Congratulations to Juanjuan Sun, 10th CPES graduate to join Linear Technology
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| Juanjuan Sun |
Within ten days after completing her Ph.D. defense in mid-June, CPES new graduate, Juanjuan Sun, was packed and ready to head for California, not only to start her new career at Linear Technology, but also to reunite with her husband, Yang Qiu, another CPES alumnus who left CPES to join Analog Devices in November 2006.
Juanjuan Sun is the 10th CPES graduate to join the team at Linear Technology. While at CPES, she was on the Power Management Consortium (PMC) team conducting research under the direction and guidance of Prof. Fred C. Lee and Prof. Ming Xu. Her dissertation, "Dynamic Performance Analyses of Current Sharing Control for DC/DC Converters," is available to industry partners (Principal Plus, Principal and Associate Members) here via password access. For a preview, please see the brief abstract below.
Linear Technology and Analog Devices are both CPES Principal Plus members and members of the Power Management Consortium. We are proud that our well-trained graduates can continue to serve CPES industry member firms and make valuable contributions in the power electronics industry!
Dynamic Performance Analyses of Current Sharing Control for DC/DC Converters
Abstract:
Paralleling operation of DC/DC converters is widely used in today's distributed power systems. Special provisions are usually necessary to ensure current sharing among the paralleled modules. A number of current sharing control methods have been proposed in recent years in order to achieve current sharing in steady state as well as during the dynamic line and load changes. This dissertation has established the fundamental relationship between the current sharing control and voltage regulation control, as well as a classification scheme to encompass different current sharing control structures. The concept of output impedance is employed as a unified scheme to investigate the effectiveness of various current sharing controls.
While the traditional modeling technique can handle the dynamic current sharing analyses for low-frequency perturbations, it is not valid when the perturbation frequency is approaching the switching frequency. A rather unusual phenomenon has been observed when the microprocessor is subject to high frequency load dynamics. Large-magnitude beatfrequency oscillations can occur in the voltage regulator phase current while it is not observable at the output port. The conventional output impedance concept is no longer suitable for predicting the beat-frequency oscillation because it does not include any beatfrequency information. A new modeling methodology was proposed based on the extended describing function method. This model made it possible to study beat-frequency oscillations and predict the amplitude of the oscillations. Based on the model, methods to reduce beatfrequency oscillations have been suggested and implemented successfully in the prototype circuit board.