Characterization of GTOs under different modes of zero current switching

Several papers have described the use of GTOs in zero current switching (ZCS) applications, with the goal of increasing the frequency range for medium- and high-power converters. Zero current switching with GTOs can be applied in series and parallel resonant converters, as well as in PWM inverters with commutation aid networks. The voltage and current waveforms at the devices differ in each of these applications, and different modes of ZCS can be identified. In this paper, a comparative view of the behavior and characteristics of the GTO in the different modes of ZCS is presented. The variety of ZCS waveforms is described and transferred into a unifying schematic. The behavior of GTOs in the different modes of operation is characterized, and requirements to the circuit environment are pointed out. The relations between the most important circuit parameters and some of the device waveform parameters are investigated experimentally