Investigation of limitations in large converters with resonant input link above 30 kHz using GTOs

Abstract

The authors investigate at what link and pulse-width modulation (PWM) frequencies the tail switching losses in relation to the conduction losses of large converters with a resonant input link and GTOs are still acceptable, as a function of converter current rating, thus establishing the achievable link and PWM frequencies with increase in device type. It is also shown that by optimizing the resonant link, high link frequencies can be achieved without incurring tail losses due to the periodic charging of the resonant link inductor. The developed loss model is compared with actual device losses. The dimensioning of the capacitor for these high-power converters shows that the order of magnitude is the same as for a conventional RCD or regenerative snubber across each device, so that turn-off losses are approximately the same. The resonant link technology, however, still has the advantage of a much simpler topology than a conventionally switched converter with six regenerative snubbers. >