The concept of soft-switching pulse-width-modulated (PWM) technique
was proposed aimed at combining the advantages of both the conventional
PWM technique and the resonant technique. This work presents four new
families of soft-switching PWM converters: the zero-voltage-switched (ZVS)
PWM converters, the zero-current-switched (ZCS) PWM converters, the zerovoltage-
transition (ZVT) PWM converters, and the zero-current-transition (ZCT)
PWM converters.
The family of ZVS- and ZCS-PWM converters are developed to improve
the performance of the ZVS and ZCS quasi-resonant converters, respectively.
The principles of operations of these two families of converters are presented,
and the merits and limitations are assessed. A number of experimental
converters are breadboarded to verify the theoretical analysis.
Both the ZVT-PWM and ZCT-PWM techniques use the concept of shunt
resonant network to achieve soft-switching. In this way, the new converters achieve
soft-switching without increasing the voltage and current stresses of the power switches
and diodes. By using the boost topology as an example, a complete dc analysis of the
ZVT-PWM and ZCT-PWM converters is presented, and the dc VOltage-conversion ratio
characteristics are derived. Design trade-ofts are examined, and design procedures
are established. The theoretical analysis and novel features of the proposed
converters are verified on a number of breadboarded converters.
Finally, the typical small-signal characteristics of the ZVT -PWM converters are
analyzed and verified experimentally by using the boost converter as an example.
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