Date of Award


Degree Type


Degree Name

Master of Engineering Science


Electrical and Computer Engineering


Dr. Gerry Moschopoulos

Second Advisor

Dr. Lyndon Brown


High frequency operation of single-switch, pulse width modulated (PWM) converters allows for the reduction of the size and weight of their magnetic and filtering components, but switching losses become significant and must be reduced. The standard approach to minimizing these losses has been to use an active auxiliary circuit that consists of an active switch and passive elements and that is not part of the main power circuit. The auxiliary circuit helps the main power switch turn on with zero-voltage switching (ZVS). The circuit is activated just before the main power switch is to be turned on and is active for only a fraction of the switching cycle, until the switching transition has been completed. A new type of active auxiliary circuit is presented in this thesis. The main feature of an auxiliary circuit of this new type is that it has the advantages of traditional nonresonant and resonant auxiliary circuits without the disadvantages. In this thesis, the fundamental principles behind the new type of circuit are explained, an example circuit of this type is analyzed, and a design procedure for the selection of the critical components is presented. A variation of the new type of circuit is then discussed, and the feasibility of the new type of auxiliary circuit is confirmed by experimental results obtained from a prototype circuit of a 500W, 100 kHz ZVT PWM boost converter.



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