This article mainly introduces the phenomena that may occur in the circuit when controlling the AC power source using the triac, and how to avoid these phenomena by controlling the trigger mode of the triac to ensure the normal operation of the circuit.
This document reviews the principles required for the correct operation of triacs when controlling inductive loads, such as motors or transformers. It highlights that operating conditions vary significantly depending on the control mode and synchronization of the firing signal.
The text details various gate control methods, including single pulses, pulse trains, and DC current, analyzing their impact on synchronization and load saturation. It specifically addresses transient phenomena during triggering, explaining how firing at zero mains voltage can cause high overloads due to magnetic saturation, whereas firing at peak voltage is generally safer. The note concludes with recommendations to avoid transient overloads by synchronizing control signals and selecting appropriate control types.
Designers must analyze various control modes and synchronization principles to guarantee correct operation and avoid overloads.
Firing at zero voltage can cause the induction to reach saturation, producing the highest transient overloads.
Firing at peak mains voltage is simple, efficient, and should be adopted whenever possible for such loads.