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The Bi-mode Gate Commutated Thyristor (BGCT) is an advanced reverse conducting device aiming high power applications. Due to the high degree of interdigitation of diode parts and Gate Commutated Thyristor (GCT) parts, it is necessary to investigate how to best separate the two and at the same time, how to maximise the individual power handling capability. This work underpins the latter, for the GCT part. In achieving that, this letter details the optimisation direction, identifies the design parameters that influence the Maximum Controllable Current (MCC) and thereafter introduces a new design attribute, the “p-zone”. This new design not only improves the MCC at high temperature, but also at low temperature, yielding temperature independent current handling capability and at least 1000 A, or 23.5 % of improvement compared to the state-of-the-art. As a result, the proposed design constitutes an enabler for optimally designed bi-mode devices rated at least 5000 A for applications with the highest power requirement.

In this letter, we use a novel 3-D model, earlier calibrated with experimental results on standard gate commutated thyristors (GCTs), with the aim to explain the physics behind the high-power technology (HPT) GCT, to investigate what impact this design would have on 24 mm diameter GCTs, and to clarify the mechanisms that limit safe switching at different dc-link voltages. The 3-D simulation results show that the HPT design can increase the maximum controllable current in 24 mm diameter devices beyond the realm of GCT switching, known as the hard-drive limit. It is proposed that the maximum controllable current becomes independent of the dc-link voltage for the complete range of operating voltage.