GTO chopper at 2000 Hz switching frequency for a DC current source 1000 A - 1200 V

Thyristors GTO are used in chopper circuits to deliver a DC current to supply resonant power inverters or plasma arc power devices. A 1,2 MW power is obtained with connection in parallel of two chopper modules including only one GTO switch with a DC rectifier. A 2000 Hz switching frequency is reached by using a two-chopper module with an overlapped 1000 Hz switch on. For each chopper the repetitive current commutated is 600 A under the nominal DC voltage of 1200 V; this is possible without increasing GTO´s switching losses by using the highly interdigited GTO´s structure in the thyristors assisted operation mode. A protection is available against direct short-circuit on the output. A current regulation allows a good dynamic response on the whole current range. This paper discuss and describes the commutation principle of GTO, and shows oscillograms and experimental results at 1 MW output power on resistive load and plasma arc