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Title: Aspects of high frequency half-bridge circuits
Author: Carter, D. R. H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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The switching frequency of power electronic converters has been increasing steadily since mode techniques became widespread in industrial and consumer electronics. The motivation for this trend has been the attraction of increased power density for converters. The work presented in this thesis addresses some important practical aspects of the half-bridge converter to allow high-performance operation at multi-megaHertz frequencies. This topology has been chosen for its good utilisation of power devices. A new, fully-electronic level-shifter topology has been developed to fulfil the requirements for half-bridge operation at high-frequencies and voltages. An analysis of its operation is given, and optimum operating conditions are described. Operation has been proven for switching frequencies up to 13.56 MHz - a frequency with lenient restrictions on electromagnetic emissions that is widely used in industry for radio frequency power sources. In order to achieve a high power density for high-frequency converters, power integrated circuit technology has been used to design a smart power switch. Each switch includes a power MOSFET, high-speed MOS-gate driver, level-shifter and half-bridge control circuitry. Two switches can be used to construct a high-frequency half-bridge converter. Fabricated parts have already demonstrated the operation of an integrated level-shifter for this purpose, and fabrication of the complete switch is underway. To gain a theoretical understanding of the high-frequency half-bridge, an analysis that takes into account the non-linear output capacitance of the output power MOSFETs has been made. This reveals a variation in timing of the converter with supply voltage and accounts for high-frequency losses in the drift region of the power MOSFETs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available