Keyue M. Smedley

Assistant Professor, Electrical Engineering and Computer Science
The Henry Samueli School of Engineering

PH.D., California Institute of Technology

Phone: (949) 824-6710
Fax: (949) 824-2321

University of California, Irvine
644D ET
Mail Code: 2625
Irvine, CA 92697
Research Interests
Area: Power Electronics, Motion Control, and Circuits & Systems. Application: Class-D Power amplifiers, Soft-Switching, and Power factor correction
Research Abstract
One-Cycle Control of Switching Converters, Inverters, and Amplifiers
Investigator: K.M. Smedley
Research Assistant: Z. Lai
Support: National Science Foundation; UC Micro; QSC Audio; Tektronix

One-Cycle Control is a fast, precise, and robust pulse-Width modulation method. It has inherent feedback and feedforward ability. Switching circuits with One-Cycle control effectively reject the power supply ripple; therefore, no precision dc power supply is required. In addition, this control method automatically corrects the switching error, so that no matching of the output semiconductor components and driver is necessary. This control method is very suitable for audio power amplification, motion control, uninterrupted power supplies, etc.

Soft-Switching Methods for Converters, Inverters, and Amplifiers
Investigator: K.M. Smedley
Research Assistant: M. Smith
Support: UCI, Tektronix

A comparison study of a group of zero-voltage soft-switching methods at UCI has shown that not all the existing soft-switching methods increase the efficiency, but only those with minimum redirection current and with redirection energy feedback. The UCI Power Electronics Laboratory has developed soft-switching methods for converters, inverters, and amplifiers with improved efficiency. Researchers at UCI are currently investigating general topologies to achieve soft-switching in switching circuits in order to reduce switching loss and EMI emission.

Power Factor Correction Methods
Investigator: K.M. Smedley
Research Assistant: Z. Lai
Support: UCI, Tektronix

Most electronic devices produce pulsed line current due to their conventional rectifier function. The pulsed line current has low power factor and high harmonic content. Researchers at UCI are investigating general control methods for rectifiers to achieve unity power factor and low harmonic distortion. A family of control methods have been developed for switching converters under continuous and discontinuous current operating conditions and with very simple circuitry.

Digital-PWM PowerAmplifiers with Noise and Ripple Shaping
Investigator: K.M. Smedley
Research Assistant: M. Smith
Support: UCI, Tektronix

The noise and ripple shaping digital-PWM power amplification technique combines both power and signal processing within the digital domain. It effectively rejects the power supply ripple, therefore, eliminates the need for highly regulated power supplies. It uses lower bits to represent a higher resolution digital number thus reduces the required speed of the PWM clock. The applications include: multimedia audio, music amplification, communication, motion control, etc.

The Power Electronics Laboratory at UCI is a newly established research facility. It is equipped with state-of-the-art instrumentation. The research in this laboratory is focused on theoretical development and experimental verification.
Available Technologies
K. Smedley and S. Cuk, "One-Cycle Control of Switching Converters," 22nd Annual IEEE Power Electronics Specialists Conference (Cat. No.91CH3008-0), Cambridge, MA, 1991. pp. 888-96. See also US patent 5,278,490 and IEEE Transactions on Power Electronics, November 1995, Volume 10, Issue 6.
K. Smedley and S. Cuk "Switching Flow-Graph Nonlinear Modeling Technique," IEEE Power Electronics Specialists Conference (Cat. No.92CH3163-3), Toledo, Spain, 29 June-3 July 1992, pp. 1173-80 vol.2. See also IEEE Transactions on Power Electronics, July 1994, vol.9, (no.4):405-13.
K. Smedley and R. Shafer "Experimental Determination of Electrical Characteristics and Circuit Models of Superconducting Dipole Magnets," IEEE Transactions on Magnetics, Sept. 1994, Vol. 30, (no.5, pt.1):2708-12.
Z. Lai and K. Smedley. "An new Extension of One-Cycle Control and its Application to dc-ac converters, IEEE transaction on Power Electronics, Jan. 1996.
M. Smith, K. Smedley, and Y. Ma "Realization of a Digital PWM Power Amplifier using Noise and Ripple Shaping," IEEE Power Electronics Specialist Conference, Atlanta, June, 1995.
Research Center
Power Electronics Laboratory
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