Thyristors and triacs control by a high frequency sine signal

The aim of this paper is to present a new control mode of AC switch (thyristors, triacs ...). The applied signal on the device gate is a "high frequency" alternating sine, instead of a pulse-shaped signal. This solution has been retained in order to integrate galvanic isolation with power-controlled switches. Control by sine signal implements the accumulation of electrical charges inside the structure leading to the SCR (silicon controlled rectifier) firing. The efficiency of the gate signal is conditioned by the architecture of the semiconductor device, particularly the gate-cathode junction which has a "pilot" role in the firing. Comprehension of physical phenomena, which occur in the switch and more precisely in the gate\´s area, during the firing phase, allows us to adapt the control circuit or to imagine new SCR structures optimised for a high frequency control.