integration of the device with semiconductor devices to yield a monolithic power supply.
The foregoing approach, while effective, requires a high voltage bias supply, the conventional generation of which decreases the utility of the design. There remains a need for improved MEM-based power conversions devices.
SUMMARY OF THE INVENTION
The present invention, generally speaking, provides an inductor-free power converter based on mechanical resonance using a single MEM device. Mechanical resonance and silicon strain energy are used as building blocks for a power converter, such as a boost converter. In such a “micromechanical boost converter,” arbitrary step-up voltages can be developed using only a single micromechanical component. A dramatic improvement in power density is obtained as compared to conventional capacitor and inductor technologies. For typical MEM applications, such a converter, operating without discrete parts, can readily be fabricated together with the MEM device it powers. For non-MEM applications (e.g., the on-chip generation of high voltages, as for EEPROM programming, for example), the improvement in power density offers significant benefits, particularly for portable equipment.
REFERENCES:
patent: 6049702 (2000-04-01), Tham et al.
Yachi et al., “A new planar microtransformer for use in micro-switching converters,”PESC, pp. 20-26, Jun. 1991.
J. Noworolski, “Self-Aligned Polysilicon MEMS Reduced Mask Count Surface Micromachining,”Proceedings of SPI, Micromachined Devices and Components, vol. 3514, Sep. 1998 (6 pages).
Jochen Franz et al., “A Silicon Microvale With Integrated Flow Sensor”, Robert Bosch GmbH, Automotive Equipment Division 8 Tubingerstrasse 123, Reutlingen, Germany, Transducers ′1995, The 8thInternational Converence on Solid-State Sensors and Actuators, and Eurosensors IX, Jun. 25-29, 1995, pp. 313-316.
William C. Tang et al, “Laterally Driven Polysilicon Resonant Microstructures”, University of CA at Berkeley, IEEE, 1989, pp. 53-59.
Meng-Hsiung Kiang et al., “Actuated Polysilicon Micromirrors For Raster-Scanning Displays”, University of CA at Berkeley, IEEE, 1997, pp. 323-326.
David A. Horsley et al., “Design and Feedback Control Of Electrostatic Actuators For Magnetic Disk Drives”, Berkeley Sensor and Actuator Center, University of CA at Berkeley (5 pages) No Date.
J. Mark Noworolski, “Micromechanical Power Conversion”, University of CA at Berkeley, Spring 1998. pp. 1-115.
J. Mark Noworolski, et al., “Microresonant devices for power conversion”, Department of Electrical Engineering and Computer Science, University of California, Berkeley “No Date” .
J. Mark Noworolski, et al., “An Electrostatic Microresonant Power Conversion Device”, department of Electrical Engineering and Computer Science, University of California, Berkeley “No Date” .
Noworolski J. Mark
Sanders Seth R.
Berhane Adolf Deneke
Burns Doane Swecker & Mathis L.L.P.
Munetix, Inc.
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