Resonant IGCT Soft-Switching: Zero-Voltage Switching or Zero-Current Switching?

Abstract

In the last thirty years the IGCT has been employed in medium voltage MW power level converters and has demonstrated some of the lowest conduction losses of any actively controlled device in traditional hard-switched, sub-kHz applications. Extending the use of the device to medium frequency applications such as DC transformers is possible through soft-switched operation, where low turnoff current and zero voltage turn-on significantly reduce switching losses. For this purpose, this paper explores the trade-offs in the transition between zero voltage and zero current switching conditions of reverse conducting IGCTs. Switching conditions resulting in minimal switching loss are identified for standard commercial devices and engineering samples subjected to increased electron irradiation to reduce switching energy at the expense of on-state voltage. The operation of the IGCTs at the record frequency of 5 kHz is thermally validated under load in the identified switching conditions.

Static and Dynamic Voltage Balancing for an IGCT-Based Resonant DC Transformer

“…This plot shows the maximum capacitance value, for a given current to perform a safe ZVS. If this criterion is not fulfilled, the ZVS will be lost and extra losses due to partial shootthrough will appear [19].…”

Copper Pipes as Medium Frequency Transformer Windings

“…The selection of the semiconductor device resulted in upper limit of 5 kHz for the operating frequency [24]. The inverter and the rectifier bridge, interconnected with the MFT and the resonant capacitors, are using the 3-level neutral point clamped (NPC) topology.…”

Practical Evaluation of Loss Reduction in Isolated Series Resonant Converter with Fixed Frequency Modulation

“…Researchers in [29] studied the resonant characteristics of the LC-DAB topology by using the transient current to extend the zero voltage switching (ZVS) range and to handle the large load variation. The integrated gate-commutated thyristor's (IGCT's) very low conduction losses make it an appealing candidate for use in soft-switched topologies that operate under favorable ZVS or ZCS conditions [30]. However, these have turn-off currents in the range of several kA, for which the device needs to be optimized with resonant converter topologies.…”