Novel power conversion circuits and control schemes including soft switching techniques

Abstract

The power conversion circuits and control schemes are explored including soft switching techniques, a snubber topology for high power GTO thyristor and a high power GTO gate driver. These are very actual circuits and systems which are implementable to AC/DC/AC, DC/AC or AC/DC conversionms. Reducing the switching losses, the soft switching techniques are the main deliberation in the power conversion. The PWM control schemes and system structures are the next important thing. Most of proposed soft switching topologies using the resonant dc-link have deficiency of real PWM capability. In this study, indispensable circuits and control schemes for power conversion are described in the following paragraphs. A soft switched space vector PWM inverter is developed using new parallel resonant dc-link (PRDCL). This PRDCL can operate on variable dc-link pulse position and width resulting in enhanced PWM capability, which is superior to other resonant dc-links. A new space vector algorithm is presented suitable for this PRDCL inverter. The suggested algorithm is able to eliminate narrow PWM pulse which impede dc-link operation. This PWM control system, however, requires complex and precise timing sequences in relation to PRDCL operation, which is nicely solved by adopting new programmed controller with a buffer and a programmable timer. Novel 3-level GTO inverter topology is presented. This new power circuit includes many advantages comparing with the conventional 3-level GTO inverter. The main advantages are snubberless and good device utilization by employing dual quasi-resonant dc-link which guarantees the complete zero voltage switching of the inverter GTO``s. This 3-level GTO inverter can be operated with lower switching loss at higher switching frequency with robust inverter swiching. The regenerative GTO snubber play an important role in high power applications. The proposed snubber operates on forward converter mode for snubber capacitor energy recovery by combining...